基于OpenSees的群桩体系桥梁连续倒塌分析

发布时间：2018-11-27 14:37

【摘要】：群桩基础是我国桥梁建设中最常用的基础,特别在高桩承台中得到广泛应用,具有沉降量小、施工周期短、适应性等优点,但根据地震灾害调查表明,其在地震作用下往往是结构的易损构件。群桩体系桥梁广泛用于非规则的桥梁结构中,传统设计方法已经不能适应发展迅速的结构性能化设计理论,探讨在强震作用下桩基础的失效模式、失效规律和损伤发展是现行桥梁抗震分析的需要,而桥梁结构在地震作用下的连续倒塌分析是一个非常复杂的问题,多数商用程序在倒塌分析时会遇到数值模拟的困难。本文基于OpenSees平台自编程序模拟群桩基础连续倒塌行为,并建立了杆件的失效准则,对Remove命令实现分析模型更新进行了深入研究,Remove命令能够处理结构的大变形、大转动,实现结构连续倒塌的模拟,解决传统有限元数值求解的困难。论文采用OpenSees中的非线性梁柱单元构建了带附属节点的非线性梁柱单元用于模拟桥梁结构,对附属节点的约束条件采用多点约束的方法处理,采用静力凝聚的方法进行控制,并通过计算验证了该方法的正确性。论文对强震作用下群桩基础的失效模式和处理方法进行了详细的研究,引入弯曲失效准则、剪切和轴向失效准则,对结构分析时进行实时的监控,对失效单元端部的约束情况进行实时的处理而改变结构分析模型。依托某实际工程建立了包含群桩基础的单墩模型,选取一组二类场地地震波进行连续倒塌分析,模拟群桩基础的内力释放和逐步失效过程,并完成在删除破坏杆件和更新模型之后,剩余有限元模型的地震响应分析。论文建立的群桩体系模型在地震作用下进行实时的修改能够真实的反应构件的逐步失效过程和连续倒塌过程。杆件逐步失效过程中的内力释放及其内力重分布将加剧结构的失效,是影响强震作用下群桩基础倒塌机理、倒塌模式与整体结构损伤演化规律的主要因素。
[Abstract]:Pile group foundation is the most commonly used foundation in bridge construction in China, especially widely used in high pile cap. It has the advantages of small settlement, short construction period, adaptability and so on. It is often a vulnerable member of a structure under earthquake action. Bridges with pile group system are widely used in irregular bridge structures. The traditional design method can no longer adapt to the rapidly developing performance-based design theory of structures. The failure mode of pile foundation under strong earthquake is discussed. Failure law and damage development are the needs of seismic analysis of bridges, and continuous collapse analysis of bridge structures under earthquake is a very complex problem, most commercial programs will encounter difficulties in numerical simulation in collapse analysis. In this paper, the continuous collapse behavior of pile group foundation is simulated on the basis of OpenSees platform, and the failure criterion of the members is established. The updating of the analytical model of the Remove command is deeply studied. The Remove command can deal with the large deformation and rotation of the structure. The simulation of continuous collapse of structures is realized, and the difficulty of traditional finite element numerical solution is solved. In this paper, nonlinear Liang Zhu element with attached nodes is used to simulate the bridge structure by using the nonlinear Liang Zhu element in OpenSees. The constraint condition of the attached node is treated by multi-point constraint method, and the static cohesion method is used to control the constraint condition. The correctness of the method is verified by calculation. In this paper, the failure modes and treatment methods of pile group foundation under strong earthquake are studied in detail. The bending failure criterion, shear failure criterion and axial failure criterion are introduced to monitor the structure analysis in real time. The structural analysis model is changed by real time processing of the end constraint of the failure unit. Based on a practical project, a single pier model including pile group foundation is established, and a group of second class site seismic waves are selected for continuous collapse analysis to simulate the release of internal force and the gradual failure process of pile group foundation. The seismic response of the residual finite element model is analyzed after deleting the damaged member and updating the model. The model of pile group system established in this paper can be modified in real time under the action of earthquake, which can be used in the process of step by step failure and continuous collapse of response components. The release of internal force and the redistribution of internal force during the gradual failure of members will aggravate the failure of the structure, which is the main factor that affects the collapse mechanism, collapse mode and damage evolution law of pile group foundation under strong earthquake.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.55

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