基于AMD的地震动强度指标与框架结构非线性响应的相关性分析

发布时间：2018-02-09 20:43

本文关键词： 解析模式分解特征峰值框架结构非线性响应相关性分析　出处：《重庆大学》2016年硕士论文　论文类型：学位论文

【摘要】：地震动输入的合理选择一直是制约时程分析法广泛应用的一大瓶颈,经过多年发展,虽然在选波方面已有一些较为合理的控制指标和选择方法,然而依然可能出现离散的计算结果。各国学者对于地震动参数的选择也并未达成共识,因此研究表征地震动特性对结构响应影响大小的地震动强度指标具有重大实际意义。解析模式分解(AMD)理论是新近提出的一种时频分析手段,能够灵活方便地分离出信号的高频和低频成分且效果极佳。本文首次将解析模式分解理论运用于地震动特性指标的研究中,用其分离出地震动中对结构非线性响应起控制作用的分量并构建地震动强度指标,通过与框架结构非线性响应的相关性分析验证了其能准确反映地震动对结构非线性响应影响的大小。具体进行了如下几方面的工作:(1)依据一定原则选择2组共60条地震动记录,并按规范要求设计设防烈度为8度和9度罕遇地震下的4榀框架结构,建立其OpenSees模型,以所选地震动记录为输入计算结构的非线性响应。(2)运用AMD算法提取上述地震动在结构基本频率以下的低频成分S1,作用于对应的框架结构计算其非线性响应,并与原地震动作用下的结果进行对比分析可知,对于基本周期较短以第一振型为主的结构,对结构响应起控制作用的地震动分量为结构基频以下的低频分量。(3)以结构基频以下地震动低频成分为主,对高频成分以结构振型参与系数之比作为权重系数得到考虑部分高频成分的低频波S作为对S1的改进,将S作用于结构所得响应与原地震动作用下结果对比可知,对于受高阶振型影响较大的结构,S是控制其地震响应的分量。(4)取S1、S的最大峰值分别为特征峰值一、二,通过二者与4榀框架结构最大非线性响应之间在发生时间和数值上的相关性分析,发现二者均与结构最大非线性响应在发生时间上对应一致,数值上的线性正相关性很强,且特征峰值二的效果优于特征峰值一。(5)另选30条地震波作用于4榀框架结构,所得结果与上述结论均一致。可见,本文所提特征峰值一、二均可以在一定程度上表征地震动对框架结构非线性响应影响的大小,可作为合理选择地震动输入时的参考强度指标,且相比而言,特征峰值二效果更好。
[Abstract]:The reasonable selection of ground motion input has been a bottleneck restricting the wide application of time-history analysis. After years of development, although there have been some reasonable control indicators and methods in wave selection, However, there may still be discrete results. There is no consensus among scholars about the choice of seismic parameters. Therefore, it is of great practical significance to study the intensity index of ground motion, which is characterized by the characteristics of ground motion. The analytical mode decomposition (AMDD) theory is a newly proposed time-frequency analysis method. The high frequency and low frequency components of the signal can be separated flexibly and conveniently, and the results are very good. In this paper, the analytical mode decomposition theory is first applied to the study of the characteristics of the ground motion. It is used to separate out the components of the ground motion that control the nonlinear response of the structure and to construct the intensity index of the ground motion. Through the correlation analysis with the nonlinear response of the frame structure, it is proved that it can accurately reflect the magnitude of the influence of ground motion on the nonlinear response of the structure. The following work is done in detail: 1) two groups of 60 ground motion records are selected according to certain principles. According to the specifications, four frame structures with fortification intensity of 8 degrees and 9 degrees of rare earthquakes are designed, and their OpenSees models are established. Taking the selected ground motion record as the input to calculate the nonlinear response of the structure, the AMD algorithm is used to extract the low-frequency component S _ 1 of the ground motion below the basic frequency of the structure, acting on the corresponding frame structure to calculate its nonlinear response. Compared with the results under the action of in-situ vibration, it can be seen that for the structure with short basic period, the first mode is the main one. The ground motion component which controls the response of the structure is the low frequency component below the basic frequency of the structure, and the low frequency component of the ground motion below the basic frequency of the structure is the main one. For the high frequency component, the ratio of the structural mode participation coefficient as the weight coefficient is taken as the weight coefficient. The low frequency wave S with part of the high frequency component is considered as the improvement of S1. The comparison of the response of S to the response of the structure under the action of in-situ vibration can be seen. For structures which are greatly affected by high-order modes, S is the component that controls its seismic response, and the maximum peak value of S _ 1N _ S is taken as characteristic peak value one and two, respectively. Through the analysis of the correlation between them and the maximum nonlinear response of four frame structures, it is found that both of them are consistent with the maximum nonlinear response of the structure in the occurrence time, and the numerical linear positive correlation is very strong. And the effect of characteristic peak value 2 is better than that of feature peak value. 5) 30 seismic waves are selected to act on 4 frame structures, and the results are consistent with the above conclusions. It can be seen that the characteristic peak value in this paper is 1. Both of them can represent the magnitude of the influence of ground motion on the nonlinear response of frame structure to some extent and can be used as a reference strength index for reasonably selecting the input of ground motion and the characteristic peak value is better than the other.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TU311.3

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