In order to evaluate the seismic stability of reinforced soil walls against bearing capacity failure,the seismic safety factor of reinforced soil walls was determined by using pseudo-dynamic method,and calculated by c...In order to evaluate the seismic stability of reinforced soil walls against bearing capacity failure,the seismic safety factor of reinforced soil walls was determined by using pseudo-dynamic method,and calculated by considering different parameters,such as horizontal and vertical seismic acceleration coefficients,ratio of reinforcement length to wall height,back fill friction angle,foundation soil friction angle,soil reinforcement interface friction angle and surcharge.The parametric study shows that the seismic safety factor increases by 24-fold when the foundation soil friction angle varies from 25°to 45°,and increases by 2-fold when the soil reinforcement interface friction angle varies from 0 to 30°.That is to say,the bigger values the foundation soil and/or soil reinforcement interface friction angles have,the safer the reinforced soil walls become in the seismic design.The results were also compared with those obtained from pseudo-static method.It is found that there is a higher value of the safety factor by the present work.展开更多
This study aims to analyze seismic damage of reinforced outlet piers of arch dams by the nonlinear finite element （FE） sub-model method. First, the dam-foundation system is modeled and analyzed, in which the effects...This study aims to analyze seismic damage of reinforced outlet piers of arch dams by the nonlinear finite element （FE） sub-model method. First, the dam-foundation system is modeled and analyzed, in which the effects of infinite foundation, contraction joints, and nonlinear concrete are taken into account. The detailed structures of the outlet pier are then simulated with a refined FE model in the sub-model analysis. In this way the damage mechanism of the plain （unreinforced） outlet pier is analyzed, and the effects of two reinforcement measures （i.e., post-tensioned anchor cables and reinforcing bar） on the dynamic damage to the outlet pier are investigated comprehensively. Results show that the plain pier is damaged severely by strong earthquakes while implementation of post-tensioned anchor cables strengthens the pier effectively. In addition, radiation damping strongly alleviates seismic damage to the piers.展开更多
In this work,a numerical study of the effects of soil-structure interaction(SSI)and granular material-structure interaction(GSI)on the nonlinear response and seismic capacity of flat-bottomed storage silos is conducte...In this work,a numerical study of the effects of soil-structure interaction(SSI)and granular material-structure interaction(GSI)on the nonlinear response and seismic capacity of flat-bottomed storage silos is conducted.A series of incremental dynamic analyses(IDA)are performed on a case of large reinforced concrete silo using 10 seismic recordings.The IDA results are given by two average IDA capacity curves,which are represented,as well as the seismic capacity of the studied structure,with and without a consideration of the SSI while accounting for the effect of GSI.These curves are used to quantify and evaluate the damage of the studied silo by utilizing two damage indices,one based on dissipated energy and the other on displacement and dissipated energy.The cumulative energy dissipation curves obtained by the average IDA capacity curves with and without SSI are presented as a function of the base shear,and these curves allow one to obtain the two critical points and the different limit states of the structure.It is observed that the SSI and GSI significantly influence the seismic response and capacity of the studied structure,particularly at higher levels of PGA.Moreover,the effect of the SSI reduces the damage index of the studied structure by 4%.展开更多
It is possible for certain building structures to encounter both the seismic load and blast load during their service life.With the development of the economy and the increase of security demand,the need for design of...It is possible for certain building structures to encounter both the seismic load and blast load during their service life.With the development of the economy and the increase of security demand,the need for design of building structures against multi-hazard is becoming more and more obvious.Therefore,the damage analysis of building structures under the combined action of multiple hazards has become a very urgent requirement for disaster prevention and reduction.In this paper,the refined finite element model of reinforced concrete(RC)columns is established by using the explicit dynamic analysis software LS-DYNA.Combined with the Monte Carlo method,the damage law of RC columns under the combined action of random single earthquake or explosion disaster and multi-hazard is studied,and the damage groups are distinguished according to the damage index.Based on the support vector machine(SVM)algorithm,the dividing line between different damage degree groups is determined,and a rapid method for determining the damage degree of RC columns under the combined seismic and blast loads is proposed.Finally,suggestions for the design of RC column against multi-disaster are put forward.展开更多
性态设计是支挡结构工程抗震设计的前沿科学问题。以模块式加筋土挡墙为试验对象,通过振动台试验,探究模块式加筋土挡墙的变形模式;收集归纳挡土墙位移计算方法,分析不同破坏模式下屈服加速度系数分布规律;对比不同计算方法计算值与实...性态设计是支挡结构工程抗震设计的前沿科学问题。以模块式加筋土挡墙为试验对象,通过振动台试验,探究模块式加筋土挡墙的变形模式;收集归纳挡土墙位移计算方法,分析不同破坏模式下屈服加速度系数分布规律;对比不同计算方法计算值与实测值的一致性。研究结果表明:挡墙的位移模式为平移与转动耦合,且以转动为主;不同破坏模式下安全系数法求解的屈服加速度系数均随输入加速度幅值增大而减小,简便方法和能量法所得屈服加速度系数为常数;将屈服加速度系数代入不同位移计算方法对比,提出在不同峰值加速度时,可分别采用Richards and Elms上限法(0.4g以下)、Cai and Bathurst平均上限法(0.4g~0.6g)、Newmark上限法(0.6g~0.8g)、Whitman and Liao平均拟合法(0.8g~1.0g)进行位移计算。最后,对模块式加筋土挡墙的抗震设计流程进行归纳。展开更多
文摘In order to evaluate the seismic stability of reinforced soil walls against bearing capacity failure,the seismic safety factor of reinforced soil walls was determined by using pseudo-dynamic method,and calculated by considering different parameters,such as horizontal and vertical seismic acceleration coefficients,ratio of reinforcement length to wall height,back fill friction angle,foundation soil friction angle,soil reinforcement interface friction angle and surcharge.The parametric study shows that the seismic safety factor increases by 24-fold when the foundation soil friction angle varies from 25°to 45°,and increases by 2-fold when the soil reinforcement interface friction angle varies from 0 to 30°.That is to say,the bigger values the foundation soil and/or soil reinforcement interface friction angles have,the safer the reinforced soil walls become in the seismic design.The results were also compared with those obtained from pseudo-static method.It is found that there is a higher value of the safety factor by the present work.
基金National Natural Science Foundation of China under Grant Nos.51179093 and 91215301Specialized Research Fund for the Doctoral Program of Higher Education under Grant No.20130002110032
文摘This study aims to analyze seismic damage of reinforced outlet piers of arch dams by the nonlinear finite element （FE） sub-model method. First, the dam-foundation system is modeled and analyzed, in which the effects of infinite foundation, contraction joints, and nonlinear concrete are taken into account. The detailed structures of the outlet pier are then simulated with a refined FE model in the sub-model analysis. In this way the damage mechanism of the plain （unreinforced） outlet pier is analyzed, and the effects of two reinforcement measures （i.e., post-tensioned anchor cables and reinforcing bar） on the dynamic damage to the outlet pier are investigated comprehensively. Results show that the plain pier is damaged severely by strong earthquakes while implementation of post-tensioned anchor cables strengthens the pier effectively. In addition, radiation damping strongly alleviates seismic damage to the piers.
文摘In this work,a numerical study of the effects of soil-structure interaction(SSI)and granular material-structure interaction(GSI)on the nonlinear response and seismic capacity of flat-bottomed storage silos is conducted.A series of incremental dynamic analyses(IDA)are performed on a case of large reinforced concrete silo using 10 seismic recordings.The IDA results are given by two average IDA capacity curves,which are represented,as well as the seismic capacity of the studied structure,with and without a consideration of the SSI while accounting for the effect of GSI.These curves are used to quantify and evaluate the damage of the studied silo by utilizing two damage indices,one based on dissipated energy and the other on displacement and dissipated energy.The cumulative energy dissipation curves obtained by the average IDA capacity curves with and without SSI are presented as a function of the base shear,and these curves allow one to obtain the two critical points and the different limit states of the structure.It is observed that the SSI and GSI significantly influence the seismic response and capacity of the studied structure,particularly at higher levels of PGA.Moreover,the effect of the SSI reduces the damage index of the studied structure by 4%.
基金supported by the National Natural Science Foundation of China (Grant Nos.51878445,51938011 and 51908405)。
文摘It is possible for certain building structures to encounter both the seismic load and blast load during their service life.With the development of the economy and the increase of security demand,the need for design of building structures against multi-hazard is becoming more and more obvious.Therefore,the damage analysis of building structures under the combined action of multiple hazards has become a very urgent requirement for disaster prevention and reduction.In this paper,the refined finite element model of reinforced concrete(RC)columns is established by using the explicit dynamic analysis software LS-DYNA.Combined with the Monte Carlo method,the damage law of RC columns under the combined action of random single earthquake or explosion disaster and multi-hazard is studied,and the damage groups are distinguished according to the damage index.Based on the support vector machine(SVM)algorithm,the dividing line between different damage degree groups is determined,and a rapid method for determining the damage degree of RC columns under the combined seismic and blast loads is proposed.Finally,suggestions for the design of RC column against multi-disaster are put forward.
文摘性态设计是支挡结构工程抗震设计的前沿科学问题。以模块式加筋土挡墙为试验对象,通过振动台试验,探究模块式加筋土挡墙的变形模式;收集归纳挡土墙位移计算方法,分析不同破坏模式下屈服加速度系数分布规律;对比不同计算方法计算值与实测值的一致性。研究结果表明:挡墙的位移模式为平移与转动耦合,且以转动为主;不同破坏模式下安全系数法求解的屈服加速度系数均随输入加速度幅值增大而减小,简便方法和能量法所得屈服加速度系数为常数;将屈服加速度系数代入不同位移计算方法对比,提出在不同峰值加速度时,可分别采用Richards and Elms上限法(0.4g以下)、Cai and Bathurst平均上限法(0.4g~0.6g)、Newmark上限法(0.6g~0.8g)、Whitman and Liao平均拟合法(0.8g~1.0g)进行位移计算。最后,对模块式加筋土挡墙的抗震设计流程进行归纳。
