地震作用下土—结构相互作用对浅基础桥结构响应的影响
发布时间：2018-10-31 12:17
【摘要】：依据现行抗震设计规范建造的浅基础桥,大多未进行抗震验算,或至多是将这类桥梁看成是墩底固定在刚性地基上的悬臂结构,不考虑地震作用下的土-结构相互作用问题,这些传统的方法无法有效预测实际桥梁在地震作用下的动力响应。一些学者在研究中考虑了土-结构相互作用效应,但研究不够系统不够深入,对于浅基桥土-结构相互作用问题做进一步系统的深入的研究是一个紧迫的课题。本文基于宏单元理论,建立了考虑土-结构相互作用的浅基桥简化模型,系统的研究了土-结构相互作用对桥梁地震响应的影响,选取工程实例,进行了考虑土-结构相互作用的桥梁地震响应参数分析,主要完成了以下工作:(1)使用有限元软件RUAUMOKO-3D分别建立了不考虑土-结构相互作用的固定基础模型、考虑线性土-结构相互作用以及考虑非线性土-结构相互作用的桥梁简化模型,通过与其他建模方法以及文献算例对比,验证了模型的正确性。(2)分别对比线性土-结构相互作用模型和固定基础模型、非线性土-结构相互作用模型和固定基础模型的地震响应,分析了土-结构相互作用对桥梁地震响应的影响。结果表明考虑线性土-结构相互作用的浅基础的系统摇摆响应和考虑非线性土-结构相互作用的浅基础的摇摆分离响应以及土的滞回特性极大的耗散了地震能量,考虑土-结构相互作用的影响是为了更准确的分析上部结构的地震反应,但也应同时注意到结构位移响应的增大以及残余位移的产生衍生出其他的一些需要解决的课题。此外,通过对比线性土-结构相互作用模型与非线性土-结构相互作用模型地震响应结果,分析不同的土-结构相互作用类型对桥梁地震响应分析结果带来的影响。(3)基于宏单元法,分别建立考虑线性土-结构相互作用以及非线性土-结构相互作用的桥梁简化模型,改变场地土的剪切波速、基础宽度、土壤粘聚力等参数,分别使用这两类模型研究了不同结构参数、土参数的改变对桥梁地震响应的影响。分析表明,较大剪切波速和较大的基础宽度有利于减小桥梁地震响应。但增加基础宽度对桥墩承载能力提出了更高要求,在桥梁抗震设计时,要综合考虑墩顶位移限值要求和墩底承载能力这两方面因素。需要特别注意的是,当考虑线性土-结构相互作用时,土壤粘聚力对桥梁结构响应无任何影响,但当考虑非线性土-结构相互作用时,随着土壤粘聚力的增大,结构位移响应减小,加速度响应增大,当土壤粘聚力小于一定值时结构倾覆。
[Abstract]:Most of the shallow foundation bridges built according to the current seismic design code have not carried out seismic checking calculation, or at most regard such bridges as cantilever structures fixed on rigid foundation at the bottom of piers without considering the soil-structure interaction problem under earthquake action. These traditional methods can not effectively predict the dynamic response of actual bridges under earthquake action. Some scholars have considered the soil-structure interaction effect in the research, but the research is not systematic enough, so it is an urgent task to do further systematic research on soil-structure interaction of shallow foundation bridge. Based on macro element theory, a simplified model of shallow foundation bridge considering soil-structure interaction is established in this paper. The influence of soil-structure interaction on bridge seismic response is systematically studied. The seismic response parameter analysis of bridge considering soil-structure interaction is carried out. The main work is as follows: (1) the fixed foundation model without considering soil-structure interaction is established by using finite element software RUAUMOKO-3D. The simplified model of bridge considering linear soil-structure interaction and nonlinear soil-structure interaction is compared with other modeling methods and reference examples. The validity of the model is verified. (2) the seismic responses of linear soil-structure interaction model and fixed foundation model, nonlinear soil-structure interaction model and fixed foundation model are compared, respectively. The influence of soil-structure interaction on bridge seismic response is analyzed. The results show that the rocking response of shallow foundation considering linear soil-structure interaction and the rocking separation response of shallow foundation considering nonlinear soil-structure interaction and hysteretic characteristic of soil dissipate seismic energy greatly. The influence of soil-structure interaction is considered in order to analyze the seismic response of superstructure more accurately, but we should also pay attention to the increase of structural displacement response and the generation of residual displacement and derive some other problems that need to be solved. In addition, the seismic responses of the linear soil-structure interaction model and the nonlinear soil-structure interaction model are compared. The influence of different soil-structure interaction types on the seismic response of bridges is analyzed. (3) based on the macro element method, A simplified bridge model considering linear soil-structure interaction and nonlinear soil-structure interaction is established to change the shear wave velocity, foundation width and soil cohesion. The effects of different structural parameters and soil parameters on the seismic response of bridges are studied by using these two models. The analysis shows that the large shear wave velocity and the large foundation width are favorable to reduce the seismic response of the bridge. However, increasing the width of the foundation puts forward higher requirements for the bearing capacity of the bridge pier. In the seismic design of the bridge, two factors should be considered comprehensively: the limit value of the pier top displacement and the bearing capacity of the pier bottom. It is important to note that when linear soil-structure interaction is considered, soil cohesion has no effect on the bridge structure response, but when nonlinear soil-structure interaction is considered, the soil cohesion increases with the increase of soil cohesion. The displacement response of the structure decreases and the acceleration response increases. When the cohesive force of the soil is less than a certain value, the structure overturns.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U442.55
本文编号：2302153
[Abstract]:Most of the shallow foundation bridges built according to the current seismic design code have not carried out seismic checking calculation, or at most regard such bridges as cantilever structures fixed on rigid foundation at the bottom of piers without considering the soil-structure interaction problem under earthquake action. These traditional methods can not effectively predict the dynamic response of actual bridges under earthquake action. Some scholars have considered the soil-structure interaction effect in the research, but the research is not systematic enough, so it is an urgent task to do further systematic research on soil-structure interaction of shallow foundation bridge. Based on macro element theory, a simplified model of shallow foundation bridge considering soil-structure interaction is established in this paper. The influence of soil-structure interaction on bridge seismic response is systematically studied. The seismic response parameter analysis of bridge considering soil-structure interaction is carried out. The main work is as follows: (1) the fixed foundation model without considering soil-structure interaction is established by using finite element software RUAUMOKO-3D. The simplified model of bridge considering linear soil-structure interaction and nonlinear soil-structure interaction is compared with other modeling methods and reference examples. The validity of the model is verified. (2) the seismic responses of linear soil-structure interaction model and fixed foundation model, nonlinear soil-structure interaction model and fixed foundation model are compared, respectively. The influence of soil-structure interaction on bridge seismic response is analyzed. The results show that the rocking response of shallow foundation considering linear soil-structure interaction and the rocking separation response of shallow foundation considering nonlinear soil-structure interaction and hysteretic characteristic of soil dissipate seismic energy greatly. The influence of soil-structure interaction is considered in order to analyze the seismic response of superstructure more accurately, but we should also pay attention to the increase of structural displacement response and the generation of residual displacement and derive some other problems that need to be solved. In addition, the seismic responses of the linear soil-structure interaction model and the nonlinear soil-structure interaction model are compared. The influence of different soil-structure interaction types on the seismic response of bridges is analyzed. (3) based on the macro element method, A simplified bridge model considering linear soil-structure interaction and nonlinear soil-structure interaction is established to change the shear wave velocity, foundation width and soil cohesion. The effects of different structural parameters and soil parameters on the seismic response of bridges are studied by using these two models. The analysis shows that the large shear wave velocity and the large foundation width are favorable to reduce the seismic response of the bridge. However, increasing the width of the foundation puts forward higher requirements for the bearing capacity of the bridge pier. In the seismic design of the bridge, two factors should be considered comprehensively: the limit value of the pier top displacement and the bearing capacity of the pier bottom. It is important to note that when linear soil-structure interaction is considered, soil cohesion has no effect on the bridge structure response, but when nonlinear soil-structure interaction is considered, the soil cohesion increases with the increase of soil cohesion. The displacement response of the structure decreases and the acceleration response increases. When the cohesive force of the soil is less than a certain value, the structure overturns.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U442.55
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2 陈兴冲,朱f^;允许提离的弹塑性Winkler地基上桥墩的地震反应[J];工程力学;1999年05期
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