土木工程毕业设计外文翻译

DESIGN AND EXECUTION OF GROUNDINVESTIGATION FOR EARTHWORKSPAUL QUIGLEY, FGSIrish Geotechnical Services LtdABSTRACTThe design and execution of ground investigation works for earthwork projects has become increasingly important as the availability of suitable disposal areas becomes limited and costs of importing engineering fill increase. An outline of ground investigation methods which can augment …traditional investigation methods‟ particularly for glacial till / boulder clay soils is presented. The issue of …geotechnical certification‟ is raised and recommendations outlined on its merits for incorporation with ground investigations and earthworks.1. INTRODUCTIONThe investigation and re-use evaluation of many Irish boulder clay soils presents difficulties for both the geotechnical engineer and the road design engineer. These glacial till or boulder clay soils are mainly of low plasticity and have particle sizes ranging from clay to boulders. Most of our boulder clay soils contain varying proportions of sand, gravel, cobbles and boulders in a clay or silt matrix. The amount of fines governs their behaviour and the silt content makes it very weather susceptible.Moisture contents can be highly variable ranging from as low as 7% for the hard grey black Dublin boulder clay up to 20-25% for Midland, South-West and North-West light grey boulder clay deposits. The ability of boulder clay soils to take-in free water is well established and poor planning of earthworks often amplifies this.The fine soil constituents are generally sensitive to small increases in moisture content which often lead to loss in strength and render the soils unsuitable for re-use as engineering fill. Many of our boulder clay soils (especially those with intermediate type silts and fine sand matrix) have been rejected at the selection stage, but good planning shows that they can in fact fulfil specification requirements in terms of compaction and strength.The selection process should aim to maximise the use of locally available soils and with careful evaluation it is possible to use or incorporate …poor or marginal soils‟ within fill areas and embankments. Fill material needs to be placed at a moisture content such that it is neither too wet to be stable and trafficable or too dry to be properly compacted.High moisture content / low strength boulder clay soils can be suitable for use as fill in low height embankments (i.e. 2 to 2.5m) but not suitable for trafficking by earthwork plant without using a geotextile separator and granular fill capping layer. Hence, it is vital that the earthworks contractor fully understands the handling properties of the soils, as for many projects this is effectively governed by the trafficability of earthmoving equipment.2. TRADITIONAL GROUND INVESTIGATION METHODSFor road projects, a principal aim of the ground investigation is to classify the suitability of the soils in accordance with Table 6.1 from Series 600 of the NRA Specification for Road Works (SRW), March 2000. The majority of current ground investigations for road works includes a combination of the following to give the required geotechnical data:▪Trial pits▪Cable percussion boreholes▪Dynamic probing▪Rotary core drilling▪In-situ testing (SPT, variable head permeability tests, geophysical etc.)▪Laboratory testingThe importance of …phasing‟ the fieldwork operations cannot be overstressed, particularly when assessing soil suitability from deep cut areas. Cable percussion boreholes are normally sunk to a desired depth or …refusal‟ with disturbed a nd undisturbed samples recovered at 1.00m intervals or change of strata.In many instances, cable percussion boring is unable to penetrate through very stiff, hard boulder clay soils due to cobble, boulder obstructions. Sample disturbance in boreholes should be prevented and loss of fines is common, invariably this leads to inaccurate classification.Trial pits are considered more appropriate for recovering appropriate size samples and for observing the proportion of clasts to matrix and sizes of cobbles, boulders. Detailed and accurate field descriptions are therefore vital for cut areas and trial pits provide an opportunity to examine the soils on a larger scale than boreholes. Trial pits also provide an insight on trench stability and to observe water ingress and its effects.A suitably experienced geotechnical engineer or engineering geologist should supervise the trial pitting works and recovery of samples. The characteristics of the soils during trial pit excavation should be closely observed as this provides information on soil sensitivity, especially if water from granular zones migrates into the fine matrix material. Very often, the condition of soil on the sides of an excavation provides a more accurate assessment of its in-situ condition.3. SOIL CLASSIFICATIONSoil description and classification should be undertaken in accordance with BS 5930 (1999) and tested in accordance with BS 1377 (1990). The engineering description of a soil is based on its particle size grading, supplemented by plasticity for fine soils. For many of our glacial till, boulder clay soils (i.e. …mixed soils‟) difficulties arise with descriptions and assessing engineering performance tests.As outlined previously, Irish boulder clays usually comprise highly variable proportions of sands, gravels and cobbles in a silt or clay matrix. Low plasticity soils with fines contents of around 10 to 15% often present the most difficulties. BS 5930 (1999) now recognises thesedifficulties in describing …mixed soils‟ – the fine soil constituents which govern the engineering behaviour now takes priority over particle size.A key parameter (which is often underestimated) in classifying and understanding these soils is permeability (K). Inspection of the particle size gradings will indicate magnitude of permeability. Where possible, triaxial cell tests should be carried out on either undisturbed samples (U100‟s) or good quality core samples to evaluate the drainage characteristics of the soils accurately.Low plasticity boulder clay soils of intermediate permeability (i.e. K of the order of 10-5 to 10-7 m/s) can often be …conditioned‟ by drainage measures. This usually entails the installation of perimeter drains and sumps at cut areas or borrow pits so as to reduce the moisture content. Hence, with small reduction in moisture content, difficult glacial till soils can become suitable as engineering fill.4. ENGINEERING PERFORMANCE TESTING OF SOILSLaboratory testing is very much dictated by the proposed end-use for the soils. The engineering parameters set out in Table 6.1 pf the NRA SRW include a combination of the following:▪Moisture content▪Particle size grading▪Plastic Limit▪CBR▪Compaction (relating to optimum MC)▪Remoulded undrained shear strengthA number of key factors should be borne in mind when scheduling laboratory testing:▪Compaction / CBR / MCV tests are carried out on < 20mm size material.▪Moisture content values should relate to < 20mm size material to provide a valid comparison.▪Pore pressures are not taken into account during compaction and may vary considerably between laboratory and field.▪Preparation methods for soil testing must be clearly stipulated and agreed with the designated laboratory.Great care must be taken when determining moisture content of boulder clay soils. Ideally, the moisture content should be related to the particle size and have a corresponding grading analysis for direct comparison, although this is not always practical.In the majority of cases, the MCV when used with compaction data is considered to offer the best method of establishing (and checking) the suitability characteristics of a boulder clay soil. MCV testing during trial pitting is strongly recommended as it provides a rapid assessment of the soil suitability directly after excavation. MCV calibration can then be carried out in the laboratory at various moisture content increments. Sample disturbance can occur during transportation to the laboratory and this can have a significant impact on the resultant MCV‟s.IGSL has found large discrepancies when p erforming MCV‟s in the field on low plasticity boulder clays with those carried out later in the laboratory (2 to 7 days). Many of the aforementioned low plasticity boulder clay soils exhibit time dependant behaviour with significantly different MCV‟s reco rded at a later date –increased values can be due to the drainage of the material following sampling, transportation and storage while dilatancy and migration of water from granular lenses can lead to deterioration and lower values.This type of information is important to both the designer and earthworks contractor as it provides an opportunity to understand the properties of the soils when tested as outlined above. It can also illustrate the advantages of pre-draining in some instances. With mixed soils, face excavation may be necessary to accelerate drainage works.CBR testing of boulder clay soils also needs careful consideration, mainly with the preparation method employed. Design engineers need to be aware of this, as it can have an order of magnitude difference in results. Static compaction of boulder clay soils is advised as compaction with the 2.5 or 4.5kg rammer often leads to high excess pore pressures being generated – hence very low CBR values can result. Also, curing of compacted boulder clay samples is important as this allows excess pore water pressures to dissipate.5. ENGINEERING CLASSIFICATION OF SOILSIn accordance with the NRA SRW, general cohesive fill is categorised in Table 6.1 as follows: ▪2A Wet cohesive▪2B Dry cohesive▪2C Stony cohesive▪2D Silty cohesiveThe material properties required for acceptability are given and the design engineer then determines the upper and lower bound limits on the basis of the laboratory classification and engineering performance tests. Irish boulder clay soils are predominantly Class 2C.Clause 612 of the SRW sets out compaction methods. Two procedures are available: ▪Method Compaction▪End-Product CompactionEnd product compaction is considered more practical, especially when good compaction control data becomes available during the early stages of an earthworks contract. A minimum Target Dry Density (TDD) is considered very useful for the contractor to work with as a means of checking compaction quality. Once the material has been approved and meets the acceptability limits, then in-situ density can be measured, preferably by nuclear gauge or sand replacement tests where the stone content is low.As placing and compaction of the fill progresses, the in-situ TDD can be checked and non-conforming areas quickly recognised and corrective action taken. This process requires the design engineer to review the field densities with the laboratory compaction plots and evaluate actual with …theoretical densities‟.6. SUPPLEMENTARY GROUND INVESTIGATION METHODS FOR EARTHWORKSThe more traditional methods and procedures have been outlined in Section 2. The following are examples of methods which are believed to enhance ground investigation works for road projects:▪Phasing the ground investigation works, particularly the laboratory testing▪Excavation & sampling in deep trial pits▪Large diameter high quality rotary core drilling using air-mist or polymer gel techniques▪Small-scale compaction trials on potentially suitable cut material6.1 PHASINGPhasing ground investigation works for many large projects has been advocated for many years –this is particularly true for road projects where significant amounts of geotechnical data becomes available over a short period. On the majority of large ground investigation projects no peri od is left to …digest‟ or review the preliminary findings and re-appraise the suitability of the methods.With regard to soil laboratory testing, large testing schedules are often prepared with no real consideration given to their end use. In many cases, the schedule is prepared by a junior engineer while the senior design engineer who will probably design the earthworks will have no real involvement.It is highlighted that the engineering performance tests are expensive and of long duration (e.g. 5 point compaction with CBR & MCV at each point takes in excess of two weeks). When classification tests (moisture contents, particle size analysis and Atterberg Limits) are completed then a more incisive evaluation can be carried out on the data and the engineering performance tests scheduled. If MCV‟s are performed during trial pitting then a good assessment of the soil suitability can be immediately obtained.6.2 DEEP TRIAL PITSThe excavation of deep trial pits is often perceived as cumbersome and difficult and therefore not considered appropriate by design engineers. Excavation of deep trial pits in boulder clay soils to depths of up to 12m is feasible using benching techniques and sump pumping of groundwater.In recent years, IGSL has undertaken such deep trial pits on several large road ground investigation projects. The data obtained from these has certainly enhanced the geotechnical data and provided a better understanding of the bulk properties of the soils.It is recommended that this work be carried out following completion of the cable percussion boreholes and rotary core drill holes. The groundwater regime within the cut area will play an important role in governing the feasibility of excavating deep trial pits. The installation of standpipes and piezometers will greatly assist the understanding of the groundwater conditions, hence the purpose of undertaking this work late on in the ground investigation programme.Large representative samples can be obtained (using trench box) and in-situ shear strength measured on block samples. The stability of the pit sidewalls and groundwater conditions can also be established and compared with levels in nearby borehole standpipes or piezometers. Over a prominent cut area of say 500m, three deep trial pits can prove invaluable and the spoil material also used to carry out small-scale compaction trials.From a value engineering perspective, the cost of excavating and reinstating these excavations can be easily recovered. A provisional sum can be allocated in the ground investigation and used for this work.6.3 HIGH QUALITY LARGE DIAMETER ROTARY CORE DRILLINGThis system entails the use of large diameter rotary core drilling techniques using air mist or polymer gel flush. Triple tube core drilling is carried out through the overburden soils with the recovered material held in a plastic core liner.Core recovery in low plasticity boulder clay has been shown to be extremely good (typically in excess of 90%). The high core recovery permits detailed engineering geological logging and provision of samples for laboratory testing.In drumlin areas, such as those around Cavan and Monaghan, IGSL has found the use of large diameter polymer gel rotary core drilling to be very successful in recovering very stiff / hard boulder clay soils for deep road cut areas (where cable percussion boreholes and trial pits have failed to penetrate). In-situ testing (vanes, SPT‟s etc) can also be carried out within the drillhole to establish strength and bearing capacity of discrete horizons.Large diameter rotary drilling costs using the aforementioned systems are typically 50 to 60% greater than conventional HQ core size, but again from a value engineering aspect can prove much more worthwhile due to the quality of geotechnical information obtained.6.4 SMALL-SCALE COMPACTION TRIALSThe undertaking of small-scale compaction trials during the ground investigation programme is strongly advised,particularly where …marginally suitable‟ soils are present in prominent cut areas. In addition to validating the laboratory test data, they enable more realistic planning of the earthworks and can provide considerable cost savings.The compaction trial can provide the following:▪Achievable field density, remoulded shear strength and CBR▪Establishing optimum layer thickness and number of roller passes▪Response of soil during compaction (static v dynamic)▪Monitor trafficability & degree of rutting.A typical size test pad would be approximately 20 x 10m in plan area and up to 1.5m in thickness. The selected area should be close to the cut area or borrow pit and have adequate room for stockpiling of material. Earthwork plant would normally entail a tracked excavator (CAT 320 or equivalent), 25t dumptruck, D6 dozer and either a towed or self-propelled roller. In-situ density measurement on the compacted fill by nuclear gauge method is recommended as this facilitates rapid measurement of moisture contents, dry and bulk densities. It alsoenables a large suite of data to be generated from the compacted fill and to assess the relationship between degree of compaction, layer thickness and number of roller passes. Both disturbed and undisturbed (U100) samples of the compacted fill can be taken for laboratory testing and validation checks made with the field data (particularly moisture conte nts). IGSL‟s experience is that with good planning a small-scale compaction trial takes two working days to complete.7. SUPERVISION OF GROUND INVESTIGATION PROJECTSClose interaction and mutual respect between the ground investigation contractor and the consulting engineer is considered vital to the success of large road investigation projects. A senior geotechnical engineer from each of the aforementioned parties should liase closely so that the direction and scope of the investigation can be changed to reflect the stratigraphy and ground conditions encountered.The nature of large ground investigation projects means that there must be good communication and flexibility in approach to obtaining data. Be prepared to compromise as methods and procedures specified may not be appropriate and site conditions can quickly change.From a supervision aspect (both contractor and consulting engineer), the emphasis should be on the quality of site-based geotechnical engineers, engineering geologists as opposed to quantity where work is duplicated.8. GEOTECHNICAL CERTIFICATIONThe Department of Transport (UK) prepared a document (HD 22/92) in 1992 for highway schemes. This sets out the procedures and documentation to be used during the planning and reporting of ground investigations and construction of earthworks.Road projects involving earthmoving activities or complex geotechnical features must be certified by the Design Organisation (DO) - consulting engineer or agent authority. The professional responsibility for the geotechnical work rests with the DO.For such a project, the DO must nominate a chartered engineer with appropriate geotechnical engineering experience. He/she is referred to as the Geotechnical Liaison Engineer (GLE) and is responsible for all geotechnical matters including preparation of procedural statements, reports and certificates.Section 1.18 of HD 22/92 states that “on completion of the ground investigation works, the DO shall submit a report and certificate containing all the factual records and test results produced by the specialist contractor together with an interpretative report produced either by the specialist contractor or DO”. The DO shall then prepare an Earthworks Design Report –this report is the Designer‟s detailed report on his in terpretation of the site investigation data and design of earthworks.The extent and closeness of the liaison between the Project Manager and the GLE will very much depend on the nature of the scheme and geotechnical complexities discovered as the investigation and design proceed.After the earthworks are completed, a geotechnical feedback report is required and is to be prepared by the DO. This addresses the geotechnical issues and problems encountered during the construction earthworks and corrective action or measures taken. Certificates are prepared by the DO to sign off on the geotechnical measures carried out (e.g. unstable slopes, karst features, disused / abandoned mine workings, ground improvement systems employed, etc).9. CONCLUSIONS▪Close co-operation is needed between ground investigation contractors and consulting engineers to ensure that the geotechnical investigation work for the roads NDP can be satisfactorily carried out.▪Many soils are too easily rejected at selection / design stage. It is hoped that the proposed methods outlined in this paper will assist design engineers during scoping and specifying of ground investigation works for road projects.▪With modern instrumentation, monitoring of earthworks during construction is very straightforward. Pore water pressures, lateral and vertical movements can be easily measured and provide important feedback on the performance of the engineered soils.▪Phasing of the ground investigation works, particularly laboratory testing is considered vital so that the data can be properly evaluated.▪Disposal of …marginal‟ soils will become increasingly difficult and more expensive as the waste licensing regulations are tightened. The advent of landfill tax in the UK has seen thorough examination of all soils for use in earthworks. This is likely to provide a similar incentive and challenge to geotechnical and civil engineers in Ireland in the coming years. ▪ A certification approach comparable with that outlined should be considered by the NRA for ground investigation and earthwork activities.土方工程的地基勘察与施工保罗·圭格利爱尔兰岩土工程服务有限公司摘要：当工程场地的处理面积有限且填方工程费用大量增加时，土方工程的地基勘察设计与施工已逐渐地变得重要。

forced concrete structure reinforced with an overviewRein Since the reform and opening up, with the national economy's rapid and sustained development of a reinforced concrete structure built, reinforced with the development of technology has been great. Therefore, to promote the use of advanced technology reinforced connecting to improve project quality and speed up the pace of construction, improve labor productivity, reduce costs, and is of great significance.Reinforced steel bars connecting technologies can be divided into two broad categories linking welding machinery and steel. There are six types of welding steel welding methods, and some apply to the prefabricated plant, and some apply to the construction site, some of both apply. There are three types of machinery commonly used reinforcement linking method primarily applicable to the construction site. Ways has its own characteristics and different application, and in the continuous development and improvement. In actual production, should be based on specific conditions of work, working environment and technical requirements, the choice of suitable methods to achieve the best overall efficiency.1、steel mechanical link1.1 radial squeeze linkWill be a steel sleeve in two sets to the highly-reinforced Department with superhigh pressure hydraulic equipment (squeeze tongs) along steel sleeve radial squeeze steel casing, in squeezing out tongs squeeze pressure role of a steel sleeve plasticity deformation closely integrated with reinforced through reinforced steel sleeve and Wang Liang's Position will be two solid steel bars linkedCharacteristic: Connect intensity to be high, performance reliable, can bear high stress draw and pigeonhole the load and tired load repeatedly.Easy and simple to handle, construction fast, save energy and material, comprehensive economy profitable, this method has been already a large amount of application in the project.Applicable scope : Suitable for Ⅱ , Ⅲ , Ⅳ grade reinforcing bar (including welding bad reinforcing bar ) with ribbing of Ф 18- 50mm, connection between the same diameter or different diameters reinforcing bar .1.2must squeeze linkExtruders used in the covers, reinforced axis along the cold metal sleeve squeeze dedicated to insert sleeve Lane two hot rolling steel drums into a highly integrated mechanical linking methods.Characteristic: Easy to operate and joining fast and not having flame homework , can construct for 24 hours , save a large number of reinforcing bars and energy. Applicable scope : Suitable for , set up according to first and second class antidetonation requirement -proof armored concrete structure ФⅡ , Ⅲ grade reinforcing bar with ribbing of hot rolling of 20- 32mm join and construct live.1.3 cone thread connectingUsing cone thread to bear pulled, pressed both effort and self-locking nature, undergo good principles will be reinforced by linking into cone-processing thread at the moment the value of integration into the joints connecting steel bars.Characteristic: Simple , all right preparatory cut of the craft , connecting fast, concentricity is good, have pattern person who restrain from advantage reinforcing bar carbon content.Applicable scope : Suitable for the concrete structure of the industry , civil building and general structures, reinforcing bar diameter is for Фfor the the 16- 40mm one Ⅱ , Ⅲ grade verticality, it is the oblique to or reinforcing bars horizontal join construct live.conclusionsThese are now commonly used to connect steel synthesis methods, which links technology in the United States, Britain, Japan and other countries are widely used. There are different ways to connect their different characteristics and scope of the actual construction of production depending on the specific project choose a suitable method of connecting to achieve both energy conservation and saving time limit for a project ends.钢筋混凝土结构中钢筋连接综述改革开放以来，随着国民经济的快速、持久发展，各种钢筋混凝土建筑结构大量建造，钢筋连接技术得到很大的发展。

外文资料翻译系别：土木工程系班级：07土本（1）班姓名：xxx指导教师： xxx2011年6月8日DESIGN AND EXECUTION OF GROUNDINVESTIGATION FOREARTHWORKSPAUL QUIGLEY, FGSIrish Geotechnical Services LtdABSTRACTThe design and execution of ground investigation works for earthwork projects has become increasingly important as the availability of suitable disposal areas becomes limited and costs of importing engineering fill increase. An outline of ground investigation methods which can augment …traditional investigation methods‟ particularly for glacial till / boulder clay soils is presented. The issue of …geotechnical certification‟ is raised and recommendations outlined on its merits for incorporation with ground investigations and earthworks.1. INTRODUCTIONThe investigation and re-use evaluation of many Irish boulder clay soils presents difficulties for both the geotechnical engineer and the road design engineer. These glacial till or boulder clay soils are mainly of low plasticity and have particle sizes ranging from clay to boulders. Most of our boulder clay soils contain varying proportions of sand, gravel, cobbles and boulders in a clay or silt matrix. The amount of fines governs their behaviour and the silt content makes it very weather susceptible.Moisture contents can be highly variable ranging from as low as 7% for the hard grey black Dublin boulder clay up to 20-25% for Midland, South-West and North-West light grey boulder clay deposits. The ability of boulder clay soils to take-in free water is well established and poor planning of earthworks often amplifies this.The fine soil constituents are generally sensitive to small increases in moisture content which often lead to loss in strength and render the soils unsuitable for re-use as engineering fill. Many of our boulder clay soils (especially those with intermediate type silts and fine sand matrix) have been rejected at the selection stage, but good planning shows that they can in fact fulfil specification requirements in terms of compaction and strength.The selection process should aim to maximise the use of locally available soils andwith careful evaluation it is possible to use or incorporate …poor or marginal soils‟ within fill areas and embankments. Fill material needs to be placed at a moisture content such that it is neither too wet to be stable and trafficable or too dry to be properly compacted.High moisture content / low strength boulder clay soils can be suitable for use as fill in low height embankments (i.e. 2 to 2.5m) but not suitable for trafficking by earthwork plant without using a geotextile separator and granular fill capping layer. Hence, it is vital that the earthworks contractor fully understands the handling properties of the soils, as for many projects this is effectively governed by the trafficability of earthmoving equipment.2. TRADITIONAL GROUND INVESTIGATION METHODSFor road projects, a principal aim of the ground investigation is to classify the suitability of the soils in accordance with Table 6.1 from Series 600 of the NRA Specification for Road Works (SRW), March 2000. The majority of current ground investigations for road works includes a combination of the following to give the required geotechnical data:Trial pitsCable percussion boreholesDynamic probingRotary core drillingIn-situ testing (SPT, variable head permeability tests, geophysical etc.)Laboratory testingThe importance of …phasing‟ t he fieldwork operations cannot be overstressed, particularly when assessing soil suitability from deep cut areas. Cable percussion boreholes are normally sunk to a desired depth or …refusal‟ with disturbed and undisturbed samples recovered at 1.00m intervals or change of strata.In many instances, cable percussion boring is unable to penetrate through very stiff, hard boulder clay soils due to cobble, boulder obstructions. Sample disturbance in boreholes should be prevented and loss of fines is common, invariably this leads to inaccurate classification.Trial pits are considered more appropriate for recovering appropriate size samples and for observing the proportion of clasts to matrix and sizes of cobbles, boulders. Detailed and accurate field descriptions are therefore vital for cut areas and trial pits provide an opportunity to examine the soils on a larger scale than boreholes. Trial pitsalso provide an insight on trench stability and to observe water ingress and its effects.A suitably experienced geotechnical engineer or engineering geologist should supervise the trial pitting works and recovery of samples. The characteristics of the soils during trial pit excavation should be closely observed as this provides information on soil sensitivity, especially if water from granular zones migrates into the fine matrix material. Very often, the condition of soil on the sides of an excavation provides a more accurate assessment of its in-situ condition.3. SOIL CLASSIFICATIONSoil description and classification should be undertaken in accordance with BS 5930 (1999) and tested in accordance with BS 1377 (1990). The engineering description of a soil is based on its particle size grading, supplemented by plasticity for fine soils. For many of our glacial till, bould er clay soils (i.e. …mixed soils‟) difficulties arise with descriptions and assessing engineering performance tests.As outlined previously, Irish boulder clays usually comprise highly variable proportions of sands, gravels and cobbles in a silt or clay matrix. Low plasticity soils with fines contents of around 10 to 15% often present the most difficulties. BS 5930 (1999) now recognises these difficulties in describing …mixed soils‟ –the fine soil constituents which govern the engineering behaviour now takes priority over particle size.A key parameter (which is often underestimated) in classifying and understanding these soils is permeability (K). Inspection of the particle size gradings will indicate magnitude of permeability. Where possible, triaxial cell tests should be carried out on either undisturbed samples (U100‟s) or good quality core samples to evaluate the drainage characteristics of the soils accurately.Low plasticity boulder clay soils of intermediate permeability (i.e. K of the order of 10-5 to 10-7 m/s) can often be …conditioned‟ by drainage measures. This usually entails the installation of perimeter drains and sumps at cut areas or borrow pits so as to reduce the moisture content. Hence, with small reduction in moisture content, difficult glacial till soils can become suitable as engineering fill.4. ENGINEERING PERFORMANCE TESTING OF SOILSLaboratory testing is very much dictated by the proposed end-use for the soils. The engineering parameters set out in Table 6.1 pf the NRA SRW include a combination of the following:Moisture contentParticle size gradingPlastic LimitCBRCompaction (relating to optimum MC)Remoulded undrained shear strengthA number of key factors should be borne in mind when scheduling laboratory testing:Compaction / CBR / MCV tests are carried out on < 20mm size material.Moisture content values should relate to < 20mm size material to provide a valid comparison.Pore pressures are not taken into account during compaction and may vary considerably between laboratory and field.Preparation methods for soil testing must be clearly stipulated and agreed with the designated laboratory.Great care must be taken when determining moisture content of boulder clay soils. Ideally, the moisture content should be related to the particle size and have a corresponding grading analysis for direct comparison, although this is not always practical.In the majority of cases, the MCV when used with compaction data is considered to offer the best method of establishing (and checking) the suitability characteristics of a boulder clay soil. MCV testing during trial pitting is strongly recommended as it provides a rapid assessment of the soil suitability directly after excavation. MCV calibration can then be carried out in the laboratory at various moisture content increments. Sample disturbance can occur during transportation to the laboratory and this can have a significant impact on the resultant MCV‟s.IGSL has found large discrepancies when performing MCV‟s in the field on low plasticity boulder clays with those carried out later in the laboratory (2 to 7 days). Many of the aforementioned low plasticity boulder clay soils exhibit time dependant behaviour with significantly different MCV‟s recorded at a later date – increased values can be due to the drainage of the material following sampling, transportation and storage while dilatancy and migration of water from granular lenses can lead to deterioration and lower values.This type of information is important to both the designer and earthworks contractoras it provides an opportunity to understand the properties of the soils when tested as outlined above. It can also illustrate the advantages of pre-draining in some instances. With mixed soils, face excavation may be necessary to accelerate drainage works.CBR testing of boulder clay soils also needs careful consideration, mainly with the preparation method employed. Design engineers need to be aware of this, as it can have an order of magnitude difference in results. Static compaction of boulder clay soils is advised as compaction with the 2.5 or 4.5kg rammer often leads to high excess pore pressures being generated –hence very low CBR values can result. Also, curing of compacted boulder clay samples is important as this allows excess pore water pressures to dissipate.5. ENGINEERING CLASSIFICATION OF SOILSIn accordance with the NRA SRW, general cohesive fill is categorised in Table 6.1 as follows:2A Wet cohesive2B Dry cohesive2C Stony cohesive2D Silty cohesiveThe material properties required for acceptability are given and the design engineer then determines the upper and lower bound limits on the basis of the laboratory classification and engineering performance tests. Irish boulder clay soils are predominantly Class 2C.Clause 612 of the SRW sets out compaction methods. Two procedures are available: Method CompactionEnd-Product CompactionEnd product compaction is considered more practical, especially when good compaction control data becomes available during the early stages of an earthworks contract. A minimum Target Dry Density (TDD) is considered very useful for the contractor to work with as a means of checking compaction quality. Once the material has been approved and meets the acceptability limits, then in-situ density can be measured, preferably by nuclear gauge or sand replacement tests where the stone content is low.As placing and compaction of the fill progresses, the in-situ TDD can be checked and non-conforming areas quickly recognised and corrective action taken. This processrequires the design engineer to review the field densities with the laboratory compaction plots and evaluate actual with …theoretical densities‟.6. SUPPLEMENTARY GROUND INVESTIGATION METHODSFOR EARTHWORKSThe more traditional methods and procedures have been outlined in Section 2. The following are examples of methods which are believed to enhance ground investigation works for road projects:Phasing the ground investigation works, particularly the laboratory testingExcavation & sampling in deep trial pitsLarge diameter high quality rotary core drilling using air-mist or polymer gel techniquesSmall-scale compaction trials on potentially suitable cut materialPHASINGPhasing ground investigation works for many large projects has been advocated for many years –this is particularly true for road projects where significant amounts of geotechnical data becomes available over a short period. On the majority of large ground investigation projects no period is left to …digest‟ or review the preliminary f indings and re-appraise the suitability of the methods.With regard to soil laboratory testing, large testing schedules are often prepared with no real consideration given to their end use. In many cases, the schedule is prepared by a junior engineer while the senior design engineer who will probably design the earthworks will have no real involvement.It is highlighted that the engineering performance tests are expensive and of long duration (e.g. 5 point compaction with CBR & MCV at each point takes in excess of two weeks). When classification tests (moisture contents, particle size analysis and Atterberg Limits) are completed then a more incisive evaluation can be carried out on the data and the engineering performance tests scheduled. If MCV‟s are perfor med during trial pitting then a good assessment of the soil suitability can be immediately obtained.DEEP TRIAL PITSThe excavation of deep trial pits is often perceived as cumbersome and difficult and therefore not considered appropriate by design engineers. Excavation of deep trial pits in boulder clay soils to depths of up to 12m is feasible using benching techniques and sump pumping of groundwater.In recent years, IGSL has undertaken such deep trial pits on several large road ground investigation projects. The data obtained from these has certainly enhanced the geotechnical data and provided a better understanding of the bulk properties of the soils.It is recommended that this work be carried out following completion of the cable percussion boreholes and rotary core drill holes. The groundwater regime within the cut area will play an important role in governing the feasibility of excavating deep trial pits. The installation of standpipes and piezometers will greatly assist the understanding of the groundwater conditions, hence the purpose of undertaking this work late on in the ground investigation programme.Large representative samples can be obtained (using trench box) and in-situ shear strength measured on block samples. The stability of the pit sidewalls and groundwater conditions can also be established and compared with levels in nearby borehole standpipes or piezometers. Over a prominent cut area of say 500m, three deep trial pits can prove invaluable and the spoil material also used to carry out small-scale compaction trials.From a value engineering perspective, the cost of excavating and reinstating these excavations can be easily recovered. A provisional sum can be allocated in the ground investigation and used for this work.HIGH QUALITY LARGE DIAMETER ROTARY CORE DRILLINGThis system entails the use of large diameter rotary core drilling techniques using air mist or polymer gel flush. Triple tube core drilling is carried out through the overburden soils with the recovered material held in a plastic core liner.Core recovery in low plasticity boulder clay has been shown to be extremely good (typically in excess of 90%). The high core recovery permits detailed engineering geological logging and provision of samples for laboratory testing.In drumlin areas, such as those around Cavan and Monaghan, IGSL has found the use of large diameter polymer gel rotary core drilling to be very successful in recovering very stiff / hard boulder clay soils for deep road cut areas (where cable percussion boreholes and trial pits have failed to penetrate). In-situ testing (vanes, SPT‟s etc) can also be carried out within the drillhole to establish strength and bearing capacity of discrete horizons.Large diameter rotary drilling costs using the aforementioned systems are typically 50 to 60% greater than conventional HQ core size, but again from a value engineering aspect can prove much more worthwhile due to the quality of geotechnical informationobtained.SMALL-SCALE COMPACTION TRIALSThe undertaking of small-scale compaction trials during the ground investigation programme is strongly advised, particularly where …marginally suitable‟ soils are present in prominent cut areas. In addition to validating the laboratory test data, they enable more realistic planning of the earthworks and can provide considerable cost savings.The compaction trial can provide the following:Achievable field density, remoulded shear strength and CBREstablishing optimum layer thickness and number of roller passesResponse of soil during compaction (static v dynamic)Monitor trafficability & degree of rutting.A typical size test pad would be approximately 20 x 10m in plan area and up to1.5m in thickness. The selected area should be close to the cut area or borrow pit and have adequate room for stockpiling of material. Earthwork plant would normally entail a tracked excavator (CAT 320 or equivalent), 25t dumptruck, D6 dozer and either a towed or self-propelled roller.In-situ density measurement on the compacted fill by nuclear gauge method is recommended as this facilitates rapid measurement of moisture contents, dry and bulk densities. It also enables a large suite of data to be generated from the compacted fill and to assess the relationship between degree of compaction, layer thickness and number of roller passes. Both disturbed and undisturbed (U100) samples of the compacted fill can be taken for laboratory testing and validation checks made with the field data (particularly moisture contents). IGSL‟s experience is that with good planning a small-scale compaction trial takes two working days to complete.7. SUPERVISION OF GROUND INVESTIGATION PROJECTSClose interaction and mutual respect between the ground investigation contractor and the consulting engineer is considered vital to the success of large road investigation projects. A senior geotechnical engineer from each of the aforementioned parties should liase closely so that the direction and scope of the investigation can be changed to reflect the stratigraphy and ground conditions encountered.The nature of large ground investigation projects means that there must be good communication and flexibility in approach to obtaining data. Be prepared to compromise as methods and procedures specified may not be appropriate and site conditions canquickly change.From a supervision aspect (both contractor and consulting engineer), the emphasis should be on the quality of site-based geotechnical engineers, engineering geologists as opposed to quantity where work is duplicated.8. GEOTECHNICAL CERTIFICATIONThe Department of Transport (UK) prepared a document (HD 22/92) in 1992 for highway schemes. This sets out the procedures and documentation to be used during the planning and reporting of ground investigations and construction of earthworks.Road projects involving earthmoving activities or complex geotechnical features must be certified by the Design Organisation (DO) - consulting engineer or agent authority. The professional responsibility for the geotechnical work rests with the DO.For such a project, the DO must nominate a chartered engineer with appropriate geotechnical engineering experience. He/she is referred to as the Geotechnical Liaison Engineer (GLE) and is responsible for all geotechnical matters including preparation of procedural statements, reports and certificates.Section 1.18 of HD 22/92 states that “on completion of the ground investigation works, the DO shall submit a report and certificate containing all the factual records and test results produced by the specialist contractor together with an interpretative report produced either by the specialist contractor or DO”. The DO shall then prepare an Earthworks Design Report –this report is the Designer‟s detailed report on his interpretation of the site investigation data and design of earthworks.The extent and closeness of the liaison between the Project Manager and the GLE will very much depend on the nature of the scheme and geotechnical complexities discovered as the investigation and design proceed.After the earthworks are completed, a geotechnical feedback report is required and is to be prepared by the DO. This addresses the geotechnical issues and problems encountered during the construction earthworks and corrective action or measures taken. Certificates are prepared by the DO to sign off on the geotechnical measures carried out (e.g. unstable slopes, karst features, disused / abandoned mine workings, ground improvement systems employed, etc).9. CONCLUSIONSClose co-operation is needed between ground investigation contractors and consulting engineers to ensure that the geotechnical investigation work for the roads NDPcan be satisfactorily carried out.Many soils are too easily rejected at selection / design stage. It is hoped that the proposed methods outlined in this paper will assist design engineers during scoping and specifying of ground investigation works for road projects.With modern instrumentation, monitoring of earthworks during construction is very straightforward. Pore water pressures, lateral and vertical movements can be easily measured and provide important feedback on the performance of the engineered soils.Phasing of the ground investigation works, particularly laboratory testing is considered vital so that the data can be properly evaluated.Disposal o f …marginal‟ soils will become increasingly difficult and more expensive as the waste licensing regulations are tightened. The advent of landfill tax in the UK has seen thorough examination of all soils for use in earthworks. This is likely to provide a similar incentive and challenge to geotechnical and civil engineers in Ireland in the coming years.A certification approach comparable with that outlined should be considered by the NRA for ground investigation and earthwork activities.土方工程的地基勘察与施工保罗·圭格利爱尔兰岩土工程服务有限公司摘要当工程场地的处理面积有限且填方工程费用大量增加时，土方工程的地基勘察设计与施工已逐渐地变得重要。

Issues in Sustainable Architecture andPossible SolutionsFatima Ghani, Member COA (India), Member IIIDAbstract—The growing concern with environmental and ecological conditions have led to the discussion/search for ‘energy conscious’, ‘Eco friendly’, ‘energy efficient’ building designs. For the better growth of the future, keeping in view the environment related issues, the first objective of the designer is sustainable development i.e. environmentally compatible building designs. Sustainable architecture also referred as green architecture is a design that uses natural building materials e.g. earth, wood, stone etc (not involving pollution in its treatment) that are energy efficient and that make little or no impact on the nature of a site and its resources. This paper discusses issues related to Sustainable/environmental architecture. It also considers possible solutions related to these issues.Index Terms—Sustainable, Green, Architecture, Building, Design. Efficiency.I. I NTRODUCTIONThe words "Green", "Ecological" and "Sustainable" are terms used by environmentalists to indicate modes of practice. From global economics to household features these practices minimize our impact on the environment and generate a healthy place of living. In a deeper sense the words involve as to what can be done to heal and regenerate the earth's ability to bear life[1-4].A.Principles of Environmentally Oriented DesignIn Architecture there are many ways a building may be "green" and respond to the growing environmental problems of our planet. Sustainable architecture can be practiced still maintaining efficiency, beauty, layouts and cost effectiveness. There are five basic areas of an environmentally oriented design. They are Healthy Interior Environment, Energy Efficiency, Ecological Building Materials, Building Form and Good Design.• Healthy Interior Environment: It has to be well insured that building materials and systems used do not emit toxic unhealthy gases and substances in the built spaces. Further extra cars and measures are to be taken to provide maximum levels of fresh air and adequate ventilation to the interior environment.• Energy Efficiency: It has to be well ensured that the building's use of energy is minimized. The various HV AC systems and methods of construction etc. should be so designed that energy consumption is minimal.• Ecological Building Materials: As far as possible the use of building materials should be from renewable sources having relatively safe sources of production.• Building Form: The building form should respond to the site, region, climate and the materials available thereby generating a harmony between the inhabitants and the surroundings.• Good Design: Structure & Material and Aesthetics are the basic parameters of defining design. They should be so integrated that the final outcome is a well built, convenient and a beautiful living space.These principles of environmentally oriented design comprise yet another meaningful and environmental building approach called Green or Sustainable design. Architects should use their creativity and perception to correlate these principles to generate locally appropriate strategies, materials and methods keeping in mind that every region should employ different green strategies [5-7].B. DefinitionSustainability means 'to hold' up or 'to support from below'. It refers to the ability of a society, ecosystem or any such ongoing system, to continue functioning into the indefinite future (without being forced into decline through exhaustion of key resources).Sustainable architecture involves a combination of values: aesthetic, environmental, social, political and moral. It's about one's perception and technical knowledge to engage in a central aspect of the practice i.e. to design and build in harmony with the environment. It is the duty of an architect to think rationally about a combination of issues like sustainability, durability, longevity, appropriate materials and sense of place [8-10].The present environmental conditions have led to the discussion/search for ‘energy conscious’, ‘Eco friendly’,‘energy efficient’ building designs. For the better growth of the future, keeping in view the environment related issues, the first objective of the designer is a sustainable development i.e. environmentally compatible. This paper discusses issues related to Sustainable/environmental architecture. The main focus of the paper is on sustainable architecture - its need, solutions and impact on the future.II. N EEDS AND I SSUESThe ecological crisis today is very serious and till date much of the debate still focuses on the symptoms rather than the causes. As a result there is an urgent need to emphasize and workout the best possible approach towards environmental protection thereby minimizing further degradation. Architecture presents a unique challenge in the field of sustainability. Construction projects typically consume large amounts of materials, produce tons of waste, and often involve weighing the preservation of buildings that have historical significance against the desire for the development of newer, more modern designs. Sustainable development is one such measure, which presents an approach that can largely contribute to environmental protection. A striking balance between Environmental protection and Sustainable development is a difficult and delicate task. Sustainable design is the thoughtful integration of architecture with electrical, mechanical, and structural engineering. In addition to concern for the traditional aesthetics of massing, proportion, scale, texture, shadow, and light, the facility design team needs to be concerned with long term costs: environmental, economic, and human as shown in Figure 1.III. CONCEPT AND RELEV ANCE OF SUSTAINABLE ARCHITECTUREIn the present day scenario the idea and concept of Sustainable Architecture/Development is relevant in the light of the following two aspects:a) Ecological and Environmental crisisb) Imminent disasters and their managementSome of the major causes, which greatly contribute to these two aspects, can be listed as:• Rapid Urbanization and Industrialization:The consequences of this can further lead to Population explosion, Geological deposits of sewage and garbage, Unsustainable patterns of living & development, Environmental degradation (pollution of air, water, soil etc, food web disruption). Thus sustainable urban development is crucial to improve the lives of urban populations and the remainder of the planet. Both people and ecosystems impacted upon by their activities.• Natural Calamities:Natural calamities like volcanic eruptions, earthquakes, flood, famine etc. which are being further aggravated by mankind add to the list of other ill effects like atomic explosion, green house effect, ozone depletion etc. Sustainable design attempts to have an understanding of the natural processes as well as the environmental impact of the design. Making natural cycles and processes visible, bring the designed environment back to life.• Depletion of Non-renewable sources:Rapid depletion of non-renewable sources is leading to serious issues related to energy & water conservation etc. Thus the rational use of natural resources and appropriate management of the building stock can contribute to saving scarce resources, reducing energy consumption and improving environmental quality.IV. SOLUTIONSA. Sustainable ConstructionSustainable construction is defined as "the creation and responsible management of a healthy built environment based on resource efficient and ecological principles". Sustainable designed buildings aim to lessen their impact on our environment through energy and resource efficiency. "Sustainable building" may be defined as building practices, which strive for integral quality (including economic, social and environmental performance) in a very broad way. Thus, the rational use of natural resources and appropriate management of the building stock will contribute to saving scarce resources, reducing energy consumption (energy conservation), and improving environmental quality.Sustainable building involves considering the entire life cycle of buildings, taking environmental quality, functional quality and future values into account environmental initiatives of the construction sector and the demands of users are key factors in the market. Governments will be able to give a considerable impulse to sustainable buildings by encouraging these developments. Further the various energy related issues during the different phases in the construction of buildings can be understood with respect to the chart shown in Figure2.B. Environmentally Friendly HousesFollowing the five basic principles of environmentally oriented design can lead to the construction of what can be called as Environmentally Friendly House. An environmentally friendly house is designed and built to be in tune with its occupants, nature, environment and ecosystem. It is designed and built according to the region it is located in, keeping in mind the climate, material, availability and building practices. The basic areas of design need to be considered at this stage can be listed as:• Orientation• Reduce Energy Gain or Loss• Lighting• Responsible Landscaping• Waste Management• External VentilationC. Green BuildingA green building places a high priority on health, environmental and resource conservation performance over its life cycle. These new priorities expand and complement the classical building design concerns: economy, utility, durability and delight. Green design emphasize a number of new environmental, resource and occupant health concerns:• Reduce human exposure to noxious materials.• Conserve non-renewable energy and scarce materials.• Minimize life cycle ecological impact of energy and materials used.• Use renewable energy and materials that are sustainable harvested.• Protect and restore local air, water, soil, flora & fauna• Support pedestrian, bicycles, mass transit and other alternatives to fossil-fueled vehicles.Most green buildings are high quality buildings they last longer, cost less to operate and maintain and provide greater occupant satisfaction than standard development.D. Green Roofs & Porous PavementsAs already discussed the rapid urbanization and industrialization is resulting in extensivedeforestation as a result the green areas are being covered with pavements and concrete. The rainwater that naturally seeps through land covered with vegetation and trees now just runoff, thereby leading to a major environmental imbalance in terms of groundwater. This problem can be solved to a great extent with the help of the construction of Green Roofs and Porous Pavements. Green roofs & porous pavements present a unique method of ground water conservation. Vegetation to hold water on rooftops, and pavement that lets it percolate in the ground are some of the latest ways that can save water tables. Visually what might come across may be a roof sprouted with plants and a parking lot that drains water like a sieve-probably the latest in groundwater conservation.E. Building MaterialsTons of materials including timber go into building construction. There are three principal approaches to improve the material efficiency of building construction:• Reducing the amount of material used in construction.• Using recycled materials that otherwise would have been waste.• Reducing waste generation in the construction process.Further as far as possible sustainable harvested building materials and finishes should be used with low toxicity in manufacturing and installation.V. CONCLUSIONSSustainability often is defined as meeting the needs of the present without compromising the ability of future generations to meet their own needs. A growing number of people are committed to reaching this goal by modifying patterns of development and consumption to reduce demand on natural resource supplies and help preserve environmental quality. Achieving greater sustainability in the field of construction is particularly important, because building construction consumes more energy and resources than any other economic activity. Not only does a home represent the largest financial investment a family is likely to make, but it also represents the most resource- and energy-intensive possession most people will ever own. Making homes more sustainable, then, has a tremendous potential to contribute to the ability of future generations to meet their own needs. Sustainable housing design is a multifaceted concept, embracing:• Affordability• Marketability• Appropriate design• Resource efficiency• Energy efficiency• Durability• Comfort• HealthAs a developed society we should not undermine our resource base, the assimilative capacity of our surroundings or the biotic stocks on which our future depends. As a sustainable society our efforts should consist of a long-term and integrated approach to developing and achieving a healthy community. We should realize that the problems associated with sustainable development are global as a result the issues need worldwide attention. If we work together we can bring change faster.R EFERENCES[1] Bruntland, G. Our Common Future: The World Commission on Environment and Development, edited by Bruntland, G., Oxford University Press, Oxford., 1987[2] /sustaindev.html[3] http://arch.hku.hk/research/BEER/sustain.htm#1.1[4] [5] Jani , V., Architecture Time Space & People, V ol. 3, Issue 4, 2003, pp32.[6] Jani , V., Architecture Time Space & People, V ol. 3, Issue 1, 2003, pp34.[7] Bergstrom , B., Architecture Time Space & People, V ol. 3 Issue 1, 2002, pp40.[8] Sinha , S..B., Architecture Time Space & People, V ol. 2, Issue 12, 2002, pp22.[9] Walker , S. , Sustainable Design Explorations in Theory and Practice by, Earthscan , 2006.[10] Datschefski , E. , The Total Beauty of Sustainable Products , Rotovision ,May 2001.可持续建筑的问题和可能的解决方案法蒂玛·加尼，会员COA（印度），会员IIID摘要：越来越多地关注环境和生态条件已经引起了人们对“节能意识”、“友好生态”、“高效节能”的建筑设计的讨论和探索。

Tall Building StructureTall buildings have fascinated mankind from the beginning of civilization, their construction being initially for defense and subsequently for ecclesiastical purposes. The growth in modern tall building construction, however, which began in the 1880s, has been largely for commercial and residential purposes.Tall commercial buildings are primarily a response to the demand by business activities to be as close to each other, and to the city center, as possible, thereby putting intense pressure on the available land space. Also, because they form distinctive landmarks, tall commercial buildings are frequently developed in city centers as prestige symbols for corporate organizations.Further, the business and tourist community, with its increasing mobility, has fuelled a need for more, frequently high-rise, city center hotel accommodations.The rapid growth of the urban population and the consequent pressure on limited space have considerably influenced city residential development. The high cost of land, the desire to avoid a continuous urban sprawl, and the need to preserve important agricultural production have all contributed to drive residential buildings upward.Ideally, in the early stages of planning a building, the entire design team, including the architect, structural engineer, and services engineer, should collaborate to agree on a form of structure to satisfy their respective requirements of function, safety and serviceability, and servicing.It is difficult to define a high-rise building . One may say that a low-rise building ranges from 1 to 2 stories . A medium-rise building probably ranges between 3 or 4 stories up to 10 or 20 stories or more .Although the basic principles of vertical and horizontal subsystem design remain the same for low- , medium- , or high-rise buildings , when a building gets high the vertical subsystems become a controlling problem for two reasons . Higher vertical loads will require larger columns , walls , and shafts . But , more significantly , the overturning moment and the shear deflections produced by lateral forces are much larger andmust be carefully provided for .The vertical subsystems in a high-rise building transmit accumulated gravity load from story to story , thus requiring larger column or wall sections to support such loading . In addition these same vertical subsystems must transmit lateral loads , such as wind or seismic loads , to the foundations. However , in contrast to vertical load , lateral load effects on buildings are not linear and increase rapidly with increase in height . For example under wind load , the overturning moment at the base of buildings varies approximately as the square of a buildings may vary as the fourth power of buildings height , other things being equal. Earthquake produces an even more pronounced effect.When the structure for a low-or medium-rise building is designed for dead and live load , it is almost an inherent property that the columns , walls , and stair or elevator shafts can carry most of the horizontal forces . The problem is primarily one of shear resistance . Moderate addition bracing for rigid frames in“short”buildings can easily be provided by filling certain panels without increasing the sizes of the columns and girders otherwise required for vertical loads.Unfortunately , this is not is for high-rise buildings because the problem is primarily resistance to moment and deflection rather than shear alone . Special structural arrangements will often have to be made and additional structural material is always required for the columns , girders , walls , and slabs in order to made a high-rise buildings sufficiently resistant to much higher lateral deformations .As previously mentioned , the quantity of structural material required per square foot of floor of a high-rise buildings is in excess of that required for low-rise buildings . The vertical components carrying the gravity load , such as walls , columns , and shafts , will need to be strengthened over the full height of the buildings . But quantity of material required for resisting lateral forces is even more significant .With reinforced concrete , the quantity of material also increases as the number of stories increases . But here it should be noted that the increase in the weight of material added for gravity load is much more sizable than steel , whereas for wind load the increase for lateral force resistance is not that much more since the weight of a concrete buildingshelps to resist overturn . On the other hand , the problem of design for earthquake forces . Additional mass in the upper floors will give rise to a greater overall lateral force under the of seismic effects .In the case of either concrete or steel design , there are certain basic principles for providing additional resistance to lateral to lateral forces and deflections in high-rise buildings without too much sacrifire in economy .⒈Increase the effective width of the moment-resisting subsystems . This is very useful because increasing the width will cut down the overturn force directly and will reduce deflection by the third power of the width increase , other things remaining cinstant . However , this does require that vertical components of the widened subsystem be suitably connected to actually gain this benefit.⒉Design subsystems such that the components are made to interact in the most efficient manner . For example , use truss systems with chords and diagonals efficiently stressed , place reinforcing for walls at critical locations , and optimize stiffness ratios for rigid frames .⒊Increase the material in the most effective resisting components . For example , materials added in the lower floors to the flanges of columns and connecting girders will directly decrease the overall deflection and increase the moment resistance without contributing mass in the upper floors where the earthquake problem is aggravated .⒋Arrange to have the greater part of vertical loads be carried directly on the primary moment-resisting components . This will help stabilize the buildings against tensile overturning forces by precompressing the major overturn-resisting components .⒌The local shear in each story can be best resisted by strategic placement if solid walls or the use of diagonal members in a vertical subsystem . Resisting these shears solely by vertical members in bending is usually less economical , since achieving sufficient bending resistance in the columns and connecting girders will require more material and construction energy than using walls or diagonal members .⒍Sufficient horizontal diaphragm action should be provided floor . This will help to bring the various resisting elements to work together instead of separately .⒎Create mega-frames by joining large vertical and horizontal components such as two or more elevator shafts at multistory intervals with a heavy floor subsystems , or by use of very deep girder trusses .Remember that all high-rise buildings are essentially vertical cantilevers which are supported at the ground . When the above principles are judiciously applied , structurally desirable schemes can be obtained by walls , cores , rigid frames, tubular construction , and other vertical subsystems to achieve horizontal strength and rigidity . Some of these applications will now be described in subsequent sections in the following .Shear-Wall SystemsWhen shear walls are compatible with other functional requirements , they can be economically utilized to resist lateral forces in high-rise buildings . For example , apartment buildings naturally require many separation walls . When some of these are designed to be solid , they can act as shear walls to resist lateral forces and to carry the vertical load as well . For buildings up to some 20storise , the use of shear walls is common . If given sufficient length ,such walls can economically resist lateral forces up to 30 to 40 stories or more .However , shear walls can resist lateral load only the plane of the walls ( i.e.not in a diretion perpendicular to them ) . There fore ,it is always necessary to provide shear walls in two perpendicular directions can be at least in sufficient orientation so that lateral force in any direction can be resisted . In addition , that wall layout should reflect consideration of any torsional effect .In design progress , two or more shear walls can be connected to from L-shaped or channel-shaped subsystems . Indeed , internal shear walls can be connected to from a rectangular shaft that will resist lateral forces very efficiently . If all external shear walls are continuously connected , then the whole buildings acts as tube , and connected , then the whole buildings acts as a tube , and is excellent Shear-Wall Seystems resisting lateral loads and torsion .Whereas concrete shear walls are generally of solid type with openings when necessary , steel shear walls are usually made of trusses . Thesetrusses can have single diagonals , “X”diagonals , or“K”arrangements .A trussed wall will have its members act essentially in direct tension or compression under the action of view , and they offer some opportunity and deflection-limitation point of view , and they offer some opportunity for penetration between members . Of course , the inclined members of trusses must be suitable placed so as not to interfere with requirements for wiondows and for circulation service penetrations though these walls .As stated above , the walls of elevator , staircase ,and utility shafts form natural tubes and are commonly employed to resist both vertical and lateral forces . Since these shafts are normally rectangular or circular in cross-section , they can offer an efficient means for resisting moments and shear in all directions due to tube structural action . But a problem in the design of these shafts is provided sufficient strength around door openings and other penetrations through these elements . For reinforced concrete construction , special steel reinforcements are placed around such opening .In steel construction , heavier and more rigid connections are required to resist racking at the openings .In many high-rise buildings , a combination of walls and shafts can offer excellent resistance to lateral forces when they are suitably located ant connected to one another . It is also desirable that the stiffness offered these subsystems be more-or-less symmertrical in all directions .Rigid-Frame SystemsIn the design of architectural buildings , rigid-frame systems for resisting vertical and lateral loads have long been accepted as an important and standard means for designing building . They are employed for low-and medium means for designing buildings . They are employed for low- and medium up to high-rise building perhaps 70 or 100 stories high . When compared to shear-wall systems , these rigid frames both within and at the outside of a buildings . They also make use of the stiffness in beams and columns that are required for the buildings in any case , but the columns are made stronger when rigidly connected to resist the lateral as well as vertical forces though frame bending .Frequently , rigid frames will not be as stiff as shear-wallconstruction , and therefore may produce excessive deflections for the more slender high-rise buildings designs . But because of this flexibility , they are often considered as being more ductile and thus less susceptible to catastrophic earthquake failure when compared with ( some ) shear-wall designs . For example , if over stressing occurs at certain portions of a steel rigid frame ( i.e.,near the joint ) , ductility will allow the structure as a whole to deflect a little more , but it will by no means collapse even under a much larger force than expected on the structure . For this reason , rigid-frame construction is considered by some to be a “best”seismic-resisting type for high-rise steel buildings . On the other hand ,it is also unlikely that a well-designed share-wall system would collapse.In the case of concrete rigid frames ,there is a divergence of opinion . It true that if a concrete rigid frame is designed in the conventional manner , without special care to produce higher ductility , it will not be able to withstand a catastrophic earthquake that can produce forces several times lerger than the code design earthquake forces . therefore , some believe that it may not have additional capacity possessed by steel rigid frames . But modern research and experience has indicated that concrete frames can be designed to be ductile , when sufficient stirrups and joinery reinforcement are designed in to the frame . Modern buildings codes have specifications for the so-called ductile concrete frames . However , at present , these codes often require excessive reinforcement at certain points in the frame so as to cause congestion and result in construction difficulties 。

附录：中英文翻译英文部分：LOADSLoads that act on structures are usually classified as dead loads or live loads.Dead loads are fixed in location and constant in magnitude throughout the life of the ually the self-weight of a structure is the most important part of the structure and the unit weight of the material.Concrete density varies from about 90 to 120 pcf (14 to 19 2KN/m)for lightweight concrete,and is about 145 pcf (23 2KN/m)for normal concrete.In calculating the dead load of structural concrete,usually a 5 pcf (1 2KN/m)increment is included with the weight of the concrete to account for the presence of the reinforcement.Live loads are loads such as occupancy,snow,wind,or traffic loads,or seismic forces.They may be either fully or partially in place,or not present at all.They may also change in location.Althought it is the responsibility of the engineer to calculate dead loads,live loads are usually specified by local,regional,or national codes and specifications.Typical sources are the publications of the American National Standards Institute,the American Association of State Highway and Transportation Officials and,for wind loads,the recommendations of the ASCE Task Committee on Wind Forces.Specified live the loads usually include some allowance for overload,and may include measures such as posting of maximum loads will not be exceeded.It is oftern important to distinguish between the specified load,and what is termed the characteristic load,that is,the load that actually is in effect under normal conditions of service,which may be significantly less.In estimating the long-term deflection of a structure,for example,it is the characteristic load that is important,not the specified load.The sum of the calculated dead load and the specified live load is called the service load,because this is the maximum load which may reasonably be expected to act during the service resisting is a multiple of the service load.StrengthThe strength of a structure depends on the strength of the materials from which it is made.Minimum material strengths are specified in certain standardized ways.The properties of concrete and its components,the methods of mixing,placing,and curing to obtain the required quality,and the methods for testing,are specified by the American Concrete Insititue(ACI).Included by refrence in the same documentare standards of the American Society for Testing Materials(ASTM)pertaining to reinforcing and prestressing steels and concrete.Strength also depends on the care with which the structure is built.Member sizes may differ from specified dimensions,reinforcement may be out of position,or poor placement of concrete may result in voids.An important part of the job of the ergineer is to provide proper supervision of construction.Slighting of this responsibility has had disastrous consequences in more than one instance.Structural SafetySafety requires that the strength of a structure be adequate for all loads that may conceivably act on it.If strength could be predicted accurately and if loads were known with equal certainty,then safely could be assured by providing strength just barely in excess of the requirements of the loads.But there are many sources of uncertainty in the estimation of loads as well as in analysis,design,and construction.These uncertainties require a safety margin.In recent years engineers have come to realize that the matter of structural safety is probabilistic in nature,and the safety provisions of many current specifications reflect this view.Separate consideration is given to loads and strength.Load factors,larger than unity,are applied to the calculated dead loads and estimated or specified service live loads,to obtain factorde loads that the member must just be capable of sustaining at incipient failure.Load factors pertaining to different types of loads vary,depending on the degree of uncertainty associated with loads of various types,and with the likelihood of simultaneous occurrence of different loads.Early in the development of prestressed concrete,the goal of prestressing was the complete elimination of concrete ternsile stress at service loads.The concept was that of an entirely new,homogeneous material that woukd remain uncracked and respond elastically up to the maximum anticipated loading.This kind of design,where the limiting tensile stressing,while an alternative approach,in which a certain amount of tensile amount of tensile stress is permitted in the concrete at full service load,is called partial prestressing.There are cases in which it is necessary to avoid all risk of cracking and in which full prestressing is required.Such cases include tanks or reservious where leaks must be avoided,submerged structures or those subject to a highly corrosive envionment where maximum protection of reinforcement must be insured,and structures subject to high frequency repetition of load where faatigue of the reinforcement may be a consideration.However,there are many cses where substantially improved performance,reduced cost,or both may be obtained through the use of a lesser amount of prestress.Full predtressed beams may exhibit an undesirable amount of upward camber because of the eccentric prestressing force,a displacement that is only partially counteracted by the gravity loads producing downward deflection.This tendency is aggrabated by creep in the concrete,which magnigies the upward displacement due to the prestress force,but has little influence on the should heavily prestressed members be overloaded and fail,they may do so in a brittle way,rather than gradually as do beams with a smaller amount of prestress.This is important from the point of view of safety,because suddenfailure without warning is dangeroud,and gives no opportunity for corrective measures to be taken.Furthermore,experience indicates that in many cases improved economy results from the use of a combination of unstressed bar steel and high strength prestressed steel tendons.While tensile stress and possible cracking may be allowed at full service load,it is also recognized that such full service load may be infrequently applied.The typical,or characteristic,load acting is likely to be the dead load plus a small fraction of the specified live load.Thus a partially predtressed beam may not be subject to tensile stress under the usual conditions of loading.Cracks may from occasionally,when the maximum load is applied,but these will close completely when that load is removed.They may be no more objectionable in prestressed structures than in ordinary reinforced.They may be no more objectionable in prestressed structures than in ordinary reinforced concrete,in which flexural cracks always form.They may be considered a small price for the improvements in performance and economy that are obtained.It has been observed that reinforced concrete is but a special case of prestressed concrete in which the prestressing force is zero.The behavior of reinforced and prestressed concrete beams,as the failure load is approached,is essentially the same.The Joint European Committee on Concrete establishes threee classes of prestressed beams.Class 1:Fully prestressed,in which no tensile stress is allowed in the concrete at service load.Class 2:Partially prestressed, in which occasional temporary cracking is permitted under infrequent high loads.Class 3:Partially prestressed,in which there may be permanent cracks provided that their width is suitably limited.The choise of a suitable amount of prestress is governed by a variety of factors.These include thenature of the loading (for exmaple,highway or railroad bridged,storage,ect.),the ratio of live to dead load,the frequency of occurrence of loading may be reversed,such as in transmission poles,a high uniform prestress would result ultimate strength and in brittle failure.In such a case,partial prestressing provides the only satifactory solution.The advantages of partial prestressing are important.A smaller prestress force will be required,permitting reduction in the number of tendons and anchorages.The necessary flexural strength may be provided in such cases either by a combination of prestressed tendons and non-prestressed reinforcing bars,or by an adequate number of high-tensile tendons prestredded to level lower than the prestressing force is less,the size of the bottom flange,which is requied mainly to resist the compression when a beam is in the unloaded stage,can be reduced or eliminated altogether.This leads in turn to significant simplification and cost reduction in the construction of forms,as well as resulting in structures that are mor pleasing esthetically.Furthermore,by relaxing the requirement for low service load tension in the concrete,a significant improvement can be made in the deflection characteristics of a beam.Troublesome upward camber of the member in the unloaded stage fan be avoeded,and the prestress force selected primarily to produce the desired deflection for a particular loading condition.The behavior of partially prestressed beamsm,should they be overloaded to failure,is apt to be superior to that of fully prestressed beams,because the improved ductility provides ample warning of distress.英译汉：荷 载作用在结构上的荷载通常分为恒载或活载。

本科毕业设计中英文翻译专业名称：土木工程年级班级：XXX学生姓名：XXX指导教师：XXX土木工程学院二○一二年六月一日Design of arch bridges and the bridge crackproduced the reason to simply analyseThis chapter considers the full range of arch bridge types and a range of materials presenting several case studies and describing the design decisions that were made. A general treatment of the analysis of arches is presented, including the derivation of the basic equations that can be used to undertake hand calculations which may beused to validate computer analysis output. Detailed arch bridge design is outside thescope of this chapter so only general issues are discussed. Most of the chapter is devoted to masonry arch bridges. Masonry arch bridge construction is discussed in its historical context and the importance for engineers to take a holistic approach to bridge assessment and design is emphasized. There is a significant section on bridge assessment which includes guidance in the application of current and emerging assessment methods. This is underpinned with background information regarding the material properties of masonry. The chapter concludes with a treatment of repair and maintenance strategies including a comprehensive table which considers common remedial and strengthening measures.The origins of the use of arches as a structural form in buildings can be traced back to antiquity (Van Beek, 1987). In trying to arrive at a suitable definition for an arch we may look no further than Hooke‘s anagram of 1675 which stated ‗Ut p endet continuum flexile, sic stabat continuum rigidum inversum‘ –‗as hangs the flexible line, so but inverted will stand the rigid arch‘. This suggests that any given loading to a flexible cable if frozen and inverted will provide a purely compressive structure in equilibrium with the applied load. Clearly, any slight variation in the loading will result in a moment being induced in the arch. It is arriving at appropriate proportions of arch thickness to accommodate the range of eccentricities of the thrust line that is the challenge to the bridge engineer. Even in the Middle Ages it was appreciated that masonry arches behaved essentially as gravity structures, for which geometry and proportion dictated aesthetic appeal and stability. Compressive strength could be relied upon whilst tensile strength could not. Based upon experience, many empirical relationships between the span and arch thickness were developed and applied successfully to produce many elegant structures throughout Europe.The expansion of the railway and canal systems led to an explosion of bridge building. Brickwork arches became increasingly popular. With the construction of the Coalbrookdale Bridge (1780) a new era of arch bridge construction began. By the end of the nineteenth century cast iron, wrought iron and finally steel became increasingly popular; only to be challenged by ferro cement (reinforced concrete) at the turn of the century.During the nineteenth century analytical technique developed apace. In particular, Castigliano (1879) developed strain energy theorems which could be applied to arches provided they remained elastic. This condition could be satisfied provided the line of thrust lay within the middle third, thus ensuring that no tensile stresses were induced. The requirement to avoid tensile stresses only applied to masonry and cast iron; it did not apply to steel or reinforced concrete (or timber for that matter) as these materials were capable of resisting tensile stresses.Twentieth century arch bridges have become increasingly sophisticated structures combining modern materials to create exciting functional urban sculptures.Types of arch bridgeThe relevant terms that are used to describe the various parts of an arch bridge are shown in Figure 1. Arches may be grouped according to the following parameters:1. the materials of construction2. the structural articulation3. the shape of the archHistorically, arch bridges are associated with stone masonry. This gave way to brickwork in the nineteenth century. Because these were proportioned to minimise the possibility oftensile stress, they tend to be fairly massive structures. By comparison the use of reinforced concrete and modern structural steel gives the opportunity for slender, elegant arches.Nowadays, timber is restricted to small bridges occasionally in a truss form but more usually as laminated curved arches. Although timber has a high strength to density ratio parallel to the grain, it is anisotropic and strength properties perpendicular to the grain are relatively weak. This requires careful detailing of connections to ensure economic use of the material.With regard to structural articulation the arch can be fixed or hinged. In the latter case either one, two or three hinges can be incorporated into the arch rib. Whilst the fixed arch has three redundancies, the introduction of each hinge reduced the indeterminacy by one until, with three hinges, the arch is statically determinate and hence, theoretically, free of the problems of secondary stresses. Figure 2 shows a range of possible arrangements. The articulation of the arch is not only dependent upon the number of hinges but is also fund amentally influenced by the position of the deck and the nature of the load transfer from the deck to the arch.The traditional filled spandrel, where the vehicular loading is transferred through the b ackfill material onto the extrados of the arch, represents at first glance the simplest structural condition. As will be seen later this is not the case and has led to much research for the specific case of the masonry arch bridge in an attempt to improve our understanding of such structures.The spandrel may be open with columns and/or hinges used to transfer the deck loads to the arch. In an attempt to minimise the horizontal thrust on the abutments, the deck may be used to ‗tie‘ the arch. Tied arches are particularly appropriate when deck construction depths are limited and large clear spans are needed (particularly if ground conditions are also difficult and would require extensive piling to resist the horizontal thrusts).Returning to Hooke‘s anagram, the perfect shape for an arch would be an inverted catenary – this would only be the case for carrying its own self-weight. Vehicle loading and varying superincumbent dead load both induce bending moments. Consequently the arch has to have sufficient thickness to accommodate the ‗wandering‘ thrust line.For ease of setting out and construction simpler shapes are adopted nowadays segmental or parabolic shapes are used. Although in situations where maximum widths of headroom have to be provided (say over a railway, road or canal) an elliptical shape may be required or its nearest ‗easy‘ equivalent the three-centred arch.It is worth commenting at this stage regarding the idealization of arch structures.Traditionally arches are perceived as being two-dimensional structures; this, of course is not true – but the extent to which it is not true should be of concern to the designer/assessor. Even in the case of a three-hinged arch whi ch ostensibly is statically determinate the ‗pins‘ are capable of transmitting shear even though they theoretically cannot transmit moments. In the case of non-uniform transverse distribution of loading the hinges will transmit a varying shear which will produce torsion in the arch. Moreover, in the case of skew arches or non-vertical ribs the structure has a much higher redundancy and hence will require greater attention to detail in regard to the releases which are engineered into the structure.From an aesthetic point of view, arches have a universal appeal. In spite of this, care must be taken as the impact of even modest sized bridges is significant. Filled arches are invariably masonry (or widening of masonry) bridges. Cleanness of line, honesty of conception and the attention to detail are vital ingredients to a successful bridge. Certainly, simple stringcourses and copings are preferable to elaborate details which would be expensive and inappropriate for most modern bridges. Where stone is used it is important to be sensitive to the nature of the material. Modern quarrying techniques should be employed (laser cutting, diamond sawing, flame texturing and sandblasting) reserving traditional dressing to conservation schemes. If brickwork is used different textured or coloured bricks and mortar can be specified. Here stringcourses can be particularly useful to mask changes in bedding angle.Historically abutments comprised either rock, or else were massive masonry supports relying on their weight to resist the thrust of the arch. In terms of structural honesty this is necessary as it is instinctive to expect such support.Reinforced concrete and steel arches are altogether much lighter structures. ‗The structure consists basically of the arch, the deck and usually some supports from the arch to the deck – in that order of importance. These elements should be expressed in both form and detail, and with due regard for their hierarchy‘ (Highways Agency, 1996).It is important that the deck, if it rests on the crown of the arch, should not mask it in any way. Any support whether spandrel columns or hinges (in the case of the tied arch) should not be allowed to dominate. Preferably they should be recessed relative to the parapet and stringcourse.Concrete arches can be either a full width curved slab or a series of ribs. Steel is almostalways a series of ribs. Where ribs are used thought should be given (if they are going to be seen from underneath) to the chiaroscuro of the soffit.The ratio of span to rise should generally be in the range 2:1 to 10:1. The flatter the arch the greater the horizontal thrust; this may affect the structural form selected, i. e. whether or not a tie should be introduced, or the stiffness of the deck relative to the arch.In recent years, the traffic capital construction of our country gets swift and violent development, all parts have built a large number of concrete bridges. In the course of building and using in the bridge, relevant to influence project quality lead of common occurrence report that bridge collapse even because the crack appears The concrete can be said to " often have illness coming on " while fracturing and " frequently-occurring disease ", often perplex bridge engineers and technicians. In fact, if take certain design and construction measure, a lot of cracks can be overcome and controlled. For strengthen understanding of concrete bridge crack further, is it prevent project from endanger larger crack to try one's best, this text make an more overall analysis, summary to concrete kind and reason of production, bridge of crack as much as possible, in order to design, construct and find out the feasible method which control the crack, get the result of taking precautions against Yu WeiRan.Concrete bridge crack kind, origin cause of formation In fact, the origin cause of formation of the concrete structure crack is complicated and various, even many kinds of factors influence each other, but every crack has its one or several kinds of main reasons produced. The kind of the concrete bridge crack, on its reason to produce, can roughly divide several kinds as follows :First, load the crack caused Concrete in routine quiet.Is it load to move and crack that produce claim to load the crack under the times of stress bridge, summing up has direct stress cracks, two kinds stress crack onces mainly. Direct stress crack refer to outside load direct crack that stress produce that cause. The reason why the crack produces is as follows: (1) Design the stage of calculating, does not calculate or leaks and calculates partly while calculating in structure; Calculate the model is unreasonable; The structure is supposed and accorded with by strength actually by strength ; Load and calculate or leak and calculate few; Internal force and matching the mistake in computation of muscle; Safety coefficient of structure is not enough. Do not consider the possibility that construct at the time of the structural design; It is insufficient to design the section; It is simply little andassigning the mistake for reinforcing bar to set up; Structure rigidity is insufficient; Construct and deal with improperly; The design drawing can not be explained clearly etc. (2) Construction stage, does not pile up and construct the machines, material limiting ; Is it prefabricate structure structure receive strength characteristic, stand up, is it hang, transport, install to get up at will to understand; Construct not according to the design drawing, alter the construction order of the structure without authorization, change the structure and receive the strength mode; Do not do the tired intensity checking computations under machine vibration and wait to the structure. (3) Using stage, the heavy-duty vehicle which goes beyond the design load passes the bridge; Receive the contact, striking of the vehicle, shipping; Strong wind, heavy snow, earthquake happen, explode etc.Stress crack once means the stress of secondary caused by loading outside produces the crack. The reason why the crack produces is as follows, (1)In design outside load function, because actual working state and routine, structure of thing calculate have discrepancy or is it consider to calculate, thus cause stress once to cause the structure to fracture in some position. Two is it join bridge arch foot is it is it assign " X " shape reinforcing bar, cut down this place way, section of size design and cut with scissors at the same time to adopt often to design to cut with scissors, theory calculate place this can store curved square in, but reality should is it can resist curved still to cut with scissors, so that present the crack and cause the reinforcing bar corrosion. (2)Bridge structure is it dig trough, turn on hole, set up ox leg, etc. to need often, difficult to use a accurate one diagrammatic to is it is it calculate to imitate to go on in calculating in routine, set up and receive the strength reinforcing bar in general foundation experience. Studies have shown, after being dug the hole by the strength component, it will produce the diffraction phenomenon that strength flows, intensive near the hole in a utensil, produced the enormous stress to concentrate. In long to step prestressing force of the continuous roof beam, often block the steel bunch according to the needs of section internal force in stepping, set up the anchor head, but can often see the crack in the anchor firm section adjacent place. So, if deal with improper, in corner of component form sudden change office, block place to be easy to appear crack strength reinforcing bar of the structure. In the actual project, stress crack once produced the most common reason which loads the crack. Stress crack once belong to one more piece of nature of drawing, splitting off, shearing. Stress crack once is loaded and caused, only seldom calculate according to the routine too, but withmodern to calculate constant perfection of means, times of stress crack to can accomplish reasonable checking computations too. For example to such stresses 2 times of producing as prestressing force, creeping, etc. , department's finite element procedure calculates levels pole correctly now, but more difficult 40 years ago.In the design, should pay attention to avoiding structure sudden change (or section sudden change), when it is unable to avoid, should do part deal with, corner for instance, make round horn, sudden change office make into the gradation zone transition, is it is it mix muscle to construct to strengthen at the same time, corner mix again oblique to reinforcing bar, as to large hole in a utensil can set up protecting in the perimeter at the terms of having angle steel. Load the crack characteristic in accordance with loading differently and presenting different characteristics differently. The crack appears person who draw more, the cutting area or the serious position of vibration. Must point out, is it get up cover or have along keep into short crack of direction to appear person who press, often the structure reaches the sign of bearing the weight of strength limit, it is an omen that the structure is destroyed, its reason is often that sectional size is partial and small. Receive the strength way differently according to the structure, the crack characteristic produced is as follows: (1) Central tension. The crack runs through the component cross section, the interval is equal on the whole, and is perpendicular to receiving the strength direction. While adopting the whorl reinforcing bar, lie in the second-class crack near the reinforcing bar between the cracks. (2)The centre is pressed. It is parallel on the short and dense parallel crack which receive the strength direction to appear along the component. (3) Receive curved. Most near the large section from border is it appear and draw into direction vertical crack to begin person who draw curved square, and develop toward neutralization axle gradually. While adopting the whorl reinforcing bar, can see shorter second-class crack among the cracks. When the structure matches muscles less, there are few but wide cracks, fragility destruction may take place in the structure. (4) Pressed big and partial. Heavy to press and mix person who draw muscle a less one light to pigeonhole into the component while being partial while being partial, similar to receiving the curved component. (5) Pressed small and partial. Small to press and mix person who draw muscle a more one heavy to pigeonhole into the component while being partial while being partial, similar to the centre and pressed the component. (6) Cut. Press obliquly when the hoop muscle is too dense and destroy, the oblique crack which is greater than 45 degreesdirection appears along the belly of roof beam end; Is it is it is it destroy to press to cut to happen when the hoop muscle is proper, underpart is it invite 45 degrees direction parallel oblique crack each other to appear along roof beam end. (7) Sprained. Component one side belly appear many direction oblique crack, 45 degrees of treaty, first, and to launch with spiral direction being adjoint. (8) Washed and cut. 4 side is it invite 45 degrees direction inclined plane draw and split to take place along column cap board, form the tangent plane of washing.(9) Some and is pressed. Some to appear person who press direction roughly parallel large short cracks with pressure.Second, crack caused in temperature change.The concrete has nature of expanding with heat and contract with cold, look on as the external environment condition or the structure temperature changes, concrete take place out of shape, if out of shape to restrain from, produce the stress in the structure, produce the temperature crack promptly when exceeding concrete tensile strength in stress. In some being heavy to step foot-path among the bridge, temperature stress can is it go beyond living year stress even to reach. The temperature crack distinguishes the main characteristic of other cracks will be varied with temperature and expanded or closed up. The main factor is as follows, to cause temperature and change. (1) Annual difference in temperature. Temperature is changing constantly in four seasons in one year, but change relatively slowly, the impact on structure of the bridge is mainly the vertical displacement which causes the bridge, can prop up seat move or set up flexible mound, etc. not to construct measure coordinate, through bridge floor expansion joint generally, can cause temperature crack only when the displacement of the structure is limited, for example arched bridge, just bridge etc. The annual difference in temperature of our country generally changes the range with the conduct of the average temperature in the moon of January and July. Considering the creep characteristic of the concrete, the elastic mould amount of concrete should be considered rolling over and reducing when the internal force of the annual difference in temperature is calculated. (2) Rizhao. After being tanned by the sun by the sun to the side of bridge panel, the girder or the pier, temperature is obviously higher than other position, the temperature gradient is presented and distributed by the line shape. Because of restrain oneself function, cause part draw stress to be relatively heavy, the crack appears. Rizhao and following to is it cause structure common reason most, temperature of crack to lower the temperature suddenly. (3) Lower thetemperature suddenly. Fall heavy rain, cold air attack, sunset, etc. can cause structure surface temperature suddenly dropped suddenly, but because inside temperature change relatively slow producing temperature gradient. Rizhao and lower the temperature internal force can adopt design specification or consult real bridge materials go on when calculating suddenly, concrete elastic mould amount does not consider converting into and reducing. (4) Heat of hydration. Appear in the course of constructing, the large volume concrete (thickness exceeds 2. 0), after building because cement water send out heat, cause inside very much high temperature, the internal and external difference in temperature is too large, cause the surface to appear in the crack. Should according to actual conditions in constructing, is it choose heat of hydration low cement variety to try one's best, limit cement unit's consumption, reduce the aggregate and enter the temperature of the mould, reduce the internal and external difference in temperature, and lower the temperature slowly, can adopt the circulation cooling system to carry on the inside to dispel the heat in case of necessity, or adopt the thin layer and build it in succession in order to accelerate dispelling the heat. (5) The construction measure is improper at the time of steam maintenance or the winter construction, the concrete is sudden and cold and sudden and hot, internal and external temperature is uneven, apt to appear in the crack. (6) Prefabricate T roof beam horizontal baffle when the installation, prop up seat bury stencil plate with transfer flat stencil plate when welding in advance, if weld measure to be improper, iron pieces of nearby concrete easy to is it fracture to burn. Adopt electric heat piece draw law piece draw prestressing force at the component, prestressing force steel temperature can rise to 350 degrees Centigrade, the concrete component is apt to fracture. Experimental study indicates, are caused the intensity of concrete that the high temperature burns to obviously reduce with rising of temperature by such reasons as the fire, etc. , glueing forming the decline thereupon of strength of reinforcing bar and concrete, tensile strength drop by 50% after concrete temperature reaches 300 degrees Centigrade, compression strength drops by 60%, glueing the strength of forming to drop by 80% of only round reinforcing bar and concrete; Because heat, concrete body dissociate ink evaporate and can produce and shrink sharply in a large amount.Third , shrink the crack caused.In the actual project, it is the most common because concrete shrinks the crack caused. Shrink kind in concrete, plasticity shrink is it it shrinks (is it contract to do ) to be the mainreason that the volume of concrete out of shape happens to shrink, shrink spontaneously in addition and the char shrink. Plasticity shrink. About 4 hours after it is built that in the course of constructing, concrete happens, the cement water response is fierce at this moment, the strand takes shape gradually, secrete water and moisture to evaporate sharply, the concrete desiccates and shrinks, it is at the same time conduct oneself with dignity not sinking because aggregate,so when harden concrete yet,it call plasticity shrink. The plasticity shrink producing amount grade is very big, can be up to about 1%. If stopped by the reinforcing bar while the aggregate sinks, form the crack along the reinforcing bar direction. If web, roof beam of T and roof beam of case and carry baseplate hand over office in component vertical to become sectional place, because sink too really to superficial obeying the web direction crack will happen evenly before hardenning. For reducing concrete plasticity shrink,it should control by water dust when being construct than,last long-time mixing, unloading should not too quick, is it is it take closely knit to smash to shake, vertical to become sectional place should divide layer build. Shrink and shrink (do and contract). After the concrete is formed hard, as the top layer moisture is evaporated progressively, the humidity is reduced progressively, the volume of concrete is reduced, is called and shrunk to shrink (do and contract). Because concrete top layer moisture loss soon, it is slow for inside to lose, produce surface shrink heavy, inside shrink a light one even to shrink, it is out of shape to restrain from by the inside concrete for surface to shrink, cause the surface concrete to bear pulling force, when the surface concrete bears pulling force to exceed its tensile strength, produce and shrink the crack. The concrete hardens after-contraction to just shrink and shrink mainly. Such as mix muscle rate heavy component (exceed 3% ), between reinforcing bar and more obvious restraints relatively that concrete shrink, the concrete surface is apt to appear in the full of cracks crackle. Shrink spontaneously. Spontaneous to it shrinks to be concrete in the course of hardenning, cement and water take place ink react, the shrink with have nothing to do by external humidity, and can positive (whether shrink, such as ordinary portland cement concrete), can negative too (whether expand, such as concrete, concrete of slag cement and cement of fly ash). The char shrinks. Between carbon dioxide and hyrate of cement of atmosphere take place out of shape shrink that chemical reaction cause. The char shrinks and could happen only about 50% of humidity, and accelerate with increase of the density of the carbon dioxide. The char shrinks and seldom calculates. The characteristic that the concrete shrinks the crack is that themajority belongs to the surface crack, the crack is relatively detailed in width, and criss-cross, become the full of cracks form, the form does not have any law.Studies have shown, influence concrete shrink main factor of crack as follows. (1) Variety of cement, grade and consumption. Slag cement, quick-hardening cement, low-heat cement concrete contractivity are relatively high, ordinary cement, volcanic ash cement, alumina cement concrete contractivity are relatively low. Cement grade low in addition, unit volume consumption heavy rubing detailed degree heavy, then the concrete shrinks the more greatly, and shrink time is the longer. For example, in order to improve the intensity of the concrete, often adopt and increase the cement consumption method by force while constructing, the result shrinks the stress to obviously strengthen. (2) Variety of aggregate. Such absorbing water rates as the quartz, limestone, cloud rock, granite, feldspar, etc. are smaller, contractivity is relatively low in the aggregate; And such absorbing water rates as the sandstone, slate, angle amphibolite, etc. are greater, contractivity is relatively high. Aggregate grains of foot-path heavy to shrink light in addition, water content big to shrink the larger. (3) Water gray than. The heavier water consumption is, the higher water and dust are, the concrete shrinks the more greatly. (4) Mix the pharmaceutical outside. It is the better to mix pharmaceutical water-retaining property outside, then the concrete shrinks the smaller. (5) Maintain the method. Water that good maintenance can accelerate the concrete reacts, obtain the intensity of higher concrete. Keep humidity high, low maintaining time to be the longer temperature when maintaining, then the concrete shrinks the smaller. Steam maintain way than maintain way concrete is it take light to shrink naturall. (6) External environment. The humidity is little, the air drying, temperature are high, the wind speed is large in the atmosphere, then the concrete moisture is evaporated fast, the concrete shrinks the faster. (7) Shake and smash the way and time. Machinery shake way of smashing than make firm by ramming or tamping way concrete contractivity take little by hand. Shaking should determine according to mechanical performance to smash time, are generally suitable for 55s / time. It is too short, shake and can not smash closely knit, it is insufficient or not even in intensity to form the concrete; It is too long, cause and divide storey, thick aggregate sinks to the ground floor, the upper strata that the detailed aggregate stays, the intensity is not even, the upper strata incident shrink the crack. And shrink the crack caused to temperature, worthy of constructing the reinforcing bar againing can obviously improve the resisting the splitting of。

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毕业设计（论文）外文翻译设计（论文）题目：宁波新城艺术宾馆2#楼结构设计与预算学院名称：建筑工程专业：土木工程学生姓名：顾丽敏学号： 06404010101指导教师：袁坚敏2010年01月10日外文原文I：A fundamental explanation of the behaviour ofreinforced concrete beams in flexure basedon the properties of concrete under multiaxial stressM. D. KotsovosDepartment of Civil EngineeringImperial College of Science and TechnologyLondon (U. K.)The paper questions the validity of the generally accepted view that for a reinforced concretestructure to exhibit "ductile" behaviour under increasing load it is necessary for the stressstrain relationships of concrete to have a gradually descending post-ultimate branch.Experimental data are presented for reinforced concrete beams in bending which indicate the presence of longitudinal compressive strains on the compressive face in excess of 0.0035. It is shown that these strains which are essential for "ductile" behaviourare caused by acomplex multiaxial compressive state of stress below ultimate strength rather than postultimate material characteristics. The presence of a complex stress system provides a fundamental explanation for beam behaviour which does not affect existing design procedures.1. INTRODUCTIONThe "plane sections" theory notonly is generally considered to describe realistically the deformation response of reinforced and prestressed concrete beams under flexure and axial loadbut is also formulated so that it provides a design tool noted for both its effectiveness and simplicity [1]. The theory describes analytically the relationshipbetween load-carrying capacity and geometric characteristics of a beam by considering the equilibrium conditions at critical cross-sections. Compatibility of deformation is satisfied by the "plane cross-sections remain plane" assumption and the longitudinal concrete and steel stresses are evaluated by the material stress-strain characteristics. Transverse stresses and strains are ignored for the purposes of simplicity.The stress-strain characteristics of concrete in compression are considered to be adequately described by the deformational response of concrete specimens such as prisms or cylinders under uniaxial compression and the stress distribution in the compression zone of a cross-section at the ultimate limit stateas proposed by current codes of practice such as CP 110 [1]exhibits a shape similar to that shown in figure 1. The figure indicates that the longitudinal stress increases with thedistance from the neutral axis up to a maximum value and then remains constant. Such a shape of stress distribution has been arrived at on the basis of both safety considerations and the widely held view that the stress-strain relationship of concrete in compression consists of both an ascending and a gradually descending portion (seefig. 2). The portion beyond ultimate defines the post-ultimate stress capacity of the material whichTypical stress-strain relationship for concrete in compression. as indicated in figure 1is generally considered to make a major contribution to the maximum load-carrying capacity of the beam.Howevera recent analytical investigation of the behaviour of concrete under concentrations of load has indicated that the post-ultimate strength deformational response of concrete under compressive states of stress has no apparent effect on the overall behaviour of the structural forms investigated ( [2][3]). If such behaviour is typical for any structurethen the large compressivestrains (in excess of 0.0035) measured on the top surface of a reinforced concrete beam at its ultimate limit state (see fig. 1)cannot be attributed to post-ultimate uniaxial stress-strain characteristics. Furthermoresince the compressive strain at the ultimate strength level of any concrete under uniaxial compression is of the order of 0.002 (see fig. 2)it would appear that a realistic prediction of the beam response under load cannot be based solely on the ascending portion of the uniaxial stress-strain relationship of concrete.In view of the abovethe work described in the following appraises the widely held view that a uniaxial stress-strain relationship consisting of an ascending and a gradually descending portion is essential for the realistic description of the behaviour of a reinforcedconcrete beam in flexure. Results obtained from beams subjected to flexure under two-point loading indicate that the large strains exhibited by concrete in the compression zone of the beams are due to a triaxial state of stress rather than the uniaxial post-ultimate stress-strain characteristics of concrete. It is shown that the assumption that the material itself suffers a completeand immediate loss of load-carrying capacity when ultimate strength is exceeded is compatible with the observed "ductile" structural behaviour as indicated by load-deflexion or moment-rotation relationships.2. EXPERIMENTAL DETAILS2.1. SpecimensThree rectangular reinforced concrete beams of 915 mm span and 102 mm height x 51 mm width cross-section were subjected to two-point load with shear spans of 305 mm (see fig. 3). The tension reinforcement consisted of two 6 mm diameter bars with a yield load of 11.8 kN. The bars were bent back at the ends of the beams so as to provide compression reinforcement along the whole length of the shear pression and tension reinforcement along each shear span were linked by seven 3.2 mm diameter stirrups. Neither compression reinforcement nor stirrups were provided in the central portion of the beams. Due to the above reinforcement arrangement all beams failed in flexure rather than shearalthough the shear span to effective depthratio was 3.The beamstogether with control specimenswere cured under damp hessian at 20~ for seven days and then stored in the laboratory atmosphere (20~and 40% R.H.) for about 2 monthsuntil tested. Full details of the concrete mix used are given in table I.2.2. TestingLoad was applied through a hydraulic ram and spreader beam in increments of approximately 0.5 kN. At each increment the load was maintained constant for approximately 2 minutes in order to measure the load and the deformation response of the specimens. Load was measured by using a load cell and deformation response by using both 20 mm long electrical resistance strain gauges and displacement transducers. The strain gauges were placed on the top and side surfaces of the beams in the longitud{nal and the transverse directions as shown in figure 4. The figure also indicates the position of the linear voltage displacement transducers (LVDT's) which were used to measure deflexion at mid-span and at the loaded cross-sections.The measurements were recorded by an automatic computer-based data-logger (Solatron) capable of measuring strains and displacements to a sensitivity of 2 microstrain and 0.002 ramrespectively.3. EXPERIMENTAL RESULTSThe main results obtained from the experiments together with information essential for a better understanding of beam behaviour are shown in figures 5 to 14. Figure 5 shows the uniaxial compression stressstrain relationships of the concreteused in the investigationwhereas figures 6 and 7 show the relationships between longitudinal and transverse strainsmeasured on the top surface of the beams (a) at the cross-sections where the flexure cracks which eventually cause failure are situated (critical sections) and (b)at cross-sections within the shear spanrespectively.Figures 6 and 7 also include the longitudinal straintransverse strain relationship corresponding to the stress-strain relationships of figure 5.Figure 8 shows the typical change in shape of the transverse deformation profile of the top surface of the beams with load increasing to failure and figure 9 provides a schematic representation of the radial forces and stresses developing with increasing load due to the deflected shape of the beams. Typical load-deflexion relationships of the beams are shown in figure 10whereas figure 11 depicts the variation on critical sections of the average vertical strains measured on the side surfaces of the beams with the transverse strains measured on the top surface. Figure 12 indicates the strength and deformation response of a typical concrete under various states of triaxial stress and figure 13 presents the typical crack pattern of the beams at the moment of collapse. Finallyfigure 14 shows the shape of the longitudinal stress distribution on the compressive zone of a critical section at failure predicted on the basis of the concepts discussed in the following section.中文翻译I：在多向应力作用下从混凝土的特性看受弯钢筋混凝土梁变化的一个基本试验M. D. Kotsovos 伦敦皇家科学与技术学院土木工程系本文所探讨的问题是通常认为在荷载递增下钢筋混凝土结构呈现弹性状态这必须是因为混凝土的应力-应变关系有一个逐渐递减的临界部分的真实性试验数据显示受弯钢筋混凝土梁会在受压面的纵向压应变超出0.0035这表明这些应变是钢筋混凝土结构的本质它是由于一个比极限强度小的复杂多向的应力状态而不是塑性材料的特性引起的一个复杂应力系统的存在为梁的状态提供了一个基本试验而不是想象的一个现有设计过程1.引言"剖面"理论不仅是通常认为能很真实地描述钢筋混凝土梁和预应力混凝土梁在弯矩和轴向荷载下的变形而且能确切地阐述所以它提供了一个设计工具因为它的有效和简单而闻名[1]假设在临界横截面伤是均衡的这个理论分析地描述了一个梁的承载能力和几何特性之间的关系变形协调必须满足"水平横截面荏苒水平"的假定和纵向混凝土和钢筋的应力是通过材料的应力-应变的特性来估算的为了简化计算忽略横向的应力和应变受压混凝土的应力-应变特性认为能够被混凝土试块的变形充分地描述例如在极限的有限状态下棱柱体或圆柱体在横截面的受压区受单轴压力和应力就像现行规范所建议的CP110[1]显示出一个与图1相似的形状图1表明纵向应力随着与中和轴的距离增加而增加至最大值然后保持不变这个分布图已经达到安全性和受压混凝土的应力-应变关系的广泛观点由上升和逐渐下降的两部分组成(如图2所示)超出极限的部分材料的塑性应力能力如图1所示被认为对梁的最大承载能力有较大的作用图1.临界面破坏建议CP为110的应力和应变分布图2.受压混凝土结构的标准应力-应变关系然而最近关于在集中力作用下的混凝土的变化的一个分析性调查表明在压应力作用下混凝土的极限强度变形没有对所有被调查的结果形式的变化产生明显的影响([2][3])如果这个变化对任何结果都是典型的那么在钢筋混凝土梁的顶面被测的很大的压应变(超出量0.0035)在它的极限有限状态下(如图1)不能对极限单轴应力-应变特性产生作用因此因为压应变在单轴压力下的任何混凝土的极限强度等级下为ε=0.002(如图2所示)在混凝土的单轴应力-应变关系下降部分将出现一个在荷载作用下梁变化的现在可行的预测根据以上的观点本文的描述都在以下的评价中广泛的支持观点的一个单轴应力-应变关系由一个上升的和一个逐渐下降的部分组成对受弯的根据混凝土梁的变化的真实描述是非常必要的这个结果是从梁在两点荷载作用下弯曲得到表明很大的应变的通过梁受压的混凝土呈现的由于三维应力而不是一味的混凝土极限应力-应变特性这表明材料本身受到一个完整和直接的承载能力损失当极限强度被超过的假定与弹性结构的变化并存的通过偏心荷载或瞬间旋转关系表明的2.试验细节2.1试块三根矩形钢筋混凝土梁跨度915mm横截面为102mm51mm受剪区跨度为305mm(如图2所示)受力筋由两个直径为6mm屈服荷载为11.8kN的钢筋组成在梁端部钢筋弯起就能为整个受剪跨度提供抗力整个受剪跨度内压缩张拉的加强筋布置了七个直径为3.2mm的箍筋在梁的中间部分没有压缩加强筋和箍筋根据上面所述的钢筋布置所有的梁都是受弯破坏而不是受剪破坏尽管剪跨比为3所有的梁与受控的试块一起放在20 的湿麻袋下七天然后贮存在实验室条件下(2040%湿度)2个月直到试验结束所有混凝土配料都在表格I中2.2试验过程通过液压锤和分布梁加载每次大约增加0.5kN为了测量荷载和试块的形变每次持荷约2分钟荷载用一个荷载单元来测量形变由20mm长的电阻应变片和位移转换器测得应变片贴在梁纵向和横向的顶面和侧面(如图4所示)图4也表明了直流电压位移转换器（LVDT'S）的位置它是用来测量跨中和加载横截面的形变测量数据记录在计算机自动数据记录仪中能够测量应变和形变的灵敏度分别为±2微应变和±0.002mm3.试验结果主要的试验结果是从试验中得到的能更好地了解梁的变化所示图5 至图14的信息是必不可少的图5表明结果的单轴压应力-应变关系应用于调查中而图6 和图7表明纵向应变与横向应变的关系分别位于(a)弯曲裂缝最终导致破坏横截面出和(b)受剪区跨内的横截面出图6和图7也包含了纵向应变-横向应变与图5的应力-应变关系是一致的图8中标准的改变在梁顶面的横向形变轮廓图中和图9提供一个轴力和应力随着荷载的增加而增大导致梁向下变形的图框表示方法梁的标准偏心荷载关系如图10所示而图11描述了测得平均竖向应变的梁侧面的临界截面变形和横向应变在顶面测得图12中标准结果的强度和形变在各种状态的十三轴应力下河图13所呈现的梁标准裂缝图样在破坏的瞬间最后图14表明在临界截面的受压区伤纵向应力的分布形状可根据概念来预测破坏在以下部分将被讨论图3.梁的细节外文原文II:Some questions on the corrosion of steel in concrete.Part Ⅱ: Corrosion mechanism and monitoringservicelife prediction and protection methodsJ.A. GonzdlezS. FelifdP. RodffguezW. LfpezE. RamlrezC. AlonsoC.AndradeABSTRACTThis second part addresses some important issues that remain controversial despite the vast amounts of work devoted to investigating corrosion in concrete-embedded steel. Specificallythese refer to: 1) the relative significance of galvanic macrocouples and corrosion microcells in reinforced concrete structures; 2) the mechanism by which reinforcements corrode in an active state; 3) the best protective methods for preventing or stopping reinforcement corrosion; 4) the possibility of a reliable prediction of the service life of a reinforced concrete structure ; and 5) the best corrosion measurement and control methods. The responses provided are supported by experimental resultsmost of which were obtained by the authors themselves.1. INTRODUCTIONConcrete-embedded steel is known to remain in apassive state under normal conditions as a result of the highly alkaline pH of concrete. The passivity of reinforcements ensures unlimited durability of reinforced concrete (1KC) structures. Howeverthere are some exceptional conditions that disrupt steel passivity and cause reinforcements to be corroded in an active state. This has raised controversial interpretationssome of which were discussed in Part I of this series [1]. This Part II analyses though far from exhaustivelyother - to the authors minds at least - equally interesting issues on which no general consensus has been reached.2. MATERIALS AND METHODSThe reader is referred to Part I for a detailed description of the materials and methods used in this work. Most of the experimental results discussed herein were obtained with the same types of specimens and slabs.Galvanic couples were determined on speciallydesigned specimenssuch as those shown in Figs. 1 and 2.Near-real conditions were simulated by using a beam that was 160cm long and 7 x 10 cm in cross-section. The beam was made from 350 kg cement/m 3half of whichcontained no additiveswhile the other half included 3% CaC12 by cement weight [2](Fig. 1). In order to study the effect of the Sanod/Scathoa ratio on galvanic macrocouplesthey were modelled by surrounding a small carbon steel anode with a stainless steel (AISI 304) cathode and vice versa(Fig. 2). In this waythe ratio's consistensy was assured. In additionthe potential and icorr of stainless steal and those of the passive structures were very similar.Fig. 1 - Beam used to measure icoTr and Ecorr in Fig. 2 - Scheme of galvanic macrocouples embeddedconcrete with and without chlorides and to in chloride- containing mortar used to study theillustrate the significance of passive steel/active effect of the Sanod/Scathod ratio and their relativesteel macrocouples. significance to corrosion microcells.3. RESULTS AND DISCUSSION3.1 What is the relative significance of galvanic macrocouples and corrosion microcells in RC structures ?According to several authors [35]the polarization resistance method provides an effective means for estimating the corrosion rate of steel in PC ; the method is quite rapidconvenientnon-destructivequantitative and reasonably precise. Howeverit is uncertain whether it may give rise to serious errors with highly-polarized electrodes by the effect of passive/active area galvanicmacrocouples in the reinforcements [6].Based on the authors' own experience with the behaviour of galvanic macrocouples in PCthe contribution of these macrocouples to overall corrosion is very modest rehtive to that of the corrosion microcells formed in the active areas of reinforcements in the presence of sufficient oxygen and moisture [278]. Thusit has been experimentally checked that:(a) Galvanic macrocouples have a slight polarizing effect on anodic areas in wet concretewhose potential is thereby influenced in only a few millivolts.(b) On the other handmacrocouples have a strong polarizing effect on passive areas despite the low galvanic currents involved relative to the overall corrosion current.(c) As a resultgalvanic currents can result in grossly underestimated icorr values for the active areas since they are often smaller than 10% of the ico= values estimated from polarization resistance measurements.(d) The corrosive effect ofcoplanar macrocouples on RC structures only proves dangerous within a small distance from the boundary of active and passive areas. Fig. 3 compares the estimated icorr and ig valuesin mortar containing 3 o~ A CaC12per anode surface unit for a number of anode/cathode surface ratios for AISI 304 stainless steel/carbon steel macrocouples in support of the above conclusions [9].3.2 By what mechanism do reinforcements corrode in an active state ?When the passive state is lostthe rate of reinforcement corrosion in inversely proportional to the resistivity of concrete over a wide resistivity range [10]. BecauseFig. 3 - Relative significance of corrosion microcells Fig. 4 - Trends in ico. and Ecorr for(icorr) and galvanic macrocouples (i.) in corrosion specimens exposed to an oxygen-freeof steel embedded in mortar containing no chloride. environment.Both currents were calculated relative to Sanod(carbon steel in the macrocouples of Fig. 2).the environment's relative humidity and ionic additives of concrete determine concrete resistivitythese factorstogether with oxygen availability at reinforcement surfacescontrol the corrosion rate [11].The electric resistivity of water-saturated concrete structures is relatively very lowand the corrosion rate is believed to be essentially controlled by the diffusion of dissolved oxygen through the concrete cover up to reinforcements. This is consistent with the widespread belief that the sole possible cathodic reaction in neutral and alkaline solutions is oxygen reduction.The significance ascribed to the role of oxygen justifies the efforts to determine its diffusion coefficient in concrete[1213]. The variety of methods and experimental conditions used for this purpose have led to a wide range of diffusivity values (from 10 -12 to 10 -8 m2/s) for oxygen in cement paste [14].Since the diffusion coefficient of oxygen in aqueous solutions (1)O2 = 10 -5 cm2/s-1)is saturation concentration (CO2 = 2.1 x 10 -7 mol/cm 3) and the approximate thickness of diffusion layers in stagnant solutions (8 = 0.01 cm) are wellknownthe limiting diffusion current can be calculated as :ilo2 = - z FD02C02/r = 8 x 10 -4 A/cm 2 (80 pA/cm 2)where z is the number of equivalents per mole (4) and F the Faraday (96500 A.s/eq).For 1-cm thick mortar covers of average porosity 15%(see Fig. 1 in Part I) [1] and a diffusioja layer thickness of the same order as the cover thickness11o2 = 0.12 laA/cm 2which is quite consistent with the icorr values estimated under pore saturation conditions at the end of the curingprocessboth for mortars containing no chloride ions and for those including 24 or 6% C1- [16].On the other handicorr values of ca. 10 liA/cm 2 (see Fig. 9 in Part I) [4] have been obtained by several authors for mortars with chlorides or carbonated mortars which are incompatible with the rates allowed by the limiting diffusion current of oxygen. Thereforein some circumstancesalternative cathodic processes allowing for faster kinetics must therefore be involved. In recent workthe concurrence of creviceschloride ions and dissolved oxygen at the steel/concrete interface was claimed to provide the thermodynamic conditions required for protons to be reduced and the alternative mechanism to occur [1117].There are a number of facts that refute oxygen reduction as being the sole corrosion rate-determining stepnamely:- Under some circumstancesonce corrosion in an activestate has startedit develops at the same rate even though oxygen is being removed from the medium (Fig. 4) [11].- As saturation of concrete pores decreaseconcrete resistivity controls ico~r over a wide resistivity range ; therefore the corrosion rate seems to decrease in proportion to the ease with which oxygen penetrates into the structure(Fig. 5)[10].On the other handthere are several arguments in favour of proton reduction in Ca(OH)2-saturated solutions or cement mortars [11] :- The pH decreases from 12.6 to ca. 5 within crevices at the steel/electrolyte interface upon exposure of the steel to a Ca(OH)2-saturated solution with C1- additions and wellaerated. If sufficient oxygen is availablethe pH can drop as low as 1-2.- The emergence of acid exudates ofpH 1-5 from cracks and macropores in chloride-containing mortar specimens under wet atmospheres at high corrosion rates (5-10 pA/cm2).- The formation of gas bubbles over iron hydroxide membrane-coated pits when the steal is polarized anodically in a Ca(OH)2-saturatedchloride-contaminated solution at potentials below those required for oxygen release. Everything points to pits with a low enough pH for the anodic current applied to overlap with a corrosion process involving proton reduction as a cathodic half-reaction.When concrete-embedded steel is corroded in an active stateits corrosion kinetics rise exponentially with increasing pore saturation (Fig. 6) similarly to atmospheric corrosion in bare steel as the environment's relative humidity increases [18]. At some points in the reinfor- cementsa catalytic cycle may take placee.g.those put forward by Schikorr for atmospheric corrosion of steel [19]with chloride ion rather than SO2-as the catalyst (Fig. 6).Fig. 5 - Relationship between mortar resistivity Fig. 6 - Influence of the degree of pore saturationand the corrosion rate of reinforcements. on the corrosion rate of reinforcements.中文翻译II:混凝土中钢腐蚀的有关问题Ⅱ：腐蚀机理和监督、使用年限的预测和保护方法J.A. GonzdlezS. FelifdP. RodffguezW. LfpezE. RamlrezC. AlonsoC.Andrade摘要:第二部分阐述几个仍然存在争议的重要问题尽管已经在混凝土中钢腐蚀的调查研究投入了大量的工作特别是这几方面：1)在钢筋混凝土结构中的大电偶和腐蚀微电池对的相对重要性；2)激活状态的钢筋腐蚀机理；3)阻止或停止钢筋腐蚀最好的保护方法；4)一个钢筋混凝土结构使用年限的可靠预测的可能性探索；5)最好的防腐措施和控制方法这些回答需要试验得出大部分都由作者们得出1.前言正常条件下强碱混凝土中的钢仍然处于钝化状态钢筋的钝性能保证钢筋混凝土结构无限的耐久性然而有一些能破坏钢的钝性和引起钢筋腐蚀的实验条件在第Ⅰ部分中讨论到的一些实验结构已经引起了很多争论[1]第Ⅱ部分的分析虽然没有竭尽全力但至少是作者的意思就像有趣的问题有不同的意见一样2.材料和方法读者指出在第Ⅰ部分详细描述了用于这项工作的材料和方法这里所讨论的大部分实验结果都是从一样的试块和平板中得到的电偶是由特殊设计的试块确定的如图1和2所示用一根长16m70mm×100 mm横截面的梁模拟近真实条件梁是由每立方米350kg水泥制成梁的一半含有添加剂另一半含有水泥的重量的3%的CaCl2[2](图1)为了了解S正极/S负极的比值对大电偶的影响用在一个小的碳素钢正极环绕一个不锈钢负极并夹紧来模拟这样比值的连贯性是可靠的此外与钝化结果的电位和不锈钢的icorr是非常相似的图1.梁用来分别测量混凝土中含有和不含有氯化物图2.用电耦合牢牢嵌入含有氯化物的砂浆里来研究的icorr和Ecorr来说明钝化钢/活跃钢耦合的意义S正极/S负极的作用和腐蚀微电池对的相对意义的方案3.结果和讨论3.1什么是在钢筋混凝土结构中大电偶和腐蚀微电池对的相对重要性？根据一些作者[35]极化电阻作用为估计钢筋混凝土中腐蚀速度提供了一个有效的方法；这个方法是非常快、方便、非破坏性、适量和相当精确的然而它不确定是否会对高度极化的电极产生严重的错误通过在钢筋中的大电偶的钝化面积与激活面积的比值的影响在作者自己对钢筋混凝土中大电偶性质的实验基础上这些大电偶对所有的腐蚀是非常适度的与存在充分的氧气和水分条件下腐蚀微电池对形成激活状态的钢筋比较[278]因此它已被实验验证：(a)大电偶对潮湿混凝土中的阳极部分由一个轻微的极化作用只要几毫伏就可以影响它的电位(b)在另一方面大电偶对钝化部分有一个很强的极化作用尽管低电流的运用相对于所有腐蚀流(c)因此电流可能会导致非常低估在激活部分的icorr的值因为它们通常比极化电阻值估算的icorr值的10%还小(d)腐蚀剂会引起钢筋混凝土结构上共面的电偶只能证明从激活面积到钝化面积边缘的一个很短的距离存在危险图3是估算的icorr与ig值的比较在砂浆中含有3%的CaCl2每个正极表面单元体为许多正极/负极表面比值作为美国钢铁学会304不锈钢/碳素钢电偶的一部分支持以上结论图3.腐蚀微电池对(icorr)和电耦合(ig)在包裹在图 4.暴露在自由氧环境下试块的icorr和Ecorr不含有氯化物砂浆里的钢腐蚀中的相对意义的变化趋势电流都是相对于S负极而计算得到的(在图2的电耦合中的碳素钢)3.2钢筋腐蚀的机理是什么？当钝化状态消失钢筋的腐蚀速度与混凝土的电阻率成反比例在一个很宽的电阻率范围内[10]因为环境中的相对湿度和混凝土的离子型外加剂确定混凝土的电阻率这些因素与氧气一起在钢筋的表面控制着腐蚀速度[11]饱和水混凝土结构的电阻率是相对非常低的而且腐蚀速度实际上是溶解氧的扩散控制的通过混凝土包住钢筋实现这与在中性和强碱条件下唯一可能的负极反应是氧气的还原作业这个理念是一致的这个重要性归因于氧气的循环作业它证明这些作用对确定它在混凝土中的扩散率是正确的[1213]各种方法和实验条件用于这个目的已得出了一定范围的水泥浆中的氧气的扩散率(从10-12到10-8m2/s)[14]因为水溶液(CO2=10-5cm2/s-1)中氧气的扩散率是饱和浓度(CO2=2.1×10-7mol/cm3) 不流动环境中(?=0.001cm)扩散层的近似密度都是众所周知的这个有限扩散流可以这样计算：其中z是等价的每摩尔(4)的数值而F就是法拉第(96500A?s/eq)平均孔隙率为15%的1cm厚的砂浆保护层厚度与扩散层厚度一样与在养护期的最后空隙饱和条件下估算得的icorr值是非常一致的这些砂浆不含氯化物离子而都含有24或6%的Cl-[16]另一方面ca.10?A/cm2的icorr(见第Ⅰ部分图9)[4]已经由一些作者从含氯化物的砂浆或碳酸盐砂浆与氧气有限的扩散流所允许的速度是不协调的因此在一些环境下替代负极的过程必须有更快的动力在最近的工作中裂缝、氯化物例子和溶解氧并存在钢与混凝土的交界面可以为质子的还原和替换机理的发生提供热动力条件[1117]有很多论据反驳氧气的还原作用作为底面腐蚀的定速步骤即：- 在一些环境下腐蚀一旦开始它发展到同一个速度尽管氧气正在从媒介中排除(图4)[11]- 当混凝土空隙饱和作用降低混凝土的电阻率控制icorr在一个宽泛的电阻率范围内；因此腐蚀速度的减小好像与氧气进入结构的难易成反比例(图5)[10]在另一方面有一些论点支持在饱和Ca(OH)2中或水泥砂浆中的质子还原反应[11]：- PH值由12.6减小到ca.5在暴露的含有Cl-的饱和Ca(OH)2中的钢与电解质溶液的交界面上如果提供充足的氧气PH值可以降低到1-2- 从在潮湿的空气中含有氯化物的砂浆试块的裂缝和大空隙中暴露的PH值1-5的酸性分泌物腐蚀速度很快(5-10?A/cm2)- 在蚀坑处涂上氢氧化铁膜的钢在含有氯化物的饱和Ca(OH)2中极化成阳极时会产生气泡因为电位的降低需要释放氧气每一个蚀坑点有一个足够低的PH因参与质子还原反应就像阴极半反应它们的腐蚀过程与阳极流互相重叠当包裹在混凝土中的钢处于腐蚀状态它的腐蚀动力指数随着空隙饱和作用的上升而升高(图6)就像裸露在大气中的钢的腐蚀随着环境的相对湿度的上升而增加一样[18]在钢筋上的一些点催化循环可能被取代等这些是由Schikorr提出的钢的大气腐蚀[19]是氯化铁而不是SO42-作为催化剂(图6)图5.砂浆电阻与钢筋腐蚀速度的相互关系图6.孔隙饱和度对钢筋腐蚀速度的影响????????宁波工程学院毕业设计（论文）1。

DESIGN AND EXECUTION OF GROUNDINVESTIGATION FOR EARTHWORKSABSTRACTThe design and execution of ground investigation works for earthwork projects has become increasingly important as the availability of suitable disposal areas becomes limited and costs of importing engineering fill increase. An outline of ground investigation methods which can augment ‘traditional investigation methods’ particularly for glacial till / boulder clay soils is presented. The issue of ‘geotechnical certification’ is raised an d recommendations outlined on its merits for incorporation with ground investigations and earthworks.1. INTRODUCTIONThe investigation and re-use evaluation of many Irish boulder clay soils presents difficulties for both the geotechnical engineer and the road design engineer. These glacial till or boulder clay soils are mainly of low plasticity and have particle sizes ranging from clay to boulders. Most of our boulder clay soils contain varying proportions of sand, gravel, cobbles and boulders in a clay or silt matrix. The amount of fines governs their behaviour and the silt content makes it very weather susceptible.Moisture contents can be highly variable ranging from as low as 7% for the hard grey black Dublin boulder clay up to 20-25% for Midland, South-West and North-West light grey boulder clay deposits. The ability of boulder clay soils to take-in free water is well established and poor planning of earthworks often amplifies this.The fine soil constituents are generally sensitive to small increases in moisture content which often lead to loss in strength and render the soils unsuitable for re-use as engineering fill. Many of our boulder clay soils (especially those with intermediate type silts and fine sandmatrix) have been rejected at the selection stage, but good planning shows that they can in fact fulfil specification requirements in terms of compaction and strength.The selection process should aim to maximise the use of locally available soils and with careful evaluation it is possible to use o r incorporate ‘poor or marginal soils’ within fill areas and embankments. Fill material needs to be placed at a moisture content such that it is neither too wet to be stable and trafficable or too dry to be properly compacted.High moisture content / low strength boulder clay soils can be suitable for use as fill in low height embankments (i.e. 2 to 2.5m) but not suitable for trafficking by earthwork plant without using a geotextile separator and granular fill capping layer. Hence, it is vital that the earthworks contractor fully understands the handling properties of the soils, as for many projects this is effectively governed by the trafficability of earthmoving equipment.2. TRADITIONAL GROUND INVESTIGATION METHODSFor road projects, a principal aim of the ground investigation is to classify the suitability of the soils in accordance with Table 6.1 from Series 600 of the NRA Specification for Road Works (SRW), March 2000. The majority of current ground investigations for road works includes a combination of the following to give the required geotechnical data:▪Trial pits▪Cable percussion boreholes▪Dynamic probing▪Rotary core drilling▪In-situ testing (SPT, variable head permeability tests, geophysical etc.)▪Laboratory testingThe importance of ‘phasing’ th e fieldwork operations cannot be overstressed, particularly when assessing soil suitability from deep cut areas. Cable percussion boreholes are normally sunk to a desired depth or ‘refusal’ with disturbed and undisturbed samples recovered at 1.00m intervals or change of strata.In many instances, cable percussion boring is unable to penetrate through very stiff, hard boulder clay soils due to cobble, boulder obstructions. Sample disturbance in boreholes should be prevented and loss of fines is common, invariably this leads to inaccurate classification.Trial pits are considered more appropriate for recovering appropriate size samples and for observing the proportion of clasts to matrix and sizes of cobbles, boulders. Detailed and accurate field descriptions are therefore vital for cut areas and trial pits provide an opportunity to examine the soils on a larger scale than boreholes. Trial pits also provide an insight on trench stability and to observe water ingress and its effects.A suitably experienced geotechnical engineer or engineering geologist should supervise the trial pitting works and recovery of samples. The characteristics of the soils during trial pit excavation should be closely observed as this provides information on soil sensitivity, especially if water from granular zones migrates into the fine matrix material. Very often, the condition of soil on the sides of an excavation provides a more accurate assessment of its in-situ condition.3. SOIL CLASSIFICATIONSoil description and classification should be undertaken in accordance with BS 5930 (1999) and tested in accordance with BS 1377 (1990). The engineering description of a soil is based on its particle size grading, supplemented by plasticity for fine soils. For many of our glacial till, boulde r clay soils (i.e. ‘mixed soils’) difficulties arise with descriptions and assessing engineering performance tests.A key parameter (which is often underestimated) in classifying and understanding these soils is permeability (K). Inspection of the particle size gradings will indicate magnitude of permeability. Where possible, triaxial cell tests should be carried out on either undisturbed samples (U100’s) or good quality core samples to evaluate the drainage characteristics of the soils accurately.Low plasticity boulder clay soils of intermediate permeability (i.e. K of the order of 10-5 to 10-7 m/s) can often be ‘conditioned’ by drainage measures. This usually entails the installation of perimeter drains and sumps at cut areas or borrow pits so as to reduc e the moisture content. Hence, with small reduction in moisture content, difficult glacial till soils can become suitable as engineering fill.4. ENGINEERING PERFORMANCE TESTING OF SOILSLaboratory testing is very much dictated by the proposed end-use for the soils. The engineering parameters set out in Table 6.1 pf the NRA SRW include a combination of the following:▪Moisture content▪Particle size grading▪Plastic Limit▪CBR▪Compaction (relating to optimum MC)▪Remoulded undrained shear strengthA number of key factors should be borne in mind when scheduling laboratory testing:▪Compaction / CBR / MCV tests are carried out on < 20mm size material.▪Moisture content values should relate to < 20mm size material to provide a valid comparison.▪Pore pressures are not taken into account during compaction and may vary considerably between laboratory and field.▪Preparation methods for soil testing must be clearly stipulated and agreed with the designated laboratory.Great care must be taken when determining moisture content of boulder clay soils. Ideally, the moisture content should be related to the particle size and have a corresponding grading analysis for direct comparison, although this is not always practical.In the majority of cases, the MCV when used with compaction data is considered to offer the best method of establishing (and checking) the suitability characteristics of a boulder clay soil. MCV testing during trial pitting is strongly recommended as it provides a rapid assessment of the soil suitability directly after excavation. MCV calibration can then be carried out in the laboratory at various moisture content increments. Sample disturbance can occur during transportation to the laboratory and this can have a significant impact on the resultant MCV’s. IGSL h as found large discrepancies when performing MCV’s in the field on low plasticity boulder clays with those carried out later in the laboratory (2 to 7 days). Many of the aforementioned low plasticity boulder clay soils exhibit time dependant behaviour with significantly different MCV’s recorded at a later date –increased values can be due to the drainage of the material following sampling, transportation and storage while dilatancy and migration of water from granular lenses can lead to deterioration and lower values.CBR testing of boulder clay soils also needs careful consideration, mainly with the preparation method employed. Design engineers need to be aware of this, as it can have an order of magnitude difference in results. Static compaction of boulder clay soils is advised as compaction with the 2.5 or 4.5kg rammer often leads to high excess pore pressures being generated – hence very low CBR values can result. Also, curing of compacted boulder clay samples is important as this allows excess pore water pressures to dissipate.5. ENGINEERING CLASSIFICATION OF SOILSIn accordance with the NRA SRW, general cohesive fill is categorised in Table 6.1 as follows:▪2A Wet cohesive▪2B Dry cohesive▪2C Stony cohesive▪2D Silty cohesiveThe material properties required for acceptability are given and the design engineer then determines the upper and lower bound limits on the basis of the laboratory classification and engineering performance tests. Irish boulder clay soils are predominantly Class 2C.Clause 612 of the SRW sets out compaction methods. Two procedures are available:▪Method Compaction▪End-Product CompactionEnd product compaction is considered more practical, especially when good compaction control data becomes available during the early stages of an earthworks contract. A minimum Target Dry Density (TDD) is considered very useful for the contractor to work with as a means of checking compaction quality. Once the material has been approved and meets the acceptability limits, then in-situ density can be measured, preferably by nuclear gauge or sand replacement tests where the stone content is low.As placing and compaction of the fill progresses, the in-situ TDD can be checked and non-conforming areas quickly recognised and corrective action taken. This process requires the design engineer to review the field densities with the laboratory compaction plots and evaluate actual with ‘theoretical densities’.6. SUPPLEMENTARY GROUND INVESTIGATION METHODS FOR EARTHWORKSThe more traditional methods and procedures have been outlined in Section 2. The following are examples of methods which are believed to enhance ground investigation works for road projects:▪Phasing the ground investigation works, particularly the laboratory testing▪Excavation & sampling in deep trial pits▪Large diameter high quality rotary core drilling using air-mist or polymer gel techniques▪Small-scale compaction trials on potentially suitable cut material6.1PHASINGPhasing ground investigation works for many large projects has been advocated for many years –this is particularly true for road projects where significant amounts of geotechnical data becomes available over a short period. On the majority of large ground investigation projects no period is left to ‘digest’ or review the preliminary fi ndings and re-appraise the suitability of the methods.With regard to soil laboratory testing, large testing schedules are often prepared with no real consideration given to their end use. In many cases, the schedule is prepared by a junior engineer while the senior design engineer who will probably design the earthworks will have no real involvement.It is highlighted that the engineering performance tests are expensive and of long duration (e.g. 5 point compaction with CBR & MCV at each point takes in exc ess of two weeks). When classification tests (moisture contents, particle size analysis and Atterberg Limits) are completed then a more incisive evaluation can be carried out on the data and the engineering performance tests scheduled. If MCV’s are perform ed during trial pitting then a good assessment of the soil suitability can be immediately obtained.6.2DEEP TRIAL PITSThe excavation of deep trial pits is often perceived as cumbersome and difficult and therefore not considered appropriate by design engineers. Excavation of deep trial pits in boulder clay soils to depths of up to 12m is feasible using benching techniques and sump pumping of groundwater.In recent years, IGSL has undertaken such deep trial pits on several large road ground investigation projects. The data obtained from these has certainly enhanced the geotechnical data and provided a better understanding of the bulk properties of the soils.It is recommended that this work be carried out following completion of the cable percussion boreholes and rotary core drill holes. The groundwater regime within the cut area will play an important role in governing the feasibility of excavating deep trial pits. The installation ofstandpipes and piezometers will greatly assist the understanding of the ground water conditions, hence the purpose of undertaking this work late on in the ground investigation programme.Large representative samples can be obtained (using trench box) and in-situ shear strength measured on block samples. The stability of the pit sidewalls and groundwater conditions can also be established and compared with levels in nearby borehole standpipes or piezometers. Over a prominent cut area of say 500m, three deep trial pits can prove invaluable and the spoil material also used to carry out small-scale compaction trials.From a value engineering perspective, the cost of excavating and reinstating these excavations can be easily recovered. A provisional sum can be allocated in the ground investigation and used for this work.7. CONCLUSIONS▪Close co-operation is needed between ground investigation contractors and consulting engineers to ensure that the geotechnical investigation work for the roads NDP can be satisfactorily carried out.▪Many soils are too easily rejected at selection / design stag e. It is hoped that the proposed methods outlined in this paper will assist design engineers during scoping and specifying of ground investigation works for road projects.▪With modern instrumentation, monitoring of earthworks during construction is very straightforward. Pore water pressures, lateral and vertical movements can be easily measured and provide important feedback on the performance of the engineered soils.▪Phasing of the ground investigation works, particularly laboratory testing is considered vital so that the data can be properly evaluated.▪Disposal of ‘marginal’ soils will become increasingly difficult and more expensive as the waste licensing regulations are tightened. The advent of landfill tax in the UK has seenthorough examination of all soils for use in earthworks. This is likely to provide a similar incentive and challenge to geotechnical and civil engineers in Ireland in the coming years.▪ A certification approach comparable with that outlined should be considered by the NRAfor ground investigation and earthwork activitie▪土方工程的地基勘察与施工摘要：当工程场地的处理面积有限且填方工程费用大量增加时，土方工程的地基勘察设计与施工已逐渐地变得重要。

毕业设计外文文献翻译院系: 土木工程系年级专业: 2011级土木工程专业姓名: XXX学号:附件: Structural Systems to resist lateral loads指导老师评语:该生的外文翻译题目《Structural Systems to resist lateral loads》该译文基本能与原文关联,思路比较清晰,语句基本通顺,层次清晰,观点表达基本准确。

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指导教师签名:年月日附件Structural Systems to resist lateral loads1、Commonly Used structural SystemsWith loads measured in tens of thousands kips, there is little room in the design of high-rise buildings for excessively complex thoughts、Indeed, the better high-rise buildings carry the universal traits of simplicity of thought and clarity of expression、It does not follow that there is no room for grand thoughts、Indeed, it is with such grand thoughts that the new family of high-rise buildings has evolved、Perhaps more important, the new concepts of but a few years ago have become commonplace in today’ s technology、Omitting some concepts that are related strictly to the materials of construction, the most commonly used structural systems used in high-rise buildings can be categorized as follows:1.Moment-resisting frames、2.Braced frames, including eccentrically braced frames、3.Shear walls, including steel plate shear walls、4.Tube-in-tube structures、5.Tube-in-tube structures、6.Core-interactive structures、7.Cellular or bundled-tube systems、Particularly with the recent trend toward more complex forms, but in response also to the need for increased stiffness to resist the forces from wind and earthquake, most high-rise buildings have structural systems built up of combinations of frames, braced bents, shear walls, and related systems、Further, for the taller buildings, the majorities are composed of interactive elements in three-dimensional arrays、The method of combining these elements is the very essence of the design process for high-rise buildings、These combinations need evolve in response to environmental, functional, and cost considerations so as to provide efficient structures that provoke the architectural development to new heights、This is not to say that imaginative structural design can create great architecture、To the contrary, many examples of fine architecture have been created with only moderate support from the structural engineer, while only fine structure, not great architecture, can be developed without the genius and the leadership of a talented architect、Inany event, the best of both is needed to formulate a truly extraordinary design of a high-rise building、While comprehensive discussions of these seven systems are generally available in the literature, further discussion is warranted here 、The essence of the design process is distributed throughout the discussion、2、Moment-Resisting FramesPerhaps the most commonly used system in low-to medium-rise buildings, the moment-resisting frame, is characterized by linear horizontal and vertical members connected essentially rigidly at their joints、Such frames are used as a stand-alone system or in combination with other systems so as to provide the needed resistance to horizontal loads、In the taller of high-rise buildings, the system is likely to be found inappropriate for a stand-alone system, this because of the difficulty in mobilizing sufficient stiffness under lateral forces、Analysis can be accomplished by STRESS, STRUDL, or a host of other appropriate computer programs; analysis by the so-called portal method of the cantilever method has no place in today’s technology、Because of the intrinsic flexibility of the column/girder intersection, and because preliminary designs should aim to highlight weaknesses of systems, it is not unusual to use center-to-center dimensions for the frame in the preliminary analysis、Of course, in the latter phases of design, a realistic appraisal in-joint deformation is essential、3、Braced FramesThe braced frame, intrinsically stiffer than the moment –resisting frame, finds also greater application to higher-rise buildings、The system is characterized by linear horizontal, vertical, and diagonal members, connected simply or rigidly at their joints、It is used commonly in conjunction with other systems for taller buildings and as a stand-alone system in low-to medium-rise buildings、While the use of structural steel in braced frames is common, concrete frames are more likely to be of the larger-scale variety、Of special interest in areas of high seismicity is the use of the eccentric braced frame、Again, analysis can be by STRESS, STRUDL, or any one of a series of two –or three dimensional analysis computer programs、And again, center-to-center dimensions are usedcommonly in the preliminary analysis、4、Shear wallsThe shear wall is yet another step forward along a progression of ever-stiffer structural systems、The system is characterized by relatively thin, generally (but not always) concrete elements that provide both structural strength and separation between building functions、In high-rise buildings, shear wall systems tend to have a relatively high aspect ratio, that is, their height tends to be large compared to their width、Lacking tension in the foundation system, any structural element is limited in its ability to resist overturning moment by the width of the system and by the gravity load supported by the element、Limited to a narrow overturning, One obvious use of the system, which does have the needed width, is in the exterior walls of building, where the requirement for windows is kept small、Structural steel shear walls, generally stiffened against buckling by a concrete overlay, have found application where shear loads are high、The system, intrinsically more economical than steel bracing, is particularly effective in carrying shear loads down through the taller floors in the areas immediately above grade、The sys tem has the further advantage of having high ductility a feature of particular importance in areas of high seismicity、The analysis of shear wall systems is made complex because of the inevitable presence of large openings through these walls、Preliminary analysis can be by truss-analogy, by the finite element method, or by making use of a proprietary computer program designed to consider the interaction, or coupling, of shear walls、5、Framed or Braced TubesThe concept of the framed or braced or braced tube erupted into the technology with the IBM Building in Pittsburgh, but was followed immediately with the twin 110-story towers of the World Trade Center, New York and a number of other buildings 、The system is characterized by three –dimensional frames, braced frames, or shear walls, forming a closed surface more or less cylindrical in nature, but of nearly any plan configuration、Because those columns that resist lateral forces are placed as far as possible from the cancroids of the system, the overall moment of inertia is increased and stiffness is very high、The analysis of tubular structures is done using three-dimensional concepts, or by two- dimensional analogy, where possible, whichever method is used, it must be capable ofaccounting for the effects of shear lag、The presence of shear lag, detected first in aircraft structures, is a serious limitation in the stiffness of framed tubes、The concept has limited recent applications of framed tubes to the shear of 60 stories、Designers have developed various techniques for reducing the effects of shear lag, most noticeably the use of belt trusses、This system finds application in buildings perhaps 40stories and higher、However, except for possible aesthetic considerations, belt trusses interfere with nearly every building function associated with the outside wall; the trusses are placed often at mechanical floors, mush to the disapproval of the designers of the mechanical systems、Nevertheless, as a cost-effective structural system, the belt truss works well and will likely find continued approval from designers、Numerous studies have sought to optimize the location of these trusses, with the optimum location very dependent on the number of trusses provided、Experience would indicate, however, that the location of these trusses is provided by the optimization of mechanical systems and by aesthetic considerations, as the economics of the structural system is not highly sensitive to belt truss location、6、Tube-in-Tube StructuresThe tubular framing system mobilizes every column in the exterior wall in resisting over-turning and shearing forces、The term‘tube-in-tube’is largely self-explanatory in that a second ring of columns, the ring surrounding the central service core of the building, is used as an inner framed or braced tube、The purpose of the second tube is to increase resistance to over turning and to increase lateral stiffness、The tubes need not be of the same character; that is, one tube could be framed, while the other could be braced、In considering this system, is important to understand clearly the difference between the shear and the flexural components of deflection, the terms being taken from beam analogy、In a framed tube, the shear component of deflection is associated with the bending deformation of columns and girders (i、e, the webs of the framed tube) while the flexural component is associated with the axial shortening and lengthening of columns (i、e, the flanges of the framed tube)、In a braced tube, the shear component of deflection is associated with the axial deformation of diagonals while the flexural component of deflection is associated with the axial shortening and lengthening of columns、Following beam analogy, if plane surfaces remain plane (i、e, the floor slabs),then axialstresses in the columns of the outer tube, being farther form the neutral axis, will be substantially larger than the axial stresses in the inner tube、However, in the tube-in-tube design, when optimized, the axial stresses in the inner ring of columns may be as high, or even higher, than the axial stresses in the outer ring、This seeming anomaly is associated with differences in the shearing component of stiffness between the two systems、This is easiest to under-stand where the inner tube is conceived as a braced (i、e, shear-stiff) tube while the outer tube is conceived as a framed (i、e, shear-flexible) tube、7、Core Interactive StructuresCore interactive structures are a special case of a tube-in-tube wherein the two tubes are coupled together with some form of three-dimensional space frame、Indeed, the system is used often wherein the shear stiffness of the outer tube is zero、The United States Steel Building, Pittsburgh, illustrates the system very well、Here, the inner tube is a braced frame, the outer tube has no shear stiffness, and the two systems are coupled if they were considered as systems passing in a straight line from the “hat” structure、Note that the exterior columns would be improperly modeled if they were considered as systems passing in a straight line from the “hat” to the foundations; these columns are perhaps 15%stiffer as they follow the elastic curve of the braced core、Note also that the axial forces associated with the lateral forces in the inner columns change from tension to compression over the height of the tube, with the inflection point at about 5/8 of the height of the tube、The outer columns, of course, carry the same axial force under lateral load for the full height of the columns because the columns because the shear stiffness of the system is close to zero、The space structures of outrigger girders or trusses, that connect the inner tube to the outer tube, are located often at several levels in the building、The AT&T headquarters is an example of an astonishing array of interactive elements:1.The structural system is 94 ft (28.6m) wide, 196ft(59.7m) long, and 601ft (183.3m)high、2.Two inner tubes are provided, each 31ft(9.4m) by 40 ft (12.2m), centered 90 ft (27.4m)apart in the long direction of the building、3.The inner tubes are braced in the short direction, but with zero shear stiffness in the longdirection、4. A single outer tube is supplied, which encircles the building perimeter、5.The outer tube is a moment-resisting frame, but with zero shear stiffness for thecenter50ft (15.2m) of each of the long sides、6. A space-truss hat structure is provided at the top of the building、7. A similar space truss is located near the bottom of the building8.The entire assembly is laterally supported at the base on twin steel-plate tubes, becausethe shear stiffness of the outer tube goes to zero at the base of the building、8、Cellular structuresA classic example of a cellular structure is the Sears Tower, Chicago, a bundled tube structure of nine separate tubes、While the Sears Tower contains nine nearly identical tubes, the basic structural system has special application for buildings of irregular shape, as the several tubes need not be similar in plan shape, It is not uncommon that some of the individual tubes one of the strengths and one of the weaknesses of the system、This special weakness of this system, particularly in framed tubes, has to do with the concept of differential column shortening、The shortening of a column under load is given by the expression△=ΣfL/EFor buildings of 12 ft (3.66m) floor-to-floor distances and an average compressive stress of 15 ksi (138MPa), the shortening of a column under load is 15 (12)(12)/29,000 or 0.074in (1.9mm) per story、At 50 stories, the column will have shortened to 3.7 in、(94mm) less than its unstressed length、Where one cell of a bundled tube system is, say, 50stories high and an adjacent cell is, say, 100stories high, those columns near the boundary between 、the two systems need to have this differential deflection reconciled、Major structural work has been found to be needed at such locations、In at least one building, the Rialto Project, Melbourne, the structural engineer found it necessary to vertically pre-stress the lower height columns so as to reconcile the differential deflections of columns in close proximity with the post-tensioning of the shorter column simulating the weight to be added on to adjacent, higher columns、抗侧向荷载的结构体系1、常用的结构体系若已测出荷载量达数千万磅重,那么在高层建筑设计中就没有多少可以进行极其复杂的构思余地了。