Analysis of Unreinforced Masonry Walls Strengthened with Glass Fiber-Reinforced Polymer Bars

Analysis of Wallace Stevens’s “Anecdote of the Jar”The poem written by Wallace Stevens is mainly about the relationship between nature and art.The poet thinks that the nature is a desultory world and only ideas can make it united as a whole.In fact, “the slovenly wilderness”is the symbol of crudity and ignorance,which indicates that the world is in a state of chaos.While as a piece of artwork the jar is the counterpart that stands for art.However,in Steven’s mind,it is not only a piece of lifeless artwork, but also has its beauty and could be appreciated by people.What’s more,it also represents imaginative creativity and makes the slovenly wilderness orderly.Though the jar itself is a member of the nature,it is not just that.The same goes as civilization to wildness and folly.Civilization is originated from wildness and folly initially,but it is superior to the original wildness.The jar is not decorated,but its brilliant rays are not covered or weaken;the jar does not have life as animals,it has its unique speciality which overshadow other ordinary creature in nature as well as being beautiful and irreplaceable.The poet placed the jar higher han other things in nature,however,it does not mean that the jar can replace the position of “the sloven wilderness”,neither can the jar be put solely away from its backdrop—the nature.Because its art fascination would not exist if it is not with the slovenly wilderness.That is to say,the jar’s being vivid and charming are built on nature and they are closely related to each other.In this poem,the readers can get the message of the aesthetic ideas of the poet,and that is the combination of art,ideas and nature.All of them are indivisible and setting off each other.As for the content of the poem,it almost has the quality of a Zen story discussing the concept of 'emptiness.' Ordinarily a jar contains what is inside it. Here, the jar “contains” what is outside it. “It made the slovenly wilderness/ Surround that hill.” Moreover, “The wilderness rose up to it, / And spra wled around, no longer wild.” So the jar starts out as a demarcation point between the civilized world and the wilderness. But then, the very presence of the jar tames the wilderness, which is “no longer wild.” Indeed, the jar “took dominion everywhere.” I n the opening stanza, Stevens mentions that the jar was round, and then he repeats that in the second stanza: it was “round upon the ground.” The geometric nature of the jar makes it unnatural or strictly man-made, and gives it dominion over what is natural and formerly wild. So at least in that sense, the jar does “contain” what is outside it. (BTW, I think this is different from a candy wrapper or a cigarette butt or other litter simply ruining the view. The poet-narrator “placed” it. The jar here contras ts with the“slovenly” wilderness. It is “tall and of a port in air.” It is not just litter.) The poem ends as a sort of joke, as so many Zen stories do. The jar “did not give of bird or bush.” Well, of course not. It will only be of use to a bird or bush if it contained something else, like water, seed, or the bird’s nest. Empty, it “contains” the wilderness. But if it has something in it, then it’s just there. It becomes part of what surrounds it.And then, in the last line, the jar is “Like nothing else in Tennessee.” There is a question: there are no other jars in Tennessee? The answer is: well, no others that contain the wilderness.In so far as the technique of this poem,the most important one is symbolism and surrealism.For example,the “I”in the poem maybe not refers to the writer Wallace Stevens himself,it can be anyone.And the jar symbolize art,while the wilderness in Tennessee is the symbol of nature.The purpose of surrealism is to put the relatively discordant verbal images and physical objects together so as to create a feeling of surreal.In this poem,the jar and the slovenly wilderness are placed together to produce the effect of being surreal.And another part of the poem to analyze is its structure.There are totally three parts in this poem.In the first stanza, “I”put a empty jar in the hill among the slovenly wilderness to make it orderly.In the second stanza,the jar is just like the king that is dignified,high up above the masses.And the wilderness is like the its people obedient.In the last stanza,though the jar controls the whole,it does not have real life as plants and birds.In the appreciation of the poem,we know that the writer is very prudent in using words,and the contrasting between the jar and the slovenly wilderness is everywhere in the poem,such as round versus slovenly in the first stanza,tall and of a port in air versus sprawled around in the second,and gray and bare versus give of bird or bush in the third stanza.。

F/503/3096:F IXING AND SECURING MEMORIAL MASONRY IN THE WORKPLACEN029195 – Fixing and securing memorial masonry in the workplace – Issue 1 © Pearson Education Limited 2012 1This version of this unit replaces all previously published versions with effect from January 2012. This unit should be used by all learners registering for qualifications that include it in their structure from this date.Unit title: Fixing and securing memorialmasonry in the workplaceUnit reference number: F/503/3096QCF level: 2Credit value: 15Guided learning hours: 50Start date: January 2012Unit summaryThe aim of this unit is to develop the skills, knowledge and understanding required to confirm competence in fixing and securing memorial masonry in the workplace, within the relevant sector of industry.Assessment requirements/evidence requirementsThis unit must be assessed in a work environment, in accordance with:–the Additional Requirements for Qualifications using the title NVQ in QCF –the ConstructionSkills’ Consolidated Assessment Strategy for Construction and the Built Environment.Assessors for this unit must have verifiable, current industry experience and a sufficient depth of relevant occupational expertise and knowledge, and must use a combination of assessment methods as defined in the Consolidated Assessment Strategy.Workplace evidence of skills cannot be simulated.F/503/3096: F IXING AND SECURING MEMORIAL MASONRY IN THE WORKPLACEN029195 – Fixing and securing memorial masonry in the workplace – Issue 1© Pearson Education Limited 20122Assessment recordingThis unit is assessed in the workplace. The table on the following pages shows the learning outcomes and the assessment criteria for this unit. The table includes space for learners to enter the types of evidence they are presenting for assessment and the submission date against each assessment criterion. Alternatively, centres can use their own documentation.F/503/3096:F IXING AND SECURING MEMORIAL MASONRY IN THE WORKPLACEN029195 – Fixing and securing memorial masonry in the workplace – Issue 1 © Pearson Education Limited 2012 3Learning outcomes and assessment criteriaLearning Outcome Assessment Criterion EvidencetypePortfolioreferenceDate1 Interpret the giveninformation relating tothe work and resourcesneeded when fixing andsecuring memorialmasonry. 1.1 Interpret and extract relevant information fromdrawings, specifications, schedules and riskassessments.1.2 Comply with information and/or instructions derivedfrom risk assessments and method statements.1.3 Statetheorganisationalprocedures developed to report and rectify inappropriate information and unsuitableresources and how they are implemented.1.4 Describe different types of information, their source andhow they are interpreted in relation to:–drawings, specifications, schedules, methodstatements, risk assessments, technical informationand regulations relating to burial and cremation.2 Know how to complywith relevant legislationand official guidancewhen fixing andsecuring memorialmasonry. 2.1 Describe their responsibilities under current legislationand official guidance whilst working:–in the workplace, below ground level, at height, with tools and equipment, with materials and substances,with movement/storage of materials and by manualhandling and mechanical lifting.2.2 Describe the organisational security procedures fortools, equipment and personal belongings in relation tosite, workplace, company and operative.2.3 Explain what the accident reporting procedures are andwho is responsible for making reports.F/503/3096: Fixing and securing memorial masonry in the workplaceN029195 – Fixing and securing memorial masonry in the workplace – Issue 1© Pearson Education Limited 20124Learning Outcome Assessment Criterion Evidence type Portfolio referenceDate3 Maintain safe workingpractices when fixing and securing memorial masonry.3.1Use health and safety control equipment safely to carry out the activity in accordance with legislation andorganisational requirements when fixing and securing memorial masonry.3.2Explain why and when health and safety controlequipment, identified by the principles of protection, should be used relating to fixing and securing memorial masonry, and the types, purpose and limitations of each type, the work situation and general work environment, in relation to:– collective protective measures – personal protective equipment (PPE) – respiratory protective equipment (RPE) – local exhaust ventilation (LEV).3.3Describe how the relevant health and safety control equipment should be used in accordance with the giveninstructions. 3.4State how emergencies should be responded to in accordance with organisational authorisation and personal skills when involved with fires, spillages, occupational injuries and other task-related hazards.F/503/3096:F IXING AND SECURING MEMORIAL MASONRY IN THE WORKPLACEN029195 – Fixing and securing memorial masonry in the workplace – Issue 1 © Pearson Education Limited 2012 5Learning Outcome Assessment Criterion EvidencetypePortfolioreferenceDate4 Select the requiredquantity and quality ofresources for themethods of work to fixand secure memorialmasonry. 4.1 Select resources associated with own work in relation tomaterials, components, tools and equipment.4.2 Describe the characteristics, quality, uses,sustainability, limitations and defects associated withthe resources in relation to:–memorial stones4.3 Describe how the resources should be used correctlyand how problems associated with the resources arereported.4.4 Explain why the organisational procedures have beendeveloped and how they are used for the selection ofrequired resources.4.5 Describe any potential hazards associated with theresources and method of work.4.6 Describe how to calculate quantity, length, area, volumeand wastage associated with the method/procedure tofix and secure memorial masonry.F/503/3096: Fixing and securing memorial masonry in the workplaceN029195 – Fixing and securing memorial masonry in the workplace – Issue 1© Pearson Education Limited 20126Learning Outcome Assessment CriterionEvidence typePortfolio referenceDate5Minimise the risk of damage to the work and surrounding area when fixing and securingmemorial masonry.5.1 Protect the work and its surrounding area from damage in accordance with safe working practices and organisational procedures.5.2Minimise damage and maintain a clean work space. 5.3Dispose of waste in accordance with legislation.5.4Describe how to protect work from damage and the purpose of protection in relation to general workplace activities, other occupations and adverse weather conditions.5.5Explain why the disposal of waste should be carried out safely in accordance with environmental responsibilities, organisational procedures, technical information, statutory regulations and official guidance. 6Complete the work within the allocated time when fixing andsecuring memorialmasonry.6.1 Demonstrate completion of the work within the allocated time.6.2 State the purpose of the work programme and explain why deadlines should be kept in relation to:– types of progress charts, timetables and estimatedtimes – organisational procedures for reportingcircumstances which will affect the work programme.F/503/3096:F IXING AND SECURING MEMORIAL MASONRY IN THE WORKPLACEN029195 – Fixing and securing memorial masonry in the workplace – Issue 1 © Pearson Education Limited 2012 7Learning Outcome Assessment Criterion EvidencetypePortfolioreferenceDate7 Comply with the givencontract information tofix and secure memorialmasonry to the requiredspecification. 7.1 Demonstrate the following work skills when fixing andsecuring memorial masonry:–measure, mark out, drill, fit, finish, position, secure, seal and clean.7.2 Erect memorial stones, to given working instructions, onground foundations.7.3 Safely use materials, hand tools and/or portable powertools and ancillary equipment.7.4 Safely store the materials, tools and equipment usedwhen fixing and securing memorial masonry.7.5 Describe how to apply safe work practices, followprocedures, report problems and establish the authorityneeded to rectify them, to:–erect memorial stones on ground foundations–lift and position memorial stones–use hand tools, power tools and equipment.7.6 Describe the needs of other occupations and how toeffectively communicate within a team when fixing andsecuring memorial masonry.7.7 Describe how to maintain the tools and equipment usedwhen fixing and securing memorial masonry.F/503/3096: Fixing and securing memorial masonry in the workplaceN029195 – Fixing and securing memorial masonry in the workplace – Issue 1© Pearson Education Limited 20128Learner name: ___________________________________________ Date: __________________________ Learner signature: ________________________________________ Date: __________________________ Assessor signature: _______________________________________ Date: __________________________ Internal verifier signature: _________________________________ (if sampled ) Date: __________________________。

国外砌体结构设计书籍Designing a masonry structure for a building requires a deep understanding of the materials and techniques involved.设计建筑物的砌体结构需要深刻地理解所涉及的材料和技术。

As an architect or designer, having a comprehensive knowledge of masonry design principles is essential in order to create safe and aesthetically pleasing structures.作为一名建筑师或设计师，具备全面的砌体设计原则知识对于创建安全且美观的结构至关重要。

There are a variety of resources available to help designers and architects learn about masonry design, including books specifically dedicated to this subject.有各种资源可供设计师和建筑师学习砌体设计，包括专门研究这一主题的书籍。

One such book is "Masonry Design and Detailing" by Christine Beall, which provides in-depth information on masonry materials, construction techniques, and design considerations.其中一本是Christine Beall的《砌体设计与细部设计》，该书详细介绍了砌体材料、施工技术和设计考虑因素。

By studying books like this, designers can gain a better understanding of how to incorporate masonry into their projects effectively.通过学习这样的书籍，设计师可以更好地理解如何有效地将砌体融入他们的项目中。

外文原文：Damage as a measure for earthquake-resistant design ofmasonry structuresauthor：Miha TomazˇevicAbstract:The results of lateral resistance tests of masonry walls and shaking table tests of a number of models of ma-sonry buildings of various structural configurations, built with various materials in different construction systems, havebeen analyzed to find a correlation between the occurrence of different grades of damage to structural elements, character-istic limit states, and lateral displacement capacity. On the basis of correlation between acceptable level of damage and displacement capacity, it has been shown that the range of elastic force reduction factor values used to determine the de-sign seismic loads for different masonry construction systems proposed by the recently adopted European standard Euro-code 8 EN-1998-1 for earthquake resistant design are adequate. By using the recommended design values, satisfactory performance of the masonry buildings that have been analyzed may be expected when subjected to design intensity earth-quakes with respect to both the no-collapse and damage-limitation requirements.Key words: masonry structures, seismic-resistant design, seismic performance, damage, limit states, behavior factor.1. IntroductionEarthquake-resistant design of masonry structures is a combination of tradition, experience, and modern engineer-ing principles based on experimental research. Usually, it is a two-step procedure: ( i ) the structure is conceived accord-ing to traditional requirements regarding structural configu-ration and ( ii ) the seismic resistance is verified by calculations and the dimensions and distribution of structural elements are modified, if necessary.Since no-collapse and damage-limitation requirements should be fulfilled, the ultimate state (associated with collap-se) and the serviceability limit state (associated with the oc-currence of minimum damage) also need to be verified in the case of masonrystructures. According to the recently adopted Eurocode 8 standard,Design of structures for earth-quake resistance (CEN 2004), the structure should be de-signed to withstand the design seismic action, i.e., earthquake, with a return period of 475 years and a 10% probability of exceedance in 50 years, and the no-collapse requirement defined in Eurocode 8 as ……without local or global collapse, thus retaining its structural integrity and a residual load bearing capacity after the seismic events.‟‟However, the structure should also be designed to withstand an earthquake having a larger probability of occurrence than the design earthquake, i.e., earthquake with return period of 95 years with 10% probability of exceedance in 10 years, as well as the damage-limitation requirement defined in Euro-code 8 as ……without the occurrence of damage and limita-tion of use, the costs of which would be disproportionately high in comparison with the costs of the structure itself.‟‟According to Eurocode 8, for all structural members and for the structure as a whole, the design resistance capacity Rd shall be greater than the design load Ed , which includes seismic actions if the structure is exposed to seismic haz-ard. The form in which the seismic action is used in seis-mic resistance verification depends on the importance and complexity of the structure under consideration. In the case of structures with regular structural configuration,where the response is not significantly affected by the con-tribution of higher modes of vibration, such as masonry structures, response spectra methods provide adequate re-sults. The calculations for these regular structures are fur-ther simplified by taking into account only one horizontal component of the seismic ground motion and analyzing the structure in each orthogonal direction separately. Non-linear dynamic response analysis is replaced by equivalent elastic static analysis, where the design seismic loads are evaluated on the basis of the design response spectra, con-sidering the structure as an equivalent single-degree-of-freedom system.The ordinates of the elastic response spectra are reduced by the structural behavior factor (elastic force reduction factor), q, defined by Eurocode 8 as a ……factor used for de-sign purposes to reduce the forces obtained from a linear analysis, in order to account for thenonlinear response of a structure‟‟ and it takes into account the energy dissipation and displacement capacity of the structure under considera-tion. According to Eurocode 8, ……the behavior factor q is an appr oximation of the ratio of the seismic forces that the structure would experience if its response was completely elastic with 5% viscous damping, to the minimum seismic forces that may be used in the design —with a conventional elastic analysis model —still ensuring a satisfactory re-sponse of the structure.‟‟ A ……satisfactory response,‟‟ in this case, means a ductile response; however, a response with a limited amount of damage to structural elements. Therefore,to prevent excessive damage to structural walls, the dam-age-limitation requirement should be the leading parameter when deciding upon the design ductility capacity of the structural type under consideration and, consequently, deter-mining the value of behavior factorq to be considered in the design.The amou A limited number of seismic vulnerability and other stud-ies already provide basic information regarding the damage-limitation requirements (Alcocer et al. 2004; Calvi 1999;D‟Ayala 1998) to be considered in the design and seismic esistance verification of masonry structures of different ypologies and construction systems.As a contribution to ex-isting information, experimental results obtained in the past by testing different walls and models of masonry buildings at the Slovenian National Building and Civil Engineering In-stitute (ZAG) in Ljubljana, Slovenia, have been analyzed.The results of this analysis indicate that structural damage is correlated with storey drift in anuniform way, not depending on the type of masonry under consideration. Consequently, adequate seismic performance of masonry structures may be expected if, besides ductility and energy dissipation capacity of the structure, damage-limitation requirements in terms of.maximum acceptable storey drift are taken into account when determining the design seismic loads and respective values of the elastic force reduction factor q2. Seismic resistance and limit statesBasic information regarding the seismic behaviour of structures or structural elements is obtained on the basis of known relationships between lateral resistance and displace-ments. By knowing the so-called resistance curve and of damage that is associated with typical limit states defined on the curve, the seismic performance of the structure for the case of the expected seismic loads can be assessed. In the case of unreinforced and confined masonry struc-tures, the resistance curve is adequately represented by the relationship between the resistance R of the critical storey, usually the first storey of the building, and storey drift d (relative storey displacement) of the same storey (Fig. 1). Usually, the curve is presented in a nondimensional form. The resistanceis given in terms of the seismic resistance co-efficient (SRC), i.e., the ratio between the resistance, R , and weight of the building, W, above the critical section (SRC = R/W ). The displacements, however, are expressed in terms of storey rotation F , which is the ratio between the storey drift, d, and storey height, h ( F = d/h). The following four main limit states, which are used in seismic resistance verification and determine the usability of buildings, are defined on the resistance curve (Fig. 1):(1) Crack (damage) limit state, where the first cracks occur in the walls causing evident changes in stiffness of the structural system. Crack limit on the resistance curve is sometimes associated with the serviceability limit state of the structure.(2) Maximum resistance.(3) Design ultimate limit state, where the resistance of the system degrades below the acceptable level. Convention-ally, 20% of degradation of the maximum resistance is acceptable. Consequently, part of the resistance curve, where the resistance degrades below 80% of the maxi-mum, is no longer considered for design purposes. It only provides information about additional ductility and energy dissipation capacity, i.e., additional safety of the structure. (4) Limit of collapse, defined by partial or total collapse of the structure.3. Correlation between damage, limit states and usabilityUsability of earthquake-damaged buildings is assessed on the basis of the observed damage. Different categories of damage such as light, moderate, heavy, and very heavy (severe) are attributed to different categories of usability. Fig. 2 provides examples of post-earthquake damage obser-vations of a number of typical central European masonry buildings, showing moderate, heavy, and severe damage (near collapse). A number of unreinforced and confined masonry walls have been tested in the laboratory, by subjecting them to cyclic lateral loading, and a series of models of the same types of masonry construction systems have been tested on a shaking table. An attempt has been made to correlate the resulting physical damage to the tested walls and model buildings with the limit states and, consequently, use this information for the assessment of usability of earthquake-damaged buildings. Complete (true replica) models have also been tested on the shaking table and correlation tests, carried out on prototype and model masonry walls, showed very good agreement between the model and prototype masonrywith respect to the similarity of resistance curves as well as damage patterns at the characteristic limit states. Therefore, although the information was obtained on the models, it can also be considered reliable for the case of the prototype structures. As the first step of analysis, typical damage categories (grades) have been defined. Although the types of damage to masonry walls and buildings vary depending on masonry materials and construction systems, damage to structural walls can be classified and damage grades can be defined in a uniform way. The classification of damage and damage grades proposed by the European macroseismic scale (EMS-98) (Gru¨ nthal 1998) for masonry buildings has been used as a basis for the description of structural damage to masonry walls. In the case of prevailing shear behavior, typical for all masonry construction systems when subjected to seismic loads, the following characteristic damage patterns can be attributed to damage grades as defined by the EMS-98 scale:Grade 1 — no structural damage.Grade 2 —slight structural damage, cracks in many walls: formation of the first hardly visible diagonally oriented cracks in the middle part of the wall, light damage. Grade 3 — moderate structural damage, cracks in many walls: increased number of cracks with limited width (less than 0.2 mm wide), oriented diagonally in both diag-onal directions; moderate, repairable damage which maybe defined as acceptable damage at the serviceability limitstate.Grade 4 —heavy structural damage, serious failure of walls: increased number of diagonally oriented cracks that are more than 1 mm but less than 10 mm wide; crushing of individual masonry units; heavy damage, which is in most cases repairable, but sometimes repair is not economical.Grade 5 —total or near total collapse: increased crack width (more than 10 mm); crushing of units along both wall diagonals; severe strength degradation and final col-lapse.Typical damage patterns at characteristic damage grades for the case of plain masonry walls tested in the laboratory are presented in Fig. 3.Similar correlation between the observed damage, attrib-uted damage grades, and limit states has been made for the case of the tested model buildings:Grade 2 —first structural damage, which may cause noticeable decay of the first natural vibration frequency of the building.Grade 3 — increased number of cracks, typical for the governing behavior mechanism of the structural system (diagonal cracks in the case of shear, horizontal tension cracks in the case of a flexural mechanism). As in the case of individual walls, this type of crack pattern is typi-cally observed at, or very soon after, the attained maxi-mum lateral resistance of the building. Moderate, repairable damage.Grade 4 —heavy damage to the walls, defined by crush-ing at the corners of the building, falling out of parts of the walls, and (or) crushing of individual masonry units.Damage is in most cases repairable, but sometimes the re-pair is not economical. Grade 5 — increased damage to the walls. Damage to horizontal structural elements, such as slabs and bond beams; crushing of concrete; and rupture or buckling of reinforcing bars (if reinforced). Final collapse.It is obvious that damage grades 2 and 5 define the crack limit and limit of collapse, respectively. As indicated by the analysis of experimentally obtained resistance curves,the displacement levels at which the crack limit and maximum resistance are attained are relatively close together (see Table 1). It has also been found that grade 3 damage can develop sometime after the attained maximum resistance. The analysis of the experiments has shown that such damage may generally occur at storey drift, equal to approximately three times the storey drift (rotation) at the occurrence of the first cracks in the walls.Grade 4 damage is observed near the point that is defined as the design ultimate limit state, where the actual resistance of the structure degrades to 80% of the maximum. However, as grade 4 damage is often not economical torepair, it is proposed that, in addition to the criterion of 20% degradation of resistance, the damage-limitation requirement should also be considered when deciding on the level of design ultimate limit state. As indicated by this analysis, the occurrence of grade 3 damage seems to be an adequate measure. It is, therefore, recommended that in their design, displacement and ductility capacity of masonry structures should not be used beyond the storey drift, which is equal to three times the displacement (rotation) at the occurrence of the first cracks in structural walls. Therefore, the design ultimate state on the idealized resistance curve may be defined by either the displacement (rotation) value, where the resistance degrades to 80% of the maximum (no-collapse requirement), or the displacement (rotation) value, which attains three times the value of the displacement (rotation) at the occurrence of cracks (damage-limitation requirement), whichever is less:Fire following an earthquake is an important factor causing damage to buildings and life-line structures. There-fore, besides satisfying structural design requirements for normal loads, such as dead and live loads including the seismichazard, buildings should also be designed to withstand the fire following earthquakes for a certain minimum duration as required for a desired level of performance. This period of time will allow occupants to evacuate the building safely and the emergency crews to cope with the fire. Also, it is essential to reduce the post-earthquake fire (PEF) ignitions and mini-mize the damage to active fire protection systems as much as possible to prevent the spread of fire. This paper presents a state-of-the-art review on the PEFhazard and discusses the causes, mitigation measures, and performance of building structures under this hazard. Mitigation measures that could be developed based on the experience from the structural engi-neering field are identified. Both local and global approaches that should be taken to mitigate the PEF hazard, including structural and nonstructural design, various urban planning aspects, and their interactive combinations, are discussed.Based on the review, it is concluded that that there is a strong need for the development of guidelines for structural firesafety design for PEF scenarios. In addition, appropriate analysis and numerical simulation techniques for the evaluationof the structural performance under earthquake-induced fire conditions need to be developed. It is also necessary to con-duct experimental studies to validate such numerical models and refine them.文献来源：Miha Tomazˇevic 《Damage as a measure for earthquake-resistant design of masonry structures》损害为砌体结构的抗震设计措施作者：Miha Tomazˇevic摘要：对砌体墙抗侧力测试和振动的砌体建筑模型的各种结构配置表测试的结果，在不同的建筑系统各种材料建成的，进行了分析，发现不同档次的损坏的结构元素的发生之间的相关性特征，极限状态，和侧位移量。

2021年5月下第50卷第10期施工技术CONSTRUCTION TECHNOLOGY113DOI：10.7672/sgjs2021100113中阿两国关于砌体填充墙构造措施做法比较与分析王少奎，黄义鸿，薛彪,黎东海(中国建筑一局(集团)有限公司，北京100161)［摘要］以砌体填充墙构造措施为岀发点，总结国内填充墙构造措施相关规定,并从设计原则、材料及连接要求方面与阿联酋地区混凝土结构砌体填充墙抗震性能方面的构造措施进行对比分析。

调研阿联酋地区7个房建及公共设施类项目设计要求，对当地项目填充墙拉结、构造柱、水平系梁等构造措施要求进行总结分析，并与国内相应规定做岀分析比较，归纳岀当地常用的构造措施。

在填充墙与主体结构连接方面，介绍当地常用连接件及其主要优点和布置原则。

［关键词］钢筋混凝土框架;砌体;填充墙;构造柱;水平系梁;拉结筋［中图分类号］TU364［文献标识码］A［文章编号］1002-8498(2021)10-0113-04Comparison and Analysis of Construction Measures forMasonry Infill Walls Between China and the UAEWANG Shaokui,HUANG Yihong,XUE Biao,LI Donghai(China Construction First Group Co.,Ltd.,Beijing100161,China)Abstract:Taking the construction measures of masonry infill walls as the starting point，summarize the relevant regulations of domestic infill wall construction measures，and compare and analyze the structural measures in terms of the seismic performance of concrete structure masonry infill walls in the UAE in terms of design principles，materials and connection requirements.Investigate the design requirements of seven housing construction and public facilities projects in the UAE,summarize and analyze the requirements for structural measures such as infill wall ties，structural columns，and horizontal tie beams in local projects，and analyze and compare with the corresponding domestic regulations，and summarize the local commonly used structural measures.In terms of the connection between the infill wall and the main structure，the local common connectors and their main advantages and layout principles are introduced.Keywords:reinforced concrete frame;masonry;infill wall;structural columns;horizontal straining beam;tie bar0引言随着施工企业不断走向国际市场，国内工程人员快速掌握当地规范、规定及通常做法已成为每个海外企业亟待解决的问题之一。

空斗墙结构现场检测及计算分析高瑾上海市房屋建筑设计院有限公司 上海 200062摘 要 空斗墙是早期砖石结构中较传统的结构形式，在老旧房屋检测中常有遇到，但由于其整体性和抗震性均较差，现行规范中已明确取消了该类结构，故现行相关规范中均无法找出空斗墙的检测评定依据，计算软件中也无空斗墙结构体系。

本文通过长期的工程实践经验总结了空斗墙结构的现场检测要点，并通过对历代砌体设计规范的研读，提出了对空斗墙结构采用普通黏土实心砖墙模拟，通过修改材料容重、修正墙体受压承载力，得出符合空斗墙实际情况的计算结果；最后介绍了空斗墙结构的抗震性评定方法，为空斗墙结构的老旧房屋现场检测与安全性评定提供参考。

关键词 空斗墙；现场检测；计算模拟；修正系数；抗震性能Field Inspection and Calculation Analysis of Cavity Wall StructureGao JinShanghai Municipal Housing Design Institute Co., Ltd., Shanghai 200062, ChinaAbstract Cavity wall is a traditional structure form in early masonry structure, which is often encountered in the inspection of old buildings. However, due to its poor integrity and seismic capacity, this kind of structure has been explicitly canceled in the current norms, so the detection and evaluation basis of cavity wall cannot be found in the current relevant norms, and there is no structural system of cavity wall structure in the calculation software. Through long-term engineering practice experience, this paper summarizes the main points of field inspection of cavity wall structure, and through the study of masonry design norms in the past, it proposes to use common clay solid brick wall simulation of cavity wall structure, through modifying the material bulk density and modifying the wall compression capacity, it obtains the calculation results in line with the actual situation of cavity wall structure. Finally, the seismic resistance evaluation method of cavity wall structure is introduced. It provides reference for the field inspection and safety assessment of the old buildings with cavity wall structure.Key words cavity wall structure; field inspection; calculation simulation; correction factor; seismic capacity引言砌体结构在我国有着悠久的历史，特别是在1949年10月以后，我国砌体结构得到了迅速的发展。

砌体墙、柱高厚比限值的研究进展摘要:目前在砌体结构设计领域中,基于规范给出的砌体墙、柱高厚比限值对特殊的墙体（带洞口墙、带壁柱墙、自承重墙、芯柱墙）的理论研究已经形成了比较完善的理论体系和设计方法;然而随着社会的发展以及新的墙体材料的出现,《砌体结构设计规范》给出的数值难以满足要求。

通过研究表明规范给出的高厚比限值还没有完善的理论体系,只是保证砌体结构在施工阶段和使用阶段稳定性的一项重要构造措施。

本文介绍了目前国内关于砌体墙、柱高厚比限值计算理论的研究。

最后讨论了存在的问题,提出了今后值得研究的若干问题。

关键词:高厚比限值、砌体结构、研究进展masonry wall, column high thickness than the research progress of the limityang super king gentleman(shenyang university of building civil engineering college in shenyang, liaoning province 110168)pick to: at present in masonry structure design field, are based on standard of masonry wall, column high thickness of special wall than limits (with the mouth of the cave walls, take bizhu wall, since the main wall, core column wall) theory research has formed a comparatively perfect theory system anddesign method; however, with the development of society and the new wall materials, the emergence of the masonry structure design specification of the numerical hard to meet the requirements are given. through the research shows that regulate the high thickness are than the limit is not perfect theory system, just ensure masonry structure in the construction stage and use the phase stability of an important structural measures. this paper introduces the domestic present about masonry wall, column high thickness calculation theory research than the limit. finally discussed the existing problems and puts forward some problems in the future is worth studying.keywords: high thickness than limits and masonry structure, research progress中图分类号：tu365 文献标识码：a1 引言我国于2005年在全国范围内取缔烧结粘土砖。

欧美部分现行土木工程标准目录欧洲结构规范（Eurocode）美国土木工程师学会标准（ASCE）美国混凝土学会标准（ACI）美国垦务局设计标准及工程手册2016.10欧洲结构规范(Eurocodes)欧洲经济共同体委员会(EEC)编制了一套适用于欧洲的建筑和土木工程的标准，简称欧洲标准(Eurocodes),成为在工程建设领域中具有较大影响力的一套区域性国际标准。

欧洲结构标准共包括ENI990至EN1999的10个规范(含58个分册)。

其中，EN1990是结构设计基本原理，是欧洲结构规范纲领性的文件；EN1991是结构作用；与材料有关的规范为EN1992到EN1996以及EN1999；EN1997是岩土工程设计规范；EN1998是抗震设计规范。

美国土木工程师学会（ASCE）现行标准目录（2016）目前，美国土木工程师学会（ASCE）共发布有61个标准，这些标准是由各领域专家编写，通过ASCE标准委员会的程序，最终由美国国家标准学会批准。

ASCE的很多标准都是与其他学会共同制定的（如：EWRI -美国环境与水资源协会、SEI -美国科学工程学学会）。

ASCE标准均是按规定程序定期更新或重新确认的。

ASCE/COPRI 61-14 |桥台与码头的抗震设计ASCE/EWRI 60-12 |水资源共享协议制定指南ASCE/SEI 59-11 |建筑物防爆ASCE/T&DI/ICPI 58-10 |市政街道及道路混凝土路面的锁定结构设计ANSI/ASCE/EWRI 56-10和57-10 |公共供水工程物理安全指南和污水/雨水工程物理安全指南ASCE/SEI 55-10 |张拉膜结构ASCE/EWRI 54-10 |均质和各向同性饱和导水率地质统计学估算及块段平均指南ASCE/G-I 53-10 |压密注浆指南ASCE/SEI 52-10 I玻璃纤维增强塑料（FRP）管设计ASCE/EWRI 50-08和51-08 |利用拟合概率密度函数的饱和导水率指南及计算有效饱和导水率指南ASCE/SEI 49-12 |建筑物和其他结构的风洞试验ASCE/SEI 48-11 |钢传动杆结构设计ASCE/EWRI 45-05、46-05 和47-05 |城市雨水系统设计指南，城市雨水系统安装指南及城市雨水系统操作和维护指南ASCE/EWRI 44-13 |过冷雾消除项目设计和操作实践ASCE/SEI 43-05 |核设施内部结构、系统和部件的抗震设计标准ASCE/EWRI 42-04 |人工增雨项目设计和操作实践ASCE/SEI 41-13 |现有建筑物的抗震加固ASCE/EWRI 40-03 |河岸整治模型代码EWRI/ASCE 39-15 |防雹项目设计和操作实践CI/ASCE 38-02 |现有地下公共工程数据收集和说明指南SEI/ASCE 37-14 |施工过程中的结构设计荷载CI/ASCE 36-15 |微型隧道建设指南EWRI/ASCE 35-01 |安装微孔曝气设备的质量保证指南EWRI/ASCE 34-01 |地下水人工补给指南EWRI/ASCE 33-09 |跨国界河流水质管理综合协议SEI/ASCE 32-01 |浅地基防霜冻设计与施工ASCE/SEI 31-03 |现有建筑物的抗震评估SEI/ASCE 30-14 |建筑物围护结构评估指南ASCE/SEI/SFPE 29-05 |结构防火计算方法ASCE 28-00 |非开挖顶进施工中预制箱形混凝土截面设计惯例ASCE 27-00 |非开挖顶进施工中预制混凝土管设计惯例ASCE 26-97 |埋设预制箱形混凝土截面设计惯例ANSI/ASCE/SEI 25-06 |地震激发气体自动关闭装置ASCE/SEI 24-14 |防洪设计与施工SEI/ASCE 23-97 |腹板开洞结构钢梁技术要求ASCE/ANSI/T&DI 21.4-08 |旅客捷运系统标准，第4部分：安全；应急准备；系统验证和证明；操作、维护和培训；操作监控ASCE/ANSI/T&DI 21.3-08 |大众自动运输工具标准，第3部分：电气、车站、网关ASCE/ANSI/T&DI 21.2-08 |大众自动运输工具标准，第2部分：车辆、牵引和制动ANSI/ASCE/T&DI 21-13 |大众自动运输工具标准，第1部分ASCE 20-96 |桩基础设计和安装指南ASCE/SEI 19-10 |建筑物钢缆结构应用ASCE 18-96 |氧气传输过程中试验指南AF&PA/ASCE 16-95 I木工程施工荷载和阻力系数设计（LRFD）标准ASCE 15-98 |标准安装的埋设预制混凝土管道设计惯例ASCE/EWRI 12-05、13-05 和14-05 |城市地下排水系统设计指南，城市地下排水系统安装指南及城市地下排水系统操作和维护指南SEI/ASCE 11-99 |现有建筑物结构条件评估指南ASCE 10-97 |钢网架传输结构设计SEI/ASCE 08-02 |冷成型不锈钢结构构件设计规范ASCE/SEI 7-10 |建筑物及其他结构的最小设计荷载ASCE 5-11 and 6-11 |圬工结构物的规范要求ASCE 4-98 |与核结构安全相关的抗震分析和评论ANSI/ASCE 3-91和9-91 |复合板结构设计标准及复合板施工与检查实践ASCE/EWRI 2-06 |洁净水中氧气传输测量ANSI/ASCE 1-82 |与核安全相关的土工结构物的设计与分析指南美国混凝土协会（ACI）技术委员会文件目录美国混凝土协会（ACI）是世界领先的混凝土技术权威之一，致力于有关混凝土和钢筋混凝土结构设计、建造和保养技术的研究。

Strength and Stiffness of Masonry-In filled Frames with Central Openings Based on Experimental ResultsMajid Mohammadi 1and Farzad Nikfar 2Abstract:An extensive statistical analysis is conducted on experimental data to achieve a formula for the strength and stiffness of masonry-in filled frames having central openings.For this,most of the available experimental data were collected and categorized based on their con fining frames and opening types.The reliability of existing empirical relations was investigated,in which a reduction factor was suggested that shows the ratio of strength or stiffness of perforated in fill to a similar solid one.The study shows that the relation recommended by the literature is the most accurate,among others,to estimate the lateral strength and stiffness of perforated in filled frames.Modi fied formulas derived from trend analysis of collected experimental data were proposed to determine the mechanical properties of perforated in filled frames.It is also shown that the reduction factor of the ultimate strength of in filled frames caused by the presence of openings depends highly on the material of the con fining frames (steel or concrete),but the reduction factor of stiffness is not affected by the frame type.Therefore,different equations are proposed for the strength and stiffness of in fills with openings.DOI:10.1061/(ASCE)ST.1943-541X.0000717.©2013American Society of Civil Engineers.CE Database subject headings:Stiffness;Masonry;Frames;Seismic design;Lateral loads;Experimentation;Openings.Author keywords:Strength;Stiffness;Masonry;In filled frame;Central opening;Seismic design;Lateral loads.IntroductionIt has been reported that addition of masonry walls in steel or RC frames raises the in-plane stiffness and strength of the structure because of the in fill-frame interaction.The resulting system is re-ferred to as an in filled frame,and it acts signi ficantly differently from each constitutive parts (frame and in fill wall),which highly affects the dynamic response of the structure.Regarding the complexity of modeling and shortcomings in en-gineering knowledge,in particular for in filled frames with openings,engineers rarely consider in fills in their structural analysis and de-sign.Such an assumption may lead to substantial inaccuracy in predicting the lateral stiffness,strength,and ductility of a structure.Given the widespread application of masonry-in filled frames in urban areas (Mosalam 1996)and the great variety in structural parameters,extensive studies have been performed on the lateral-load behavior of in filled frames both experimentally and analytically since the 1950s.Stafford-Smith (1962,1966)conducted experi-mental investigations on behavior of masonry-in filled steel frames.Polyakov (1960)suggested that an equivalent diagonal strut can be used to consider the effects of in fill panels.Subsequently,Holmes (1961)pursued this idea and proposed using diagonal struts with the same properties as the in fill panel and width equal to one-third the diagonal length.Stafford-Smith (1969)linked the width ofequivalent diagonal strut to the contact length between the frame and in fill panel and employed this model to investigate the behavior of in filled frames.Mainstone (1971,1974)performed a series of experiments similar to those of Stafford-Smith and proposed a set of empirical equations for equivalent strut stiffness.Liauw and Kwan (1983)carried out a series of small-model microconcrete-in fill tests.Based on this experimental work,they developed a plastic collapse theory for masonry in fills.A comprehensive review of research studies on masonry-in filled frames has been reported by Moghaddam and Dowling (1987).Although there have been many experimental investigations on the lateral behavior of solid masonry-in filled frames,few tests have been conducted on in filled frames with openings despite the fact that door or window openings are provided in many masonry panels for archi-tectural reasons.It has been shown by many studies that openings change the behavior of in filled frames and make it more complicated.The presence of openings in in fill panels normally reduces the stiffness and strength of the in fill.An increase in the dimensions of an opening results in a decrease in the strength and effective stiffness of the in filled frame (Mosalam et al.1997;Polyakov 1952;Benjamin and Williams 1958;Holmes 1961;Coul 1966).Mallick and Garg (1971)experi-mentally investigated the effects of opening positions on the lateral stiffness of in filled frames with and without shear connectors.They concluded that if the opening is at either end of the loaded diagonal of an in filled frame without shear connectors,the strength and stiffness are reduced by about 75and 85–90%,respectively,compared with those of a similar solid in fill.It also has been recommended that the best location for a window or door opening is at the center of the in fill panel (Dawe and Seah 1989;Mallick and Garg 1971).Liauw (1972)pre-sented the concept of an equivalent element for the analysis of in filled frames with or without openings.This concept was developed by transforming the in filled framed into an equivalent frame whose members have the properties of the composite sections of the actual structure.A comparison between the experimental and analytical results showed good agreement when the openings were more than 50%of the full in fill area.1Assistant Professor,International Institute of Earthquake Engi-neering and Seismology,No.21,Arghavan Gharbi,Dibaji Shomali,1953714453Tehran,Islamic Republic of Iran (corresponding author).E-mail:m.mohammadigh@iiees.ac.ir 2Ph.D.Student,Dept.of Civil Engineering,McMaster Univ.,Ham-ilton,ON,Canada L8S 4L8.E-mail:nikfarf@mcmaster.caNote.This manuscript was submitted on April 1,2012;approved on August 30,2012;published online on September 3,2012.Discussion period open until November 1,2013;separate discussions must be submitted for individual papers.This paper is part of the Journal of Structural Engi-neering ,Vol.139,No.6,June 1,2013.©ASCE,ISSN 0733-9445/2013/6-974–984/$25.00.974/JOURNAL OF STRUCTURAL ENGINEERING ©ASCE /JUNE 2013D o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y U n i v e r s i t y O f S y d n e y o n 01/16/14. C o p y r i g h t A S CE .F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .Schneider et al.(1998)conducted an experimental program to investigate the in-plane seismic behavior of steel frames with un-reinforced masonry in fills having large window openings.Test parameters included the masonry pier width and the number of wythe.The conclusion was that narrow piers and double-wythe in fills tend to be more ductile than wide piers.Furthermore,the experimental results established that for an imposed drift of 0.2%,the effective stiffness deteriorated to about 30%of the initial stiffness.Amplitudes of drift larger than 0.75%produced excessive splitting and crushing of the bricks in the masonry in fill.The stiffness continued to deteriorate uniformly until no stiffness remained.This occurred at a 2.0%drift.Kakaletsis and Karayannis (2007)con-ducted an experimental program to find the effect of window and door openings on the hysteretic characteristics of in filled RC frames and studied the relative advantages and disadvantages of different positions for windows and doors.They found that the presence of in fills,even with eccentric openings,improves the performance of concrete frames in terms of strength,stiffness,ductility,and energy dissipation.Based on their experimental results,and in contrast with those of some other researches,the location of the opening must be as near to the edge of the in fill as possible to provide an improvement in the performance of the in filled frame.Furthermore,Kakaletsis and Karayannis (2008)experimentally investigated the effect of masonry-in fill compressive strength and openings on failure modes,strength,stiffness,and energy dissipation of in filled RC frames under cyclic loading.They found that in fills with openings can signi ficantly improve the performance of RC frames.In addition,they presented an analytical approach based on the equivalent di-agonal strut to predict the lateral strength of the studied in filled RC frames with openings.In another research effort,they reported the results of an experimental study on eight in filled RC frames in-vestigating the in fluence of masonry opening shape and size on the seismic performance of the frames.The results show the signi ficance of opening properties on the reduction of stiffness,strength,and energy-dissipation capability of the tested in filled frames (Kakaletsis and Karayannis 2009).The collective results of the experiments have been employed to present a continuous force-deformation model for masonry-in filled panels with openings (Kakaletsis 2009).Further-more,they proposed a continuous force-deformation model for non-linear analysis of masonry-in fill panels with openings.Mosalam et al.(1997)carried out a series of experimental tests on gravity load –designed steel frames with semirigid connections in filled with unreinforced masonry walls subjected to cyclic lateral loads.The ex-perimental tests were conducted to evaluate the effects of the relative strength of the concrete blocks and mortar joints,the number of bays,and the opening con figuration of the in fill on the performance of single-story reduced-scale in filled frames.The experimental results demonstrated that the compressive strength of the concrete blocks determines the mode of failure,such as corner crushing or mortar cracking of the in fill panels.Also,the ultimate load for the two-bay specimen is about double the capacity of the single-bay specimen,and the presence of openings reduces solid-in fill panel stiffness values by about 40%for lateral loads below the cracking-load level.Moreover,openings in in fills lead to a more ductile behavior.A simple iterative FEM was proposed by Achyutha et al.(1986)to investigate the in filled frames with openings and with or without stiffeners around the openings.The analytical results demonstrated that for cases of window-opening areas greater than 50%of the solid-in fill area,the contribution of the in fill panels with openings can be neglected when compared with that of solid-in filled frames.The effect of location and size of the opening on the behavior of in filled frames is normally investigated by FEM.By this method,Asteris (2003)proposed graphs to estimate the stiffness-reduction factor corresponding to the size and location of the opening.The analyticalresults demonstrated that for the samples considered,a 20–30%opening reduces the stiffness of the solid-in filled frame by about 70–80%.The addition of in fills to frames normally results in improving the mechanical characteristics of the system,but it is necessary to consider the interaction effects,such as the short-column effect in partially in filled frames and the increasing column forces due to the increase in stiffness.Chiou el al.(1999)investigated the necessity of controlling these effects when using in filled frames with or without openings.The results of the most intensive experimental program conducted on perforated masonry-in filled steel frames were reported by Dawe and Seah (1989).In this study,the effects of a doorway in the panel on the stiffness and strength of the in filled frames were examined.Yáñez et al.(2004)investigated the effect of the opening as well as masonry panel materials (e.g.,clay and concrete blocks)on in filled frames by examining 16specimens.Tasnimi and Mohebkhah (2011)studied the behavior of steel frames with masonry-in fill panels by examining six full-scale one-story,one-bay specimens with central openings.Cyclic tests show that contrary to previous studies,perforated in fills do not always increase the ductility of the frames,and this matter depends more on the failure mode of the in fill.Furthermore,in this research,a simple analytical method based on the equivalent-diagonal-strut concept is introduced to estimate maximum shear strength of in filled frames with central openings.Moreover,a new relation to determine the equivalent strut ’s width-reduction factor is proposed.The effects of openings on stiffness and strength of in filled frames are primarily taken into consideration by reduction factors (Tasnimi and Mohebkhah 2011;Al-Chaar et al.2003;Al-Chaar 2002;New Zealand Society for Earthquake Engineering 2006;Durrani and Luo 1994;Mondal and Jain 2008;Asteris 2003).The reduction factor shows the ratio of stiffness or strength of a perfo-rated in fill to that of a similar solid one.The proposed relations for the reduction factor are based on the statistical analysis of a limited number of experimental test results and therefore is valid just for similar specimens.The main purpose of this paper is to determine the accuracy of the suggested relations as well as to propose new formulas for reduction factors based on all experimental data from previous studies.For this,almost all available experimental data were collected and classi fied based on such effective parameters as the type of surrounding frame and the type of opening (i.e.,door or window).In this paper,common empirical relations are introduced,and their parameters are explained.Average errors of these relations in predicting stiffness and strength of perforated in filled frames are determined.New modi fied relations are proposed by means of statistical analysis on classi fied experimental data.Analytical MethodsThe equivalent-strut concept is one of the simplest and most prac-tical methods to consider the effect of masonry in fills in structural analyses.This method takes into account the effect of in fill panels on the global dynamic response of a structure by means of replacing an in fill panel with two diagonal struts each acting in compression.One of the dif ficulties that practicing engineers may face is the reliability of models for in filled frames with openings.The single-strut model accurately takes into account the in fluence of solid-in fill walls on a structure,but for in fill walls with openings,it must be calibrated by FEM analyses (FEMA 2000).As mentioned earlier,some empirical relations are recommended in the literature to determine the re-duction factor for the effect of openings on in fill panels,in which the effective width of the in fill with opening W eo is considered to be the result of multiplying the effective width of the corresponding solid in fill W e by a reduction factor R F ;thereforeJOURNAL OF STRUCTURAL ENGINEERING ©ASCE /JUNE 2013/975D o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y U n i v e r s i t y O f S y d n e y o n 01/16/14. C o p y r i g h t A S CE .F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .W eo ¼R F ÂW e ð1ÞIt is worth noting that the reduction factor just accounts for the re-duction in the stiffness and strength of the in filled frame caused by the opening and does not represent the stress distributions likely to occur.In other words,applying the reduction factor is proposed for evaluation of the global structural capacity.Local effects caused by the presence of openings,including the stress fields,should be considered by other methods such as FEM modeling.In the following section,some empirical relations for the re-duction factor and their parameters are introduced.Tasnimi and MohebkhahTasnimi and Mohebkhah (2011)proposed a reduction factor R F given by Eq.(2)based on regression analysis of lateral peak-load ratio H o =H t versus the opening ratio A o =A P of specimens with openings.The correlation factor of the regression analysis for their specimens was obtained as 0.99R F ¼1:49AoA P222:238 Ao A Pþ1for A o ,0:4A Pð2Þwhere A o and A P 5area of the opening and in fill panel,respectively.For in fills with A o .0:4A P ,the value of R F is zero;thus,the stiffening and strengthening effect of the perforated-in fill panels with large openings is ignored (Tasnimi and Mohebkhah 2011).Therefore,to evaluate the maximum shear capacity of masonry-in filled frames with openings,Eq.(3)is proposedH o ¼R F ÂHð3Þwhere H o and H 5peak-load capacity of in filled frames with and without openings,respectively.Al-Chaar et al.In an effort to study the effects of door and window openings on lateral strength and stiffness of in filled frames,Al-Chaar et al.(2003)conducted a series of tests.Experimental results,supported by analytical studies,were used to estimate overall reductions in the strength and stiffness because of the presence of openings in panels.In this respect,a reduction factor given by Eq.(4)was proposed to account for the effect of openingsR F ¼0:6AoA P221:6 Ao A Pþ1ð4ÞIt can be seen from the Eq.(4)that if the area of the openings A o is greater than or equal to 60%of the area of the in fill panel A P ,then the effect of the in fill should be neglected (Al-Chaar 2002).New Zealand Society for Earthquake Engineering The New Zealand Society for Earthquake Engineering (NZSEE)(2006)recommends a simpli fied approach based on the work of Dawe and Seah (1989).According to this code,if an in fill is pierced with either a door or window opening,then the strength and stiffness may be reduced by the factor shown in Eq.(5)R F ¼121:5ÂL oL iR F $0ð5Þwhere L o and L i 5maximum widths of the opening and the in fill,measured across a horizontal plane,respectively.This equation implies that if the opening exceeds two-thirds of the bay width,it may be assumed that the in fill has no in fluence on system perfor-mance.Contrary to other equations,this equation determines the reduction factor by the opening width and does not consider the effect of opening height.Durrani and LuoDurrani and Luo (1994)proposed an empirical equation given by Eq.(6)to determine the strength and stiffness reduction factor of an in fill with length and width of l and h having a central opening with length and width of l o and h oR F ¼12A d h Âl2ð6ÞwhereA d ¼h Âl 2½ðR sin 2u Þ2R o Âsin ðu þu o Þ 22Âsin 2uð7ÞR o ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffih 2o þl 2o q ð8ÞR ¼ffiffiffiffiffiffiffiffiffiffiffiffiffiffih 2þl 2p ð9ÞIn Eq.(7),u and u o are the angles whose tangents are the in fill and opening aspect ratios (height to length),respectively.When the opening within the in fill extends across the full width or height of the panel,the effective width should be taken as zero.Eq.(6)was developed numerically by FEM analyses only and was not veri fied with experimental results.Mondal and JainIn this study,a FEM model is calibrated with previous experimental data.Subsequently,a parametric study was carried out to investigate the effects of openings.It was concluded that only the area of the opening is important regardless of the aspect ratios,and further,the number of stories does not play an important part.Therefore,Mondal and Jain (2008)proposed a reduction factor [Eq.(10)]for the effective width of a diagonal strut over that of the solid RC in filled frame to calculate its initial lateral stiffness when a central window opening is present.This study is based on initial lateral stiffness,which is taken at 10%of the lateral strength of the in filled framesR F ¼122:6 AoA Pð10ÞIt can be conclude from Eq.(10)that the stiffness contribution of the in fill should be neglected when the opening area is greater than 40%of the in fill area (Mondal and Jain 2008).AsterisAsteris (2003)proposed diagrams to determine the effect of size and location of openings on lateral stiffness of masonry-in filled frames using FEM ing this technique,a parametric study lead to the following relation [Eq.(11)]for the in fill wall stiffness-reduction factor (Asteris et al.2011):976/JOURNAL OF STRUCTURAL ENGINEERING ©ASCE /JUNE 2013D o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y U n i v e r s i t y O f S y d n e y o n 01/16/14. C o p y r i g h t A S CE .F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .R F ¼122 AoA P0:54þA o A P1:14ð11ÞIn this equation,for an opening percentage greater than 50%,the stiffness-reduction factor approaches zero.Applications of the empirical methods mentioned are summa-rized in Table 1.These applications were concluded based on the details and recommendations of the corresponding researchers.As can be seen in the table,the applications of reduction factors may be speci fic or general.For example,the equation proposed by Tasnimi and Mohebkhah (2011)[Eq.(2)]is derived for the ratio of ultimate strength of in filled frames,and the equations recommended by Mondal and Jain (2008)[Eq.(10)]and Asteris (2003)[Eq.(11)]are derived just for the ratio of initial stiffness of in filled frames.However,reduction factors proposed by Al-Chaar et al.(2003)[Eq.(4)],the New Zealand Society for Earthquake Engineering (2006)[Eq.(5)],and Durrani and Luo (1994)[Eq.(6)]are rec-ommended for both initial stiffness and ultimate strength.This distinction is made when comparing analytical methods with ex-perimental results.Experimental results presented in following section will be used to evaluate the reliability and accuracy of the proposed equations indicated in Table 1.Experimental StudiesAs shown in preceding section,the proposed empirical equations introduced the effects of openings using a reduction factor R F .Most of the proposed equations [Eqs.(2),(4),(10),and (11)]depend only on the opening area ratio A o =A P ,whereas others depend on other geometric properties of the opening.Experimental results can be employed to verify these empirical equations and determine their accuracies.In each case,stiffness and strength of a perforated-in fill specimen are compared with a similar reference solid-in fill frame.Hence,experimental programs that have the following conditions are chosen in this study:1.Both solid and perforated specimens are tested;2.Almost the same materials are used in both solid and perforatedspecimens;3.Ultimate strength or initial stiffness of the specimens ismentioned;and4.Testing models should be as similar to real structures aspossible (nonrealistic specimens in material,shape,and scal-ing are ignored).A brief description of each chosen experimental study is pre-sented in the following subsections,and the study is summarized in Table 2:Dawe and YoungDawe and Young (1985)investigated the effect of joint re-inforcement,mortar strength,interface condition,and doorwayopening on lateral strength and stiffness of masonry-in filled steel frames using 12full-scale specimens.The panels consisted of concrete blocks.A horizontal monotonic load was applied at the beam level.The measured ultimate strength and initial stiffness of Specimens 3B and 4B (in which the doorways are centrally located)and Specimen 3A (which is the reference solid-in filled frame)have been used in this study.Dawe and SeahThe effect of doorway openings on the behavior of masonry-in filled steel frames was one of the objectives of Dawe and Seah ’s (1989)experimental study.Five of their 28large-scale specimens had doorway openings,all with moment-resisting frames.Panels were made of concrete blocks.All the specimens were tested mono-tonically until failure.Specimens WC3and WC4contained central openings.Specimens WB2and WB3were the reference specimens used for calculating strength and stiffness ratio of the corresponding solid-in filled frames.These specimens were constructed with little differences in strength of masonry material.Mosalam et al.Mosalam et al.(1997)tested single-story one-and two-bay in filled steel frames under quasi-static loading.Concrete blocks were used for the in fill panels.Specimen S2-SYM is only the applicable specimen used in this study.It is a two-bay model with a window opening located at the center of each bay.Specimen S2-N-II is the reference solid-in filled frame that followed the same pattern of cyclic loading.Ya´n ˜ez et al.Sixteen full-scale specimens were tested in this experimental pro-gram to investigate the effect of window and doorway openings on strength and stiffness of in filled RC frames (Yáñez et al.2004).Eight specimens were of concrete masonry and eight of hollow clay-brick masonry units.There were four patterns of specimen,each of them constructed with the masonry materials mentioned.There were two specimens for each pattern.A horizontal cyclic load was applied along the axis of the top beam and controlled by displacement.Pattern 2and 3specimens contained central window openings.Pattern 4had a doorway opening located just 9%of the panel length away from the center of the panel and thus is considered a central opening.Pattern 1was the reference solid-in filled frame used for the determination of opening reduction factors.Among the specimens tested,the first specimen of Pattern 3,which has a central window opening,gave higher capacity than the solid-in filled specimen.This may be attributed to construction or measuring errors;therefore,the result has not been included in the comparisons.The averages of the maximum loads in the directions of loading and unloading are considered the ultimate strength of the specimens.Table 1.Applications of the Proposed Empirical EquationsParameter Opening typeTasnimi and Mohebkhah (2011)Al-Chaar et al.(2003)NZSEE (2006)Durrani and Luo (1994)Mondal and Jain (2008)Asteris (2003)F UWindow √√√√——Door √√√√——K 1Window —√√√√√Door —√√√——Note:F U 1JOURNAL OF STRUCTURAL ENGINEERING ©ASCE /JUNE 2013/977D o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y U n i v e r s i t y O f S y d n e y o n 01/16/14. C o p y r i g h t A S CE .F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .Kakaltesis and KarayannisKakaletsis and Karayannis (2007,2008,2009)conducted a series of one-third-scale experimental tests to determine the effect of open-ings on cyclic behavior of masonry-in filled RC frames.Kakaletsis and Karayannis (2009)summarized the results of whole tested specimens to provide data for developing an analytical model.Eight of 15specimens contained central window and doorway openings of different sizes.Tasnimi and MohebkhahIn this study,five large-scale,single-story,single-bay steel-frame specimens were tested under in-plane cyclic loading applied at the roof level (Tasnimi and Mohebkhah 2011).Three out of five specimens contained central window openings (PW1,PW2,and PW3),and one with a doorway opening (PW4),all of which wereconstructed by clay-brick masonry.Specimen SW is the reference solid model used for comparisons.Veri fication of Proposed Formulas by Experimental Test ResultsThe proposed analytical methods and experimental programs were explained in previous sections.In this section the accuracy of the proposed analytical methods is studied by implementing the results of the experimental tests.Thus,the veri fications have been per-formed for initial stiffness and ultimate strength of perforated-in filled frames of Table 2.The ratio of experimental reduction factor R experiment divided by predicted reduction factor R predicted is calculated using Eq.(12).This ratio,which is used in the comparisons,shows how a method performsTable 2.Test Specimens and Results ResearcherSpecimen nameIn fill panelOpening typeFraming typeH inf (m)L inf (m)h o (m)l o (m)K 1(kN/mm)F U (kN)Dawe and Young (1985)3A Concrete block Solid Steel 2.8 3.6——43.85563B Door 2.8 3.6 2.20.834.22854B Door 2.8 3.6 2.20.834.2335Dawe and Seah (1989)WB2Concrete block Solid Steel 2.6 3.1——74556WC4Door 2.6 3.1 2.20.834335WB3Solid 2.6 3.1——67538WC3Door 2.6 3.1 2.20.834285Mosalam et al.(1997)S2-N-II Concrete block Solid Steel 0.9398 1.8034——8.9342.7S2-SYM Window 0.9398 1.80340.3050.3054.433Yáñez et al.(2004)Pat.1-CB1Concrete block Solid RC 2.05 3.25——44116.5Pat.2-CB1Window 2.05 3.25 1.23 2.0642373.5Pat.4-CB1Door 2.05 3.25 2.050.64530109Pat.1-CB2Solid 2.05 3.25——49130Pat.2-CB2Window 2.05 3.25 1.23 2.0642582.5Pat.3-CB2Window 2.05 3.25 1.230.82542112.5Pat.4-CB2Door 2.05 3.25 2.050.6453594.5Pat.1-BB1Brick block Solid 2 3.2—60162Pat.2-BB1Window 2 3.2 1.125 2.0052886Pat.3-BB1Window 2 3.2 1.1250.78557146Pat.4-BB2Door 2 3.220.4850113.5Pat.1-BB2Solid 2 3.2——82191Pat.2-BB2Window 2 3.2 1.125 2.0052998Pat.3-BB2Window 2 3.2 1.1250.78566146.5Pat.4-BB3Door 2 3.220.4848136.5Kakaletsis andKarayannis (2007,2008,2009)S Brick block Solid RC 0.8 1.2——20.7181.46W02Window 0.8 1.20.3330.314.5566.56W03Window 0.8 1.20.3330.45614.6166.3W04Window 0.8 1.20.3330.616.6265D02Door 0.8 1.20.640.313.161.56D03Door 0.8 1.20.640.45615.0356.8D04Door 0.8 1.20.640.615.0355IS Ceramic block Solid 0.8 1.2——21.8772.92IWO2Window 0.8 1.20.3330.320.8868.13IDO2Door 0.8 1.20.640.314.4559.06Tasnimi and Mohebkhah (2011)SW Brick block Solid Steel 1.87 2.4——20.84201.5PW1Window 1.87 2.40.50.522.24176.1PW2Window 1.87 2.40.80.721.93151.9PW3Window 1.87 2.40.6 1.219.21137PW4Door 1.87 2.4 1.450.717.38116.5Note:H inf inf o o 1U 978/JOURNAL OF STRUCTURAL ENGINEERING ©ASCE /JUNE 2013D o w n l o a d e d f r o m a s c e l i b r a r y .o r g b y U n i v e r s i t y O f S y d n e y o n 01/16/14. C o p y r i g h t A S CE .F o r p e r s o n a l u s e o n l y ; a l l r i g h t s r e s e r v e d .。

Engineering Structures31(2009)1930–1943Contents lists available at ScienceDirectEngineering Structures journal homepage:/locate/engstructFinite element modelling of deformation characteristics of historical stone masonry shear wallsR.Senthivel∗,P.B.LourençoDepartment of Civil Engineering,University of Minho,Guimarães,Portugala r t i c l e i n f o Article history:Received27April2008 Received in revised form14August2008Accepted11February2009 Available online22April2009 Keywords:Shear wallFEMStone masonryDeformation characteristics Failure modesInterface elements a b s t r a c tTwo dimensional nonlinear finite element analysis based on experimental test data has been carried out to model deformation characteristics,such as load–displacement envelope diagrams and failure modes of historical stone masonry shear walls subjected to combined axial compression and lateral shear loading. An experimental research work was carried out on three different types of historical stone masonry shear walls that can be considered representative of ancient stone masonry constructions.Those three types of masonry are:(i)sawn dry-stack or dry-stone masonry without bonding mortar,(ii)irregular stone masonry with bonding mortar,and(iii)rubble masonry with irregular bonding mortar thickness.Plasticity theory based micro modelling techniques has been used to carry out the analysis.The stone units were modelled using eight node continuum plane stress elements with full Gauss integration.The joints and unit-joint interfaces were modelled using a six node zero thickness line interface elements with Lobatto integration.This paper outlines the experimental research work,details of numerical modelling carried out and report the numerical lateral load–displacement diagrams and failure modes.The numerical analysis results were compared with the experimental test results and good agreement was found.©2009Elsevier Ltd.All rights reserved.1.IntroductionStone masonry is the most ancient,durable,and widespread building method devised by mankind.Stone structures built without mortar rely on the skill of the craftsmen and the forces of gravity and frictional resistance.Stone has been a successful building medium throughout the ages and around the world because of its unique range of benefits.The structures are remarkably durable and,if correctly designed,can be made earthquake resistant.They resist fire,water,and insect damage. The mason needs a minimum of tools;the work is easily repaired; the material is readily available and is recyclable.Dry stone masonry,aesthetically,complements and enhances the landscape. Archaeologists have determined that the Chinese built dry stone terraces at least10000years ago.In Britain,ancient tribes built dry stone shelters just after the last ice age,8000years ago. High quality stone tools recently found in Europe are2.2million years old.The technique of dry stacking in construction has existed in Africa for thousands of years.The Egyptian pyramids and the Zimbabwe ruins,a capital of ancient Shona Kingdom around400AD,are good examples.In addition to the neglect and destruction of historic structures,the craft is handicapped due to lack of technical information and skilled preservation personnel.∗Corresponding author.Tel.:+351963614995;fax:+351253510217.E-mail address:drsenthivel@(R.Senthivel).Construction and engineering data that professionals need are scarce and,if recorded at all,are difficult to locate.A large part of historical buildings are built with:(i)sawn dry-stack or dry-stone masonry without bonding mortar;(ii)irregular stone masonry with bonding mortar;(iii)rubble masonry with irregular bonding mortar thickness;(iv)a combination of the three techniques.When bonding mortar is used,it is usually low strength.In addition,masonry with mortar joints can experience a significant loss of mortar due to combined chemical,physical and mechanical degradation.Due to the partial or total disappearance of mortar,the behaviour of these constructions can then become similar to those made of dry joint masonry.The primary function of masonry elements is to sustain a vertical gravity load.However,structural masonry elements are required to withstand combined shear,flexure and compressive stresses under earthquake or wind load combinations consisting of lateral as well as vertical loads.Only few experimental results are available on the behaviour of stone masonry walls,e.g.Chiostrini and Vignoli[1]addressed strength properties and Tomaževič[2] reported tests on strengthening and improvement of the seismic performance of stone masonry walls.More recently,Corradi et al.[3]carried out an experimental study on the strength properties of double-leaf roughly cut stone walls by means of in-situ diagonal compression and shear-compression tests.A comprehensive experimental and numerical study on his-torical dry stone masonry walls has been reported by Lourenço et al.[4].Displacement controlled experimental study for ma-sonry walls under combined compression and shear loading was0141-0296/$–see front matter©2009Elsevier Ltd.All rights reserved. doi:10.1016/j.engstruct.2009.02.046R.Senthivel,P.B.Lourenço /Engineering Structures 31(2009)1930–19431931Unit (brick,block,etc)Head jointBed jointUnitMortarInterface Unit/mortar(a)Masonry sample.(b)Micro-modelling."Unit""Joint"Composite(c)Simplified micro-modelling.(d)Macro-modelling.Fig.1.Micro-and macro-modelling techniques.done for monotonic loading.Based on the material properties ob-tained from the experimental tests,numerical analysis was car-ried out to model the monotonic load–displacement diagrams using non-linear finite elements.Similar numerical modelling us-ing rigid blocks limit analysis and discrete element analysis has been carried out by Azevedo et al.[5]and Orduña and Lourenço [6].However,these studies were limited to regular (sawn)dry stack mortarless stone masonry only.A detailed literature survey on numerical modelling of monuments and historical construc-tions including structure and component level are presented by Lourenço [7]and Lemos [8].A research programme was carried out by Vasconcelos [9]at University of Minho to experimentally evaluate the in-plane seismic performance of ancient stone masonry without and with bonding mortar of low tensile strength to simulate existing ancient stone masonry structures.Monotonic and reversed cyclic loading tests with three different pre-compression loading (low,moderate and high)were performed to investigate the strength,deformation capacity,load–displacement hysteresis response,stiffness characterisation and failure modes.The data obtained from this experimental research has been used as a base for the present numerical analysis.The objective of the analysis carried out here was limited to modelling the peak load points of reversed cyclic hysteresis diagrams,or the so-called load–displacement envelope diagram,and failure modes of three different types of ancient stone masonry subjected to three different axial pre-compression loads.Masonry is highly anisotropic due to the presence of discrete sets of horizontal and vertical mortar joints.Lourenço,Saadegh-vaziri and Mehta,Papa [10–12]have divided models for masonry into two categories:micro and macro.Fig.1shows details of micro-and macro-modelling techniques.Fig.1(b)shows a detailed micro-modelling where joints are represented by mortar continuum elements and discontinuum interface elements.Fig.1(c)shows simplified micro-modelling where joints are represented by dis-continuum elements.Fig.1(d)shows macro-modelling where joints are smeared out in the continuum.In the micro-modelling techniques,it is possible to model the unit-mortar interface and mortar joint which is responsible for most cracking as well as slip.Young’s modulus,Poisson’s ratio,inelastic properties of both unit and mortar are taken into account in micro-modelling.The in-terface represents a potential crack/slip plane with dummy stiff-ness to avoid interpenetration of the continuum.Due to the zeroTable 1thickness of the interface elements,the geometry of the unit has to be expanded to include the thickness of the joint.In the macro-modelling technique,mortar is smeared out in the interface element and in the unit.In micro models,masonry units and mortar are separately discretised using continuum or discrete elements,whereas in the macro model (also known as equivalent material model),masonry is modelled as a single material using average properties of masonry.Page [13]made an attempt to use a micro-model for masonry structures assuming units as elastic continuum elements bonded with interface elements.Arya and Hegemier [14]proposed a von Mises strain softening model for compression with a tension cut-off for the units.Joints were modelled using interface elements with softening on both the cohesion and friction angle.The collapse load obtained from their model shows good agreement with experimental results from shear wall testing.Ghosh et al.[15]concluded that macro-modelling could predict the deformations satisfactorily at low stress levels and inadequately at higher stress levels when extensive stress redistribution occurs.Pande et al.[16]categorically stated that macro-modelling would not accurately predict the stress distribution within the units and mortar.In micro-modelling,two approaches are followed in finite element analyses.In the first,both the units and the mortar joints are discretised by using continuum finite elements,whereas in the second approach interface elements are used to model the behaviour of mortar joints.Several researchers [12,17,18]have reported that the interface elements used in heterogeneous models reproduce essentially the interaction between two adjoining masonry units,and further degrees of freedom are not required to be introduced.For masonry walls subjected to either vertical load only or a combined shear and vertical loading,2-D analyses are found effectively producing stress results that are close to those produced by 3-D analyses.Dhanasekar and Xiao [19]proposed a special 2D element and validated its results using a 3D model of masonry prisms.To determine the internal stress distribution1932R.Senthivel,P.B.Lourenço /Engineering Structures 31(2009)1930–1943(a)Tensile cracking in joint.(b)Joint slip.(c)Direct tensile cracking inunit.(d)Diagonal tensile cracking in the unit.(e)Crushing of masonry.Fig.2.Failure mechanism formasonry.(a)Dry stack sawn masonry.(b)Irregular masonry with bonding mortar joints.(c)Rubble masonry.Fig.3.Details of experimental test specimens.in unreinforced masonry,Page [13]modelled joints as linkage elements in conjunction with units as plane stress continuum elements.Dhanasekar et al.[20]proposed a macro model for solid masonry,which was capable of reproducing the effects of material nonlinearity and progressive local failure.To determine the internal stress distribution in masonry panels under concentrated loading,Ali and Page [21]modelled the masonry units and mortar joints separately.They used four-noded quadrilateral elements with refined mesh in concentrated load regions to allow redistribution of stresses.Khattab and Drysdale [22]also formulated a homogeneous model of masonry considering mortar joints as planes of weakness.Louren ¸o and Rots [17]modelled masonry units as continuum elements while mortar joints and potential cracks in units were represented as zero-thickness interface elements.Interface elements were modelled with a cap model to include all possible failure mechanisms of masonry structures.The following failure mechanisms (Fig.2)are considered;(a)cracking in the joint (Fig.2(a)),(b)sliding along bed or head joints at low values ofnormal stress (Fig.2(b)),(c)cracking of the units in direct tension (Fig.2(c)),(d)diagonal tension cracking of the units at values of normal stress sufficient to develop friction in the joints (Fig.2(d))and (e)Splitting of the units in tension as a result of mortar dilatancy at high values of normal stress (Fig.2(e)).This model has been used successfully to reproduce the complete path of the load–displacement diagram for standard masonry and dry stacked sawn masonry.An extension for cyclic loading using bounding surface plasticity is given in Oliveira and Louren ¸o [23].The novelty of the present paper is in the application of the micro-model to simulate the response of rubble masonry.2.Outline of experimental research programmeThe experimental research work was carried out by Vasconce-los [9]in the Structural Engineering Laboratory at the University of Minho,Guimarães,Portugal.Test walls were made of locally avail-able two mica and medium grain granite stone.A ready-mix mortarR.Senthivel,P.B.Lourenço /Engineering Structures 31(2009)1930–19431933(a)Experimental testset-up.(b)Loading history.Fig.4.Experimental test set-up and load history.made of naturally hydrated lime and aggregates of granular size be-tween 0.1and 0.2mm was used to bond the units.The seven days average compressive strength of mortar was 3N /mm 2which was considered to be close to the strength of mortar found in ancient building constructions.The main object of the experimental research work was to evaluate the in-plane seismic performance of stone masonry shear walls found in ancient masonry structures.Table 1and Fig.3shows the three different types of experimental masonry test walls with description and dimensions respectively;Type (I)Sawn dry-stone or dry-stack mortarless stone masonry (Fig.3(a)).This wall type was to represent historical masonry constructions where there is no bonding material between stone units or where the greater part of the bonding material of low strength has vanished due to physical and mechanical weathering effects.Type (II)Irregular stone masonry with bonding mortar (Fig.3(b))can be representative of large stone block construction,possibly in wealthier housing and monumental buildings,and Type (III)Rubble masonry with irregular bonding mortar joint thickness (Fig.3(c)),can be representative of vernacular buildings and historical city centre houses.In case of a type I masonry test specimen,all the units were mechanically sawn to achieve a smooth surface.Dimension of the sawn stone used in type I masonry was 200mm (length )×150mm (height )×200mm (width ).Type II masonry consisted of hand-cut irregular shaped units and low strength head and bed joint bonding mortar.The size of the irregular stone used in type II masonry was approximately 1.3times larger than the sawn stone used in type I masonry.Type III masonry is composed of mixed stones of different shape,size and texture and low strength mortar.The thickness of all three types of walls was 200mm and single wythe.Considering the capacity of testing equipments available in the1934R.Senthivel,P.B.Lourenço/Engineering Structures31(2009)1930–1943(a)Unit and interface around unit.(b)Potential crack at the middle of the unit.Fig.5.Mesh generation for swan(regular)dry-stack stonemasonry.(a)Eight nodes continuumplane stress element(CQ16M)for units.(b)Six node zero thickness line interface elements(CL12I)for joints.(c)Assemblage of CQ16M and CL12I elements.Fig.6.Two dimensional elements for units and joints.laboratory,the dimension of model masonry test walls was fixedas1000mm(length)×1200mm(height)×200mm(width)andthe height to length ratio was1.2.Fig.4(a)and(b)shows the experimental test set-up and loadinghistory respectively.Monotonic and reversed lateral cyclic testswere carried out with three distinct axial pre-compression loadlevels including low,100kN(σ0=0.5N/mm2),moderate,175kN(σ0=0.875N/mm2)and high,250kN(σ0=1.25N/mm2).Thebase of the walls was fixed to the test floor and the first course ofthe wall was horizontally supported using a special arrangementconsisting of steel plates,angles,bolts,and nuts.To test theexperimental test set-up,a monotonic load test on Type I masonrywas made.The preliminary test was carried out by increasingthe load steadily until failure of the wall.From the preliminarytest results,a load–displacement curve was established for TypeI.After the successful completion of the monotonic test,thereversed lateral cyclic load tests were carried out of all three typesof masonry according to pre-defined load history presented inFig.4(b).Construction of all three types of test walls was performedmanually by the same mason to ensure uniform workmanship.For easy transportation and to avoid local damage during transit,test walls were built on thick steel beams.Construction of thetype I masonry wall was easier and straightforward.Horizontaland vertical alignment of the wall was checked using a plumbline during the construction of each course.As there is nocuring involved,the wall was ready to test immediately after theconstruction.Type II and III masonry test walls were constructedusing low strength bonding mortar,cured for7days under dampconditions and tested.Before construction,the units were soakedin water to avoid absorption of water from the mortar duringconstruction and shrinkage during curing.A total number oftwenty four walls have been tested including ten type I walls,seven type II walls and seven type III walls.Table2shows the totalnumber of walls tested in each masonry type and under differentaxial pre-compression loading.Axial pre-compression loading was applied by using a verticalactuator with a maximum capacity of250kN.Through a set ofroller supports,a deep and stiff beam was used to distribute thevertical load from the actuator to a thick steel beam(similar to thebase beam)that was erected on top of the wall after construction.The axial pre-compression load(either100or175or250kN)waskept constant throughout the test using an independent dedicatedoil pressure system.The top thick stiff steel beam was also usedto apply the shear lateral load from the horizontal actuator asshown in Fig.4(a).The purpose of the steel rollers placed betweenthe deep beam and top beam,was to allow the wall to displacehorizontally during the application of lateral shear load.Carewas taken to avoid possible out-of-plane movement of test wallduring the lateral load application.After applying the desired axialpre-compression load,the lateral load was applied in terms ofcontrolled displacement at the rate of100µm/s.Deformationof the walls was measured using needle type Linearly VariableDifferential Transducers(LVDTs)mounted at different criticalregions,Fig.4(a),and on both sides of the wall.The monotonicload test was done for type I masonry only.Reversed cyclic shearloading test was carried out for all the masonry types.Here,it is noted that the experimental envelope curves onthe reversed cyclic test will be assumed as representative ofquasi static monotonic loading.It is certain that the envelopesfor the former do not exactly coincide with the later.The authorsare not aware of specific papers addressing this issue but nosignificant differences are expected in terms of peak load,as energydissipation in the hysteretic behaviour of shear walls seems to bemostly related to compressive failure and large drifts.In Oliveiraand Lourenço[23],for a severely compressed and asymmetric wall,a difference of about10%was found in terms of peak load,whilecomparing monotonic response versus cyclic envelop.For theR.Senthivel,P.B.Lourenço /Engineering Structures 31(2009)1930–19431935(a)Tension.(b)Shear.(c)Compression.Fig.7.Inelastic behaviour of interface model and validation with experiments,Lourenço and Rots [17].Table 2masonry type I (regular/sawn dry stone masonry)of the present experimental campaign,similar results were found for monotonic and reversed cyclic loading tests,Vasconcelos [9].3.Finite element analysis of stone masonryThe data obtained from the ancient stone masonry shear wall test carried out by Vasconcelos [9]has been used as a base for the present finite element modelling.Prior to the testing of model masonry walls,mechanical tests such as compression,tension and shear tests were done on stone units,mortar cubes,prisms made out of mortarless dry-stone,irregular stone with bonding mortar and rubble stone with bonding mortar.These tests on materials were done to determine the elastic,inelastic and strength parameters required for the present finite element modelling.Average compressive strength,tensile strength and Young’s modules of stone was 69.2N /mm 2,2.8N /mm 2and 20200N /mm 2respectively.Average compressive strength of mortar was 3.0N /mm 2.Table 33.1.Mesh generation and element selectionFor type I (dry-stack stone masonry),the finite element mesh was generated using a FORTRAN programme developed by Lourenço [24].The following input data was required to generate a mesh for regular masonry walls such as type I;(i)whether potential vertical cracks in the middle of the units are to be included in the model,(ii)whether a masonry joint is to be included in the bottom of the model,(iii)whether a masonry joint is to be included in the top of the model,(iv)whether each course contains an integer number of units,(v)whether the first (bottom)course starts with a full unit or half unit,(vi)the number of masonry courses in the model,vii)the number of complete units per course,(viii)the number of divisions (finite elements)per unit in the x direction,(ix)the number of divisions (finite elements)per unit in the y direction,(x)the width of the units (plus 1/2of thickness of the mortar joint),(xi)the height of the units (plus 1/2of thickness of the mortar joint),(xii)the half of a thin fake joint thickness for joints,only for visual or identification purposes.Fig.5(a)shows division of units in x and y directions,interface1936R.Senthivel,P.B.Lourenço/Engineering Structures31(2009)1930–1943 Table4around the unit and fake thickness of joints.Fig.5(b)shows apossible potential crack at the middle of the stone unit.As the experimental test results showed no cracks in the unit,potential cracks in the units were not considered in the entiremodelling work for all three types of masonry.The FORTRANprogramme cannot be used for type II or III as it has complexirregular units of different texture and size.For type II and IIImasonry,the nodal points were calculated using a special imagescanning software and Microsoft Excel,and the rest of the meshingprocedure is same as that of the Type I masonry.The units were modelled using eight node quadrilateralisoparametric continuum plane stress elements,CQ16M(Fig.6(a)),with quadratic interpolation and full Gauss integration.The jointswere modelled using a six node and zero thickness line interfaceelements,CL12I(Fig.6(b))with Lobatto integration.Fig.6(c)showsthe unit and interface element assemblage.3.2.Material properties(strength,elastic and inelastic parameters)The average Young’s modulus of dry-stone prisms was14800N/mm2(based on test results of four prisms built withfour course dry-stacked stones).Young’s modulus of large wallsis usually different from the Young’s modulus measured in smalltest specimens.This phenomenon has been found and reportedby Lourenço[10].A micro-modelling approach based on inter-face finite elements requires two distinct stiffnesses,namely,the stiffness of the stone units and the stiffness of the joints.Once the stiffness of the stone units is known,the stiffness ofthe joints can be calculated from the experimental axial pre-compression load–displacement curve of the walls.Normal jointstiffness(K n,joint)was calculated using the following formulationproposed by Lourenço[10]in which the wall is consider as a seriesof two springs in vertical direction,one representing the stone andthe other representing the joint.K n,joint=1/(h(1/E w all−1/E stone))(1)whereK n,joint=Normal joint stiffnessh=Height of stone(150mm)E w all=Young’s modulus of wallE stone=Young’s modulus of stone.The tangential stiffness(K s,joint)was calculated directly from thenormal stiffness using the theory of elasticity as follows,[10]:K s,joint=K n,joint/2(1+ν)(2)whereK s,joint=Normal joint stiffnessν=Poisson’s ratio(0.2).The following inelastic properties of the unit-mortar interfacewere taken in to account[17]:(i)tensile criterion:f t(tensilestrength)and G If (fracture energy for Mode-I);(ii)friction criterion:c(cohesion),tanϕ(tangent of the friction angle),tanψ(tangent of the dilatancy angle)and Mode-II fracture energy,G IIf;(iii)capcriterion:f c(compressive strength)and G cf (compressive fractureenergy).The inelastic parameters required for the analysis were extracted from Vasconcelos[9],when available,or following the recommendations given in[10].Tables3and4presents elastic and inelastic parameters.Again,note that the elastic stiffness of theFig.8.Critical regions in masonry shear wall.interfaces was adjusted from the measured experimental results, becoming clear that the stiffness decreases consistently from Type I to Type III,due to the increasing thickness of the joint and irregular shape of the units.The equations that govern the inelastic behaviour of masonry are given in detail in[17],where exponential softening for tension and for shear is assumed,followed by parabolic hardening,parabolic softening and exponential softening in compression,see Fig.7.3.3.FEM analysis procedureFirst(step-1),the desired total vertical pre-compression load (either100kN or175kN or250kN)was divided into small steps and gradually applied on the top surface of the stiff steel beam(Fig.8).Then the horizontal load in terms of incremental displacement was applied in small steps at the top right corner of the steel beam(step-2).For a good insight into the stress distribution at different horizontal load increment,the horizontal displacement was increased gradually to2.5mm,then to5mm, then to10mm and finally until failure/collapse,which provided the behaviour of each critical region(Fig.8)of the walls,in addition to the overall deformation characteristics.The vertical and horizontal loads were applied in small steps to achieve a converged solution,particularly in the case of dry stone masonry, which features no tensile strength or cohesion.R.Senthivel,P.B.Lourenço/Engineering Structures31(2009)1930–19431937(a)Deformation progress of Type I,Sawn masonry under175kN.(b)Incremental deformed mesh at collapse(175kN)and experimental failure.(c)Incremental deformed mesh at collapse(250kN)and experimental failure.Fig.9.Deformation progress of type I,Sawn masonry.3.4.FEM analysis resultsResults of the nonlinear finite element analyses were postprocessed and are presented in this section.Axial pre-compressionload,lateral shear load and material properties are the mainparameters that significantly influenced the behaviour of theshear walls.Load flow in the whole body of the wall at differentlateral displacement levels,failure modes and state of load and1938R.Senthivel,P.B.Lourenço /Engineering Structures 31(2009)1930–1943Fig.10.Deformed shape of Type II,Irregular masonry atcollapse.(a)Deformed shape of original mesh.Fig.11.Deformed shape of original and modified mesh of Type III,Rubble masonry.displacement in critical nodes are presented in the following sections.3.4.1.Modes of failureHeel,toe,centre and local point of application of load on the shear wall are the critical regions (Fig.8).Failure in these regions mainly controlled the overall behaviour of the shear walls.Walls failed due to either flexure or rocking or toe crushing or tensile cracking at the heel followed by shear failure along the bination of two or more failures has also occurred at critical load level.At lower pre-compression levels (100kN),walls usually failed due to a progressive flexural mechanism characterised by heel cracking followed by rocking and toe crushing.Irrespective of masonry types,axial pre-compression stress significantly influenced the behaviour of the shear walls.A small increase in vertical load provided the walls with a larger strength due to the improvement of bond resistance mechanisms between joint and masonry units.A substantial increase of axial stress changes the failure mode of the wall from flexure to shear.Figs.9–11present the deformed shape and the minimum principal (compressive)stresses of Type I,II and III masonry models respectively under different lateral displacement,and axial pre-compression loadings.Lower axial pre-compression load caused flexural or rocking failures and higher pre-compression load caused rocking,toe crushing,crushing at region of load application and diagonal shear failures along the diagonal direction.Flexural cracking in the bed joints occurs when the tensile stress on a horizontal mortar joint exceeds the sum of the bond strength of that mortar joint and the frictional stress between the mortar and the units.The rocking mode of failure occurs due to overturning caused by either a low level of axial load and/or weak tensile bond strength of mortar joints dominated.Diagonal shear failure occurs when the diagonal tensile stress resulting from the compression shear state exceeds the splitting tensile strength of masonry.Fig.9details the progress of cracking and redistribution of compressive stresses upon loading,which leads to a series of struts defined by the geometry and stone arrangement.For a good insight into the stress distribution at different horizontal load increments,the horizontal displacement was increased gradually。

墙体抗剪承载力计算公式在砌体结构设计中的应用墙体抗剪承载力计算公式在砌体结构设计中的应用[提要] 利用ALGOR FEA计算程序,分析了竖向压应力和水平力共同作用下无筋砖墙的应力。

基于文中提出的平面受力砌体的破坏准则,对墙体裂缝分布进行了描述,并提出了不同高宽比砖墙的水平开裂荷载的计算公式。

最后建立了墙体抗剪承载力计算公式,其计算结果与试验值吻合较好。

所提出的方法可供砌体结构设计和研究参考。

[关键词] 砖墙剪切承载力The stress of unreinforced brick wall under vertical compression and horizontal force has been analysed by ALGORFEAcomputer software.The formulas for calculation of horizontal cracking load of brick wall of different ratio ofheight to width have been proposed on the basis of failure criterions of plane-stress masonry.The crack distribution ofwall has been described in detail.In the end,the calculating formula of shearload-bearing capacity of wall has been es-tablished.The calculating results agree well with the ex perimental data.This method can provide reference for mason-ry structural design and research.Keywords:brick wall;shear;load-bearing capacity混合结构房屋中,墙体除了承担屋(楼)盖传来的竖向压力以及本身的自重外,还承担风、地震引起的水平力。

Chapter 1 Masonry Structures1.1.Masonry PropertiesMasonry is typically site constructed using manufactured masonry units and site mixed mortar. The units are laid in mortar to various heights, with the strength of the assembly being achieved during curing of the mortar.Masonry is normally used for components subjected to compressive loading. Masonry walls also have a limited capacity to support horizontal loads and bending moments.1.1.1.Masonry Materials1.Masonry UnitsSeveral different types of masonry units are commonly used. Common masonry unit types include clay and concrete units, which may be solid or hollow. Other masonry unit types include stone and calcium silicate units.Masonry units are categorized by grade (MU) and type. The masonry grade depends on the required durability of the units. Clay units with a minimum grade of MU10 are required. In areas where freezing cycles are anticipated, clay units with a minimum grade of MU20 should be used.Clay masonry units primarily consist of clay, shale or similar naturally occurring earthy substances, water and additives. The units can be hollow (cores occupy greater than 25% of unit), perforated, or solid. For most exterior walls, units categorized as solid are used.Hollow concrete masonry units are made from a mixture of Portland cement and aggregates under controlled conditions. A hollow unite has a net area not more than 75 percent of the gross area. Most hollow concrete masonry unites range from 50 to 55 percent of the gross area. The units can be made to various dimensions, but typically have dimensions of 390mm long x 190mm high x 90mm wide. Concrete masonry units are categorized based on the weight (lightweight and normal weight). Structural masonry units are normal weight. Lightweight units are used for non-load-bearing conditions or as veneers. The cores provide continuous vertical voids that are often reinforced. Steel bars are placed in the cores with grout installed surrounding the bars. In this fashion, the wall acts similar to a reinforced concrete element.Stone units should be square dressed with parallel faces. Random rubble is not adequate in earthquake zones.2.MortarMortar is typically composed of cement, lime and sand, although lime mortars can also be composed in which no cement is used. Components and proportions of mortars vary depending on the desired mortar properties. Mortars consisting of portland cement and lime as well as sand are most common.Mortar serves to bond masonry units together to form a composite structural material. As such, mortar is a factor in the compressive, shear, and flexural strengths of the masonry assemblage. In addition, mortar compensates for dimensional and surface variations of masonry units, resists water and air penetration through masonry, and bonds to metal ties, anchors, and joint reinforcement so that they perform integrally with the masonry units.Well-graded sand with a uniform distribution of particle sizes is necessary to produce a workable mortar which is dense and strong in the hardened state. Sand on the finer side of the permitted gradation range will produce a more workable mortar than a mortar made with coarser sand. However, the mortar with finer sand requires more water to be workable and is therefore weaker.1.1.2.Mechanical propertiespressive StrengthThe compressive strengths of masonry assemblages may be established by testing a small masonry assemblage referred to as “prisms.” To establish the compressive strength of a given unit-mortar assemblage, a minimum of three prisms must be tested. Prisms may be constructed in stack-bond or in a bonding arrangement which simulates the bonding pattern to be used in the structure, except no structural reinforcement is used in the prisms. Masonry prisms should be constructed with the same materials, joint thickness, and workmanship used in the structure.A number of important points have been derived from compression tests on masonry. These include, first, that masonry loaded in uniform compression will fail by the development of tensile splitting cracks parallel to the axis of loading, as shown in Figure 7.1. Secondly, it is observed that the strength of masonry in compression is smaller than the nominal compressive strength of the units as given by a standard compressive test. On the other hand, the masonry strength may greatly exceed the cube compressive strength of the mortar used in it. From testing observations it may be inferred that:(1) The tensile stresses which cause the splitting type of failure result from the restrained deformation of the mortar in the bed joints of the masonry.(2) The apparent crushing strength of the unit in a standard test is not a direct measure of the strength of the unit in the masonry, since the mode of failure is different in the two situations.(3) Mortar withstands higher compressive stresses in a brickwork bed joint because of the lateral restraint on its deformation from the unit.Figure 7.1 Tensile splitting of a wall under vertical compressive load.The mean compressive strength of plain masonry m f made with general purpose mortar may be calculated on the basis of mean compressive strength of masonry units 1f and compressive strength of mortar 2f as follows:()22107.011k f f k f m m += (7.1)and 1f is neither larger than 20 MPa nor smaller than 2f . The value of constant 1k and 2k depend on the classification of masonry units and mortar strength, respectively.2. Shear StrengthIn reinforced masonry, shear loads may be carried either by the masonry or, if the masonry is not adequate, by the reinforcing steel. Masonry is an assemblage of discrete units and mortar, so when the shear force is carried by the masonry, two forms of shear strength exist. These strengths are diagonal tension strength and sliding shear strength along the mortar joint. The standard tests used to determine the shear strength in masonry are diagonal tension tests and shear sliding tests.Shear strength of masonry is defined as a combination of initial shear strength under zero compressive load and increase in strength due to compressive stresses perpendicular to the shear plane. Initial mean shear strength at zero compressive stress is denoted with m v f ,0. This property is determined by testing a triplet specimen such that only shear stresses develop in the mortar to masonry unit contact planes. A minimum of five triplets are tested. The minimum acceptable value of m v f ,0 is 0.03 MPa. The mean shear strength of plain masonry isthen calculated as follows:k m v m v f f 0,0,αμσ+= (7.2)whereσis the characteristic compressive stress perpendicular to the shear plane, αis k0correction factor which depends on the classification of masonry units, μis influence coefficient corresponding to the combination of shear and compressive load.Masonry walls resisting shear loads usually exhibit three modes of failure, as shown in Figure 7.2.(a) Sliding along bed joints (Low vertical compression stress)(b) Cracking through masonry (Strong mortar and weak units)(c) Stair-step cracks through bed and head joints (Weak mortar and strong units)Figure 7.2Failure modes of masonry walls resisting shear loads3.The Tensile Strength of MasonryDirect tensile stresses can arise in masonry as a result of in-plane loading effects. These may be caused by wind, by eccentric gravity loads, by thermal or moisture movements or by foundation movement. The tensile resistance of masonry, particularly across bed joints, is low and variable and therefore is not generally relied upon in structural design. Nevertheless, it is essential that there should be some adhesion between units and mortar.The mechanism of unit-mortar adhesion is a physical-chemical process in which the pore structure of both materials is critical. It is known that the grading of the mortar sand is important and that very fine sands are unfavorable to adhesion. In the case of clay brickwork the moisture content of the brick at the time of lying is also important: both very dry and fully saturated bricks lead to low bond strength.4.Flexural Tensile StrengthFlexural test establishes flexural tensile bond strength in a direction perpendicular to the bed joint by third-point or uniform loading of stack-bond specimens.The flexural capacity of unreinforced masonry walls depends either upon the tensile bond between units, as shown in Figure 7.3(a), or upon the shear-bond of overlapping units,as depicted in Figure 7.3(b), depending on the direction of flexure and type of construction. Flexure which induces shear-bond stresses between overlapping units may be limited by shear bond strength or by flexural tensile unit strength.(a) (b)(a) Vertical orientation of failure plane and corresponding bending strength normal to bed joints (b)Horizontalorientation of failure plane and corresponding bending strength parallel to bed jointsFigure 7.3Flexural tensile failureIf a wall is supported only at its base and top, its lateral resistance will depend on the shear-bond strength of the bed joints. If it is supported also on its vertical edges, lateral resistance will depend also on the tensile bond strength of the brickwork in the direction at right angles to the bed joints. The shear-bond strength is typically about three times the tensile bond strength. If the brick-mortar adhesion is good, the bending strength parallel to the bed joint direction will be limited by the flexural tensile strength of the units. If the adhesion is poor, this strength will be limited mainly by the shear strength of the unit-mortar interface in the bed joints.The flexural strength is dependent on the absorption characteristics of the bricks and on the type of mortar used. Calcium silicate brickwork and concrete blockwork have rather lower flexural tensile strength than clay brickwork, that of concrete blockwork depending on the compressive strength of the unit and the thickness of the wall.1.1.3.Effects of Workmanship on Masonry Strength1.Failure to Fill Bed JointsIt is essential that the bed joints in brickwork should be completely filled. Gaps in the mortar bed can result simply from carelessness or haste or from a practice known as …furrowing‟, which means that the bricklayer makes a gap with his trowel in the middle of the mortar bed parallel to the face of the wall. Tests show that incompletely filled bed joints can reduce the strength of brickwork by as much as 33%.Failure to fill the vertical joints has been found to have very little effect on the compressive strength of brickwork but does reduce the flexural resistance. Also, unfilledperpendicular joints are undesirable from the point of view of weather exclusion and sound insulation as well as being indicative of careless workmanship generally.2.Bed Joints of Excessive ThicknessIncrease in joint thickness has the effect of reducing masonry strength because it generates higher lateral tensile stresses in the bricks than would be the case within joints. Thus, bed joints of 16–19mm thickness will result in a reduction of compressive strength of up to 30% as compared with 10mm thick joints.3.Deviation from Verticality or AlignmentA wall which is built out of plumb, which is bowed or which is out of alignment with the wall in the storey above or below will give rise to eccentric loading and consequent reduction in strength. Thus a wall containing a defect of this type of 12–20mm will be some 13–15% weaker than one which does not.4.Exposure to Adverse Weather after LayingNewly laid brickwork should be protected from excessive heat or freezing conditions until the mortar has been cured. Excessive loss of moisture by evaporation or exposure to hot weather may prevent complete hydration of the cement and consequent failure to develop the normal strength of the mortar. The strength of a wall may be reduced by 10% as a result. Freezing can cause displacement of a wall from the vertical with corresponding reduction in strength. Proper curing can be achieved by covering the work with polythene sheets, and in cold weather it may also be necessary to heat the materials if bricklaying has to be carried out in freezing conditions.5.Incorrect Proportioning and Mixing of MortarA reduction in mortar strength could also result from a relatively high water/cement ratio whilst still producing a workable mix. It is therefore important to see that the specification for mortar strength is adhered to although there is an inherent degree of tolerance sufficient to accommodate small errors in proportioning and mixing the mortar. The use of unsuitable or an excessive amount of plasticizer in place of lime will produce a porous and possibly weak mortar and has to be guarded against.Words and Expressionsbed joint （砌体）灰缝brickwork [ ♌❒✋♦] n. 砖结构, 砌砖工作calcium silicate brickwork 硅酸盐砌块砌体characteristic compressive stress压应力标准值clay brickwork 粘土砖砌体concrete blockwork 混凝土砌块砌体furrow [ ♐✈❒☜◆] vt. 开沟；作垄grout [♈❒♋◆♦] n. 水泥浆lime [laim] n. 石灰masonry [ ❍♏♓♦⏹❒♓] n. 砌体masonry unit n.砌块mean compressive strength 抗压强度平均值mean shear strength抗剪强度平均值perforated [ ☐☜♐☜❒♏♓♦] adj.有孔的或多孔的,尤指有一排小孔的polythene [ ☐●♓♓⏹] n. 聚乙烯rock vi.摇, 摇动specification [ ♦☐♏♦♓♐♓♏♓☞☜⏹] n.规程,规范triplet [ ♦❒♓☐●♓♦] n. 三个一组trowel [ ♦❒♋◆☜●] n. 泥铲veneer [ ☜⏹♓☜] n. 饰面verticality [ ♦✋♊✌●☜♦✋] n.垂直状态Questions the common masonry unit types.2.What are the compositions of mortar? What is the function of mortar?3.How would you test the compressive strengths of a masonry assemblage?4.What are the main factors influencing the compressive strengths of masonryassemblages?5.How would you determine the shear strength in masonry?6.Why is the tensile resistance of masonry not generally relied upon in structuraldesign?7.How do support conditions determine the flexural strength of masonry?8.Describe the modes of failure of masonry.9.What are the effects of workmanship on masonry strength?1.2.Masonry Construction System1.2.1.Unreinforced MasonryUnreinforced clay brick masonry is a traditional form for construction of low-rise houses that has been extensively practiced in almost every part of the world. With the increased popularity and availability of reinforced concrete, improved masonry forms of construction, like confined and reinforced masonry became more common for low-rise houses. However traditional houses with load-bearing system of unreinforced burnt clay brick walls are still being constructed in many areas of Asia, Indian Subcontinent and Latin America. This form of construction is not considered earthquake resistant and its use should be disallowed.1.2.2.Reinforced MasonryUse of reinforcement such as steel bars or mesh in masonry can improve its load carrying capacity and its flexure and shear behavior under earthquake loads. Reinforcements are embedded in mortar or concrete so that all the materials act together in resisting forces. Four systems of reinforced masonry are in common use:(1) Steel mesh reinforced brick masonryThe steel mesh reinforcements of 3-4mm in diameter are embedded into the horizontal mortar joints every 2-5 courses, as shown in Figure 7.4. Steel mesh reinforcements can restrain the lateral deformation of masonry in compression, and results in improved compressive strength of masonry.Figure 7.4Steel mesh reinforced brick masonry(2) Reinforced hollow unit masonry.This is achieved by placing bed joint reinforcement at 600mm centers, and verticals bars, as shown in Figure 7.5. The holes containing the vertical bars are filled with concrete. The reinforcing bars should be anchored adequately into the tie columns or intersecting walls. Minimum thickness of mortar cover above reinforcing bars should be 15mm.Figure 7.5Reinforced hollow unit masonry(3) Reinforced grouted cavity masonry.As shown in Figure 7.6, this system consists of two leaves of masonry units, separated by a cavity into which the vertical and horizontal reinforcement is placed and the cavity is filled with either concrete infill or mortar. The leaves are usually 100mm thick and the cavity 60-100mm. In order to achieve integrity of the wall the two leaves are connected by means of standard wall ties or rebars. The size and number of connecting ties are determined according to design calculations. However at least 4 6 rebar links or an equivalent wall ties per m2 of wall area should be provided. After completion of the reinforcement details the cavity is grouted or infilled with concrete.Figure 7.6Reinforced grouted cavity masonry construction(4) Composite brick masonryThe composite brick wall is common for engineered structural masonry construction. Vertical wall reinforcement can be placed in vertical ducts formed on both sides of the wall or vertical joints. The composite brick masonry also allows for forming reinforced masonrycolumns, where ducts of bigger size can accommodate multiple bars as well as stirrups for concrete infill or grout confinement.For this type of reinforced masonry the vertical rebars are placed into position ideally before the laying of masonry units. Horizontal reinforcement is placed in the bed joints at vertical spacing maximum 600 mm. The vertical reinforced ducts are filled with concrete or grout as the construction of the wall progresses. Proper planning is necessary to ensure rebar splices lengths, anchoring lengths, concrete cover. Composite brick masonry is shown in Figure 7.7.Figure 7.7Composite brick masonryThe effectiveness of the reinforcement strongly depends on the type and quality of masonry units and mortar. When subject to seismic load the bond between the rebars and mortar deteriorates. Consequently, high tensile stresses and yielding in rebars cannot be develop preventing ductile behavior and energy dissipation. For certain hollow masonry units premature crushing of face shells under cyclic lateral load may occur even in cases where the compressive strength of the units is good.In order to achieve a ductile behavior of masonry, it is necessary that the shear strength of the wall is greater than the bending strength to ensure bending failure. Therefore increased amount of vertical reinforcement at the edges of wall may not improve the resistance of the wall particularly with weak masonry units. Thus the minimum percentage of reinforcement, either vertical or horizontal, depends on the strength of the masonry units.The maximum percentage of reinforcement should also be limited based on the strength of the masonry units and mortar such that a ductile bending failure is possible. The requirements for anchoring and lapping of reinforcement are similar to those specified for reinforced concrete structures. All reinforcement should be anchored to allow for the stresses in the bar to develop.1.2.3.Confined MasonryThis is a construction system where masonry structural walls are surrounded on all four sides with reinforced concrete beams and columns (Figure 7.8). The major improvements in the performance of the confined masonry building over the plain masonry building are as follows:(1) Enhances greatly the connection between structural walls(2) Improves the stability of masonry walls(3) Improves the strength of masonry walls(4) Provides ductility under earthquake loading(5) Improves the integrity and containment of earthquake damaged masonry wallsThe RC confining elements are horizontal members called bond beams and vertical members called tie columns (Figure 7.8). In the case of confined masonry, floors should be reinforced concrete cast in-situ. Good floor to wall connection is achieved by horizontal bond beams cast just below slabs.Figure 7.8Methods of confining masonryThe confining elements are not intended nor designed to perform as a moment-resisting frames. The masonry walls are load-bearing and are constructed to carry all of the gravity loads as well as lateral loads. Therefore the load-bearing masonry walls are constructed first. Then the vertical and horizontal confining elements are cast simultaneously with the floors, which are constructed as RC slab.In order to achieve effective confinement of walls, tie columns should be located at all corners and changes of wall contour, and at all joints, wall intersections and free ends of structural walls. Vertical confining members are also necessary at both sides of large openings. The distance between tie columns should not exceed 15m. Figure 7.9, below shows typical distribution of vertical confining elements in the plan of the building.Figure 7.9Typical distribution of vertical confining elements in the plane of building Words and Expressionsbond beam 圈梁composite brick masonry 组合砖砌体hollow concrete blocks 混凝土空心砌块reinforced cavity masonry 配筋空心砌体reinforced hollow units masonry 配筋空心砌块砌体reinforced masonry配筋砌体tie columns 构造柱unreinforced masonry无筋砌体Questions1.What are the four systems of reinforced masonry that are in common use?1.3.Structure Performance of Confined Masonry Building1.3.1.Factors Influencing the Structure Performance of Masonry BuildingThe structural performance of confined masonry buildings depends on the following four types of connections within masonry elements:(1) Integrity and shear resistance of masonry walls is influenced by the extent and quality of bond between mortar and masonry units. It is essential for the masonry units to be properly constructed to allow for the best possible level of bonding to develop.(2) The second level of connection is among the wythes of masonry walls.A wythe is a continuous vertical section of masonry. A wythe may be independent of, or interlocked with, the adjoining wythe(s). Modern masonry construction standards require regularly spaced ties between the wythes of a cavity wall to ensure monolithic behavior and redistribution between the wall wythes. In historic masonry construction it is common for the walls to be either one-or two-brick-wide solid brick, or to consist of two external wythes with a cavity filled with rubble (to improve the thermal capacity of the wall). The connection between the two wythes was ensured by headers(bricks placed through the wall at regular intervals).(3) The third level of connection is among the walls at the corners and junctions and depends on the specific fabric of corner returns. Such connections ensure 3-D behavior of the masonry box-like structure and the redistribution of lateral forces among walls.(4) The forth level of connection is between the walls and the horizontal structures (floors and roof); this connection highly influences the seismic performance of the building.Use of strong mortars, high strength masonry, added reinforcement, improved detailing and the introduction of good anchorage between masonry walls and floors and roofs can enhance the resistance of masonry to seismic stress, and enable the masonry building to act as a box-type structure. Vertical gravity loads are transferred from the floors and roof, which act as horizontal tension elements, to the bearing walls, which support the floors and act as vertical compression members. During earthquakes, however, floors and roofs act as horizontal diaphragms that transfer the seismic forces, developed at floor levels, into the walls. In addition to this, floors and roofs connect the structural walls together and distribute the horizontal seismic forces among the structural walls in proportion to their lateral stiffness. Bond beams are provided at floor levels to assist the floors in connecting the structural walls.1.3.2.Effect of Door and Window OpeningsThe sizes and positions of wall openings have strong effect on the in-plane resistance of masonry shear walls.This wall shown in Figure 7.10(a) will not resist lateral loading as effectively as the wall shown in Figure 7.10(b). The wall in Figure 7.10(a) tends to act as three separate short lengthsrather than one while wall in Figure 7.10(b) tends to act as one long portion of brickwork and will be more resistant to lateral loading.(a) (b)Figure 7.10Effect of openings on shear strength of walls When subjected to seismic loads, stress concentration takes place in the opening zones, causing cracking and deterioration of masonry. If openings in longitudinal walls are so located that portions of these walls act as flanges to cross walls, the strength of the cross walls are considerably increased and structure becomes much more stable.Part of load over an opening in the wall is transferred to the sides of the opening by arching action. For good arching action, masonry units should have good shear strength. Further, portions of the wall on both sides of the opening should be long enough to serve as effective abutments for the arched masonry above the opening since horizontal thrust for the arch is to be provided by the shear resistance of the masonry at the springing level on both sides of the opening. If an opening is too close to the end of a wall, shear stress in masonry at springing level of imaginary arch may be excessive and thus no advantage can be taken from arching action for design of lintel s. An opening should be located not closer than 1000mm to the inside corner of its wall.Words and Expressionsarching action 拱的作用headers [ ♒♏♎☜] n.拉结石lintel [ ●♓⏹♦●] n.过梁springing level 起拱面Questions1.What are the four levels of connections within masonry elements?2.What is the effect of wall openings on the in-plane resistance of masonry shearwalls?1.4.Masonry Structural Design1.4.1.Walls1.Walls DistributionMasonry structures gain stability from the support. Lateral support may be in the vertical or horizontal direction. The former consists of floor/roof bearing on the wall, and the latter consists of cross walls, piers or buttresses. Lateral supports can limit slenderness of a masonry element so as to prevent or reduce possibility of buckling of the member due to vertical loads, and resist horizontal components of forces so as to ensure stability of a structure against overturning.A structure should have adequate stability in the direction of both the principal axes. The so called 'cross wall' construction may not have much lateral resistance in the longitudinal direction (Figure 7.11(b)). In multi-storey buildings, it is desirable to adopt 'cellular' or 'box type' construction from consideration of stability and economy as illustrated in Figure 7.11(a). Walls are to be uniformly distributed along each principal axis of the plan, and minimum thickness of structural walls should be 240mm.(a) Cellular construction (b) A cross wall construction-unstable in longitudinal directionFigure 7.11Distribution of structure walls in plan Cross walls acting as stiffening walls continuous from outer wall to outer wall or outer wall to a load bearing inner wall. The maximum spacing of cross wall in masonry structure with reinforced concrete floor and roof is 18m for seismic fortification intensity of6 and 7, 15m for seismic fortification intensity of 8, and 11m for seismic fortification intensity of9.Load bearing walls are structurally more efficient when the load is uniformly distributed and the structure is so planned that eccentricity of loading on the members is as small as possible. Providing adequate bearing of floor/roof on the walls can avoid eccentric loading, provide adequate stiffness in slabs and avoid fixity at the supports.2.Height to Thickness Ratio of WallsLoad carrying capacity of a masonry member depends upon its height to thickness ratio, which is the ratio of effective height to effective thickness. A masonry member may fail, either due to excessive stress or due to buckling. For materials of normal strength with height to thickness ratio less than 30, the load carrying capacity of a member at ultimate load is limited by stress, while for members with higher value of height to thickness ratio failure is initiated by buckling. Further, mode of failure of a very short member having height to thickness ratio of less than 4 is predominantly through shear action, while with height to thickness ratio of equal or greater than 4 failure is by vertical tensile splitting.From consideration of structural soundness and economy of design, the maximum height to thickness ratio of walls and columns shall be controlled so as to ensure failure by excessive stress rather than buckling. The height to thickness ratio for a wall shall not exceed 26 when the grade of mortar is not less than M7.5. Limiting values of height to thickness ratio for column is less than that of walls because column can buckle around either of the two horizontal axes where walls can buckle around the weak horizontal axis only. The height to thickness ratio for a load bearing unreinforced column shall not exceed 17 when the grade of mortar is not less than M7.5.3.Double-Leaf WallsThe traditional stone masonry construction with two outer layers of uncoursed irregularly sized rubble stones with an inner infill consisting of smaller pieces of stone bound together with lime mortar is not recommended in earthquake zones.Single-leaf walls should be preferred to double-leaf walls. Double-leaf cavity walls, where the cavity is filled with concrete, should be preferred to normal cavity walls, since they ensure monolithic behavior of the wall under seismic conditions.1.4.2.Bond BeamsThe function of bond beams is to transfer horizontal shear induced by the earthquakes from the floor and roof to the structural walls. They connect the structural walls with each other and improve the rigidity of the horizontal diaphragms.Bond beams should be constructed in-situ from reinforced concrete and cast simultaneously with the floor slab. Bond beams should be cast on top of all structural walls at every floor level. The minimum cross section of bond beam is recommended to be 240 x 120mm. The bigger dimension being the thickness of the wall. Typical examples of monolithic cast in-situ RC bond beams with RC slabs are shown in Figure 7.12.。

建筑类英文翻译-CAL-FENGHAI.-(YICAI)-Company One1英语翻译1外文原文出处：Geotechnical, Geological, and Earthquake Engineering, 1, Volume 10, Seismic Risk Assessment and Retrofitting, Pages 329-342补充垂直支撑对建筑物抗震加固摘要：大量的钢筋混凝土建筑物在整个世界地震活跃地区有共同的缺陷。

弱柱，在一个或多个事故中，由于横向变形而失去垂直承载力。

这篇文章提出一个策略关于补充安装垂直支撑来防止房子的倒塌。

这个策略是使用在一个风险的角度上来研究最近实际可行的性能。

混凝土柱、动力失稳的影响、多样循环冗余的影响降低了建筑系统和组件的强度。

比如用建筑物来说明这个策略的可行性。

1、背景的介绍：建筑受地震震动，有可能达到一定程度上的动力失稳，因为从理论上说侧面上有无限的位移。

许多建筑物，然而，在较低的震动强度下就失去竖向荷载的支撑，这就是横向力不稳定的原因(见图。

提出了这策略的目的是为了确定建筑物很可能马上在竖向荷载作用下而倒塌，通过补充一些垂直支撑来提高建筑物的安全。

维护竖向荷载支撑的能力，来改变水平力稳定临界失稳的机理，重视可能出现微小的侧向位移(见图。

在过去的经验表明，世界各地的地震最容易受到破坏的是一些无筋的混凝土框架结构建筑物。

这经常是由于一些无关紧要的漏洞，引起的全部或一大块地方发生破坏，比如整根梁、柱子和板。

去填实上表面来抑制框架的内力，易受影响的底层去吸收大部分的内力和冲力。

这有几种过去被用过的方法可供选择来实施:1、加密上层结构，可以拆卸和更换一些硬度不够强的材料。

2、加密上层结构，可以隔离一些安装接头上的裂缝，从而阻止对框架结构的影响。

3、底楼，或者地板，可以增加结构新墙。

这些措施(项目1、2和3)能有效降低自重，这韧性能满足于一层或多层。

Earthquake and Tsunami Smart ManualA guide for protec ting your familyE ARTHQUAKE AND TSUNAMI SM ART M ANUAL2PreparedBCA Narrative of Huu-ay-aht Seismic HistoryOn January 26, 1700 at about 9 p.m., a powerful magnitude 9 earthquake struck off the coast of B.C. and, without warning, was followed by a catastrophic tsunami that devastated the village of Loht’a. With no time to respond, all 5,000 residents of Loht’a were lost to this devastating event. This is the story of the Great Tsunami and Earthquake that was told to me by my grandparents, George and Louisa Johnson. For generations, Elders in our community as well as other First Nations along the coast have maintained this legend and others like it, as an oral history of our people. Today, our people call Anacla (Pachena Bay) home and this oral history plays a central role in how we understand tsunami risks in our community. We are able to use our history to learn from the past and preparing for future tsunamis.E ARTHQUAKE AND TSUNAMI SM ART M ANUAL3Unreinforced masonry structures may sustainsignificant damage from earthquakes.Earthquake and Tsunami SmartEarthquakes are common in B.C., with more than 2,500 recorded each year in and around the province. Most are too small to be felt, but an earthquake capable of causing structural damage is expected to occur somewhere in the province about once every decade. There is a real risk that one of these could be “the big one.”Tsunamis can be associated with earthquakes. Sometimes a large earthquake beneath the ocean floor will produce a tsunami, which is a series of large waves. A damaging tsunami is a rare, but serious event. If you live in or near a coastal region of our province, there is a possibility that you may have to respond to a tsunami threat one day.Preparation is the key to survival in the event of an earthquake or tsunami. However, for some of us, putting together an emergency supplies kit and creating a family disaster plan can seem overwhelming.Following these Earthquake and Tsunami Smart guidelines is simple and takes little time. Sharing what you have learned with neighbours, family and friends may save lives. Take the time now to prepare.The B.C. coast is considered a high-risk earthquake zone. In this region,the movement of these plates that causes small earthquakes (daily),potentially damaging earthquakes (decades apart), and some of the3 types of earthquakesCrustal earthquakesDeep earthquakesSubduction zone The shaking motion of an earthquake is due to this sudden release ofenergy. The first sign of an earthquake may be a loud bang or a roar. several seconds to several minutes. Over the following hours or days,E ARTHQUAKE AND TSUNAMI SM ART M ANUALEarthquakes are an unavoidablenatural hazard, but properplanning and a well-informed andwell-prepared public can reducetheir impact.5E ARTHQUAKE AND TSUNAMI SM ART M ANUAL6PreparedBCKnow the Risks – TsunamisLike earthquakes, tsunamis can happen at any time of the day or night, under any kind of weather conditions, and in all seasons. Beaches open to the ocean or by bay entrances, as well as tidal flats and the shores of coastal rivers or inlets exposed to the open ocean, are especially vulnerable to tsunamis.The force of tsunami waves can cause great destruction. The first wave of a tsunami is often not the largest. Other waves may follow every few minutes, for a period of hours.Tsunami waves can kill and injure people and cause great property damage where they come ashore. Understanding what a tsunami can do, and how to react during its approach, is vital to local communities and people along B.C.’s coast.The first wave of atsunami may not bethe largest. Otherwaves may followevery few minutes,for a period of hours.E ARTHQUAKE AND TSUNAMI SM ART M ANUAL7Following an earthquake far away in the Pacific Ocean, it may take hours for waves to reach coastal B.C. However, a closer earthquake couldgenerate a tsunami capable of reaching the shore in a matter of minutes.This logo has been adopted as the tsunami hazard symbol forBritish Columbia.There is a Tsunami NotificationsProcess Plan in place to pass thewarning to coastal communities asquickly as possible, but sometimesthere is not enough time to reacheveryone – especially in moreremote communities.It is important to remember that tsunamis are rare events and not all earthquakes will generate a tsunami. However, it is also critical to know what to do as a precaution if you live in a vulnerable area.The potential power of a tsunami is illustrated here. A car has been tossedonto the roof of a building.E ARTHQUAKE AND TSUNAMI SM ART M ANUAL8PreparedBCTake the First Critical Step Toward Personal PreparednessImagine that a major earthquake has occurred, causing widespread damage, cutting power and gas lines. Or, you have just been warned that a tsunami is on its way towards your community.If your home is no longer safe – you must leave immediately. You cannot gather food from the kitchen, fill bottles with water, grab a first-aid kit from the closet and snatch a flashlight and a portable radio from the bedroom quickly enough. You need to have these items packed and ready in one place before disaster strikes.It makes sense – and doesn’ttake much time – to beprepared. This checklist willget you started.E ARTHQUAKE AND TSUNAMI SM ART M ANUAL 9Basic Emergency Supply KitFirst Aid kit andmedicationsBattery-poweredor hand crankradio tuned toEnvironmentCanada weatherBattery-poweredor hand crankflashlight withextra batteriesWhistle to signalfor helpCell phone withchargers, inverteror solar chargerLocal maps (identifya family meetingplace) and somecash in small bills At least a three-day supply of non-perishable food. Manual can opener for cans Garbage bags, moist towelettes and plastic ties for personal sanitation Water, four litres per person per day for at least three days, for drinking and sanitation Dust mask to help filter contaminated air Seasonal clothing and footwareE ARTHQUAKE AND TSUNAMI SM ART M ANUAL 10PreparedBCWhen an Earthquake Happens – Remember to Drop, Cover and Hold On DuringIt’s 7:00 p.m. and an earthquake strikes. Each family member is in a different room – do you know how to protect yourselves?By planning ahead, all members of a family will know what to do during an earthquake. Knowing what to expect can reduce panic and ensure you think clearly and act quickly. It’s a good idea when forming an earthquake preparedness plan for families to walk from room to room choosing the best places to be during a quake. It’s also a good idea to discuss what to do if you are away from home.A tsunami is a series ofwaves – the first wavemay not be the largest.Dangerous waves andcurrents can last formany hours.E ARTHQUAKE AND TSUNAMI SM ART M ANUALIndoors, the safest places are beneath sturdy furniture, beside a solidinside wall or in a corner or inside an inner hallway. Hold on tight toheavy furniture if you are using it as cover to keep it from movingaround. Avoid windows.If you’re outdoors, stay in the open, away from trees, buildings andpower lines. You could be driving when a quake hits. Stop your car awayfrom overpasses, bridges and power lines and stay inside your vehicle.Once you’re in a safe place, protect your head and hold on until allmotion stops.11E ARTHQUAKE AND TSUNAMI SM ART M ANUAL12PreparedBCAfterWhen an earthquake is over, it’s important to stay calm and move cautiously, checking for unstable objects and other hazards above and around you. You or others may be injured. Treat yourself first and then assist others.Check gas, water and electrical lines. Also, be aware that there may be other types of hazards caused by earthquakes, including fire, landslides, highway damage, dike failures, liquefaction, cracks, etc.This turn-of-the-century wooden residence in Christchurch New Zealand was moved off its foundation during a 6.3 magnitude earthquake in 2011.E ARTHQUAKE AND TSUNAMI SM ART M ANUAL13Check around your residence. If yoususpect a gas leak, turn off the gasvalve and open the windows of yourhome. Caution! Once the gas is shutoff at the meter, DON’T try to turnIf your house has suffered considerable damage and is unsafe, you may need to leave immediately. Gather your emergency supplies together and listen to a battery-operated radio or car radio for instructions by emergency officials through the news media. Evacuation reception centres may be opened to help with food and lodging, and medical centres may be opened for those who have been injured.E ARTHQUAKE AND TSUNAMI SM ART M ANUAL14PreparedBCTsunami Warning – Head for High GroundThe Tsunami Warning System is an international program to detect tsunamis and provide notification and warnings to all countries bordering the Pacific Ocean, Indian Ocean and the Caribbean. Emergency Management BC receives alerts and advises:B.C. coastal communities in the risk areas (municipalities, regional districts and First Nations)RCMPCanada Coast Guard, the Canadian Forces, Nav Canada, Environment Canada, and other federal government agencies media networks and outlets, and other provincial and federal officialsIf a large undersea earthquake takes place near the B.C. coast, the first tsunami waves may reach the shore minutes after the ground stops shaking. The best warning is the earthquake itself. Residents in tsunami risk areas should be prepared to get to higher ground or inland immediately.NEVER go to the coast to watch a tsunami.NEVER go down to the water if you see it startto recede as this could be an indication that atsunami may follow. A tsunami moves fasterthan a person can run. MOVE to high groundimmediately!Zone AZone DZone EThe North Coast and Haida GwaiiThe Central Coast and northeast Vancouver Island coast including Kitimat, Bella Coola and Port HardyThe outer west coast of Vancouver Island from Cape Scott to Port RenfrewThe Juan de Fuca Strait from Jordan River to Greater Victoria including the Saanich PeninsulaThe Strait of Georgia including the Gulf Islands, Greater Vancouver and Johnstone StraitZone CZone BE ARTHQUAKE AND TSUNAMI SM ART M ANUAL15Depending upon an earthquake’s origin, atsunami could reach the B.C. coast in as littleas 15 minutes – or over 15 hours later. Littlecan be done to warn of local tsunamis becausetheir travel time is so short.A tsunami struck B.C.’s west coast in1964, causing extensive damage toPort Alberni and other communitiesin the area.E ARTHQUAKE AND TSUNAMI SM ART M ANUAL16PreparedBCDuringIf you are near the ocean and you feel a large earthquake, you should go inland or to higher ground immediately – do not wait for an official warning. Know your local community’s suggested evacuation routes to safe areas and proceed there immediately. Be aware that damaged roads and bridges and debris caused by the earthquake may prevent driving.If you are on a boat when a tsunami is coming, you should leave the harbour for the open water, but do not risk your life to move your boat into deeper water if it is too close to the wave arrival time. Tsunamis are scarcely noticed when they pass under a boat in deep water. If you are in a float plane in a harbour, take off for a safe landing area on a lake or on land, or away from areas at risk.E ARTHQUAKE AND TSUNAMI SM ART M ANUAL17If you are camping on a beach or near the ocean, you may have to abandon your belongings in order to save your life.Remember: you cannot outrun a tsunami sodon’t go down to the water if you see it startto recede.Once a community is alerted that the arrival of a distant tsunami is (or may be) expected, residents will be warned in a number of different ways. In some locations, a siren is used, while others depend on a telephone fan-out or a door-to-door or loud hailer system. Once you have the initial warning, listen to your radio for updates.own for at least three days – thismeans when you leave, takeyour emergency supplies kitfrom your home, work or carwith you.E ARTHQUAKE AND TSUNAMI SM ART M ANUAL18PreparedBCAfterFollowing a tsunami that reaches our shores, do not return to the area after the first wave. Tsunamis generally involve several powerful waves. Wait for emergency management officials to give the “all clear” before you return to your home.Stay tuned to your radio or marine radio during a disaster. Bulletins will be issued by emergency officials providing updates on the situation.Call 911 only for life-threatening emergencies.Remember, taking the time to preparenow can save lives in the future.The aftermath of a tsunami can be devastating. The debris at this location in the Sendai region of Japan was about one metre deep following thecatastrophic 9.0 magnitude earthquake and tsunami in 2011.E ARTHQUAKE AND TSUNAMI SM ART M ANUAL19For Additional InformationPreparedness and awareness information is available through Emergency Management BC gov.bc.ca/PreparedBCInformation about current earthquake activity and past events can be found at Natural Resources Canadawww.earthquakescanada.nrcan.gc.ca/index-eng.phpInformation about tsunamis can be found at Fisheries and Oceans Canada www.dfo-mpo.gc.ca/science/Publications/article/2005/ 24-04-2005-eng.htmThis material has been prepared by the Province of British Columbia in cooperation with:Governmentof CanadaNatural Resources CanadaFisheries and Oceans Canada Gouvernementdu Canada Ressources Naturelles CanadaPêches et Océans CanadaThe British Columbia Ministry of Justice and the Crown accept no responsibility or liability for any loss or damage that any person may sustain as a result of the information in, or anything done or omitted pursuant to this manual.。

Enhancement in in-plane shear capacity of unreinforced masonry (URM)walls strengthened with fiber reinforced polymer compositesAyman Mosallam a ,⇑,Swagata Banerjee ba University of California,Irvine,Irvine,CA 92697,USAbPennsylvania State University,University Park,PA 16802,USAa r t i c l e i n f o Article history:Received 17July 2010Received in revised form 11February 2011Accepted 25March 2011Available online 30March 2011Keywords:A.Polymer-matrix composites (PMCs)minatesC.Analytical modelingD.Mechanical testing Masonry wallsa b s t r a c tExperimental study was performed to evaluate the enhancement in in-plane shear capacity of unrein-forced masonry (URM)walls externally retrofitted and/or rehabilitated with fiber reinforced polymer (FRP)composites.Six identical wall specimens of size 1.83m Â1.83m were used;four of them were externally retrofitted using different composite retrofitting schemes and one was repaired with compos-ite laminates after having diagonal cracks on wall faces.All specimens were tested under in-plane cyclic shear in presence of constant gravity load.Wall response with the gradual increase in lateral loading was recorded in the form of hysteretic load deflection curves from which wall ductility under cyclic loading is computed.During experiment,the damage progression in wall specimens and their ultimate failure modes were recorded.From these observations,the enhancement in ultimate in-plane shear capacity and wall ductility are calculated by comparing the response of retrofitted and non-retrofitted walls.A sig-nificant enhancement in wall ultimate capacity is observed due to the application of fiber reinforced polymer composite laminates.Experiment showed that the ultimate failure modes of the walls shifted from brittle to ductile nature when they were externally retrofitted with fiber reinforced polymer com-posites.Furthermore,the in-plane shear capacities of the same wall specimens are calculated using currently available code-based and research-based analytical models.Four such analytical models are used accord-ing to their applicability for different retrofitting schemes.The comparison of analytical result with experimental observations indicated that analytical models are very case specific and their applications are very restrictive.Thus further study is required to develop analytical models that will be generally applicable to a higher population of concrete masonry walls externally retrofitted with different combi-nations of composite materials and lamination schemes.Published by Elsevier Ltd.1.IntroductionFiber reinforced polymer (FRP)composite is a widely used struc-tural material.Major applications of this material in the field of Civil Engineering include the repair and strengthening of existing struc-tural systems which are either partially damaged or structurally deficient to sustain under extreme natural events such as earth-quakes.One such application of FRP is to upgrade the seismic perfor-mance of unreinforced masonry (URM)walls,which are the primary load carrying components of unreinforced masonry buildings.In old building constructions,these walls were primarily designed to carry gravity loads.Due to the absence of any lateral load carrying compo-nent,such constructions are generally fragile during ground excita-tion resulted from seismic events.In fact,a significant damage of these walls is observed in past due to earthquakes [1].Hence,seis-mic retrofitting of these buildings is required in order to upgrade their seismic performance and improve the ductile behavior.Experimental research demonstrated that the external applica-tion of FRP composite laminates either on single or on both sides of masonry walls can remarkably enhance their in-plane and out-of-plane shear carrying capacity [2–10].A comprehensive literature review on this can be found in ACI 440.7R-10[11].In conjunction,numerical studies have also been performed by developing finite element models to predict the in-plane behavior of FRP retrofitted masonry walls [12–14].It is observed that the degree of enhance-ment of wall capacity greatly depends on several factors such as the wall aspect ratio,masonry type (brick,stone or concrete),ret-rofitting scheme,type of FRP material used,and application of lat-eral loads (in-plane or out-of-plane).In addition,the purpose of FRP application either to repair partially damaged walls or to retro-fit undamaged walls can make considerable difference in wall shear strength enhancement.1359-8368/$-see front matter Published by Elsevier Ltd.doi:10.1016/positesb.2011.03.015⇑Corresponding author.Tel.:+19498243369;fax:+19498242217.E-mail addresses:mosallam@ (A.Mosallam),swagata@ (S.Banerjee).FRP-to-masonry interface bond strength is found to have great influence on the enhanced shear capacity of FRP retrofitted ma-sonry walls.The bond behavior is characterized by performing pull-out test experiments [15,16]and/or through numerical analy-sis [12,13]involving masonry panels.Petersen [17]provided a de-tailed literature review on this.It is understood from the above observations that analytical prediction of shear strength of FRP retrofitted URM walls depends on the appropriate incorporation of several factors into the predic-tive model.A good predictive model should include all influencing factors and must be applicable for all types of masonry walls retro-fitted with various FRP lamination schemes.Development of such a predictive model requires a comprehensive knowledge-base on the in-plane shear capacity of URM walls externally retrofitted with FRP laminates.As a first step towards this,the present paper aims to examine the applicability of different analytical models currently available in practice and/or developed through research for predicting the in-plane shear capacity of FRP retrofitted URM walls.This objective is achieved in two phases:(i)experimental study is performed to investigate the efficiency of different FRP composite systems such as carbon/epoxy wet lay-up,E-glass/epoxy wet lay-up,and pro-cured carbon/epoxy strips to retrofit and rehabilitate URM walls which were originally constructed as shear deficient walls and (ii)total in-plane shear capacity of the experimental wall speci-mens is calculated using currently available code-based and re-search-based analytical models.Six wall specimens (one as-built,one repaired and four retrofitted)were tested under in-plane cyclic shear force in the presence of gravity loads.All of these specimens,with 1:1aspect ratio,were constructed with unreinforced concrete (RC)masonry units.For repaired and retrofitted specimens,FRP laminates were applied either on one side or on both sides of the walls to make different combinations of retrofitting schemes.The experimental study made it possible to evaluate the increase in the in-plane shear capacity and the displacement ductility of re-paired and retrofitted walls in compare to the as-built unreinforcedwall.In analysis,lateral in-plane shear capacities of four retrofitted walls,as constructed for the experimental program,are calculated using analytical models proposed in ACI 440.7R-10[11],AC125[18],Garbin et al.[19],Triantafillou [20].Among these,ACI 440.7R-10[11],AC125[18]are code-based and Garbin et al.[19],Triantafillou [20]are research-based models.This study identified the applicability of these analytical guidelines to predict the in-plane shear strength of masonry walls externally retrofitted with different FRP materials.2.Experimental program 2.1.Test set-upExperimental study was performed in the Structural Engineer-ing Test Hall (SETH)at the University of California,Irvine (UCI)to evaluate the in-plane shear capacity of unreinforced and externally strengthened masonry walls.Six full-scale wall specimens were tested under a combination of constant axial and incremental lat-eral (push–pull)cyclic loads.Each wall specimen of dimension 1.83m (height)Â1.83m (length)was fabricated with 152mm Â203mm Â406mm hollow concrete blocks (Fig.1).These walls were built with height-to-length aspect ratio of 1:1to promote a shear dominated behavior under in-plane loading.Each wall was placed on a 0.45m thick reinforced concrete footing,which was attached to the strong floor of SETH at the base with 38mm diameter Diwidag bars.A 0.20m wide and 0.45m high ri-gid concrete beam,referred to as RC loading beam,was con-structed over the top of the wall specimens to transfer both vertical (i.e.,axial)and lateral (i.e.,shear)loads.Fig.2shows the actual laboratory test set-up,where the schematic is shown in Fig.3.Two steel load transfer beams were mounted on the top of the RC loading beam.These steel beams were used to transfer the axial (gravity)load applied through the four hydraulic jacks that were installed on the top of the masonry shear walls.The change in the applied vertical loads was monitored through loadRC footing RC cap beamFour Diwidag Φ 1.0"1.83 m2.92 mGrouted Concrete MasonryUnitSteel Rebar 5#6 at 203mm on centerconcrete masonry walls with vertical steel reinforcement used in the experimental 1658 A.Mosallam,S.Banerjee /Composites:Part B 42(2011)1657–1670cells connected to the hydraulic jacks and since the lateral defor-mations were relatively small,minor changes were observed.Each wall was fully grouted with concrete and vertically reinforced with five#6(Ø=19mm)steel rebars uniformly distributed203mm on center from the footing base to the top beam without any lap splice (Fig.1).All wall specimens had a vertical steel reinforcement ratio of0.54%.However,no horizontal reinforcement was provided in the direction of applied shear force in order to make wall speci-mens deficient in in-plane shear.Thus these walls represented old concrete masonry wall constructions which are generally inca-pable in resisting in-plane shear due to seismic excitation.The detail description of wall specimens and retrofitting schemes are presented in Table1.Two unreinforced wall speci-mens WU1and WU2were tested until WU1completely failed un-der in-plane shear and WU2had diagonal cracks on both wall faces at a lateral load level of276kN.These two walls were referred as control(as-built)specimen and pre-cracked specimen,respec-tively.The pre-cracked specimen(WU2)was then repaired with one layer of carbon/epoxy laminate on both sides of the wall and renamed as W2-C-R.This specimen is further used in the following test to investigate the effectiveness of the repair technique.An-other four original(i.e.,pre-tested)masonry walls were retrofitted directly after the construction of these walls.These retrofitted specimens were W3-C-R(retrofitted with unidirectional carbon/ epoxy laminates on one side of the wall),W4-C-R(retrofitted with unidirectional carbon/epoxy laminates on both sides of the wall), W5-C-R(retrofitted with E-glass/epoxy laminates on both sides of the wall)and W6-CS-R(retrofitted with pre-cured carbon strips overlay on one side of the wall).The reason of having different ret-rofitting schemes is to check the effectiveness of these schemes in enhancing the in-plane shear capacity of URM walls.All of these six original masonry walls were built at the same time and were having the same material properties.Concrete blocks were bonded in mortar bed with2:1sand cement ratio to fabricate the walls.28-days compressive strength of masonry prisms,grout cylinders and mortar cylinders were calculatedas Fig.2.typical laboratory test set-up at SETH,UCI.Table1Layout of the experimental program.Wall specimen Type of specimen DescriptionWU1Control(ultimate)As-builtWU2Control(cracked)As-built to be repaired with carbon/epoxy laminateWU2-C-R Repaired Repaired with single layer of carbon/epoxy laminate on both sides of the pre-cracked wall W3-C-RT Retrofitted Retrofitted with single layer carbon/epoxy laminate on one side of the retrofitted wallW4-C-RT Retrofitted Retrofitted with Single layer of carbon/epoxy laminate on both sides of the retrofitted wall W5-E-RT Retrofitted Retrofitted with double layers of E-glass/epoxy laminate on both sides of the retrofitted wall W6-CS-RT Retrofitted Retrofitted with horizontal strips spaced at101mm(400)on center,on one side of the retrofitted wallPart B42(2011)1657–167016592.16MPa,18.96MPa and14.62MPa,respectively.All reinforcing steel rebars used in this experiment had yield and ultimate strengths as414MPa and648MPa,respectively.2.2.Application of FRP composite laminate for repair and retrofit of wallsThree different FRP composite strengthening systems(carbon/ epoxy wet lay-up laminates,E-glass/epoxy wet lay-up laminates and pre-cured carbon strips)were used to explore their application and effectiveness in repairing and retrofitting unreinforced con-crete masonry walls.One repaired and four retrofitted wall speci-mens were tested under in-plane lateral cyclic loading to estimate the enhanced shear capacity of the walls.All composite laminates used here were unidirectional withfibers running in the direction of applied lateral load.Properties of these FRP materials such as ultimate strength,ultimate strain and modulus at elasticity were obtained by performing coupon tests following the guidelines of ASTMD3039-76‘‘Standard Test Method for Tensile Properties of Fiber-Resin Composites’’.Evaluated properties are listed in Table2.2.3.Loading scheme and instrumentationA combination of axial and in-plane cyclic loads was used to test the wall specimens.During testing,axial load of480kN was applied vertically on wall specimens through axial load rods of 38mm diameter and maintained constant throughout the test. These loading rods were connected to the steel load transfer beams at top and the strongfloor at bottom(through RC base footing)as shown in Figs.2and3.There were four hinge connections between the loading roads and the base footing that allowed the in-plane rotation of walls under lateral loading.was applied through a hydraulic actuator ofwas connected to the RC loading beam via twoeach side of the beam(Figs.2and3).Thesetightly with four steel rods to ensure fullplates to the loading beam.Load cell and computer data acquisitionmonitor the hydraulic actuator.The load cell wasreading for all channels before tests began.ments were monitored through fourwhich were instrumented at the heights of1816mm and2082mm from the wall base.represented the displacement profiles of themental load levels.For repaired and retrofittedstrain gages were bonded on the external surfaceand distributed on the FRP composite layer tocompressive strain in compositefibers.A specified load-control regime is followedmens under in-plane(lateral)cyclic loading.Inand pre-cracked specimens(WU1and WU2),to cyclic loading starting at44.9kN with anof44.9kN in each following steps.For alland retrofitted specimens(W3-C-RT,W4-C-RT,RT),both the starting and incremental loadsspecimens,however,lateral load levels were and an axial(gravity)load of480kN was kept constant throughout these tests.3.Experimental observations3.1.As-built wall specimen(WU1)The control as-build specimen(WU1)was tested under cyclic loading to examine the shear capacity of an unreinforced masonry (URM)wall.The failure of this wall was initiated at a load level of 320kN when a diagonal shear crack formed at the lower left corner of the wall in the push direction.In following loading cycles,the crack is gradually propagated along the middle two-thirds of the wall face towards the upper right corner.The specimen failed sud-denly by splitting into two portions at a load level of369kN (shown in Fig.4).This indicated that the as-built wall failure was dominated by a shear failure mechanism since the wall was diag-onally brittle due to lack of horizontal shear reinforcement.No other failure mode such as wall uplifting and sliding of masonry blocks at the mortar bed joint was observed.The hysteretic loop of the wall specimen is shown in Fig.5 which illustrates the sudden degradation of wall stiffness at rela-tively low displacement values.The yield displacement(D y)and ultimate displacement(D u)of this specimen were recorded as 3.45mm and8.94mm,respectively.Therefore the displacement ductility(DD=D u/D y)of this specimen is evaluated to be 2.6. The calculation of ultimate displacement from the load–deflection curve and displacement ductility is shown in Appendix A.3.2.Pre-cracked wall specimen(WU2)Table2Properties of FRP composites materials.System Thickness(t)mm(in.)Ultimate strength MPa(ksi)Strain at ultimate(l-strain)Modulus of elasticity GPa(ksi)Carbon/epoxy 1.60(0.063)1061(154)0.01296.5(14Â103)E-Glass/epoxy 2.10(0.083)510(74)0.02224.2(3.5Â103)Carbon strips a 1.19(0.047)2896(420)0.018151.7(22Â103)a Strip width=50.8mm(200).plete failure of as-built wall(WU1).1660 A.Mosallam,S.Banerjee/Composites:Part B42(2011)1657–1670loops of the specimen,as observed from the experiment,are shown in Fig.7.3.3.Repaired wall specimen (WU2-C-R)After performing the above test with specimen WU2,the cracked wall is repaired with carbon/epoxy laminate and renamed as WU2-C-R.Developed diagonal cracks and the damaged wall toe were first repaired with high strength epoxy resin.The wall surface was roughen using mechanical grinders.The wall surface was then cleaned from debris and dusts.The cracks were filled with a two-part epoxy-based putty.Sequentially,a low-viscosity epoxy resin was injected inside the crack cavity through small nozzles uni-The repaired specimen was tested under cyclic loading to eval-uate the enhanced shear capacity of the damaged wall.Test result indicated that the wall failure was dominated by a combination of shear and flexural modes.The primary failure was due to the excessive compressive stress generated at wall-end elements.As a result,the wall lost its overall stiffnessand became unable to re-sist any further lateral load.The application of a U-shaped laminate at the pre-damaged toe during repair process resulted in an en-hanced strength at this location,and thus,failure switched to the other side of the wall as shown in Fig.9.The recorded failure load was 445kN.Until this load level,observed hysteretic loops were symmetric (Fig.10).The test result attributed to the fact that the repair technique was effective to increase the overall shear capac-ity of the pre-cracked masonry wall.at load level 276kN:(a)diagonal shear cracks across the wall and (b)compressive crushing of A.Mosallam,S.Banerjee /Composites:Part B 42(2011)1657–16701661displacement-control regime with an incremental displacement 1.27mm at each following step.Result from this experiment showed that the retrofitted speci-men suffered from a localized failure in the form of compression crushing at one of the wall toes (Fig.11).In fact,this failure mode entirely contributed to the ultimate failure of the wall at 422.5kNlateral load,when the wall had a lateral displacement of 10.2mm.Additionally,at this load level,a combination of diagonal tensioncrack in the pre-cracked wall (WU2),(b)repair of damaged toe in the pre-cracked wall (WU2)and (c)repaired specimen Fig.9.Failure of repaired wall (WU2-C-R).-30-20-100Displacement (mm)-600-400-2000200400600L o a d (k N )Fig.10.Hysteretic loops of the repairedA.Mosallam,S.Banerjee/Composites:Part B42(2011)1657–16701663failure of the masonry blocks from the grout coreFig.11.Separation of masonry blocks at the wall compression side(W3-C-RT).3.7.Retrofitted wall with single-sided pre-cured carbon strips (W6-CS-RT)The as-built wall specimen was retrofitted at one side with pre-cured unidirectional carbon/epoxy composite strip placed equally at 121mm center to center.The width of the pre-cured strips is 50.4mm.The ultimate failure of this specimen was governed by the compressive crushing of masonry blocks at wall toes and a diagonal shear cracking along the unstrengthened face of the wall.failure modes observed in other retrofitted W4-C-RT and W5-E-RT),cohesive debonding specimen at high stress levels at the 3.8.Enhancement in wall behavior3.8.1.In-plane shear capacityTable 3lists the observed ultimate in-plane shear capacities (V u )of different wall specimens.It is evident from the obtained result that substantial gains in strength,stiffness and ductility were achieved by applying the FRP laminates either on one or on both sides of the walls.Application of a single layer of carbon/epoxy in.(25.4mm)wide opening at the wall wedge Specimen W6-CS-RT:(a)compressive failure at the wall toe,(b)diagonal shear crack in the unstrengthened wall side and (c)cohesive failure of the vertical Part B 42(2011)1657–16703.8.2.Ultimate displacements and displacement ductilityLoad–displacement envelopes for as-built and retrofitted speci-mens are shown in Fig.19.Corresponding yield and ultimate dis-placement values of these specimens are listed in Table4.The figure and the table clearly indicate the enhancement in ductile behavior of the retrofitted walls.As compared to the as-built unre-inforced wall(UW1),increase in ultimate displacements of14%, 57%,59%and71%were observed for retrofitted specimens W3-C-RT,W4-C-RT,W5-E-RT and W6-CS-RT,respectively.Such enhance-ment of wall ultimate displacement however has no significant influence on the displacement ductility of the walls due to the fact that external retrofitting also contributed to the enhancement of wall displacement at yielding level.Exception is observed for spec-imen W5-E-RT,in which displacement ductility increased from2.6 to3.74due to retrofitting.3.8.3.Ultimate failure modeThe predominant failure mode of the as-built wall(WU1)was observed to be the diagonal cracking.The nature of failure was brittle due to the lack of horizontal shear reinforcement in this specimen.In retrofitted specimens,the common governing failure mode was compression failure of masonry units at one of the wall toes. In addition,a combination of diagonal tension cracks and step cracks was observed in the unstrengthened face of the specimen W3-C-RT(single-sided wet lay-up FRP strengthened wall)at ulti-mate load level.In specimen W6-CS-RT(wall retrofitted with pre-cured carbon strips),cohesive debonding of pre-cured car-bon/epoxy strips was observed at high stress levels.This failure mode was very unique to specimen W6-CS-RT and occurred fol-lowing a large deformation caused by the compression crushing of masonry at one of the wall toes.Overall,the brittle failure mode of unreinforced specimen changed to ductile failure due to the application of FRP composites on wall faces.4.Analytical estimation of in-plane shear strength of masonry wallsThe nominal shear strength(V n)of a masonry wall strengthened with FRP composites can be written as:V n¼V mþV fð1Þwhere V m and V f represent the shear strength contributions of ma-sonry units and FRP composites,respectively.4.1.In-plane shear strength of masonryThree kinds of failure modes namely joint sliding,diagonal ten-sion and toe crushing have generally been observed in unrein-forced masonry walls under in-plane shear force(ACI440.7R-10 [11]).Based on the physical parameters such as wall geometry, material properties,experimental loading scheme and wall bound-ary conditions,one of these three failure modes governs the ulti-mate failure of the wall.Testing of WU1under in-plane cyclic shear force clearly showed the failure mode of the unreinforced wall as diagonal tension.However,the unavailability of required mechanical properties of masonry(i.e.,axial compressive stress due to gravity load and masonry diagonal tensile strength)from the experimental set-up restricts the calculation of in-plane shear carrying capacity of WU1corresponding to the observed failure mode(i.e.,diagonal cracking).Therefore,this study uses the ana-lytical model given by Pauley and Priestley[21]to calculate the shear carrying capacity of unreinforced masonry units.According to this,shear contribution of masonry units(V m)can be expressed asV m¼v m d w t wð2Þwhere v m is the in-plane shear strength of masonry,and d w and t ware respectively the effective length and thickness of the wall.For a fully grouted wall,d w is generally considered as0.8times the length of the wall(L w).In regions except potential plastic hinges,v m(in MPa)is expressed asTable3Ultimate strength of tested wall specimens.Wall specimen Brief description ofspecimensUltimatestrength kN(kips)Strengthenhancement(%)WU1Control(as-built)369.2(83)–WU2Control(pre-cracked)275.8(62)–WU2-C-R Repair(both sides)444.8(100)20 W3-C-RT Retrofit with carbon/epoxy(one side)422.6(95)14W4-C-RT Retrofit with carbon/epoxy(both sides)480.4(108)30W5-E-RT Retrofit with E-glass/epoxy(both sides)498(112.1)35W6-CS-RT Retrofit with carbonstrips(one side)435.9(98)18A.Mosallam,S.Banerjee/Composites:Part B42(2011)1657–16701665v m¼0:17ffiffiffiffiffif0 mqþ0:3ðP u=A gÞ61:3ð3Þbut not greater thanv m¼0:75þ0:3ðP u=A gÞð4ÞHere f0mis the compressive strength of masonry,P u is the axial load on the wall and A g is the gross cross-sectional area of the wall foraxial loading.Applying f0m=2.16MPa,P u=480kN(axial load on walls),L w=1.83m and t w=152.4mm in above equations,the in-plane shear capacity of unretrofitted masonry wall(V m)is estimated as171kN.4.2.Shear strength contributions from FRP composite laminatesThis section calculates the contributions of FRP composite lam-inates to the total shear capacity of the retrofitted walls.Three ana-lytical models given in ACI440.7R-10[11],AC125[18],Garbin et al.[19]are used here which are discussed in the following sub-sections.In these,ACI440.7R-10[11],AC125[18]are code-based models while Garbin et al.[19]is a research-based model.Another research-based model,proposed by Triantafillou[20],to evaluate the shear carrying capacity of FRP retrofitted wall is discussed sep-arately in the later part of the paper.4.2.1.ACI440.7R-10[11]modelACI440.7R-10[11]provides the following equation to calculate the shear contribution of FRP strips(V f):V f¼pfw f L ws fð5Þwhere w f and s f respectively represent the width and spacing of FRP strips and L w is the length of masonry wall in the direction of shear force.p f expresses shear force per unit width of FRP laminates which can be evaluated aspf¼nt f f fe6260N=mmð6ÞHere n is the number of plies of FRP laminates with thickness t f andf fe represents the effective stress of FRP.According to ACI440.7R-10[11],f fe¼j vÂE fÂe fu in which e fu and E f are the ultimate shear strain and modulus of elasticity of composite material,respectively. The bond-dependent coefficient j v for shear-controlled failure modes depends on FRP reinforcement index x f in the following mannerxf ¼185A f E fA mffiffiffiffiffif0mpð7Þj v¼0:40for x f60:200:64À1:2x f for0:20<x f60:450:10for x f>0:458><>:ð8Þwhere A f and A m are the cross-sectional areas of FRP and masonry wall,respectively.The above equations are proposed for masonry walls retrofitted with FRP strips placed with a spacing s f in the direction of applied in-plane shear.The similar FRP lamination lay-out is found in specimen W6-CS-RT.Therefore,ACI440.7R-10guide is applicable for calculating the in-plane shear capacity of thisspecimen.In general,structural systems are more vulnerable under cyclicloading than static loading.Predictive models should account forthe effect of different lateral loading schemes on the nominal shearstrength of FRP systems.In this relation,ACI440.7R-10recom-mends reduced stress limits of FRP laminates to avaid creep-rup-ture of the externally applied FRP reinforcement under sustainedplus cyclic service loads.The loading scheme used in the presentexperimental study was cyclic loading.Therefore to be consistentwith the experimental set-up,a strength reduction factor r(=0.55for carbonfiber;recommended in ACI440.7R-10)is used in theanalytical evaluation.Hence,the effective stress of FRP under sus-tained and cyclic loading becomes f fe¼rÂj vÂE fÂe fu.Table5 shows the effective stress of specimen ing the valuesof A f,s f,L w from experimental set-up and the properties of pre-cured carbon strips,V f of specimen W6-CS-RT is calculated as238kN(Table5).ACI440.7R-10does not provide any guideline for calculating V fwhen masonry walls are retrofitted with continuousfiber lami-nates such as in specimens W3-C-RT,W4-C-RT and W5-E-RT.Hence,no calculation of V f of these specimens are done using ACI440.7R-10model.4.2.2.AC125[18]modelAccording to section7.3.2.6.3of AC125[18],the shear strengthenhancement due to the application of FRP composite laminateeither on one or on both sides of rectangular wall specimens is cal-culated as follows.For one-sided retrofit:V f¼0:75t f f f L w sin2hð9ÞFor both-sided retrofit:V f¼2t f f f L w sin2hð10Þwhere L w,t f and h respectively represent the length of the wall in the direction of applied shear force,thickness of FRP laminates and angle offibers to the member axis.In these above two equa-tions(Eqs.(9)and(10)),f f denotes developed stress in composite laminates which is expressed as0.0015E f for one-sided retrofitted walls and0.004E f for completely wrapped(from all four sides)walls with E f being the modulus of elasticity of composite materials.In both cases,f f should be smaller or equal to0.75times the ultimate tensile strength of composite materials(f fu).For wall specimen W3-C-RT(retrofitted with one layer of carbon/epoxy laminate on one side),Eq.(9)is used to calculate V f and the value is obtained as 291kN.For both-sided retrofitted wall specimens(i.e.,W4-C-RT and W5-E-RT),Eq.(10)cannot be applied to calculate V f as these walls were not completely wrapped with FRP laminates.However, according to the retrofitting scheme of these specimens,wall faces are regarded as two individual one-sided retrofitted specimens. Such consideration allows us to apply Eq.(9)for specimens W4-C-RT and W5-E-RT with a multiplication factor of2.0.Calculation resulted in V f of these two specimens as582kN and401kN, respectively.AC125does not provide any guideline for calculating in-plane shear strength contribution of FRP when masonry walls are retro-Table4Yield and ultimate displacements and displacement ductility of wall specimens.Wall specimens WU1W3-C-RT W4-C-RT W5-E-RT W6-CS-RT Yield displacement D y(mm) 3.45 3.66 5.08 3.8 6.1 Ultimate displacement D u(mm)8.9410.1614.0014.2015.30 Enhancement in ultimate displacement(%)D u;WÃÀRTÀD u;WU1D u;WU1Â100%–14575971 Displacement ductility DD=D u/D y 2.6 2.78 2.75 3.74 2.51666 A.Mosallam,S.Banerjee/Composites:Part B42(2011)1657–1670。

Masonry StructuresMasonry is one of man’s oldest building materials and probably one of the most maligned and most certainly least understood. Such misconceptions have led over the years to a serious misuse of the material through inadequate or even nonexistent design procedures and poor construction practices. However, perhaps because of the considerable amount of information and data available today, both as to its properties and structural performance, sound design techniques and vastly improved construction practices have evolved within recent years, all of which make for optimum use of the material’s capabilities. This is in no small way due to the effort continually being exerted toward this evolution by such diverse agencies as the International Conference of Building Officials and the Masonry Institute of America (MIA)Masonry is a totally different and distinct type of construction material, not one that is “sort of like reinforced concrete.” It is not, and should not, be treated as such. Furthermore, the wind, seismic, and structural performance research carried on during the recent past has resulted in building codes of increasing complexity. This, in turn, has led to more sophisticated and comprehensive methods of design.Masonry is primarily a hand-placed material whose performance is highly influenced by factors of placement. Hence, knowledge of the basic ingredients (i.e., mortar, grout, masonry unit, and reinforcement) is essential if a practical and efficient design conception is to be achieved. In addition, if the design is to be brought to a successful fruition, as its designer conceived it, proper inspection procedures must be followed to ensure that its delivery will be more certain. Furthermore, before anyone can hope to turn out an adequate design of any sort, he or she must possess a rudimentary knowledge of the properties and performance of the material employed.Next in the process comes the need for a description of the various load sources and intensities, a presentation of the fundamental precepts, and the development of the very basic design and analysis expressions as they evolve from the basic structural mechanics without reference to code limitations or empirical rules. The many code requirements must then be incorporated into these basic expressions and relations to produce an integrated design procedure, one that will result in very practical solutions to the engineering problems normally encountered by structural engineers in everyday practice. The total design of a masonry building begins with a consideration of the preliminary and nonstructural aspects of masonry bearing on the case study, such as its fire-resistive orenvironmental features. Following this examination comes the determination of the live, dead, seismic, and wind loads — their magnitudes and stress paths from point of application to ground. Finally, the member sizes and reinforcing requirements are selected, adequate connections are devised, and the system is detailed such that it can be readily constructed. The latter is an extremely important consideration, but one too often slighted or ignored. In the past, this total concept has not been given the emphasis it deserves. Many textbooks seem to ignore the aspect of stability of the total framing system as it resistslateral loads, focusing instead on the behavior of the individual beams, columns, walls, and other elements comprising the system. Certainly, modern buildings almost everywhere are subjected to significant lateral loads of one type or another to varying degrees of magnitude. The placement of the entire country into seismic zones of various degrees of probability and intensity has only served to accentuate this critical factor. To ignore it is folly, as some have found to their chagrin. It really is not overly difficult to design a building to withstand gravity loads. But developing a lateral-force-resisting system (frame, shear walls, or combination thereof) requires skill and imagination — a process that taxes the ingenuity of structural engineers to come up with solutions that are in all ways safe, practical, and yet economical.Brick is actually the oldest manufactured building material remaining in use today. In the premodern era, the development of brick masonry reached its fruition in the United States and Europe. The successful use of this ancient material is certainly demonstrated in many early American brick structures, such as in Chicago. But its very massiveness discouraged further use of unreinforced masonry bearing walls for high-rise buildings. This condition remained unchanged for nearly 50 years, awaiting the advent of modern reinforced masonry. The Monadnock represented the watershed, in America at least, of the use of plain masonry bearing walls.Modern Techniques of Design and ConstructionProbably the most advanced state of the art of masonry construction in its present from is to be found in California. With its long history of earthquake activity, this is not surprising. The 1933 Long Beach earthquake proved conclusively that unreinforced masonry, with its lime-mortar joins, cannot adequately withstand seismic shocks because of the lack of tensile and shear resistance. This fact provided the impetus for further development of design techniques for reinforced masonry as well as for improved high-rise construction methods by using a structurally integrated masonry element (masonry unit + mortar + grout +reinforcement) , thereby producing much greater lateral load resistance. This was an absolutely imperative step if brick masonry were to remain a major construction material. California under the revised building codes. Otherwise, it would have been “codified” out of existence. These advanced techniques of design and construction are embodied in modern high-rise buildings being constructed throughout the United States.In this new concept of high-rise reinforced masonry, the walls function to carry both the gravity and the lateral forces, and the floors and roofs serve as horizontal diaphragms to transfer wind or seismic loads to the bearing shear walls. To achieve this behavior, however, the floor-to-wall connections must be capable of transferring all lateral forces to or from those walls. In addition, the gravity loads on the walls are counted develop resistance to overturning. This concept results in reduced construction time while providing a final building from that is esthetically pleasing. This type of construction has the advantages of sound control, thermal inertia, fire resistance, and low maintenance—features long associated with masonry structures, and ones that carry a high priority in our present energy-deficient era.Classifications of Masonry ConstructionThe classifications of masonry construction and the types of masonry walls appear in the UBC. The distinction between these various categories must be thoroughly understood by anyone who intends to design masonry under UBC jurisdiction. For this reason, they are thoroughly delineated in the following sections.Masonry construction is classified as follows: (1) “reinforced masonry,” which must be engineered on the basis of sound theoretical principles combined with a set of empirical rules and limitations set forth by the Building Code, plus sound engineering judgment stemming from long experience; (2) “partially reinforced masonry,” which was introduced into the Uniform Building Code primarily for those areas in which all the requirements of reinforced masonry were not needed, since the seismicity of the locale did not so dictate; (3) “unreinforce d engineered masonry,” which was developed in the East as an attempt to improve on past practices, many of which were unsound; and (4) “traditional masonry,” which encompasses the use of masonry as it evolved over the years from certain arbitrary limitations and past practices without any real consideration for theoretical design characteristics; although it did provide for a generally conservative and safe type of construction for the majority of conditions.Types of Masonry WallsUnburned Clay MasonryUnburned clay masonry consists of unburned clay units, commonly referred to as “adobe” in the southwestern part of the United States. In earlier and less sophisticated days, it did perform quite satisfactorily where no seismic activity of any magnitude occurred. The early adobe was actually reinforced with straw and often also contained an emulsion that provided for greater compressive strength and durability. No particular energy problem was posed here, since it was sun-dried. Structural connections were a problem and, of course, the adobe possessed practically no tension value. It can still be used in restricted areas with type M or S mortar. At any rate, it served a very important function in the early day, as the numerous missions in California and throughout the Southwest will attest. It also was utilized as an important housing material. The church located in the Los Angeles Plaza, was built of sun-dried clay and protected by plaster.Gypsum MasonryGypsum masonry consists of gypsum block or gypsum tile units laid up with gypsum mortar.It has been used in the past,with considerable success,for interior partitions,primarily because of the ease with which it can be formed around ducts,window openings,and otherdiscontinuities.It is also permitted in some “partially reinforced”walls.Gypsum tile is laid up in gypsum mortar,similar to that used in plaster.The proportions consist of approximately one part gypsum to three parts sand,mixed with a sufficient amount of water to provide a good workable mortar.Since gypsum is fast-setting,the mortar sets up so rapidly that it has alimited”board”life.Thus,it is generally necessary to add a retarder of somesort,composed usually of certain organic materials.Gypsum tile,like unreinforced brick masonry,received a bad press after the 1933 Long Beach earthquake,again because of material misuse,not because of any property deficiencies.Without adequate reinforcing and connections,these materials cannot stand up against earthquake load intensities.One method of bolstering the capability of the gypsum wall would be achieved by attachinga”chicken-wire”reinforcing mesh directly to bothsides of the partition.Plaster is then applied over these surfaces.The resulting wire plaster facing has porved to be effective,at least in resisting the perpendicular horizontal loads on a nonbearing wall.A similar approach was advanced back in the 1950s,by the Los Angeles Board of Education,ostensibly as a means of rehabilitating pre-1933 unreinforced masonry school building.Glass MasonryGlass masonry units are used in the openings lf non-load bearing exterior or interior walls.These filler panels must be at least 3 in.(1in=1/2ft)thick and the mortared surfaces of the boocks have to be treated to provide an adequate mortar-bonding effect.This is usually achieved by applying a roughened surface abhesive to the glass edges.The panels themselves must be restrained laterally to resist the lateral-force effects of winds or earthquakes. Also, the sizes of the exterior panels are arbitrarily limited to a maximum vertical or horizontal dimension of 15 ft(1ft=0.305m) and an area of 144 ft2. For interior glass block panels, these limits are 25 ft and 250 ft2. Exceptions are permissible if calculations can substantiate the deviations.The glass blocks must be laid in Type S mortar with both vertical and horizontal joints being between 1/4 and 3/8 in.(1 in= 1/12 ft) thick. Reinforcement, as required by calculations, is provided. Exterior glass block panels have to be provided with 1/2-in. expansion joints at the sides and at the top, and they must be entirely free of mortar so that the space can be filled with a resilient material to provide for needed movement. The expansion joint, of course, must also provide for lateral support while permitting expansion and contraction of the glass panel.Stone MasonryStone masonry is that form of construction made with natural or cast stone as the basic masonry unit, set in mortar with the joints thoroughly filled.In ashlar masonry, the bond stones are uniformly distributed and have to cover at least 10% of the area of the exposed facets. Rubble stone masonry, 24 in. or less in thickness, will have bond stones spaced a maximum of 3 ft both vertically and horizontally. Should the thickness exceed 24 in. , the bond stone spacing is increased to 6 ft on both sides.There are other limits, arbitrarily established. The maximum height/thickness ratio is 14, and the minimum wall thickness is 16 in. If regularly cut or shaped stones are used, they may be laid as solid or grouted brick masonry.Cavity Wall MasonryCavity wall masonry is construction using brick, structural clay tile, concrete masonry, or any combination thereof, in which the facing and the backing wythesare completely separated except for metal ties that serve as cross ties or bonding elements. This is the type now permitted by the UBC in lieu of an earlier type of cavity wall masonry, in which the two faces of the walls were separate but bonded together with transverse solid masonry units. The maximumheight/thickness ratio is limited to 18, with the minimum thickness being 8in.The cavity wall facing and backing wythes cannot be less than 4 in. in thickness, expect that when both are constructed with clay or shale brick the limit decreases to 3 in.nominal thickness. The separating cavity must be between 1 and 4in. in width; however, special calculation in tie size or spacing may permit the use of greater or lesser cavitiesThe two wythes have to be bonded together with 3/16in. metal ties embedded in the horizontal mortar joint. Tie spacing is limited such that they support to more than 4.5ft of wall area for cavity widths up to 3.5in. Where the cavity width exceeds 3.5 in. this limit becomes 3ft of wall area. The tie spacing is always staggered in alternate courses, with the maximum vertical distance between ties being 24in. and the maximum horizontal spacing 35 in. For hollow masonry units laid with the cells vertical, the ties have to be rectangular in shape. Where other types of units are units are used, a 90 bend provides the special anchorage. Additional bonding ties must be placed at all openings, spaced at 3 ft maximum around the perimeter of the openings, within 12in. of openings.Hollow Unit MasonryHollow unit masonry describes a type of wall construction that consists of hollow masonry units set in mortar as they are laid in the wall. All units have to be laid with full-face shell mortar beds, with the head or end joints filled solidly with mortar for a distance in from the face of the unit not less than the thickness of the longitudinal face shells. This type of construction usually refers to an unreinforced state, although it actually can be reinforce.Where the wall thickness consists of two or more hollow units placed side by side, the stretcher unit must be bonded at vertical intervals not to exceed 34 in. This bonding is accomplished by lapping a block at least 4in. over the unit below, or by lapping them at vertical intervals not to exceed 17. whit units that are at least 50% greater in thickness than the units below. They can also be bonded together with corrosion-resistant metal ties which conform to those requirements for cavity walls, as previously noted. Ties at alternate courses need to be staggered, with the maximum vertical distance between ties being 18. and the maximum horizontal distance 36. walls bonded with metal ties must then conform to the allowable stress, lateral support, thickness(excluding cavity), height, and mortar requirements for cavity walls. Since this material is not reinforced, the maximum height/thickness ratio is 18, with a minimum thickness of 8 in.Solid masonrySolid masonry consists of brick, or solid load-bearing concrete masonry units laid up contiguously in mortar. All units are laid with full shoved mortar joints, and the head, bed, and wall joints have to be solidly filled with mortar. In each wythe, at least 75% of the units in any vertical transverse plane must lap the ends of theunit above and below a distance notless than 1.5 in.. , nor less than one-half the height of the units, whichever is greater. Otherwise, the masonry is to be reinforced longitudinally to provide for a loss of bond, as in the case of masonry laid in stack bond. The longitudinal reinforcement amounts to a minimum of two continuous wires in each wythe, with a minimum total cross-sectional area of 0.017 in2. being provided in the horizontal bed joints, with the spacing not to exceed 16 in. center to center vertically. Considerable dispute has arisen over this arbitrarily selected amountof reinforcement. For example, if one uses 6-in.-high units, the horizontal reinforcement may be spaced at 18 in. instead of 16 in. so that it conforms to the module of three 6-in. courses. This alternative of replacing the masonry unit bond by reinforcing steel is more significant with concrete units than with clay units, simply because the mortar bond to clay units is generally better than the mortar bond to concrete units. Even more important, the clay units do not have the very considerable drying shrinkage characteristic that the concrete units possess. On the contrary, clay units undergo a slight expansion due to moisture content rather than demonstrating any tendency to shrink.Facing and backing can be bonded with corrosion-resistant unit metal ties or cross wires conforming to the cavity wall requirements previously noted. The unit ties have to be long enough to engage all wythes, with the ends embedded no less than 1 in. in mortar, or they can consist of two lengths, with the inner embedded ends hooked lapped not less than 2 in. When the space between the metal tied wythes is solidly filled with mortar, the allowable stresses and other provision for bonded masonry walls apply. However, where the space is not filled, they must meet the requirements for cavity walls.。

第35卷第3期2019年6月Vol. 35 ,No. 3Jun82019结构工程师 SUucturai Engineers用于装配式墙体的加长型混凝土砌块砌体的受力性能试验研究朱婉婕％黄靓滕瀚思％林波2蔡安谷2（1.湖南大学土木工程学院，长沙410082 ； 2.贵州兴贵恒远新型建材有限公司，安顺561000）摘要为方便机械砌筑，装配式砌块砌体墙体被设计成无竖向灰缝,加长砌块砌筑形式。

通过对比两种不同影响因素（不同砌筑方式、有无竖向灰缝）18个抗压试件、27个抗剪试件的静力试验，研究了用于装配式墙体的加长型混凝土砌块砌体的抗压强度、抗剪强度及破坏模式等力学性能。

试验结果表明,无竖向灰缝的机器砌筑工厂预制试件与有竖向灰缝的人工砌筑试件的抗压强度和抗剪强度均满足规范 要求，说明无竖向灰缝的机器砌筑替代有竖向灰缝人工砌筑可行。

关键词 装配式墙体，混凝土砌块砌体，机器砌筑，力学性能Research on Mechanical Properties of PrefabricatedLengtUened Concrete Block MasonryZHU Wanjia 1 HUANG Liang 1，* TENG Hansi 1 LIN Bo 2 CAI Angu 2收稿日期：2018 -03 -20基金项目：国家自然科学基金（5178193）作者简介：朱婉婕，女，助理工程师，主要研究方向为装配式建筑。

Email ：358911383@qq. 50m*联系作者：黄 靓，男，教授，主要研究方向为装配式建筑。

Email ：huangliangstudy@ 126. 50m(1. Colleae of Civil Engineering , Hunan University , Changsha 410082 , China ；2. Xing Guiyang Heng Yuan Building Materials , Anshun 561000, China )Abstraci In order to OOPtma ths mechanical masonry , tha prefabricated masonry wal l was designed to no eeeeicaam7eeaaand used aengehened back mas7ney.In ehispapee , 18 c7mpee s ieespecimensand 27 sheae specimens were tested U investiyata to tha mechanical propertias and failure mods of extension typo concretablock masonry for prefabricated wall ,through tuo kinds of factors ( building method and vertical mortal joint )- Tha result shows that tha prefabricated masonry specimen without vertical mortar and tha artificial masonryspecimen with vertical mortar meet tha design requirement. It is proved that tha machina masonry without vertical mortar is feasibia for artiPcial masona with vertical mortar .Keyworis prefabricated wall , concreta block wall , machina masonry , mechanical property0引言目前我国填充墙主要是利用小型空心砌块现场砌筑的砌体墙,此类砌体墙虽具有造价低、材料可就地取材、隔火隔热和隔音性能好等优点,但其同时存在施工过程中劳动力成本高，劳动强度大,费时长，施工工艺复杂以及施工质量、成本不易控制等缺点。

1引言墙体作为房屋的承重结构，在建筑的稳定性和安全性方面起着关键作用。

然而，在实际的施工过程中，由于墙体砌筑施工对材料和技术要求较高，选材不当可能导致墙体强度不够，施工工艺不够合理可能导致墙体出现开裂等问题。

其次，随着房屋使用年限的增加，墙体可能会出现老化、沉降等问题，需要进行加固来提升墙体的承重能力和稳定性。

通过分析和总结不足之处，可以改进选材、施工工艺和加固方法，提高墙体的质量和可靠性。

因此，本研究旨在探讨房建工程中墙体砌筑施工与加固工程的相关问题，提出改进方案并加以实践验证。

2墙体砌筑施工概述砌筑施工是指在房屋建设过程中，使用砖、石、混凝土等材料，按照一定的施工工艺，将墙体逐层逐块地搭建起来的过程。

墙体的砌筑应遵循科学的施工工艺和标准，以确保施工质量和建筑的安全可靠。

目前房建工程中墙体砌筑主要有4种类型，具体见图1。

a一顺一丁b 梅花丁c三顺一丁d上下错缝图1墙体砌筑的几种类型图1a 为一顺一丁砌墙法，砖墙每层砌筑方向相同，每两层错开一个砖头，形成一顺一丁的错缝；图2b 为梅花丁砌墙法，每一层砖墙砌筑时，砖头的位置交错，形成梅花状的错缝；图3c 为三顺一丁砌墙法，每3层砖墙方向相同，每两层以及第三层与第一层错开一个砖头，形成三顺一丁的错缝；图4d 为上下错缝法，上下相邻的两层砖墙方向相反，使得两层之间的砖头错开，形成上下错开的错缝。

这几种形式的砌筑方式能【作者简介】罗凤林（1974~），男，贵州黄平人，高级工程师，从事土建工程研究。

房建工程中墙体砌筑施工与加固工程研究Research on Wall Masonry Construction and Reinforcement Engineeringin Housing Engineering罗凤林（贵州中建伟业建设（集团）有限责任公司,贵州凯里556100）LUO Feng-lin(Guizhou Zhongjian Weiye Construction(Grop)Co.Ltd.,Kaili 556100,China)【摘要】针对现阶段房建工程中墙体砌筑施工与加固工程的相关问题，分析了墙体砌筑施工的基本步骤和技术要点，提出了嵌入钢筋加固墙体的方法和要点。