单向张弦梁结构的地震易损性研究

发布时间：2018-03-27 16:51

本文选题：易损性　切入点：张弦梁　出处：《东南大学》2016年硕士论文

【摘要】：张弦梁结构是一种具有良好应用前景的大跨度空间结构,虽然具有良好的抗震性能,但地震作用尤其是大地震作用对其仍具有很大的危害性,因此对张弦梁结构进行抗震研究是非常必要的。传统的抗震分析没有充分考虑地震动的随机性和结构参数的不确定性的影响,难以对结构的抗震性能进行全面准确的判定,而地震易损性分析可以综合考虑各种随机或不确定因素,从概率的角度研究结构在不同强度地震作用下发生破坏的概率。截止目前为止,以张弦梁结构为研究对象的地震易损性分析还很少,规范中也未列出关于结构各破坏状态的指标界限值。基于此,本文对单向张弦梁结构进行易损性研究,通过分析单向张弦梁结构在不同地震动强度下的破坏概率,为该类结构的灾害风险评估、损失预测提供依据,以利于设计师们更好的把握该类结构的抗震性能。本文首先对单向张弦梁结构的力学性能进行了分析,提出了预应力取值的设计建议值,探讨了运用SAP2000程序对张弦梁结构进行建模的方法,并对其在不同地震波下的地震响应差异进行了分析对比。然后以三个不同索梁刚度比的单向张弦梁结构为研究对象(基本模型、强梁模型、强索模型),考虑结构参数和地震动参数的随机性,利用蒙特卡洛抽样法,为三个模型分别生成100组“结构一地震动”样本,以跨中最大挠度作为地震需求参数,以地震峰值加速度(PGA)为地震动强度参数,对三个模型的各100个样本分别进行时程分析,对结构的地震响应进行回归分析,以完成概率地震需求分析。其次,本文针对单向张弦梁结构,以跨中挠度作为评估指标,提出了不同破坏状态的界定方法,据此对上述三个模型的各100个样本,采用竖向静力弹塑性分析(Push-down分析)方法,进行概率抗震能力分析,分别得到三个模型各级破坏状态的挠度界限值的平均值。最后,本文通过大量的计算分析,计算出不同强度地震动作用下结构的破坏概率,得到了三个张弦梁结构的地震易损性曲线,通过易损性曲线的分析比较,验证了单向张弦梁结构良好的抗震能力,并提出了相应的设计建议：在低强度地震动作用下加强索的刚度更利于提高结构的安全性能,而在高强度地震作用下,加强上弦梁的刚度能更好的降低破坏概率。
[Abstract]:Beam string structure is a kind of large span space structure with good application prospect. Although it has good seismic performance, earthquake action, especially large earthquake action, still has great harm to it. Therefore, it is very necessary to study the seismic behavior of beam string structure. The traditional seismic analysis does not fully consider the randomness of ground motion and the uncertain influence of structural parameters, so it is difficult to judge the seismic performance of the structure comprehensively and accurately. But the seismic vulnerability analysis can consider all kinds of random or uncertain factors synthetically, and study the probability of structure failure under the action of different intensity earthquake from the angle of probability. So far, The seismic vulnerability analysis of beam string structure is rare, and the limit value of each failure state of the structure is not listed in the code. Based on this, the vulnerability of unidirectional beam string structure is studied in this paper. Through analyzing the failure probability of unidirectional beam string structure under different ground motion intensity, it provides the basis for the disaster risk assessment and loss prediction of this kind of structure. In order to help designers to better grasp the seismic performance of this kind of structure. Firstly, the mechanical performance of unidirectional beam string structure is analyzed, and the design suggestion value of prestressing force is put forward. The modeling method of beam string structure with SAP2000 program is discussed. The difference of seismic response under different seismic waves is analyzed and compared, and then three unidirectional beam string structures with different stiffness ratio of cable and beam are taken as the research object (basic model, strong beam model, and so on). Considering the randomness of structural parameters and ground motion parameters, the strong cable model, using Monte Carlo sampling method, generates 100 groups of "structure-ground motion" samples for each of the three models, taking the maximum mid-span deflection as the seismic requirement parameter. Taking the peak acceleration of earthquake (PGA) as the seismic intensity parameter, 100 samples of each of the three models are analyzed by time history analysis, and the seismic response of the structure is regressed to complete the probabilistic seismic demand analysis. In this paper, aiming at the unidirectional beam string structure, taking the mid-span deflection as the evaluation index, a method of defining different failure states is proposed. According to this method, the vertical static elastic-plastic analysis (Push-down analysis) method is used for 100 samples of each of the above three models. Through the probabilistic seismic capacity analysis, the average values of the deflection limit values of the three models at different failure states are obtained. Finally, the failure probability of the structure under the action of different strength ground motion is calculated by a lot of calculation and analysis. The seismic vulnerability curves of three beam string structures are obtained. Through the analysis and comparison of the vulnerability curves, the good seismic capacity of the unidirectional beam string structures is verified. The corresponding design suggestions are put forward: strengthening the stiffness of the cable under the action of low strength ground motion is more conducive to improving the safety performance of the structure, while strengthening the stiffness of the upper chord beam under the action of high intensity earthquake can better reduce the failure probability.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU399

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