Engineering Structures31(2009)
1930–1943
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Finite element modelling of deformation characteristics of historical stone masonry shear walls
R.Senthivel?,P.B.Louren?o
Department of Civil Engineering,University of Minho,Guimar?es,Portugal
a r t i c l e i n f o Article history:
Received27April2008 Received in revised form
14August2008
Accepted11February2009 Available online22April2009 Keywords:
Shear wall
FEM
Stone masonry
Deformation characteristics Failure modes
Interface elements a b s t r a c t
Two dimensional nonlinear finite element analysis based on experimental test data has been carried out to model deformation characteristics,such as load–displacement envelope diagrams and failure modes of historical stone masonry shear walls subjected to combined axial compression and lateral shear loading. An experimental research work was carried out on three different types of historical stone masonry shear walls that can be considered representative of ancient stone masonry constructions.Those three types of masonry are:(i)sawn dry-stack or dry-stone masonry without bonding mortar,(ii)irregular stone masonry with bonding mortar,and(iii)rubble masonry with irregular bonding mortar thickness.Plasticity theory based micro modelling techniques has been used to carry out the analysis.The stone units were modelled using eight node continuum plane stress elements with full Gauss integration.The joints and unit-joint interfaces were modelled using a six node zero thickness line interface elements with Lobatto integration.This paper outlines the experimental research work,details of numerical modelling carried out and report the numerical lateral load–displacement diagrams and failure modes.The numerical analysis results were compared with the experimental test results and good agreement was found.
?2009Elsevier Ltd.All rights reserved.
1.Introduction
Stone masonry is the most ancient,durable,and widespread building method devised by mankind.Stone structures built without mortar rely on the skill of the craftsmen and the forces of gravity and frictional resistance.Stone has been a successful building medium throughout the ages and around the world because of its unique range of benefits.The structures are remarkably durable and,if correctly designed,can be made earthquake resistant.They resist fire,water,and insect damage. The mason needs a minimum of tools;the work is easily repaired; the material is readily available and is recyclable.Dry stone masonry,aesthetically,complements and enhances the landscape. Archaeologists have determined that the Chinese built dry stone terraces at least10000years ago.In Britain,ancient tribes built dry stone shelters just after the last ice age,8000years ago. High quality stone tools recently found in Europe are2.2million years old.The technique of dry stacking in construction has existed in Africa for thousands of years.The Egyptian pyramids and the Zimbabwe ruins,a capital of ancient Shona Kingdom around400AD,are good examples.In addition to the neglect and destruction of historic structures,the craft is handicapped due to lack of technical information and skilled preservation personnel.?
Corresponding author.Tel.:+351963614995;fax:+351253510217.
E-mail address:drsenthivel@https://www.doczj.com/doc/7019277568.html,(R.Senthivel).Construction and engineering data that professionals need are scarce and,if recorded at all,are difficult to locate.
A large part of historical buildings are built with:(i)sawn dry-stack or dry-stone masonry without bonding mortar;(ii)irregular stone masonry with bonding mortar;(iii)rubble masonry with irregular bonding mortar thickness;(iv)a combination of the three techniques.When bonding mortar is used,it is usually low strength.In addition,masonry with mortar joints can experience a significant loss of mortar due to combined chemical,physical and mechanical degradation.Due to the partial or total disappearance of mortar,the behaviour of these constructions can then become similar to those made of dry joint masonry.
The primary function of masonry elements is to sustain a vertical gravity load.However,structural masonry elements are required to withstand combined shear,flexure and compressive stresses under earthquake or wind load combinations consisting of lateral as well as vertical loads.Only few experimental results are available on the behaviour of stone masonry walls,e.g.Chiostrini and Vignoli[1]addressed strength properties and Toma?evi?[2] reported tests on strengthening and improvement of the seismic performance of stone masonry walls.More recently,Corradi et al.
[3]carried out an experimental study on the strength properties of double-leaf roughly cut stone walls by means of in-situ diagonal compression and shear-compression tests.
A comprehensive experimental and numerical study on his-torical dry stone masonry walls has been reported by Louren?o et al.[4].Displacement controlled experimental study for ma-sonry walls under combined compression and shear loading was
0141-0296/$–see front matter?2009Elsevier Ltd.All rights reserved. doi:10.1016/j.engstruct.2009.02.046
R.Senthivel,P.B.Louren?o /Engineering Structures 31(2009)1930–19431931
Unit (brick,block,etc)
Head joint
Bed joint
Unit
Mortar
Interface Unit/mortar
(a)Masonry sample.(b)
Micro-modelling.
"Unit"
"Joint"
Composite
(c)Simplified micro-modelling.(d)Macro-modelling.
Fig.1.Micro-and macro-modelling techniques.
done for monotonic loading.Based on the material properties ob-tained from the experimental tests,numerical analysis was car-ried out to model the monotonic load–displacement diagrams using non-linear finite elements.Similar numerical modelling us-ing rigid blocks limit analysis and discrete element analysis has been carried out by Azevedo et al.[5]and Ordu?a and Louren?o [6].However,these studies were limited to regular (sawn)dry stack mortarless stone masonry only.A detailed literature survey on numerical modelling of monuments and historical construc-tions including structure and component level are presented by Louren?o [7]and Lemos [8].
A research programme was carried out by Vasconcelos [9]at University of Minho to experimentally evaluate the in-plane seismic performance of ancient stone masonry without and with bonding mortar of low tensile strength to simulate existing ancient stone masonry structures.Monotonic and reversed cyclic loading tests with three different pre-compression loading (low,moderate and high)were performed to investigate the strength,deformation capacity,load–displacement hysteresis response,stiffness characterisation and failure modes.The data obtained from this experimental research has been used as a base for the present numerical analysis.The objective of the analysis carried out here was limited to modelling the peak load points of reversed cyclic hysteresis diagrams,or the so-called load–displacement envelope diagram,and failure modes of three different types of ancient stone masonry subjected to three different axial pre-compression loads.
Masonry is highly anisotropic due to the presence of discrete sets of horizontal and vertical mortar joints.Louren?o,Saadegh-vaziri and Mehta,Papa [10–12]have divided models for masonry into two categories:micro and macro.Fig.1shows details of micro-and macro-modelling techniques.Fig.1(b)shows a detailed micro-modelling where joints are represented by mortar continuum elements and discontinuum interface elements.Fig.1(c)shows simplified micro-modelling where joints are represented by dis-continuum elements.Fig.1(d)shows macro-modelling where joints are smeared out in the continuum.In the micro-modelling techniques,it is possible to model the unit-mortar interface and mortar joint which is responsible for most cracking as well as slip.Young’s modulus,Poisson’s ratio,inelastic properties of both unit and mortar are taken into account in micro-modelling.The in-terface represents a potential crack/slip plane with dummy stiff-ness to avoid interpenetration of the continuum.Due to the zero
Table 1
thickness of the interface elements,the geometry of the unit has to be expanded to include the thickness of the joint.In the macro-modelling technique,mortar is smeared out in the interface element and in the unit.
In micro models,masonry units and mortar are separately discretised using continuum or discrete elements,whereas in the macro model (also known as equivalent material model),masonry is modelled as a single material using average properties of masonry.Page [13]made an attempt to use a micro-model for masonry structures assuming units as elastic continuum elements bonded with interface elements.Arya and Hegemier [14]proposed a von Mises strain softening model for compression with a tension cut-off for the units.Joints were modelled using interface elements with softening on both the cohesion and friction angle.The collapse load obtained from their model shows good agreement with experimental results from shear wall testing.Ghosh et al.[15]concluded that macro-modelling could predict the deformations satisfactorily at low stress levels and inadequately at higher stress levels when extensive stress redistribution occurs.Pande et al.[16]categorically stated that macro-modelling would not accurately predict the stress distribution within the units and mortar.In micro-modelling,two approaches are followed in finite element analyses.In the first,both the units and the mortar joints are discretised by using continuum finite elements,whereas in the second approach interface elements are used to model the behaviour of mortar joints.Several researchers [12,17,18]have reported that the interface elements used in heterogeneous models reproduce essentially the interaction between two adjoining masonry units,and further degrees of freedom are not required to be introduced.
For masonry walls subjected to either vertical load only or a combined shear and vertical loading,2-D analyses are found effectively producing stress results that are close to those produced by 3-D analyses.Dhanasekar and Xiao [19]proposed a special 2D element and validated its results using a 3D model of masonry prisms.To determine the internal stress distribution
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1930–1943
(a)Tensile cracking in joint.
(b)Joint slip.(c)Direct tensile cracking in
unit.
(d)Diagonal tensile cracking in the unit.
(e)Crushing of masonry.
Fig.2.Failure mechanism for
masonry.
(a)Dry stack sawn masonry.
(b)Irregular masonry with bonding mortar joints.
(c)Rubble masonry.
Fig.3.Details of experimental test specimens.
in unreinforced masonry,Page [13]modelled joints as linkage elements in conjunction with units as plane stress continuum elements.Dhanasekar et al.[20]proposed a macro model for solid masonry,which was capable of reproducing the effects of material nonlinearity and progressive local failure.To determine the internal stress distribution in masonry panels under concentrated loading,Ali and Page [21]modelled the masonry units and mortar joints separately.They used four-noded quadrilateral elements with refined mesh in concentrated load regions to allow redistribution of stresses.Khattab and Drysdale [22]also formulated a homogeneous model of masonry considering mortar joints as planes of weakness.Louren ?o and Rots [17]modelled masonry units as continuum elements while mortar joints and potential cracks in units were represented as zero-thickness interface elements.Interface elements were modelled with a cap model to include all possible failure mechanisms of masonry structures.The following failure mechanisms (Fig.2)are considered;(a)cracking in the joint (Fig.2(a)),(b)sliding along bed or head joints at low values of
normal stress (Fig.2(b)),(c)cracking of the units in direct tension (Fig.2(c)),(d)diagonal tension cracking of the units at values of normal stress sufficient to develop friction in the joints (Fig.2(d))and (e)Splitting of the units in tension as a result of mortar dilatancy at high values of normal stress (Fig.2(e)).This model has been used successfully to reproduce the complete path of the load–displacement diagram for standard masonry and dry stacked sawn masonry.An extension for cyclic loading using bounding surface plasticity is given in Oliveira and Louren ?o [23].The novelty of the present paper is in the application of the micro-model to simulate the response of rubble masonry.
2.Outline of experimental research programme
The experimental research work was carried out by Vasconce-los [9]in the Structural Engineering Laboratory at the University of Minho,Guimar?es,Portugal.Test walls were made of locally avail-able two mica and medium grain granite stone.A ready-mix mortar
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(a)Experimental test
set-up.
(b)Loading history.
Fig.4.Experimental test set-up and load history.
made of naturally hydrated lime and aggregates of granular size be-tween 0.1and 0.2mm was used to bond the units.The seven days average compressive strength of mortar was 3N /mm 2which was considered to be close to the strength of mortar found in ancient building constructions.
The main object of the experimental research work was to evaluate the in-plane seismic performance of stone masonry shear walls found in ancient masonry structures.Table 1and Fig.3shows the three different types of experimental masonry test walls with description and dimensions respectively;Type (I)Sawn dry-stone or dry-stack mortarless stone masonry (Fig.3(a)).This wall type was to represent historical masonry constructions where there is no bonding material between stone units or where the greater part of the bonding material of low strength has vanished due to physical and mechanical weathering effects.Type (II)Irregular stone masonry with bonding mortar (Fig.3(b))can be representative of large stone block construction,possibly in wealthier housing and monumental buildings,and Type (III)Rubble masonry with irregular bonding mortar joint thickness (Fig.3(c)),can be representative of vernacular buildings and historical city centre houses.In case of a type I masonry test specimen,all the units were mechanically sawn to achieve a smooth surface.Dimension of the sawn stone used in type I masonry was 200mm (length )×150mm (height )×200mm (width ).Type II masonry consisted of hand-cut irregular shaped units and low strength head and bed joint bonding mortar.The size of the irregular stone used in type II masonry was approximately 1.3times larger than the sawn stone used in type I masonry.Type III masonry is composed of mixed stones of different shape,size and texture and low strength mortar.The thickness of all three types of walls was 200mm and single wythe.Considering the capacity of testing equipments available in the
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(a)Unit and interface around unit.(b)Potential crack at the middle of the unit.
Fig.5.Mesh generation for swan(regular)dry-stack stone
masonry.
(a)Eight nodes continuum
plane stress element
(CQ16M)for units.
(b)Six node zero thickness line interface elements(CL12I)for joints.(c)Assemblage of CQ16M and CL12I elements.
Fig.6.Two dimensional elements for units and joints.
laboratory,the dimension of model masonry test walls was fixed
as1000mm(length)×1200mm(height)×200mm(width)and
the height to length ratio was1.2.
Fig.4(a)and(b)shows the experimental test set-up and loading
history respectively.Monotonic and reversed lateral cyclic tests
were carried out with three distinct axial pre-compression load
levels including low,100kN(σ0=0.5N/mm2),moderate,175kN
(σ0=0.875N/mm2)and high,250kN(σ0=1.25N/mm2).The
base of the walls was fixed to the test floor and the first course of
the wall was horizontally supported using a special arrangement
consisting of steel plates,angles,bolts,and nuts.To test the
experimental test set-up,a monotonic load test on Type I masonry
was made.The preliminary test was carried out by increasing
the load steadily until failure of the wall.From the preliminary
test results,a load–displacement curve was established for Type
I.After the successful completion of the monotonic test,the
reversed lateral cyclic load tests were carried out of all three types
of masonry according to pre-defined load history presented in
Fig.4(b).
Construction of all three types of test walls was performed
manually by the same mason to ensure uniform workmanship.
For easy transportation and to avoid local damage during transit,
test walls were built on thick steel beams.Construction of the
type I masonry wall was easier and straightforward.Horizontal
and vertical alignment of the wall was checked using a plumb
line during the construction of each course.As there is no
curing involved,the wall was ready to test immediately after the
construction.Type II and III masonry test walls were constructed
using low strength bonding mortar,cured for7days under damp
conditions and tested.Before construction,the units were soaked
in water to avoid absorption of water from the mortar during
construction and shrinkage during curing.A total number of
twenty four walls have been tested including ten type I walls,
seven type II walls and seven type III walls.Table2shows the total
number of walls tested in each masonry type and under different
axial pre-compression loading.
Axial pre-compression loading was applied by using a vertical
actuator with a maximum capacity of250kN.Through a set of
roller supports,a deep and stiff beam was used to distribute the
vertical load from the actuator to a thick steel beam(similar to the
base beam)that was erected on top of the wall after construction.
The axial pre-compression load(either100or175or250kN)was
kept constant throughout the test using an independent dedicated
oil pressure system.The top thick stiff steel beam was also used
to apply the shear lateral load from the horizontal actuator as
shown in Fig.4(a).The purpose of the steel rollers placed between
the deep beam and top beam,was to allow the wall to displace
horizontally during the application of lateral shear load.Care
was taken to avoid possible out-of-plane movement of test wall
during the lateral load application.After applying the desired axial
pre-compression load,the lateral load was applied in terms of
controlled displacement at the rate of100μm/s.Deformation
of the walls was measured using needle type Linearly Variable
Differential Transducers(LVDTs)mounted at different critical
regions,Fig.4(a),and on both sides of the wall.The monotonic
load test was done for type I masonry only.Reversed cyclic shear
loading test was carried out for all the masonry types.
Here,it is noted that the experimental envelope curves on
the reversed cyclic test will be assumed as representative of
quasi static monotonic loading.It is certain that the envelopes
for the former do not exactly coincide with the later.The authors
are not aware of specific papers addressing this issue but no
significant differences are expected in terms of peak load,as energy
dissipation in the hysteretic behaviour of shear walls seems to be
mostly related to compressive failure and large drifts.In Oliveira
and Louren?o[23],for a severely compressed and asymmetric wall,
a difference of about10%was found in terms of peak load,while
comparing monotonic response versus cyclic envelop.For the
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(a)Tension.(b)
Shear.
(c)Compression.
Fig.7.Inelastic behaviour of interface model and validation with experiments,Louren?o and Rots [17].
Table 2
masonry type I (regular/sawn dry stone masonry)of the present experimental campaign,similar results were found for monotonic and reversed cyclic loading tests,Vasconcelos [9].3.Finite element analysis of stone masonry
The data obtained from the ancient stone masonry shear wall test carried out by Vasconcelos [9]has been used as a base for the present finite element modelling.Prior to the testing of model masonry walls,mechanical tests such as compression,tension and shear tests were done on stone units,mortar cubes,prisms made out of mortarless dry-stone,irregular stone with bonding mortar and rubble stone with bonding mortar.These tests on materials were done to determine the elastic,inelastic and strength parameters required for the present finite element modelling.Average compressive strength,tensile strength and Young’s modules of stone was 69.2N /mm 2,2.8N /mm 2and 20200N /mm 2respectively.Average compressive strength of mortar was 3.0N /mm 2.
Table 3
3.1.Mesh generation and element selection
For type I (dry-stack stone masonry),the finite element mesh was generated using a FORTRAN programme developed by Louren?o [24].The following input data was required to generate a mesh for regular masonry walls such as type I;(i)whether potential vertical cracks in the middle of the units are to be included in the model,(ii)whether a masonry joint is to be included in the bottom of the model,(iii)whether a masonry joint is to be included in the top of the model,(iv)whether each course contains an integer number of units,(v)whether the first (bottom)course starts with a full unit or half unit,(vi)the number of masonry courses in the model,vii)the number of complete units per course,(viii)the number of divisions (finite elements)per unit in the x direction,(ix)the number of divisions (finite elements)per unit in the y direction,(x)the width of the units (plus 1/2of thickness of the mortar joint),(xi)the height of the units (plus 1/2of thickness of the mortar joint),(xii)the half of a thin fake joint thickness for joints,only for visual or identification purposes.Fig.5(a)shows division of units in x and y directions,interface
1936R.Senthivel,P.B.Louren?o/Engineering Structures31(2009)1930–1943 Table4
around the unit and fake thickness of joints.Fig.5(b)shows a
possible potential crack at the middle of the stone unit.
As the experimental test results showed no cracks in the unit,
potential cracks in the units were not considered in the entire
modelling work for all three types of masonry.The FORTRAN
programme cannot be used for type II or III as it has complex
irregular units of different texture and size.For type II and III
masonry,the nodal points were calculated using a special image
scanning software and Microsoft Excel,and the rest of the meshing
procedure is same as that of the Type I masonry.
The units were modelled using eight node quadrilateral
isoparametric continuum plane stress elements,CQ16M(Fig.6(a)),
with quadratic interpolation and full Gauss integration.The joints
were modelled using a six node and zero thickness line interface
elements,CL12I(Fig.6(b))with Lobatto integration.Fig.6(c)shows
the unit and interface element assemblage.
3.2.Material properties(strength,elastic and inelastic parameters)
The average Young’s modulus of dry-stone prisms was
14800N/mm2(based on test results of four prisms built with
four course dry-stacked stones).Young’s modulus of large walls
is usually different from the Young’s modulus measured in small
test specimens.This phenomenon has been found and reported
by Louren?o[10].A micro-modelling approach based on inter-
face finite elements requires two distinct stiffnesses,namely,
the stiffness of the stone units and the stiffness of the joints.
Once the stiffness of the stone units is known,the stiffness of
the joints can be calculated from the experimental axial pre-
compression load–displacement curve of the walls.Normal joint
stiffness(K n,joint)was calculated using the following formulation
proposed by Louren?o[10]in which the wall is consider as a series
of two springs in vertical direction,one representing the stone and
the other representing the joint.
K n,joint=1/(h(1/E w all?1/E stone))(1)
where
K n,joint=Normal joint stiffness
h=Height of stone(150mm)
E w all=Young’s modulus of wall
E stone=Young’s modulus of stone.
The tangential stiffness(K s,joint)was calculated directly from the
normal stiffness using the theory of elasticity as follows,[10]:
K s,joint=K n,joint/2(1+ν)(2)
where
K s,joint=Normal joint stiffness
ν=Poisson’s ratio(0.2).
The following inelastic properties of the unit-mortar interface
were taken in to account[17]:(i)tensile criterion:f t(tensile
strength)and G I
f (fracture energy for Mode-I);
(ii)friction criterion:
c(cohesion),tan?(tangent of the friction angle),tanψ(tangent of the dilatancy angle)and Mode-II fracture energy,G II
f
;(iii)cap
criterion:f c(compressive strength)and G c
f (compressive fracture
energy).The inelastic parameters required for the analysis were extracted from Vasconcelos[9],when available,or following the recommendations given in[10].Tables3and4presents elastic and inelastic parameters.Again,note that the elastic stiffness of the
Fig.8.Critical regions in masonry shear wall.
interfaces was adjusted from the measured experimental results, becoming clear that the stiffness decreases consistently from Type I to Type III,due to the increasing thickness of the joint and irregular shape of the units.The equations that govern the inelastic behaviour of masonry are given in detail in[17],where exponential softening for tension and for shear is assumed,followed by parabolic hardening,parabolic softening and exponential softening in compression,see Fig.7.
3.3.FEM analysis procedure
First(step-1),the desired total vertical pre-compression load (either100kN or175kN or250kN)was divided into small steps and gradually applied on the top surface of the stiff steel beam(Fig.8).Then the horizontal load in terms of incremental displacement was applied in small steps at the top right corner of the steel beam(step-2).For a good insight into the stress distribution at different horizontal load increment,the horizontal displacement was increased gradually to2.5mm,then to5mm, then to10mm and finally until failure/collapse,which provided the behaviour of each critical region(Fig.8)of the walls,in addition to the overall deformation characteristics.The vertical and horizontal loads were applied in small steps to achieve a converged solution,particularly in the case of dry stone masonry, which features no tensile strength or cohesion.
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(a)Deformation progress of Type I,Sawn masonry under175
kN.
(b)Incremental deformed mesh at collapse(175kN)and experimental failure.(c)Incremental deformed mesh at collapse(250kN)and experimental failure.
Fig.9.Deformation progress of type I,Sawn masonry.
3.4.FEM analysis results
Results of the nonlinear finite element analyses were post
processed and are presented in this section.Axial pre-compression
load,lateral shear load and material properties are the main
parameters that significantly influenced the behaviour of the
shear walls.Load flow in the whole body of the wall at different
lateral displacement levels,failure modes and state of load and
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1930–1943
Fig.10.Deformed shape of Type II,Irregular masonry at
collapse.
(a)Deformed shape of original mesh.
Fig.11.Deformed shape of original and modified mesh of Type III,Rubble masonry.
displacement in critical nodes are presented in the following sections.
3.4.1.Modes of failure
Heel,toe,centre and local point of application of load on the shear wall are the critical regions (Fig.8).Failure in these regions mainly controlled the overall behaviour of the shear walls.Walls failed due to either flexure or rocking or toe crushing or tensile cracking at the heel followed by shear failure along the https://www.doczj.com/doc/7019277568.html,bination of two or more failures has also occurred at critical load level.At lower pre-compression levels (100kN),walls usually failed due to a progressive flexural mechanism characterised by heel cracking followed by rocking and toe crushing.Irrespective of masonry types,axial pre-compression stress significantly influenced the behaviour of the shear walls.A small increase in vertical load provided the walls with a larger strength due to the improvement of bond resistance mechanisms between joint and masonry units.A substantial increase of axial stress changes the failure mode of the wall from flexure to shear.Figs.9–11present the deformed shape and the minimum principal (compressive)stresses of Type I,II and III masonry models respectively under different lateral displacement,and axial pre-compression loadings.Lower axial pre-compression load caused flexural or rocking failures and higher pre-compression load caused rocking,toe crushing,crushing at region of load application and diagonal shear failures along the diagonal direction.Flexural cracking in the bed joints occurs when the tensile stress on a horizontal mortar joint exceeds the sum of the bond strength of that mortar joint and the frictional stress between the mortar and the units.The rocking mode of failure occurs due to overturning caused by either a low level of axial load and/or weak tensile bond strength of mortar joints dominated.Diagonal shear failure occurs when the diagonal tensile stress resulting from the compression shear state exceeds the splitting tensile strength of masonry.
Fig.9details the progress of cracking and redistribution of compressive stresses upon loading,which leads to a series of struts defined by the geometry and stone arrangement.For a good insight into the stress distribution at different horizontal load increments,the horizontal displacement was increased gradually
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(b)Deformed shape of modified mesh.
Fig.11.(continued)
to2.5mm,then to5mm,then to10mm and until failure/collapse, which provided the behaviour of the critical regions at different magnitudes of applied loads.When the applied displacement is 2.5mm,a larger number of diagonal compressive struts are clearly formed and the whole wall is still mostly structurally sound.As the displacement is increased from2.5mm to5mm and then to10mm etc,the number of compression struts is reduced and diagonal cracking starts to occur.A complete diagonal crack propagates and the failure mode is mostly controlled by shear,together with localised rocking of the cracked stone pieces in the compressed
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(a)Axial pre-compression =100kN.(b)Axial pre-compression =175
kN
(c)Axial pre-compression =250kN.(d)Comparison of envelopes of monotonic and cyclic loading (100
kN).
(e)Comparison of envelopes of monotonic and cyclic loading (175kN).(f)Comparison of envelopes of monotonic and cyclic loading (250kN).
Fig.12.Load–displacement envelope curves of Type I,Sawn stone masonry.
toe region of the wall.This agrees reasonably well with the failure mechanisms observed in experimental tests,see Fig.9.
The failure of Type II,irregular masonry is not so different from Type I,sawn masonry,even if the orientation of the diagonal crack is different and more shear failure is apparent,see Fig.10.
The deformed shape of original mesh of Type III,rubble masonry is shown in Fig.11(a).Unexpectedly,the model failed in sliding along a weak plane at about mid-height,at very low level applied lateral load.This clearly indicates that failure is influenced by the irregular internal arrangement and unrealistic results can be obtained.To avoid the sliding failure,a shear key along the weak plane was provided by adding an extra corner to a four corner stone unit at middle of the weak plane/path,and the original mesh was modified.The modified mesh was subsequently used in all
analyses.Moreover,as the internal structure is not symmetric,the results are provided from Left to Right loading (L–R)and Right to Left loading (R–L).The deformed shapes at collapse for the modified mesh are shown in Fig.11(b).Under different pre-compression levels,the failure occurring in the modified Type III mesh is not so different from the Type I and II masonry particularly at higher level of axial pre-compression load,including a diagonal shear crack and toe crushing.Certainly a major difference is that no really stepped cracks are found,cracks being mostly straight.3.4.2.Load–displacement curves
From the experimental cyclic hysteresis curves,the peak load points were used to establish experimental load–displacement
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(a)Axial pre-compression load =100kN.(b)Axial pre-compression load =175
kN.
(c)Axial pre-compression load =250kN.
Fig.13.Load–displacement envelope curves of Type II,Irregular stone masonry.
envelope curves.These experimental curves are compared with numerical results,and presented in Figs.12(a)–(c),13and 14for Type I,II and III masonry respectively.As mentioned in Section 2,monotonic tests were performed for Type I (regular/sawn)masonry only.The load–displacement envelope curve obtained under monotonic loading was superimposed with the envelope curves of cyclic loading and presented in Fig.12(d)–(f).As can be seen from the Fig.12(d)–(f),these two (monotonic and cyclic)curves follow exactly a same path until the appearance of the first crack at about 60%–80%of the failure load.After the appearance of a crack in the ascending zone,these two curves still follow the same path with little difference that can be neglected.After reaching close to failure,these two curves stabilise and follow exactly the same path again with increasing displacement and almost constant load level.A similar finding has been reported by Senthivel and Sinha [25]for masonry subjected to monotonic and cyclic loading.For the rest of the case (Type II and III),it was assumed that the peak points of cyclic hysteresis curves approximately coincide with the monotonic envelope curve.
Envelope curves of Type I masonry exhibited three different ranges and trends:an initial linear portion with a high rate stiffness (which is directly proportional to the applied axial pre-compression load)followed by a transitory non-linear portion and,finally a relatively approximate linear portion with a slow rate of increase in load and a faster rate of increase in displacement.Similar trends can be seen in the case of type II and III masonry except for the sudden load drops occurring in the ascending branch of the curves due to movement or sliding of stones.Initially,the curves exhibited large stiffness with a linear behaviour up to about 30%of the respective peak load.As the lateral load increases,stiffness degradation takes place.A good correspondence between
numerical and experimental load–displacement curves has been found for Type I and Type II masonry.
In case of Type III,due to irregular and random assembly of units with different size and texture,the load–displacement response was sensitive to the direction of lateral load.This leads to a significant scatter of the results and less good agreement in the results,particularly for the case of higher precompression.Still,the asymmetry of the results can be replicated by the numerical results,see Fig.14.Possibly,better agreement could be obtained by fine tuning the adopted shape of the units for each test,but this is outside the scope of this paper.
Finally,it is noted that the model of Louren?o and Rots[17]is not capable of reproducing crack closure adequately and cannot be used for reversed cyclic loading.The cyclic loading model available,Oliveira and Louren?o [23],requires significant additional data and experiences severe convergence difficulties upon a large number of cycles or large displacements,the monotonic model being much more robust.The combination of dry stacked masonry,which requires very small steps due to the lack of tensile strength and cohesion,makes the analysis process unwieldy with cyclic loading.Therefore,no attempt is made here to replicate the cyclic results of the experimental testing programme.It seems that more robust material models are needed for this purpose.4.Discussion and conclusions
Masonry is a material which exhibits distinct directional prop-erties due to the mortar joints which act as planes of weakness.A large number of influencing factors,such as anisotropy of units,dimension of units,joint width,material properties of the units
1942R.Senthivel,P.B.Louren?o /Engineering Structures 31(2009)
1930–1943
(a)Axial pre-compression load =100
kN.
(b)Axial pre-compression load =175
kN.
(c)Axial pre-compression load =250kN.
Fig.14.Load–displacement envelope curves of Type III,Rubble stone masonry.
and mortar,arrangement of bed as well as head joints and qual-ity of workmanship,make the simulation of masonry difficult.The main objective of the present finite element modelling work was to evaluate analytically the in-plane seismic performance of three different types of stone masonry shear walls found in ancient ma-sonry structures in Europe particularly in north of Portugal:Type (I)Sawn dry-stone or dry-stack mortarless stone masonry,Type (II)Irregular stone masonry with bonding mortar,and Type (III)Rubble masonry with irregular bonding mortar joint thickness.
A plasticity theory based micro-modelling techniques has been employed to carry out the analysis.The analysis results showed that the failure patterns and load–deformation response of the shear walls are highly influenced by the by axial pre-compression and material properties.The strength of masonry is different for type I,II and III but the behaviour remain almost same particularly under higher axial pre-compression (175kN and 250kN).Lower axial pre-compression load caused flexural or rocking failures and higher pre-compression load caused rocking,toe crushing and diagonal shear failures along the diagonal direction.The predicted numerical failure modes are in good correspondence with the experimental failure modes.The numerical and experimental load–displacement diagrams are compared and presented.A good correspondence between numerical and experimental response has been found for all the cases of the pre-compression level.
R.Senthivel,P.B.Louren?o/Engineering Structures31(2009)1930–19431943
Acknowledgements
The Authors would like to acknowledge Dr.D.V.Oliveira and Dr.G.Vasconcelos,Assistant Professors in the Civil Engineering Department at the University of Minho for their assistance during the present modelling work.The first author,R.Senthivel would like to acknowledge the Portuguese National Science and Technology Foundation(FCT),Lisbon for their financial support (Ref.No.:SFRH/BPD/20924/2004)to carry out his Post-Doctoral Research in the Civil Engineering Department at the University of Minho,Portugal.
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华南师范大学实验报告 课程名称：仪器分析实验实验项目：原子吸收光谱法测定水 中的铜含量 原子吸收光谱法测定水中的铜含量 一、实验目的 1. 掌握火焰原子吸收光谱仪的操作技术； 2. 优化火焰原子吸收光谱法测定水中铜的分析火焰条件； 3. 熟悉原子吸收光谱法的应用。 二、方法原理 原子吸收光谱法是一种广泛应用的测定元素的方法。它是一种基于待测元素基态原子在蒸气状态对其原子共振辐射吸收进行定 量分析的方法。为了能够测定吸收值，试样需要转变成一种在适合的介质中存在的自由原子。化学火焰是产生基态气态原子的方便方法。 待测试样溶解后以气溶胶的形式引入火焰中。产生的基态原子吸收适当光源发出的辐射后被测定。原子吸收光谱中一般采用的空心阴极灯这种锐线光源。这种方法快速、选择性好、灵敏度高且有着较好的精密度。 然而，在原子光谱中，不同类型的干扰将严重影响方法的准确性。干扰一般分为四种：物理干扰、化学干扰、电离干扰和光谱干扰。物
理和化学干扰改变火焰中原子的数量，而光谱干扰则影响原子吸收信号的准确测定。干扰可以通过选择适当的实验条件和对试样的预处理来减少或消除。所以，应从火焰温度和组成两方面作慎重选择。 由于试样中基本成分往往不能准确知道，或是十分复杂，不能使用标准曲线法，但可采用另一种定量方法——标准加入法，其测定过程和原理如下。 取笑体积的试液两份，分别置于相同溶剂的两只容量瓶中。其中一只加入一定量待测元素的标准溶液，分别用水稀释至刻度，摇匀，分别测定其吸光度，则： Ax＝kfx Ao＝k(fo十fx) 式中，fx，为待测液的浓度；f。为加入标准溶液后溶液浓度的增量；测量的吸光度，将以上两式整理得：Ao分别为两次在实际测定中，采取作图法(图6—6)的结果更为准确。一般吸取四份等体积试液置于四只等容积的容量瓶中，从第二只容量瓶开始，分别按比例递增加人待测元素的标准溶液，然后用溶剂瓶稀释至刻度，摇匀，分别测定溶液fx，cx十fo，fx十2co，cx十3fo的吸光度为Ax，A1，Az，A：，然后以吸光度A对待侧元素标准溶液的加入量作图，得图6—6所示的直线，其纵轴上截距Ax为只含试样fx 的吸光度，延长直线与横坐标轴相交于cX，即为所需要测定的试样中该元素的浓度。
“十二五”规划12th Five-Year Plan 《关于禁止发展、生产和储存细菌（生物）及毒素武器和销毁此种武器的公约》（于1972年4月10日在伦敦、莫斯科和华盛顿签订）Prohibition of the Development, Production and Stockpiling of Bacteriological (Biological) and Toxin Weapons and on Their Destruction, (signed at London, Moscow and Washington on 10 April 1972) 《关于禁止在战争中使用窒息性、毒性或其他气体和细菌作战方法的议定书》（1925年《日内瓦议定书》）的原则和目标the principles and objectives of the Protocol for the Prohibition of the Use in War of Asphyxiating, Poisonous or Other Gases, and of Bacteriological Methods of Warfare, signed at Geneva on 17 June 1925 (the Geneva Protocol of 1925) 《联合国宪章》的宗旨和原则purposes and principles of the Charter of the United Nations 《维也纳外交关系公约》Vienna Convention on Diplomatic Relations ?根据本公约进行规定活动的视察组成员应免纳外交代表根据《维也纳外交关系公约》第34条所免纳的一切捐税。The members of the inspection team carrying out prescribed activities pursuant to this Convention shall be accorded the exemption from dues and taxes accorded to diplomatic agents pursuant to Article 34 of the Vienna Convention on Diplomatic Relations. 1, 3-二（2-氯乙硫基）正丙烷1,3-Bis (2-chloroethylthio)-n-propane 1, 4-二（2-氯乙硫基）正丁烷1,4-Bis (2-chloroethylthio)-n-butane 1, 5-二（2-氯乙硫基）正戊烷1,5-Bis (2-chloroethylthio)-n-pentane 1925年《日内瓦议定书》规定的义务obligations assumed under the Geneva Protocol of 1925 2,2-二苯基-2-羟基乙酸2,2-Diphenyl-2-hydroxyacetic acid 2-氯乙基氯甲基硫醚2-Chloroethylchloromethylsulfide atmospheric storage tank BZ：二苯乙醇酸-3-奎宁环酯BZ: 3-Quinuclidinyl benzilate DCS(分散控制系统、集散控制系统) distributed control system DF：甲基膦酰二氟DF: Methylphosphonyldifluoride flash drum HN1：N, N-二（2-氯乙基）乙胺HN1: Bis(2-chloroethyl)ethylamine HN2：N, N-二（2-氯乙基）甲胺HN2: Bis(2-chloroethyl)methylamine HN3：三（2-氯乙基）胺HN3: Tris(2-chloroethyl)amine O形环O-ring PFIB: 1,1,3,3,3 - 五氟-2-三氟甲基-1-丙烯PFIB:1,3,3,3-Pentafluoro-2-(trifluoromethyl)-1-propene pump (for firefighting water) QL：甲基亚膦酸乙基-2-二异丙氨基乙酯QL O-Ethyl O-2-diisopropylaminoethyl methylphosphonite slide valve U-V组合坡口combination U and V groove U形螺栓U-bolt U形弯管“U” bend VX（甲基硫代膦酸乙基-S-2-二异丙氨基乙酯）VX (O-Ethyl -2-diisopropylaminoethyl methyl phosphonothiolate) V形坡口V groove V型混合机V-type mixer X形坡口double V groove Y型粗滤器Y-type strainer γ射线照相Gamma radiography 安（培）Ampere (A) 安瓶ampule 安全safety 安全标志safety mark 安全等级safety class 安全防护装置safety protection device 安全连锁safety interlock (SI) 安全喷淋洗眼器safe spray eye wash 安全设施safety device 安全完整性等级safety integrity level (SIL) 安全卫生safety & health 安全系数margin of safety; safety coefficient; safety factor; coefficient of safety 安全仪表系统safety instrumented system (SIS) 安全照明safety lighting 安慰剂dummy drug ?他们对第二组用了安慰剂（无任何作用的药）。For the second group they used dummy drug. 安装erection; installation 氨氮ammonia-nitrogen (NH4+-N) 氨分离器ammonia separator 氨分缩器ammonia partial condenser 氨解ammonolysis 氨冷冻剂ammonia refrigerant 氨冷凝器ammonia condenser 氨冷器ammonia chiller 氨气ammonia gas 氨收集器ammonia accumulator 氨树脂amino resin 氨吸收制冷ammonia absorption refrigeration 鞍座saddle ?固定鞍座fixed saddle ?滑动鞍座sliding saddle 按国际惯例in line (accordance) with internationally accepted practices; compatible with established international practices; in accordance with international practice 胺吸磷：硫代磷酸二乙基-S-2-二乙氨基乙酯及相应烷基化盐或质子化盐Amiton: O,O-Diethyl S-[2-(diethylamino)ethyl] Phosphorothiolate and corresponding alkylated or protonated salts 奥氏体不锈钢Austenitic stainless steel 板框压滤器plate-and-fram filter press 板式输送机slat type conveyor 半成品semi-manufactured goods; semi- finished products; semi-finished goods semi-processed goods 半径radius (R) 半模拟盘（屏）semi-graphic panel 半贫液semi-lean solution 半衰期half-life; half-life period 半自动程序控制器semi-automatic sequence controller 1
响应式布局 什么叫做响应式布局？ 也即是响应式Web设计。响应式布局是Ethan Marcotte在2010年5月份提出的一个概念，简而言之，就是一个网站能够兼容多个终端——而不是为每个终端做一个特定的版本。这个概念是为解决移动互联网浏览而诞生的。 怎样实现响应式布局？ 对于这个问题，我们可以通过CSS3中的Media Query来实现，即媒介查询。媒体查询让CSS 可以更精确作用于不同的媒体类型和同一媒体的不同条件。媒体查询的大部分媒体特性都接受min和max用于表达”大于或等于”和”小与或等于”。如：width会有min-width和max-width 媒体查询可以被用在CSS中的@media和@import规则上，也可以被用在HTML和XML中。通过这个标签属性，我们可以很方便的在不同的设备下实现丰富的界面，特别是移动设备，将会运用更加的广泛。 首先我们要允许网页宽度自动调整 在网页代码的头部，加入一行viewport元标签： viewport是网页默认的宽度和高度，上面这行代码的意思是，网页宽度默认等于屏幕宽度（width=device-width），原始缩放比例（initial-scale=1）为1.0，即网页初始大小占屏幕面积的100%。 下面通过Media Query我们可以得到不同设备屏幕的宽和高，从而我们就可以分别处理了。根据不同的设备屏幕宽度，设置不同的CSS。那么这里有两种方法：
1、外联样式表 在这里我们可以根据不同的设备载入不同的CSS样式表 当页面宽度大于等于960px时，载入样式表gt-960px.css 当页面宽度大于等于600px且小于等于960px时，载入样式表gt-600px-lt-960px.css 当页面宽度小于等于600px时，载入样式表lt-600px.css 2、样式表中内嵌法 当页面宽度大于等于960px时 当页面宽度大于等于600px且小于等于960px时 当页面宽度小于等于600px时
SA T II 化学词汇表 Part 1 foundation chemistry 基础化学 Chapter 1 acid 酸 apparatus 仪器，装置 aqueous solution水溶液 arrangement of electrons 电子排列 assumption 假设 atom 原子 atomic mass原子量 atomic number 原子序数 atomic radius原子半径 atomic structure 原子结构 be composed of 由……组成 bombard ment 撞击 boundary 界限 cathode rays 阴极射线 cathode-ray os cilloscope (C.R.O) 阴极电子示波器ceramic 陶器 charge-clouds 电子云 charge-to-mass ratio(e/m) 质荷比 chemical behaviour 化学行为 chemical property化学性质 clockwise顺时针方向的 compound 化合物 configuration 构型 copper 铜 correspond to 相似 corrosive 腐蚀 d-block elements d 区元素 deflect 使偏向，使转向 derive from 源于 deuterium (D)氘 diffuse mixture 扩散混合物 distance effect 距离效应? distil 蒸馏 distinguish 区别 distribution 分布 doubly charged(2+) ion正二价离子 dye 染料 effect of electric current in solutions 电流在溶液里的影响electrical charge电荷 electrical field 电场
分享16个最佳的响应式HTML 5框架 HTML5框架可以快速构建响应式网站，它们帮助程序员减少编码工作，减少冗余的代码。如今有很多免费的HTML5框架可供使用，由于它们有着响应式设计、跨浏览器兼容、相对轻量级等特点，这些框架在开发中都十分流行。如果你也对HTML5框架感兴趣，你可以看看下面我列出的一些最佳的响应式HTML5框架，帮助你快速开发网站。 1、Twitter Bootstrap Bootstrap来自Twitter，是目前最受欢迎的前端框架，它简洁灵活，使得Web开发更加方便快捷。它有着优雅的HTMCSS规范，以及构建响应式网站的基本的组件，例如12列栅格布局、jQuery插件、Bootstrap控件等等。 2、HTML5 Boilerplate HTML5 Boilerplate的核心是用于帮助开发HTML5站点和应用程序的组件，它有着出色的性能和独立性，帮助你开始一个新的项目。 3、Foundation
Foundation一款非常先进的前端框架，易用、强大而且灵活，可用于构建基于任何设备上的Web应用，提供多种Web上的UI组件，如表单、按钮、Tabs 等等。 4、Ulkit 5、Ulkit Ulkit是一个轻量级、模块化的前端框架，帮助开发出快速、强大的Web接口，它有着全面的HTML、CSS和JS集合，易于使用和扩展。 HTML5 KickStart集合了HTML5、CSS和JS，帮助开发人员快速开发Web产品，它覆盖了所有的UI组件，同时也包含一些有用的JS插件。 6、Gumby
Gumby 2基于Sass开发，是一款出色的响应式CSS框架，它包括一个Web UI工具包，有好看按钮，表格，导航、标签、JS插件等。 7、Skeleton Skeleton有着简单、界面友好的特点，有一系列CSS和JS文件的集合，它可以帮你快速地调整网页在不同分辨率下的显示效果，可以优雅地等比例缩放桌面、平板、手机上的浏览尺寸。 8、Groundwork
英语化学词汇的组词规律 1．化学元素（Chemical elements） A—音译transliteration 锂lithium 镁magnesium 硒selenium 氦helium 锰manganese 钡barium 氟fluorine 钛titanium 铀uranium 氖neon 镍nickel 钙calcium B—意译transcribe or free translation 氧铝溴 氢hydrogen 硅silicon 钾potassium 碳carbon 磷phosphorus 汞mercury 氮nitrogen 硫sulphur(sulfur) 钠sodium C—意音兼译translation by meaning and pronunciation 碘iodine 氯chlorine 砷arsenic 2．化学基团chemical groups 各种元素element的原子atom组合成分子molecule，按性质可以把分子分为不同的原子团radicle，分子中这些具有相对独特性质的原子团，称为官能团functional group，或范围更广一点，称作化学基团chemical group. propylene 丁/四butyl butane butanol butylene butyne butanone 戊/五pentyl pentane pentanol pentylene戊二烯 pentene 戊烯 pentyne pentanone 己/六hexyl hexane hexanol hexylene hexyne hexanone 庚/七heptyl heptane heptanol heptylene heptyne heptanone 辛/八octyl octane octanol octylene octyne octanone 壬/九nonyl nonane nonanol nonylene nonyne nonanone 癸/十decatyl decane decanol decylene decyne decanone 说明：-ol表示醇羟基，-an与烷有关，表示是饱和状态，-en与烯有关，有不饱和的意义，相应的饱和状态的羟基即醇-anol，不饱和状态的羟基即酚-enol。在结构较为复杂的醇类化合物中，常常只用-ol；酮-one是相当于用氧o替换了烯-ene中的一个碳，二者均为不饱和结构。 ether(醚)，ester(酯)，只要在化学基后加上这两个词，就获得了两组英文词。例如：甲醚methyl ether，甲酯methyl ester。 3．化合物类别及化学官能团Classes of compounds and functional groups 化合物类别 烃hydrocarbon 酚hydroxybenzene/phenol 胺amine 烷alkane 醚ether 亚胺imine 烯alkene 酮ketone 腈nitrile 炔alkyne 醛aldehyde 亚砜sulfoxide 苯benzene 酸acid 砜sulfone 醇alcohol 酐anhydride 碱alkali/base 官能团 烷基alkyl 羟基hydroxyl 羰基carbonyl
最近研究响应式设计框架的时候，发现网上很多相关的属性介绍，却很少有系统的入 门级使用的文章，我自己整理了一篇入门知识，并没有什么高深的理论，也不牵扯到框架。 目前已经越来越多的站点以及wap站点使用响应式设计，因为大屏幕的移动设备越 来越普及。而自适应布局已经无法胜任各种浏览需求。响应式设计的目的是尽可能以最好 的布局显示您的数据，以实现用户友好的 Web 页面。 css2的时期有一个不是很常用的media type，他拥有比如aural（声音）braille（触摸）print（打印）handheld（移动设备）等等十种媒体类型，（附加媒体类型详细 https://www.doczj.com/doc/7019277568.html,/TR/CSS2/media.html#media-types）利用@media规则可以在同一样 式表里为不同终端使用不同的样式。尴尬的是这个media type并没有被多少终端真正的支持。 现在CSS3有了个更为实用的 media query。而移动终端的浏览器基本已经完全支持 了css3.他可以为你获取各种终端的数据。 先举个例子，大家看这个demo。（由于相应区域过大，就不截图了，请大家点击打 开这个连接） https://www.doczj.com/doc/7019277568.html,/demo/media/ 一个普通的自适应显示的三栏网页，当你用不同的终端来查看这个页面的时候，他会 根据几种终端来显示不同的样式，在电脑上是三列，在pad上应该也是三列，在大屏手机 上是三行，在屏幕小于320的手机上只显示主要内容，隐藏掉了次要元素。（这里关于响 应式布局还有个比较好的消息，就是拖动浏览器也可以触发判断条件，测试的时候你不需 要去找一堆手机，只要把自己的浏览器窗口缩小到一定尺寸就可以了，这个demo也可以 用拖动浏览器大小的方式测试。） 这就是一个最简单的响应式布局的页面。我们就从这个例子里认识下media query 属性吧。 就从这个条件语句开始介绍，media属性后面跟着的是一个 screen 的媒体类型（上 面说过的十种媒体类型之一）。然后用 and 关键字来连接条件（其他关键字还有 not，only，看字面大家能理解，就不多说。），然后括号里就是一个媒体查询语句，稍微懂点
Atoms，Elements and Ions atom 原子 element 元素 ion 离子 anion 阴离子 cation 阳离子 electron 电子 neutral 中性的 proton 质子 atomic nucleus 原子核 nucleon 核子 nuclide symbol 核素符号 nuclide 核素 isotope 同位素 alpha particle 粒子 alpha ray 射线 beta particle 粒子 anode 阳级，正极 cathode 阴极 atomic mass unit 原子质量单位 element symbol 元素符号 atomic number 原子序数 atomic weight 原子量 mass number 质量数 atomic theory 原子理论 brownian motion 布朗运动 cathode ray 阴极射线 chemical change 化学变化，化学反应 compound 化合物 deuterium 氘 electric charge 电荷 heavy water 重水 isotopic abundance 同位素的丰度 natural abundance 自然丰度 isotopic mass 同位素质量 law of conservation of mass 物质守恒定律，物质不灭定律 law of definite proportions 确定化定律 law of multiple proportions 整比定律 mass spectrometer 质谱仪 mass spectrometry 质谱学，质谱测量，质谱分析 mass spectrum 质谱（复数形式：mass spectra） nuclear binding energy 核能量 radioactivity 放射能 X–ray spectrum X射线光谱（复数形式：X-ray spectra）
铜、银及其它常考的过渡金属元素 【重要知识点回顾】 一、铜 1.铜：（1）铜的颜色色（2）火法或湿法制铜： （3）铜与下列物质反应：铜在空气中生成铜绿、浓硫酸（加热）、双氧水（加稀硫酸酸性）；硝酸（浓）、硝酸（稀）、硝酸银溶液、铁盐溶液、稀硫酸中加入少量铜不溶解，若加（通）入下列物质，能使铜溶解的是①硫酸铁②硝酸钾③双氧水④氧气（加热）。 （4）粗铜精炼：阳极为，有关电极反应式，比铜活泼的金属如铁以进入，比铜不活泼的金属沉积在中；阴极为，电极反应式；电解质溶液为，电解过程中电解质溶液浓度。 （5）溶液中Cu2+含量测定（碘量法）有关反应的离子方程式： 、 2.氧化铜：色。做用氢气还原氧化铜的实验时应先后，实验结果时应先 后。可用于还原氧化铜的物质有： 将铜丝在空气中加热后迅速插入乙醇中，现象为，有关化学方程式为、，总方程式为，铜的作用是。3、氧化亚铜：色。氧化亚铜溶于稀硫酸： 氧化亚铜溶于稀硝酸： 检验用氢气还原氧化铜所得产物中是否含氧化亚铜的实验方法是 4、氢氧化铜：色。配制新制氢氧化铜悬浊液的操作： 乙醛与新制氢氧化铜加热的化学方程式为 5、硫化铜：色。制备方法硫酸铜溶液中通入硫化氢： 硫化铜不溶于盐酸、稀硫酸但溶于稀硝酸： 硫化亚铜：色。制备方法铜在硫蒸气中加法： 硫化亚铜溶于稀硝酸： 鉴别CuS和Cu2S两种黑色粉末的方法是 6、CuH：红色固体，难溶于水；CuH与氯气点燃 CuH中加稀盐酸 CuH中加稀硝酸酸（只产生一氧化氮一种气体） 二、银 1、银溶于稀硝酸：（应用：试管的洗涤） 2、银氨溶液的配制方法是：， 有关反应为 乙醛发生银镜反应的离子方程式为 3、往硝酸银溶液中依次滴加足量氯化钠溶液、溴化钠溶液、碘化钠溶液、硫化钠溶液，现象为、、、，加入硫化钠溶液的离子方程式 三、其他过渡元素 1. Zn （1）实验室常用锌与稀硫酸反应制取氢气，为了加快反应速率，可采取的措施有： （2）银锌电池的负极是锌，正极是氧化银，电解质是氢氧化钾，负极反应式为，正极反应式为 2.Mn（1）实验室制氧气、氯气都可用到锰的化合物，写出有关化学方程式： 氧气氯气
表2-1 中英文对照
CC
表8-1 中英文对照 常用玻璃仪器英文表示 adapter 接液管广口瓶air condenser 空气冷凝管beaker 烧杯boiling flask 烧瓶 boiling flask-3-neck 三口烧瓶burette clamp 滴定管夹 burette stand 滴定架台Busher funnel 布氏漏斗Claisen distilling head 减压蒸馏头 condenser-Allihn type 球型冷凝管 condenser-west tube 直型冷凝管
crucible tongs 坩埚钳 crucible with cover 带盖的坩埚distilling head 蒸馏头 distilling tube 蒸馏管 Erlenmeyer flask 锥型瓶evaporating dish (porcelain) 瓷蒸发皿filter flask(suction flask) 抽滤瓶florence flask 平底烧瓶fractionating column 分馏柱 Geiser burette (stopcock) 酸氏滴定管graduated cylinder 量筒 Hirsch funnel 赫氏漏斗 long-stem funnel 长颈漏斗medicine dropper 滴管 Mohr burette for use with pinchcock 碱氏滴定管 Mohr measuring pipette 量液管mortar 研钵 pestle 研杵 pinch clamp 弹簧节流夹 plastic squeeze bottle 塑料洗瓶reducing bush 大变小转换接头rubber pipette bulb 吸耳球 screw clamp 螺旋夹 separatory funnel 分液漏斗stemless funnel 无颈漏斗 test tube holder 试管夹 test tube 试管 Thiele melting point tube 提勒熔点管transfer pipette 移液管 tripod 三角架 volumetric flask 容量瓶 watch glass 表皿 wide-mouth bottle 广口瓶 【分享】有机物英语单词后缀表 有机物英语单词后缀表 -acetal 缩醇 acid 酸 -al 醛 alcohol 醇 -aldehyde 醛 -aldechydic acid 醛酸
响应式布局调研报告 2019年 响应式布局已经被越来越多的网站采用，它的优势也很明显，它会根据不同的设备及设备分辨率的大小自动调整页面布局，充分利用屏幕尺寸达到最佳视觉效果。 由于很多网站针对于手机端已经单独做了webapp，这里主要介绍的是PC端各分辨率对页面的影响，先看某页面各分辨率占比分布表，可以供交互及UE一个设计数据参考： 百度文库系统环境各分辨率占比情况（数据来自百度统计） 来看几个临界值，分辨率宽度大于1200、大小980且小于1200，小于980
从统计数据看，分辨率宽度大于980的份额达到了99.5%，基本涵盖了所有的用户，分辨率大于1200的占比已达到82.84%，占据了绝大多数。为了充分利用用户的显示器可视区域，此次新首页将之前980的宽度提高到1200，由于980到1200的占比还是相对较大（16.66%），此次改版同时也需要兼容980的宽度。 此次新首页改版，如果pad端和pc端要共用同一套模板的话，由于各代ipad的分辨率大小都在980以上，同时配合设置viewport相关属性，可以呈现和pc端一样的布局。下表是业内一些网站针对响应式布局的一些处理方式： 从调研这些网站来看，只有淘宝兼容了800 – 980之间的宽度，即当800*600分辨率的显示器访问淘宝首页时，在不通过拉动横向滚动条也能正常看到所有内容的。大多都是对两
种特定的宽度做了处理，即针对窄屏980和宽屏的1190两种宽度，像百度图片及亚马逊，会在最小宽度和最大宽度之间完全自适应，即当可视区域宽度在最小宽度和最大宽度间发生变化时，显示的内容都会做出相应的调整，最大化利用用户的显示区域。 此次文库新版首页也将采用两种宽度，即最小宽度980，最大宽度1200两种布局。实现方案有很多种，以下是常用的两种方式： 1.css3 的media query，通过检测当前屏幕的尺寸，加载不同的css样式控制页面的布局， 不支持css3的media query，如ie9以下，通过js来动态计算当前可视区域的尺寸，设置相应的class。 2.利用min-width和min-height，采用流体布局，即用百分比作为宽度的单位，这样当宽 度发生变化时，显示内容会按照设置的百分比自动调整，当然ie6不支持min-width属性，也只能通过js来实现。 采用响应式布局，其中很重要的一点是当宽度发生变化时，哪些内容需要显示或隐藏以及显示的策略，设计时对宽度的一些限制和要求，这些需要和交互、设计一起沟通、讨论、确认，以达到最使用体验！
Bunsen burner 本生灯 product 化学反应产物 flask 烧瓶 apparatus 设备 PH indicator PH值指示剂,氢离子(浓度的)负指数指示剂 matrass 卵形瓶 litmus 石蕊 litmus paper 石蕊试纸 graduate, graduated flask 量筒,量杯 reagent 试剂 test tube 试管 burette 滴定管 retort 曲颈甑 still 蒸馏釜 cupel 烤钵 crucible pot, melting pot 坩埚 pipette 吸液管 filter 滤管 stirring rod 搅拌棒 element 元素 body 物体 compound 化合物 atom 原子 gram atom 克原子 atomic weight 原子量 atomic number 原子数 atomic mass 原子质量 molecule 分子 electrolyte 电解质 ion 离子 anion 阴离子 cation 阳离子 electron 电子 isotope 同位素 isomer 同分异物现象 polymer 聚合物 symbol 复合 radical 基 structural formula 分子式 valence, valency 价 monovalent 单价 bivalent 二价 halogen 成盐元素bond 原子的聚合mixture 混合combination 合成作用compound 合成物alloy 合金 metal 金属metalloid 非金属Actinium(Ac) 锕Aluminium(Al) 铝Americium(Am) 镅Antimony(Sb) 锑Argon(Ar) 氩Arsenic(As) 砷Astatine(At) 砹Barium(Ba) 钡Berkelium(Bk) 锫Beryllium(Be) 铍Bismuth(Bi) 铋Boron(B) 硼Bromine(Br) 溴Cadmium(Cd) 镉Caesium(Cs) 铯Calcium(Ca) 钙Californium(Cf) 锎Carbon(C) 碳Cerium(Ce) 铈Chlorine(Cl) 氯Chromium(Cr) 铬Cobalt(Co) 钴Copper(Cu) 铜Curium(Cm) 锔Dysprosium(Dy) 镝Einsteinium(Es) 锿Erbium(Er) 铒Europium(Eu) 铕Fermium(Fm) 镄Fluorine(F) 氟Francium(Fr) 钫Gadolinium(Gd) 钆Gallium(Ga) 镓Germanium(Ge) 锗Gold(Au) 金Hafnium(Hf) 铪Helium(He) 氦
物质的转化和元素的循环 （一）金属的氧化和金属氧化物的还原 1、铜与氧化铜之间的相互转化实验 （1）实验步骤和实验现象： ①用坩埚钳夹着铜片在酒精灯的外焰上加热。现象：发现紫红色铜片变成了黑色。铜的表面生成了氧化铜。 ②把在酒精灯外焰上加热后的铜片，马上插入酒精(乙醇)中。现象：铜片表面又由黑色变成了紫红色。 （2）实验结论： 在这个过程中，铜在加热的条件下能和空气中的氧气结合形成黑色的氧化铜，铜片表面生成的黑色氧化铜马上和酒精(乙醇)反应又转化成了铜。 （3）注意事项： 铜一定要在酒精灯的外外焰上加热，不要使铜碰到酒精灯的灯芯。因为在铜的表面生成的氧化铜与酒精灯的内焰或灯芯接触，实质上是和还没有燃烧的酒精(乙醇)蒸气接触，会使已经生成的氧化铜又被酒精还原成铜。 （4）实验小结： ①氧气在加热的条件下能和铜结合生成氧化铜。金属获得氧的过程被称为金属的氧化(oxidation)。 ②酒精能与灼热的氧化铜反应从氧化铜中夺取氧，使氧化铜转化为铜。金属氧化物失去氧的过程被称为金属氧化物的还原(deoxidation)。 2、使铁的表面形成氧化层保护膜实验
铁片放在浓硝酸、浓硫酸中，没有气体放出，这是因为铁在浓硝酸、浓硫酸中生成了铁的氧化物，正是这层致密的氧化膜保护了铁，使铁不能与酸反应生成氢气。但将铁片放在稀硫酸中，则有气体放出，即生成了氢气。 绝大部分金属都能在一定条件下与氧气化合生成金属的氧化物，但一些不活泼的金属如：金、铂等，很难和氧化合生成氧化物。金属还能和某些能提供氧的物质如：硝酸、浓硫酸等反应，生成金属氧化物。 3、氢气还原氧化铜实验 （1）实验步骤： 在干燥的硬质试管里铺一薄层黑色氧化铜粉末，固定在铁架台上，通入氢气，待空气排尽后，加热氧化铜。反应完成后停止加热，再继续通入一会儿氢气，直到试管冷却。 （2）实验装置： （3）实验现象： 黑色的氧化铜变成紫红色，试管口有水珠生成。 （4）注意事项： ①试管口应略向下倾斜，防止反应过程中生成的水流到试管底部使试管破裂； ②氢气的导入管要伸到试管的底部； ③反应开始前要先通入氢气，以排尽试管中的空气；当反应完成时，要先停止加热，继续通入氢气，直到试管冷却，再停止通入氢气，以防止生成的灼热的铜又被空气中的氧气氧化成氧化铜。
Media Query 的使用方法
通过不同的媒体类型和条件定义样式表规则，媒体查询让CSS可以更精确作用于不同的媒体类型和同一媒体的不同条件。媒体查询的大部分媒体特性都接受min和max用于表达”大于或等于”和”小与或等于”。如：width会有min-width 和max-width媒体查询可以被用在CSS中的@media和@import规则上，也可以被用在HTML和XML中。通过这个标签属性，我们可以很方便的在不同的设备下实现丰富的界面，特别是移动设备，将会运用更加的广泛。 媒体查询能够获取的值如下： ?设备的宽和高device-width，device-heigth显示屏幕/触觉设备。 ?渲染窗口的宽和高width，heigth显示屏幕/触觉设备。 ?设备的手持方向，横向还是竖向orientation(portrait|lanscape)和打印机等。 ?画面比例aspect-ratio点阵打印机等。 ?设备比例device-aspect-ratio-点阵打印机等。 ?对象颜色或颜色列表color，color-index显示屏幕。 ?设备的分辨率resolution。
语法结构及用法 媒体查询有两种使用方式，一种是在CSS样式中内嵌“@media”，在同一个CSS中通过不同窗口编写不同的样式去选择。 另一种是使用外部样式表的引用，在@import和link中使用“@media”，根据不同的窗口大小选择对应的样式文件。这两种方式的使用方法是一样的。Media Queries的使用方法如下所示： @media 设备类型 only (选取条件) not (选取条件) and (设备特性)，设备二 { 样式代码 }
普通化学术语中英文对照表原子atom 原子核nucleus 质子proton 中子neutron 电子electron(abbr.e) 离子ion[an] 阳离子cation 阴离子anion 分子molecular[mlekjl] 单质element 化合物compound 纯净物puresubstance/chemicalsubstance 混合物mixture 相对原子质量relativeatomicmass(abbr.Ar) 相对分子质量relativemolecularmass(abbr.Mr) 化学式量relativeformulamass 物质的量amountofsubstance 阿伏加德罗常数Avogadroconstant(abbr.NA) 摩尔mole 摩尔质量molarmass 实验式/最简式/经验式empiricalformula 气体摩尔体积molarvolume 阿伏加德罗定律Avogadro’sLaw 溶液solution 溶解dissolve 浓度concentration 质量/体积分数mass/volumeconcentration 浓缩concentrate 稀释dilute 蒸馏distillation 萃取extraction 化学反应方程式chemicalequation 反应物reactant 生成物product 固体solid 液体liquid 气体gaseous
溶液aqueous 配平balance 化学计量学stoichiometry 酸acid 碱 base/alkali(referstosolublebases)盐salt 酸式盐acidsalt 离子方程式ionicequation 结晶水waterofcrystallisation 水合的hydrated 无水的anhydrous 滴定titration 指示剂indicator 氧化数oxidationnumber 氧化还原反应redoxreaction 氧化反应oxidationreaction 还原反应reductionreaction 歧化反应disproportionationreaction 归中反应 comproportionation(symproportiona tion) reaction 氧化剂oxidisingagent 还原剂reducingagent 电子层(壳)(electron)shell 电离能ionisationenergy(abbr..) 第一，第二，第三等电离能 first,second,third,etc.ionisation energy(abbr.1st,2nd,3rd,etc..) 电子亲和能 electronaffinityenergy(abbr..) 屏蔽效应electronicshielding(screening) 原子轨道atomicorbital 电子云electroncloud 电子亚层sub-shell 能层layer 能级energylevel 电子排布electronconfiguration 电子云重叠shelloverlap 洪特规则Hund’srule 泡利原理Pauliexclusionprinciple
无机化学实验题答案 实验习题p 区非金属元素( 卤素、氧、硫)1. 氯能从含碘离子的溶液中取代碘，碘又能从氯酸钾溶液中取代氯，这两个反应有无矛盾?为什么?答：这两个反应无 矛盾。因为氯的氧化性强于碘，而碘的氧化性又强于氯酸钾。 2. 根据实验结果比较：① S2O82-与MnO4-氧化性的强弱；② S2O32-与I- 还原性的强弱。答：因为S2O82-可以将Mn2+氧化为MnO4-，所以S2O82-的氧化性强于MnO4-,S2O32-能将I2 还原为 I- ，S2O32-和还原性强于I- 。3. 硫代硫酸钠溶液与硝酸银溶液反应时，为何有时为硫化银沉淀，有时又为[Ag(S2O3)2]3- 配离子?答：这与溶液的浓度和酸碱性有关，当酸性强时，会生成硫化银沉淀，而在中性条件下就会生成[Ag(S2O3)2]3- 配离子。 4. 如何区别：①次氯酸钠和氯酸钠；②三种酸性气体：氯化氢、二氧化硫、硫化氢；③硫酸钠、亚硫酸钠、硫代硫酸钠、硫化钠。答：① 分别取少量两种固体，放入试管中，然后分别往试管中加入适量水，使固体全部溶解，再分别向两支试管中滴入两滴品红溶液，使品红溶液褪色的试管中放入的固体为次氯酸钠，剩下的一种为氯酸钠。②将三种气体分别通入品红溶液中，使品红褪色的是二氧化硫，然后将剩余的两种气体分别通入盛有 KMnO4溶液的试管中，产生淡蓝色沉淀的是H2S，剩下的一种气体是氯化氢。③分别取四种溶液放入四支试管中，然后向四支试管中分别加入适量等量的H2SO4溶液，有刺激性气味 气体产生的是亚硫酸钠，产生臭鸡蛋气味气体是的硫化钠，既有刺激性气味气体产生，又有黄色沉淀产生的是硫代硫酸钠，无明显现象的是硫酸钠。 5. 设计一张硫的各种氧化态转化关系图。 6. 在氯酸钾和次氯酸钠的制备实验中，如果没有二氧化锰，可改用哪些药品代替地二氧化锰?答：可用高锰酸钾代替二氧化锰。7. 用碘化钾淀粉试纸检验氯气时，试纸先呈蓝色，当在氯气中放置时间较长时，蓝色褪去，为什么?答：因为2KI+Cl2=2KCl+I2,I2 遇淀粉变蓝，因此试纸呈蓝色，但氯气有氧化性，可生成HClO，可以将蓝色漂白，所以在氯气中放置时间较长时，蓝色褪去。8. 长久放置的硫化氢、硫化钠、亚硫酸钠水溶液会发生什么变化?如何