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Numerical investigation of progressive collapse resistance of reinforced

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Advances in Structural Engineering 1–13

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Numerical investigation of progressive collapse resistance of reinforced concrete frames subject to column removals from different stories

Yi Li 1,Xinzheng Lu 2,Hong Guan 3and Peiqi Ren 2

Abstract

This article presents a nonlinear static pushdown analysis to evaluate the progressive collapse-resisting capacity curves of typical rein-forced concrete frames under different deformations.Unlike the previous studies in which only a few typical columns,such as a col-umn on the bottom storey,are removed,this study examines the column removal scenarios for various typical locations from different stories.The primary findings are as follows:(1)the Vierendeel action causes different internal forces in the beams of different stories,which reduces the progressive collapse resistance under the beam mechanism and delays the development of the catenary mechanism.This may result in the beams failing successively from one floor to another in a frame system,which differs from the theo-retical assumption that the beams are damaged simultaneously on different floors;(2)seismic designs significantly improve the progres-sive collapse resistance under the beam mechanism,especially for lower stories.However such an improvement is less significant for the catenary mechanism and little improvement is found for the top regions of the frame structures.Furthermore,a nonlinear dynamic analysis is conducted to validate the predicted resistances of the reinforced concrete frames in satisfying the requirement of collapse prevention.The design parameters as specified in the existing codes are also discussed.

Keywords

nonlinear dynamic alternative load path analysis,nonlinear static pushdown analysis,numerical investigation,progressive collapse resis-tance,reinforced concrete frame,Vierendeel action

Introduction

Progressive collapse is a disproportional collapse of an entire structure caused by initial local failure of a few structural elements due to accidental events (American Society of Civil Engineers (ASCE),2005).Progressive collapse of building structures has two significant char-acteristics:(1)it is a mechanical behavior of the entire structural system,in which the collapse spreads throughout a large part of or the entire structure (Starossek,2007).In resisting a progressive collapse,on the other hand,the primary contributor is the alter-native load paths within the structural system (Department of Defense (DoD),2010;General Service Administration (GSA),2003).(2)It is a mechanical behavior of the structure under large deformations.In conventional laboratory tests and numerical studies,when a structural member reaches a certain amount of deformation after the peak load,the member is consid-ered to have failed,and the residual loading capacity is not considered.For example,in the published litera-ture on fire resistance (International Organization for

Standardization (ISO),1999)and seismic resistance (ASCE,2007;Jiang et al.,2014b),when the beam deflection reached 1/50–1/30the span length,the beam was considered to have failed.This is however not the case for progressive collapse,where large deformation (deflection approaching 1/5the span length)character-istics of the beams must be carefully examined (DoD,2010;GSA,2003).Under large deformations,the strength of the beams may have degenerated signifi-cantly,and the load-carrying mechanism may have changed (e.g.from a beam mechanism to a catenary

Key Laboratory of Urban Security and Disaster Engineering,Ministry of Education,Beijing University of T echnology,Beijing,China 2

Key Laboratory of Civil Engineering Safety and Durability,Ministry of Education,Tsinghua University,Beijing,China 3

Griffith School of Engineering,Griffith University,Gold Coast Campus,Southport,QLD,Australia

Corresponding author:

Xinzheng Lu,Key Laboratory of Civil Engineering Safety and Durability,Ministry of Education,Tsinghua University,Beijing 100084,China.Email:Luxz@https://www.wendangku.net/doc/5817785820.html,

mechanism)(Li et al.,2011,2014a,2014b).These mechanical behaviors of the beams are very important to the progressive collapse resistance of the structure.

Significant progress has been achieved in the past decade with the development of experimental technol-ogies and numerical simulation methods which have promoted fundamental research being conducted on progressive collapse of building structures.For the experimental studies,both static and dynamic methods are used to investigate the collapse behavior of struc-tural members and sub-structural systems under large https://www.wendangku.net/doc/5817785820.html,ing the static test method,researchers have studied these progressive collapse behaviors of different types of structures and components such as continuous concrete beams(Su et al.,2009),reinforced concrete(RC)or steel beam–column subassemblages (Sadek et al.,2011;Yap and Li,2011),three-storey, four-bay small-scale RC plane frame structures(Yi et al.,2008),single-storey small-scale RC flat-plate structures(Yi et al.,2011),and two-storey full-scale RC flat-plate structures(Kokot et al.,2012).The dynamic tests are commonly conducted using a special device as substitute support components,so that the locally failed structural member can be simulated by instantaneously releasing the special device.Qian and Li(2012a,2012b)conducted static and dynamic tests to study the collapse behavior of a corner substructure of a concrete frame and comparatively analyzed the dynamic effects of the collapse process.Some research-ers took the opportunity of demolishing abandoned buildings to study the dynamic progressive collapse resistance of the entire structures(Matthews et al., 2007;Sasani and Sagiroglu,2010;Sasani et al.,2007, 2011;Song and Sezen,2009).

As a supplement to the experimental techniques, numerical methods have proven to be convenient and efficient for analyzing the progressive collapse beha-vior of an entire structural system,either statically or dynamically.Specially,numerical methods are suitable for comprehensive analyses of the various factors that influence the progressive collapse behavior and resis-tance.Typical studies in this area include:composite slabs using refined finite element analysis approach by Alashker et al.(2010);a concrete structure subjected to the impact of an explosion using the same method by Luccioni et al.(2004);a multi-storey steel frame with two different types of brace members studied by Khandelwal et al.(2009),where the joints and the structural components were simulated using the macro model and fiber model,respectively;a20-storey steel frame structure with two different lateral resistant sys-tems investigated by Fu(2009);the effects of the num-ber of stories and bays on the progressive collapse resistance of steel frame structures,evaluated by Kim et al.(2009);steel frames with different strengths and stiffnesses studied by Galal and El-Sawy(2010),who concluded that the strength of framed beams has a great impact on the progressive collapse resistance of a steel frame;the progressive collapse mechanisms of steel frames exposed to fire studied by Jiang et al. (2014a).Furthermore,Kim et al.(2011)used a rando-mized method to generate different values for key parameters such as the live load,the elastic modulus, and the yield strength of beams,columns,and braces. The sensitivity of the progressive collapse resistance of the steel frame to these parameters was analyzed. Similar reliability assessment on the damaged RC frame has been conducted by Huang et al.(2014). Kwasniewski(2010)also developed a detailed3D model to evaluate the progressive collapse resistance of an eight-storey steel frame in the Cardington Fire Test.The structural responses of RC structures under instantaneous and gradual removal of columns were also compared by Rahai et al.(2013).

The majority of the numerical analysis on the pro-gressive collapse of overall structural systems adopted the conventional nonlinear dynamic alternate path (NDAP)method to obtain the dynamic responses of the structures(e.g.the time-history responses of the displacement and the internal force after the initial local failure occurred).In addition to the dynamic responses,the progressive collapse resistance of struc-tural systems is also helpful for understanding the pro-gressive collapse mechanism.However,the structural resistance varies with the structural deformation.To evaluate the progressive collapse-resisting capacity curves of structures under different deformations,the vertical load applied to the structures(i.e.the gravity) should be incrementally changed in each NDAP analy-sis,similar with the incremental dynamic analysis (IDA)in the seismic studies(Vamvatsikos and Cornell, 2002).Obviously,that is very time-consuming.On the other hand,existing numerical research mainly focuses on the collapse response of entire structures after the initial failure of a few representative structural mem-bers,primarily the perimeter columns in the bottom floor(DoD,2010;GSA,2003).However,accidents may occur anywhere in the building.Therefore,it is necessary to comprehensively study the progressive collapse resistance of structures under different defor-mations subsequent to initial damages occurring at all possible locations in a structure.This will provide a valuable reference for engineering practices,yet such research is still lacking presently.

In RC frame structures with precast slabs,the frames as the subassemblies of beams and columns are the major structural components resisting progressive collapse.In this article,a typical eight-storey RC frame designed in accordance with low seismic action is first studied.A nonlinear static pushdown analysis is

2Advances in Structural Engineering

performed to investigate the progressive collapse resis-tance of the RC frame with initial local damage at typ-ical locations of different stories.In addition,the RC frame is redesigned in accordance with high seismic action and the effect of seismic design on the progres-sive collapse resistance is analyzed by comparing the two RC frames with different seismic design intensi-ties.The resistance of the RC frames is also validated via the nonlinear dynamic method,in which the design parameters as specified in the existing codes are dis-cussed.The outcomes of these analyses can be used as references to further develop the design specifications and methods specific to progressive collapse.

RC frame model

The RC frame structure studied herein has eight stor-ies.The height of the first storey is4.2m,and that of the remaining stories is3.6m.A plan view of the RC frame is shown in Figure1.The bottom ends of the first storey columns are fixed to the ground.Table1 lists the sectional sizes and material parameters for the structural elements.The frame is designed in accor-dance with the Chinese Code for the Design of Concrete Structures(GB50010-2010)(The Ministry of Housing and Urban-Rural Development of the People’s Republic of China(MOHURD),2010a)and the Code for Seismic Design of Buildings(GB50011-2010)(MOHURD,2010b).The main design para-meters are given in Table2.To study the influence of seismic design on the progressive collapse resistance, reinforcement details are designed according to two different seismic design intensities,while the other design parameters(e.g.plan,sectional size,materials) remain unchanged.This results in two frame models, namely Model A,designed for a low-seismic-intensity region and Model B,designed for a high-seismic-intensity region.

The amount of reinforcement in Model B is about twice that in Model A.The additional reinforcement in the beams of Model B is mainly concentrated at the beam ends where the seismic action is large.However, there is no significant difference in the mid-span rein-forcement in the beams between the two models because such reinforcement is mainly controlled by the gravity load,which is the same for the two models. Note that the RC frame is designed to have a regular structural arrangement which is popular in engineering practices.As such,the conclusions achieved

can Figure1.Plan view of the RC frame.

T able1.Parameters of the structural members in the RC frame.

Longitudinal beam(X-direction)T ransverse beam(Y-direction)Column Slab

Section300mm3500mm300mm3550mm550mm3550mm120mm(thickness) Concrete C30(compressive strength=20.1MPa)

Reinforcing steel Longitudinal reinforcement:HRB335(yield strength=335MPa)

Hoop reinforcement:HPB235(yield strength=235MPa)

RC:reinforced concrete.

T able2.Design loads and action on the RC frame.

Model A Model B Seismic action a50cm/s2200cm/s2 Dead load Floor:5.0kN/m2;Roof:7.5kN/m2

Live load Floor:2.0kN/m2;Roof:0.5kN/m2

Wind load Wind pressure:W0=0.45kN/m2

Gravity load of filled wall Floor:8.0kN/m;Roof:6.0kN/m

RC:reinforced concrete.

a PGA(peak ground acceleration)of the design earthquake(i.e.a10%probability of exceedance in50years).

Li et al.3

provide useful fundamental understandings for future analysis and design tasks for progressive collapse pre-vention,although some of the conclusions may not be applicable for irregular structures (this should be investigated case by case).

Analysis method Fiber beam element model

A fiber beam element model named THUFIBER (Li et al.,2011;Lu et al.,2013)is used to build the numeri-cal model of the frame.THUFIBER takes into account the complex interaction mechanisms of the internal forces in the beam sections and has robust material models covering both unloading and reload-ing paths.Published literatures show that RC frames exhibiting flexural and axial failures under large defor-mations can be satisfactorily simulated using THUFIBER with a very efficient computational work-load (Li et al.,2011;Lu et al.,2013;Ren et al.,2015).

Nonlinear pushdown method

The nonlinear static pushdown method proposed by Khandelwal and El-Tawil (2008)is used in this study to analyze the collapse mechanisms and the progres-sive collapse resistance of the RC frames.First,the ini-tially damaged columns are removed from the RC frame models.Note that only one column is removed in each analysis.Then,an increasing vertical load q is imposed in the damaged region while keeping the design vertical load g unchanged in other regions (as shown in Figure 2).Using this method,the relation-ship between the internal forces in the structural ele-ments and the structural deformation during the collapse process,from small to large deformation stages,can be obtained and analyzed.Likewise,the

relationship between the progressive collapse resistance of the structure,that is,the vertical load q ,and the structural deformation can also be established (see the following discussion).All representative columns on each floor,located at the short-edge,long-edge,cor-ner,and interior on the plan layout as shown in Figure 1,are considered individually as the initially damaged columns.

Nonlinear static analysis algorithm based on multiple point constraints

A softening process occurs when the RC beams trans-form from the compressive arch mechanism or the beam mechanism to the catenary mechanism.Problems may be encountered with numerical diver-gence in the computation for this softening process if the model is loaded by a force-controlled algorithm.Therefore,the nonlinear static analysis algorithm pro-posed by Huang (2009)is used in this study.Based on multiple point constraints,this algorithm can shift the loading mode from a force-controlled algorithm to a displacement-controlled one which is robust to obtain structural responses at the unstable softening stage.This allows for an entire structural resistance curve of the RC frames to be successfully established,as facili-tated by this algorithm.

Progressive collapse resistance of multi-storey frames

In this section,the progressive collapse mechanisms and resistance of Model A (designed for a lower seis-mic design intensity)are evaluated through the analy-sis of the resistance curves as a result of removing typical columns on different stories.The internal force–displacement relationships obtained for multi-storey frames will facilitate examination of the collapse resistance influenced by the interaction characteristics of multi-storey frames.

Characteristics of the resistance curve

Figure 3shows the resistance curves of Model A,obtained from the nonlinear static pushdown analysis,for various column removal scenarios.The displace-ment of the joint on top of the removed column D is chosen as the representative deformation parameter,and the relative resistance (i.e.q /g ,where q is the applied vertical load and g is the design vertical load)is chosen as the resistance parameter.The analysis results obtained after the removal of a column on the xth storey are represented by the legend ‘‘xth’’in the figure.It can be found that with an increase in

the

Figure 2.Load pattern for pushdown analysis of the RC frames.

Advances in Structural Engineering

joint displacement in the long-edge,short-edge,and interior areas,the relative resistance q /g develops sig-nificantly at the initial stage and then declines signifi-cantly after the first peak.The value of q /g reaches its minimum when D =500–850mm.However,with fur-ther increase of the joint displacement,q /g starts to increase again until the second peak.The first peak resistance is provided by the bending moments at the beam ends (viz.the beam mechanism),and the second is provided by the axial tensile force in the beams (viz.the catenary mechanism).Particularly,pushdown analysis of the corner column removal scenario shows that there is only one peak in the resistance curve,indi-cating that only the beam mechanism works in this area.This phenomenon coincides with the results dis-cussed by Li et al.(2011).Note that in this study,the first peak resistance is referred to as the beam mechan-ism instead of the compressive arch mechanism because not all the beams are able to provide

compressive arch action under small deformations to resist progressive collapse,whereas all the beams can resist progressive collapse by the bending moments developed at the beam ends.

Resistance under the beam mechanism

Figure 3also indicates that the progressive collapse resistance of Model A under the beam mechanism has the following two characteristics:(1)for the long-edge,short-edge,and interior areas,if the removed column is located on the top two stories,the relative resis-tances are generally higher than those of lower storey column removal scenarios at the corresponding loca-tions.The highest resistance is achieved when the top storey columns are removed.In addition,no signifi-cant difference exists in the relative resistance if the removed column is located on the lower six stories.(2)For the corner area,no significant difference in

the

Figure 3.Progressive collapse resistance curves for Model A:(a)short-edge area,(b)long-edge area,(c)corner area,and (d)interior area.

Li et al.5

relative resistance can be observed regardless of the storey the removed column is located on.

Again for Model A,designed for a lower seismic design intensity,the gravity load dominates the design,and the amount of reinforcing steel in the beams is mainly governed by the dead and live loads acting on the floor.Due to the same design loads applied to each floor,there is little difference in steel amount for dif-ferent stories.Therefore,in theory,the progressive col-lapse resistance should also be similar among different stories.To explain the unusually high progressive col-lapse resistance of the top storey,the internal forces of beams L-1and L-2(see Figure 1)obtained under dif-ferent column removal scenarios (i.e.the long-edge middle column of the xth storey is removed,where x =6,7,or 8)are analyzed,as shown in Figures 4and 5,respectively.In the figures,F j i and M j i represent the axial force and the bending moment,respectively,of beams L-1and L-2on the i th storey after the long-edge middle column on the j th storey is removed.

Considering the removal of the eighth storey col-umns,before the joint displacement D of the edge peri-meter beam L-1reaches 500mm,the internal force in these beam ends is a combination of the flexural and

axial actions (F 88,M 8

8),as shown in Figure 4(a).However,when columns on the other stories are removed,the internal forces in the beams on different stories are not identical:those in the beams just above

the removed column (e.g.(F 66,M 66)and (F 77,M 7

7))are

close to (F 88,M 88),whereas (F 67,M 67),(F 68,M 68),and (F 7

8,M 7

8)are much smaller,as shown in Figure 4(c)and (d)This is due to the existence of the Vierendeel action in beams within the multi-stories.The axial compressive forces in the beams of different stories form a new moment M F to resist the external loads,as shown in Figure 4(b).Thus,the same forces in the beams of the upper stories are much smaller.For a single beam,the existence of the axial compressive force can signifi-cantly improve its flexural capacity.However,for a multi-storey frame subject to the external loads as a whole,only the beams closer to the lower stories and those having higher axial compressive forces (see Figure 4(c))can benefit from improved flexural capaci-ties.Hence,with an increase in the number of stories,such an increased,residual flexural capacity will con-tinuously be redistributed or ‘‘diluted,’’leading to a converged resistance capacity.This explains why,in Figure 3,the removal scenarios on the top two stories result in higher relative resistance,while there is little change in the relative resistance for the removal sce-narios on the bottom six stories.Yi et al.(2008)also discovered this phenomenon of uneven internal

force

Figure https://www.wendangku.net/doc/5817785820.html,bined action of beams on different stories (beam L-1):(a)force diagram (eighth storey column removal scenario),(b)force diagram (sixth storey column removal scenario),(c)axial force,and (d)bending moment.

6Advances in Structural Engineering

development among different stories in the progressive collapse test of a three-storey frame,where the reinfor-cement strain of the bottom beams was larger than that of the upper beams,which agrees with the above discussion.

For beam L-2perpendicular to the edge,the differ-ence in axial forces in the beams of different stories is not obvious (Figure 5(c))because there is no compres-sive arch action.The difference in bending moments in the beams of different stories is also insignificant (Figure 5(d)).Therefore,the Vierendeel action does not exist in beam L-2,and the progressive collapse resistance for different column removal scenarios from different stories is almost identical.The mechanism of beams C-1and C-2in the corner area (see Figure 1)is similar to that of beam L-2,in that the relative resis-tance of the top storey is not higher than those of the bottom stories (Figure 3(c)).

Resistance under the catenary mechanism

Figure 3further illustrates that in the catenary mechan-ism stage,the relative resistances of the removal sce-narios on the upper stories are higher than those on the lower stories,for corresponding locations of long-edge,short-edge,and interior areas.This phenomenon is similar to that in the beam mechanism stage.It can be

found from Figure 4that the internal forces in the beams of different stories are not evenly developed when considering the interaction of different stories.If the removed column is located on the j th storey,the internal forces in the beam on the (j +1)th storey rapidly convert from compression to tension (700–900mm).However,such transformation of internal forces is delayed slightly (800–1000mm)on the (j +2)th storey but significantly (800–1200mm)on the (j +3)th storey.Therefore,the catenary action of the beams cannot be fully developed at the same time.The lower the storey on which the column is removed,the smaller the resistance of the catenary action will be provided at the same deformation,due to the delay of the transformation of internal forces in upper storey beams.

Structural vulnerability due to uneven internal force development

Regarding the theoretical models in the existing codes (DoD,2010;GSA,2003),for example,the catenary model in the tie force method,development of the internal force in structural members is assumed to be even from different stories when resisting progressive collapse.Based on this hypothesis,each floor system is considered to independently carry the collapse

load

Figure https://www.wendangku.net/doc/5817785820.html,bined action of beams on different stories (beam L-2):(a)force diagram (eighth storey column removal scenario),(b)force diagram (sixth storey column removal scenario),(c)axial force,and (d)bending moment.

Li et al.7

acting on the corresponding floor,and in turn,the whole substructure will successfully resist the total col-lapse load,as shown in Figure 6.However,as discussed in sections ‘‘Resistance under the beam mechanism’’and ‘‘Resistance under the catenary mechanism,’’the internal force development among different stories is uneven in the frame system.More specifically,the forces developed in the lower storey beams are larger than those in the upper stories.Hence,the lower storey beams will be damaged prior to the others.After that,the same mechanism will be applied to the remaining upper storey beams,and in turn,they fail successively from one storey to the other.A similar mechanism also presents in the Vierendeel action of the frame beams.Hence,the combined action of the multi-storey floors may reduce the progressive collapse resistance of RC frames.

Effect of seismic design on progressive collapse resistance

Resistance under the beam mechanism

The effect of seismic design on progressive collapse resistance is examined through Model B,designed for a high-seismic-intensity region.Figure 7shows the resistance curves for this model obtained after the removal of the typical columns from each storey.It can be found that in contrast to Model A,for which the seismic design intensity is lower,the relative resistance of Model B in the beam mechanism stage increases sig-nificantly at various locations from the top to the bot-tom stories (Figure 7).This difference is because,for RC frames designed with high seismic design intensity,earthquake action is dominant in the design.The beam reinforcement is governed by the horizontal earth-quake action;therefore,the amount of aseismic rein-forcement gradually increases from the top to the bottom stories.This increased amount is mainly located in the beam ends,thereby significantly improv-ing the flexural capacity of the beam.This in turn increases the progressive collapse resistance of the RC frame under the beam mechanism.Figure 8compares the resistance curves of the model for two different

column removal scenarios from the top and the bottom stories.It is evident that a stronger seismic design improves the progressive collapse resistance of the bot-tom floors more than the top ones because the increase in the amount of seismic reinforcement on the bottom stories is much larger.

Resistance under the catenary mechanism

Continuous reinforcement in the beam creates an axial tension under the catenary mechanism.Thus,mid-span reinforcement is the key factor influencing the progres-sive collapse resistance of RC frames under the caten-ary mechanism.Seismic design primarily increases the amount of bending reinforcement at the beam ends,whereas such an increase at the mid-span is far less.For the RC frames presented in this study,the amount of mid-span reinforcement for Model B increases slightly on the top storey as compared to Model A.In addition,the increase in the axial strength of the top storey beam is also very limited.Therefore,for the top storey column removal scenario,the progressive col-lapse resistance of these two models is basically the same under the catenary mechanism (see Figure 8).For the bottom frame beams,on the other hand,the amount of mid-span reinforcement increases notice-ably,and therefore,the resistance clearly increases for Model B under the catenary mechanism (see Figure 8).However,such an increase is still less significant than that under the beam mechanism,as shown in Figure 8.Considering delayed development of the catenary mechanism when multi-storey beams work together,the interaction of the above aspects leads to such a change in the progressive collapse resistance due to stronger seismic design being less obvious under the catenary mechanism.This is illustrated in Figure 7for Model B.

Assessment of the design parameters in the existing codes and validation of the collapse resistance of RC frames

The progressive collapse resistance of RC frames can be evaluated via a nonlinear static pushdown

analysis.

Figure 6.Structural vulnerability due to uneven internal force development.

8Advances in Structural Engineering

Given that the collapse process exhibits a strong dynamic effect,a maximum structural resistance that is larger than the design vertical load must be attained in order to prevent progressive collapse from happen-ing.In other words,the maximum relative resistance q max /g must be larger than 1.0.Based on this consider-ation,the resistance of the RC frames is further vali-dated using the nonlinear dynamic alternative load path method (DoD,2010;Li et al.,2011).

For the two models,Figure 9presents the maximum relative resistance q max /g versus the ductility ratio m for a total of 32column removal scenarios.For the portion of the frames undergoing large deformations,m is defined as the ratio of the joint displacement corre-sponding to the maximum relative resistance to the yield displacement (Pujol and Smith-Pardo,2009;Tsai,2010).The expression q max /g refers to the peak value of each resistance curve presented in Figures 3and 7.In Figure 9,the hollow and solid marks demote col-lapse and non-collapse scenarios,respectively,based on the outcome of the nonlinear dynamic alternative load path analysis.It is evident that a collapse can be prevented when q max /g of the RC frames is larger than 1.236.In addition,the minimum values of q max /g to prevent collapse for the corner,short-edge,long-edge and internal column removal scenarios are 1.296,1.327,1.236,and 1.280,respectively.The factors for different column removal scenarios are very close because the ductility ratios of RC beams designed by the Chinese codes (MOHURD,2010a,2010b)are simi-lar (varying from 3to 4).This can also be confirmed by the existing theoretical study (Li et al.,2014a)that the dynamic amplification factor (DAF)(i.e.the required values of q max /g ,for regular RC frame struc-tures)equals 1.33when the structural ductility ratio equals 4.0.

To facilitate practical designs,the linear static and nonlinear static methods are recommended by the existing codes as the simplified approaches to calculate the progressive collapse resistance.In these

methods,

Figure 7.Progressive collapse resistance curves for Model B:(a)short-edge area,(b)long-edge area,(c)corner area,and (d)interior area.

Li et al.9

the resistance directly obtained from the linear static and nonlinear static analyses,which is equivalent to the applied vertical load g in this study,is further cor-rected using the DAF and the demand capacity ratio (DCR),respectively,to account for the dynamic and nonlinear effects.In the GSA guideline (GSA,2003),the required equivalent values of q max /g ,that is,DAF/DCR,are 1.0and 1.33,respectively,for typical and atypical structural configurations (see Figure 9).The analysis results presented in Figure 9demonstrate that the GSA requirement for atypical structures is ade-quately met while that for typical structures cannot be met which would lead to unsafe designs.This is because the dynamic effect is consistently neglected (q max /g =1).

In the DoD2005guideline (DoD,2005),a DAF of 2.0,considering the nonlinear effect,is used for the lin-ear and nonlinear static analyses in which the required equivalent value of q max /g is also 2.0.The validation shown in Figure 9demonstrates that the design para-meter is over-conservative because the structures satis-fying such requirement will exhibit elastic behavior after the column removal.

In the DoD2010guideline (DoD,2010),different values of DAFs are given for the linear and nonlinear static analyses.An expression of the DAF for

nonlinear static analyses is regulated by equation (1)which is presented by the solid line in Figure 9

DAF =1:04+

0:45m +0:48

e1T

It can be seen that the GSA2003requirement is higher than that for typical structures but is still unsafe for the RC frames discussed herein.Model A

and

Figure https://www.wendangku.net/doc/5817785820.html,parison between the progressive collapse resistance of Model A and Model B:(a)short-edge area,(b)long-edge area,(c)corner area,and (d)interior

area.

Figure 9.Design parameters in the existing codes.

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Model B will collapse under three and two column removal scenarios,respectively.This is because equa-tion(1)is obtained from the numerical analyses of typ-ical planar3-storey and10-storey frames,from which the results cannot accurately describe the nonlinear dynamic effect of all types of frame buildings (Marchand et al.,2009).

On the other hand,two DAFs are regulated for lin-ear static analyses in the DoD2010guideline.The force-controlled DAF is2.0for fragile structures(i.e.m=1). Although rational,this DAF is only suitable for the elastic response when no structural ductility can be con-sidered.The deformation-controlled DAF,on the other hand,is much larger than2.0.This is because it is obtained based on the equal deformation demand in which the same deformation is applied to the RC frames in both linear static and dynamic analyses(Marchand et al.,2009).This is however not the focus of this study in which the nonlinear static method is used and the equal deformation demand is not required. Discussion and concluding remarks

In this study,the progressive collapse behavior of an RC frame with two different seismic design intensities is analyzed using the nonlinear static pushdown method.The following conclusions are drawn and rec-ommendations for future seismic designs against pro-gressive collapse are given:

1.Vierendeel action leads to uneven internal

forces in the beams of different stories.This

may result in the beams failing successively

from one floor to the other in a frame system,

which differs from the theoretical assumption

that the beams are damaged simultaneously on

different floors.This action also weakens the

compressive arch mechanism of the beams,and

therefore reduces the relative collapse resistance

of RC frames under the beam mechanism.This

is particularly true for frames with more stor-

ies.In view of this,considering only the pure

flexural strength of the beams under the beam

mechanism is a conservative and rational

approach for design purposes.Furthermore,

the catenary action is the prototype model of

the tie force method in existing design codes

and is assumed to be able to develop fully on

all stories.However,Vierendeel action delays

the catenary action on upper stories thereby

reducing the progressive collapse resistance.

Neglecting this effect will result in insufficient

resistance to prevent progressive collapse.

Hence,this phenomenon is recommended to be

considered in future improvement of the tie

force method.

2.Seismic design significantly enhances the pro-

gressive collapse resistance of RC frames under

the beam mechanism.However,such enhance-

ment is not as significant under the catenary

mechanism.This is because the axial tension of

the catenary mechanism is provided by contin-

uous reinforcement in the beam.Seismic design

consideration significantly increases the reinfor-

cement amount in the beam ends;however,

such an increase at the mid-span is small.

Hence,it is suggested that the progressive col-

lapse resistance can be improved by extending

and connecting a portion of the seismic reinfor-

cement which is proven very effective and eco-

nomical for RC frames constructed in the

seismic areas.In addition,seismic design signif-

icantly enhances the progressive collapse resis-

tance of the bottom stories.However,such

enhancement is limited for the top stories.

Thus,the top stories may become the weakest

location in progressive collapse designs.This is

a very important and useful finding,because

more attention is paid to the bottom stories of

a structure in the existing design specifications.

It is therefore recommended to specifically

examine the progressive collapse resistance of

the top stories of RC frames to ensure a safe

design of the entire structure.

3.Based on the RC frames presented in this study,

the validation demonstrates that the GSA sim-

plified static method for atypical structures pro-

vides adequate resistance to prevent progressive

collapse,whereas that for typical structures is

inadequate due to the absence of dynamic

effects which would result in unsafe designs.

Furthermore,the nonlinear static analysis spec-

ified in DoD2010also leads to unsafe designs

for the RC frames concerned and further inves-

tigations in this area are needed.

Declaration of Conflicting Interests

The author(s)declared no potential conflicts of interest with respect to the research,authorship,and/or publication of this article.

Funding

The author(s)disclosed receipt of the following financial sup-port for the research,authorship,and/or publication of this article:The authors are grateful for the financial support received from the National Basic Research Program of China

Li et al.11

(No.2012CB719703),the National Science Foundation of China(No.51578018,51208011),and the Australian Research Council through an ARC Discovery Project (DP150100606).

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英文自我介绍合集(大黄蜂资料大集合)

General Introduction I am a third year master major in automation at Shanghai Jiao Tong University, P. R. China. With tremendous interest in Industrial Engineering, I am writing to apply for acceptance into your Ph.D. graduate program. Education background In 1995, I entered the Nanjing University of Science & Technology (NUST) -- widely considered one of the China?s best engineering schools. During the following undergraduate study, my academic records kept distinguished among the whole department. I was granted First Class Prize every semester,In 1999, I got the privilege to enter the graduate program waived of the admission test. At the period of my graduate study, my overall GPA(3.77/4.0) ranked top 5% in the department. In the second semester, I became teacher assistant that is given to talented and matured students only. This year, I won the Acer Scholarship as the one and only candidate in my department, which is the ultimate accolade for distinguished students endowed by my university. Presently, I am preparing my graduation thesis and trying for the honor of Excellent Graduation Thesis. Research experience and academic activity When a sophomore, I joined the Association of AI Enthusiast and began to narrow down my interest for my future research. With the tool of OpenGL and Matlab, I designed a simulation program for transportation scheduling system. It is now widely used by different research groups in NUST. I assumed and fulfilled a sewage analysis & dispose project for Nanjing sewage treatment plant. This was my first practice to convert a laboratory idea to a commercial product.

2020年简单英语自我介绍合集

简单的英语自我介绍1篇简单的英语自我介绍1篇简单的英语自我介绍（一） Hello， everyone。My name is Zhang Wenxin， fourteen years old this year。大家好，我叫张温馨。今年14岁。 I’m studying in Xiamen PE and Sports School， a member of free bat team。就读于厦门市体育运动学校，是散打队的一名队员。 I am an active， bright， friendly and humorous girl。我是一个性格活泼开朗，热情幽默的女生。 So happy to stand here and introduce myself to you。很高兴能够站在那里向大家介绍我自我。 Next， I’d like to sing an English song。 Its name is 接下来呢我要表演的才艺是一首英文歌名字叫…… 简单的英语自我介绍（二） Good morningafternoonIt is really my honor to have this opportunity for a interview。 I hope I can make a good performance today。My name is xx。 I am 2 years old，born in a little village in Southern Zhejiang。 My parents are farmers，and I am the only child。 Though not well-to-do，the family always be hopeful。 My major is engineering technology。 I will graduate in July，211。

指南测试题三及答案

汤塘镇中心幼儿园《3-6岁儿童学习与发展指南》测试题（三）单位姓名分数一、填空题（每题分,共15分） 1、中国教育部网站2012年10月15日发布，对防止和克服学前教育“小学化”现象提供了具体和。 2、《指南》分别对3至4岁、4至5岁、5至6岁三个年龄段末期幼儿应该、，大致可以达到什么发展水平提出了，指明了幼儿的具体方向。 3、幼儿做错事时要冷静处理，不，更不能。 4、《指南》教育建议部分列举了一些能够有效和幼儿学习与发展的）与。 5、《指南》的五大领域共有个子领域，个学习和发展目标，条教育建议。 6、幼儿的语言能力是在交流和运用的过程中发展起来的。应为幼儿创设的语言交往环境，鼓励和支持幼儿与、交流，让幼儿想说、敢说、喜欢说并能得到积极回应。 7、数学认知的目标是让幼儿初步感知生活中数学的和。 8、幼儿的思维特点是是以思维为主，应注重引导幼儿通过和（）进行科学学习，不应为追求知识和技能的掌握，对幼儿进行灌输和强化训练。 9、科学探究目标一体现了幼儿好奇心和探究兴趣的高度重视，可以用、、、三个关键词来概括。 10、幼儿园开运动会，跑步的跑道合理设计是3-4岁米、4-5岁米、5-6岁米。二、单项选择题（每题1分,共10分） 1、《指南》是谁制定的（）。 A、国务院 B、教育部 C、国家 D、教育厅 2、《指南》是哪一年颁布的（）。 A、2001 B、2010 C、2011 D、2012 3、《指南》从几个领域描述幼儿的学习与发展（）。 A、2 B、3 C、4 D、5 4、培养幼儿具有良好的生活与卫生习惯，不用脏手揉眼睛，4-5岁幼儿连续看电视等不超过多少分钟？（） A、10分钟 B、15分钟 C、20分钟 D、30分钟 5、《指南》以什么为目标（） A、促进幼儿体、智、德、美各方面的协调发展 B、促进幼儿学习与发展的教育途径与方法 C、帮助幼儿园教师和家长了解3-6岁幼儿学习与发展的基本规律和特点 D、为幼儿后继学习和终身发展奠定良好素质基础。６、以下说法，正确的是（） A、健康是指身体上的完满状态及良好的适应能力

五分钟详细的英语自我介绍(精选多篇)

五分钟详细的英语自我介绍(精选多篇) 第一篇：五分钟自我介绍第二篇：五分钟面试自我介绍第三篇：五分钟自我介绍第四篇：五分钟自我介绍第五篇：五分钟自我介绍更多相关范文五分钟自我介绍各位尊敬的考官，xx好：今天能在这里参加面试，有机会向各位考官请教和学习，我感到十分的高兴，同时通过这次面试也可以把我自己展现给大家，下面通过五分钟求职自我介绍让您了解我的基本情况。我叫xxx,xx省xx人，今年6月将从xxxxx专业本科毕业。除了简历上您看到的内容，我愿意特别说一下我来xxx应聘这份职位的原因：首先，我最大的特点是有比较强的沟通能力和良好的团队精神。在与人合作工作中，我会非常认真的聆听和分析别人的意见，也不会没有原则的轻易放弃自己的意见。其次，我觉得自己有较强的学习和实践能力，在遇到困难的时候会冷静分析事情所处的状态，和各种可能发生的结果，并努力做到最好承担自己的责任。正是基于对自己这方面的自信，使我有勇气来应聘xxx这一职位。在求职面试自我介绍时，一直以来有一分钟自我介绍，三分钟自我介绍，一般都提倡时间不宜过长，因为往往时间长会显得内容比较啰嗦，但以下这个五分钟求职自我介绍则大为不同。尊敬的各位考官、各位评委老师：通过考试，今天，我以本岗位笔试第一的成绩进入了面试。对我来说，这次机会显得尤为珍贵。

我叫，今年24岁。xx年7月我从**师范学校艺师美术专业计划内自费毕业。由于从97年起国家不再对自费生包分配，使我与“太阳底下最光辉的职业”失之交臂。幸好，当时河西马厂完小师资不足，经人介绍，我在该完小担任了一年的临时代课教师。回想起那段时光真是既甜蜜又美好，虽然代课工资很低，但听着同学们围在身旁“老师”、“老师”的叫个不停，看着那一双双充满信任的眼睛，那一张张稚气的小脸，生活中的所有不快都顿时烟消云散了。工作中，不停地给自己做着工作总结，向老教师多请教来丰富自己的教学经验。我原想，即使不能转正，只要学校需要，就是当一辈子代课教师我也心甘情愿。不料，1998年起国家开始清退临时工和代课教师，接到了学校的口头通知后，我怀着恋恋不舍的心情，悄悄地离开了学校。今天，我想通过此次考试重新走上讲坛的愿望是那样迫切!我家共有三姊妹，两个姐姐在外打工，为了照顾已上了年纪的父母，我一直留在他们身边。我曾开过铺子，先是经营工艺品，后又经营服装。但不论生意做得如何得心应手，当一名光荣的人民教师始终是我心向往之并愿倾尽毕生心血去追求的事业。我曾多次参加考试，但都由于各种原因而未能实现梦想，但我暗下决心，只要有机会，我就一直考下去，直到理想实现为止。如今的我，历经生活的考验，比起我的竞争对手在年龄上我已不再有优势，但是我比他们更多了一份对孩子的爱心、耐心和责任心，更多了一份成熟和自信。

新《指南》测试题答案.doc

《3-6岁儿童学习与发展指南》测试题及答案学校：姓名：得分：一、填空（每空0.5分，共30分） 1、中国教育部网站2012年10月15日发布《3－6岁儿童学习与发展指南》，对防止和克服学前教育“小学化”现象提供了具体方法和建议。（0.5分） 2、《指南》教育建议部分列举了一些能够有效帮助和促进幼儿学习与发展的教育途径与方法。（2分） 3、为深入贯彻《国家中长期教育改革和发展规划纲要（2010—2020）》和《国务院关于当前发展学前教育的若干意见》，指导幼儿园和家庭实施科学的保育和教育，促进幼儿身心全面和谐发展，制定了《3~6岁儿童学习与发展指南》。（1分） 4、《指南》中每个领域按照幼儿学习与发展最基本、最重要的内容划分为若干方面。每个方面由学习与发展目标和教育建议两部分组成。（1分） 5、丰富幼儿的语言表达能力，应为幼儿提供丰富、适宜的低幼读物，经常和幼儿一起看图书、讲故事，培养阅读兴趣和良好的阅读习惯，进一步拓展学习经验。（1分） 6、《指南》共有 5 个领域11 子领域，32 个学习和发展目标，87 条教育建议。（2分） 7、语言是交流和思维的工具，幼儿的语言能力是在交流和运用的过程中发展起来的。（2分） 8、健康是指人在身体、心理和社会适应方面的良好状态。健康领域有三大内容：身心状况、动作发展和生活习惯与生活能力。（3分） 9、语言领域有两大内容：倾听与表达和阅读与书写准备。（1分） 10、社会领域有两大内容：：人际交往和社会适应。（1分） 11、科学领域有两大内容：科学探究和数学认知。（1分）

12、艺术领域有两大内容：感受与欣赏和表现与创造。（1分） 13、保证幼儿每天睡11~12小时，幼儿午睡一般应达到2小时左右。（1分） 14、幼儿做错事时要冷静处理，不厉声斥责，更不能打骂。（1分） 15、成人用恰当的方式表达情绪，为幼儿做出榜样。如生气时不乱发脾气，不迁怒于人。（1分） 16、3—4岁幼儿能快跑15 米左右。（0.5分） 17、数学认知的目标是让幼儿初步感知生活中数学的有用和有趣。（1分） 18、艺术是人类感受美、表现美、创造美的重要形式，也是表达自己对周围世界的认识和情绪态度的独特方式。（2.5分） 19、幼儿的语言能力是在交流和运用的过程中发展起来的。应为幼儿创设自由、宽松的语言交往环境，鼓励和支持幼儿与成人、同伴交流，让幼儿想说、敢说、喜欢说并能得到积极响应。（2.5分） 20、《指南》中幼儿科学探究的目标包括三个维度：情感态度、方法能力、和知识经验。（1.5分） 21、“数学认知”这一子领域以“解决问题”为核心。发现问题、分析和解决问题即是幼儿数学学习的重点，也是幼儿数学学习的基本途径。（1.5分）22、良好的倾听习惯的养成是从学前阶段开始的，因此就幼儿语言学习和发展而言，倾听是不可缺少的一种行为能力。（1分）二、判断题（6分） 1、《指南》在目标部分别对3～4岁、4～5 岁、5～6 岁三个年龄段中期幼儿应该知道什么、能做什么，大致可以达到什么发展水平提出了合理期望。（错） 2、对于拍球、跳绳等技能性活动，不要过于要求数量，更不能机械训练。（对） 3、5-6岁手的动作灵活协调的目标是，能沿边线较直的画出简单图形，或能边线基本对齐地折纸，会用筷子吃饭，能沿轮廓线检出由直线构成的简单图形，边线吻和（错） 4、幼儿每天的户外活动时间一般不少于3小时，其中体育活动时间不少于1小时。（错） 5、《指南》中艺术领域有3个子领域，健康领域有2个子领域。（错） 6、健康包括身体和心理两个方面，是一种在身体上和精神上的完满状态及良好的适应能力。（错）

英语书写资料带一张字帖

单词练习：

书面表达一：内容分别是你去北京分别参观了故宫、天安门、北京胡同和长城，要求按参观顺序写。（要用一般过去时来写）开头已经给出： Thursday, August 1st Today I went to the Palace Museum. It was cool. Then I... 范文： Thursday, August 1st Today I went to the Palace Museum. It was cool. Then I visited the Tian An Men Square. There were so many people. After that, I walked in some famous Beijing alleys and enjoyed the some delicious food there. At last, I came to the Great Wall. My teacher taught us "He who doesn't reach the Great Wall is not a true man." At that time, I felt I was so proud. What a nice day it was ! 书面表达二： Henry今天和父母去动物园，他们看了很多动物，Henry最喜欢的是大象。假如你是Henry，请你根据下面的提示词写一篇50词左右的短文，描述一下今天的经历。提示词：zoo, see, best, smart, friendly, eat, other, happy

英文自我介绍合集

自我介绍合集篇英语自我介绍范文 ` General Introduction I am a third year master major in automation at Shanghai Jiao Tong University, P. R. China. With tremendous interest in Industrial Engineering, I am writing to apply for acceptance into your Ph.D. graduate program. Education background In 1995, I entered the Nanjing University of Science & Technology (NUST) -- widely considered one of the China’s best engineering schools. During the following undergraduate study, my academic records kept distinguished among the whole department. I was granted First Class Prize every semester,In 1999, I got the privilege to enter the graduate program waived of the admission test. At the period of my graduate study, my overall GPA(3.77/4.0) ranked top 5% in the department. In the second semester, I became teacher assistant that is given to talented and matured students only. This year, I won the Acer Scholarship as the one and only candidate in my department, which is the ultimate accolade for distinguished students endowed by my university. Presently, I am preparing my graduation thesis and trying for the honor of Excellent Graduation Thesis. Research experience and academic activity When a sophomore, I joined the Association of AI Enthusiast and began to narrow down my interest for my future research. With the tool of OpenGL and Matlab, I designed a simulation program for transportation scheduling system. It is now widely used by different research groups in NUST. I assumed and fulfilled a sewage analysis & dispose project for Nanjing sewage treatment plant. This was my first practice to convert a laboratory idea to a commercial product.

关于英语专业英语自我介绍合集8篇

关于英语专业英语自我介绍合集8篇英语专业英语自我介绍篇1 Hello,every one!I am a girl.I am eighteen years old.I have many hobbies.I’m very enjoy every nice things.I think they are very wonderful! I am very glad to take part in this compitation. Long ago,I am a shy girl, but in three years in the school,I began to become happy and more comfident.Now,I will act a program. I hope you will like it.Thank you. 英语专业英语自我介绍篇2 各位领导，大家好。我叫朱，来自湖南常德，是一名湖南xxxxx外国语学院的应届毕业生，我的专业是商务英语。我喜欢打羽毛球，喜欢听音乐，是个活泼开朗，热情大方的女孩子。喜欢交朋友，也总会给别人带来欢笑。我是一个来自农村的普通女孩，从小被农村淳朴的感情渲染。我有一个幸福的家庭，和爸爸妈妈，妹妹一起生活。从小我亲眼目睹了爸爸妈妈为了这个家所付出的辛苦，劳累与奔波，一点一滴都深深的刻在我的心中。在大学三年，不仅只是能力还是个人修养上，我都受益匪浅。在老师的教导和个人的努力下，我具备了扎实的专业基础知识，并系统的掌握了各方面的理论知识，几倍了听说读写译的能力。在大学第一期，我顺利的通过了大学英

语三级的考试，并在第二年就具备了大学英语四级的水平。并且，我能够熟练的进行计算机Word， Excel， Photoshop 的软件操作，在大学第三年掌握了外贸单证制单与跟单的操作。大学期间，我担任学生会女生部部长一职，工作上细心，负责市我任职期间遵守的原则。我带领部门的其她成员，把女生部的工作管理的井井有条，并得到了学校领导和老师的一职肯定。在期末总结大会上，我并作为学生会所有成员代表进行了发言。暑假期间，我曾参加过学校的留校实践，不仅仅是希望问母校做一些力所能及的贡献，更期望能一次来巩固自己的专业知识和应变能力。我热爱参加学校组织的各种活动，比如：文艺汇演，英语角还有班会主持，我都积极参加，并取得了不错的效果。尽管我只是一名应届毕业生，但我有应届毕业生上刻苦，热情的精神，希望贵公司能给我这次机会，能为贵公司添砖加瓦。英语专业英语自我介绍篇3 大家好，很高兴借此机会来介绍我自己。我叫…...，英文名叫……，来自美丽的广西桂林，现就读于南宁职业技术学院，主修会计。我在业余生活喜欢读书、写字、听音乐、交朋友。我是一个自信的人，执着而有耐心是我最大的特点。英语是我的最爱，对我很重要，我希望将来能成为一位英语老师，和许许多多的学生分享我的经历。谢谢!

3 6岁儿童学习与发展指南学习测试题有答案

《3-6岁儿童学习与发展指南》测试卷答案国务院关于当前发展学前教育的若干意2020年）》和《1、为深入贯彻《国家中长期教育改革和发展规划纲要（2010—岁儿童，制定《3-6保育和教育，促进幼儿身心全面和谐发展》（国发〔见2010〕41号），指导幼儿园和家庭实施科学的学习与发展指南》。五个领域描述幼儿的学习与发展。每个领域按照幼儿学习与发展最基本、、《指南》从健康、语言、社会、科学、艺术243～教育建议两部分组成。3、《指南》目标部分分别对最重要的内容划分为若干方面。每个方面由学习与发展目标和三个年龄段末期幼儿应该知道什么、能做什么，大致可以达到什么发展水平提出了合理期望，指明岁岁、5～6岁、4～5 的具体方向；了幼儿学习与发展。教育途径与方法、《指南》教育建议部分列举了一些能够有效4帮助和促进幼儿学习与发展的）个学习和发展目标，（87）条教育建议。 5、《指南》共有（32 成、幼儿的语言能力是在交流和运用的过程中发展起来的。应为幼儿创设自由、宽松的语言交往环境，鼓励和支持幼儿与6读物，经常和幼儿一起看图回应。为幼儿提供丰富、适宜的低幼人、同伴交流，让幼儿想说、敢说、喜欢说并能得到积极习惯，进一步拓展学习经验。书、讲故事，丰富其语言表达能力，培养阅读兴趣和良好的阅读岁三个年龄段中期幼儿应该知道什么、能做什么，大致可以达～56 4～5 岁、～1、《指南》在目标部分别对34岁、到什么发展水平提出了合理期望，（1、（错）（末期）） 2、健康是指人在身体、心理和社会适应方面的良好状态。（错） 3、保证幼儿的户外活动时间一般不少于两小时，体育活动时间不少于1小时，提高幼儿适应季节变化的能力。（对） 4、对于拍球、跳绳等技能性活动，不要过于要求数量，更不能机械训练。(对 ) 5、5-6岁手的动作灵活协调的目标是，能沿边线较直的画出简单图形，或能边线基本对齐地折纸，会用筷子吃饭，能沿轮廓线检出由直线构成的简单图形，边线吻和（（错）（正确答案是能根据需要画出图形，线条基本平滑，能熟练使用筷子，能沿轮廓线剪出由曲线构成的简单图形，边线吻合且平滑，能使用简单的劳动工具或用具。） 6、《指南》是2012年5月通过中国教育部网站颁布的；（对））小时）11-12（（错）（个小时10-11、幼儿每天要睡7．三、选择 1、幼儿的科学学习是在探究具体事物和解决实际问题中，尝试发现事物间的异同和联系的过程。幼儿在对自然事物的探究和运用数学解决实际生活问题的过程中，不仅获得丰富的感性经验，充分发展形象思维，而且初步尝试（ a、b、c、 d ），逐步发展逻辑思维能力，为其它领域的深入学习奠定基础。 A归类、 B排序、 C判断、 D推理 2.保证幼儿每天睡( 11～12小时)，其中午睡一般应达到2小时左右。午睡时间可根据幼儿的年龄、季节的变化和个体差异适当减少。 3.如何锻炼幼儿适应生活环境变化的能力（ a、b ） A、注意观察幼儿在新环境中的饮食、睡眠、游戏等方面的情况，采取相应的措施帮助他们尽快适应新环境。 B、经常带幼儿接触不同的人际环境，如参加亲戚朋友聚会，多和不熟悉的小朋友玩，使幼儿较快适应新的人际关系。 C、幼儿每天的户外活动时间一般不少于两小时，其中体育活动时间不少于1小时，季节交替时要坚持。 D、气温过热或过冷的季节或地区应因地制宜，选择温度适当的时间段开展户外活动，也可根据气温的变化和幼儿的个体差异，适当减少活动的时间。 4、5-6岁幼儿男孩子的身高应该达到(106.1-125.8cm ) 5、5-6岁幼儿基本能够达到双手抓杠悬空吊起（ 20）秒左右 6、4-5岁幼儿能够在较热或较冷的户外环境中连续活动（半个小时左右）《指南》是谁制定的教育部《指南》是哪一年颁布的 2012 《指南》从几个领域描述幼儿的学习与发展 5 《指南》中每个领域按照幼儿学习与发展最基本、最重要的内容划分为若干方面。每个方面由几部分组成 2 《指南》以什么为目标为幼儿后继学习和终身发展奠定良好素质基础以下说法，正确的是《指南》是《纲要》的细化

英语书写标准格式字帖

__________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ ______________________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ _ __________________ ______________ ______________ ________________ _______________ __________________ ______________ ______________ ________________ _______________ Hello Hello Hello Hello Hello Hi hi hi hi hi Goodbye goodbye goodbye goodbye Bye bye bye bye bye I ’m I ’m I ’m I ’m I ’m I I I I I Am am am am am Fine fine fine fine fine Good good good good good Morning morning morning morning what ’s what ’s what ’s what ’s what ’s What what what what what Is is is is is My my my my my

英文自我介绍最新合集

英文自我介绍最新合集假如你要去外企工作，一段流利的英文自我介绍是必不可少的。下面是为您精心整理的英文自我介绍大全，欢迎参考，希望对大家有所帮助! 英文自我介绍大全1 It’s my pleasure to introduce myself to you here. My name is _, I come from _ which is a beautiful city. And I am a candidate for the position of Sales Representative. I attended Nantong University in 2003. My major is Information and Computing Science and I got my Bachelor’s degree four years later. I am especially interested in “computer and web”. And in 2005, I became a member of The Communist party. I am 25 years old, and have had one years working experience in an export company, which I am leaving to look for better opportunities. I have learned a lot about business and mastered basic office skills. In addition, I learned how to cooperate with my colleagues from my previous job. With strong determination, I believe I can succeed in the future.

精彩的英语自我介绍范文6篇

精彩的英语自我介绍范文6篇Wonderful English self introduction model 编订：JinTai College

精彩的英语自我介绍范文6篇前言：自我介绍是向别人展示你自己，直接关系到你给别人的第一印象的好坏及以后交往的顺利与否，也是认识自我的手段。自我介绍是每个人都必然要经历的一件事情，日常学习、工作、生活中与陌生人建立关系、打开局面的一种非常重要的手段，通过自我介绍获得到对方的认识甚至认可，是一种非常重要的技巧。本文档根据自我介绍内容要求和特点展开说明，具有实践指导意义，便于学习和使用，本文下载后内容可随意调整修改及打印。本文简要目录如下：【下载该文档后使用Word打开，按住键盘Ctrl键且鼠标单击目录内容即可跳转到对应篇章】 1、篇章1：精彩的英语自我介绍范文 2、篇章2：精彩的英语自我介绍范文 3、篇章3：精彩的英语自我介绍范文 4、篇章4：精彩的英文自我介绍范文 5、篇章5：精彩的英文自我介绍范文 6、篇章6：精彩的英文自我介绍范文英语自我介绍，首先，要先写好英语自我介绍的稿子，好让心里有底，把一些关键的内容熟记。那么你知道精彩的英

语自我介绍要怎么说吗?今天小泰和你分享精彩的英语自我介绍范文，欢迎阅读。篇章1:精彩的英语自我介绍范文 I am a recent college graduate with a B.A. degree in automotive marketing on the other hand, in the spirit of serving the people, adhere to help others, serve the community members of the strict demands on themselves. Finally the beginning of the glorious junior joined the Chinese Communist Party, and successfully turned positive after one year. Four years in college, I know a lot of friends, they gave me a lot of help, let me learn a lot, this is college, in addition to expertise outside of an additional valuable asset. In short, four years of school life, whether professional or social knowledge about, or people skills, have learned a lot I can say that four years of my life the most significant period of time, my ideal life and the pursuit of life during this period