考虑两次地震作用的RC框架结构地震反应分析研究

发布时间：2018-03-14 18:06

本文选题：地震动序列　切入点：RC框架结构　出处：《中国地震局工程力学研究所》2017年博士论文　论文类型：学位论文

【摘要】：大量地震表明,地震过程中仅发生单次地震的情况较少,即孤立型地震发生的概率较低,一般为11%。强震的发生通常伴随多次余震,且大部分余震与主震时间间隔较短,受损结构在未进行加固的情况下再次遭受地震作用,致使结构发生更为严重的破坏,甚至倒塌。目前国内外抗震规范的设计方法仅考虑了单次地震作用,即只考虑主震影响。因此,探讨合适的途径考虑多次地震作用对结构的影响具有重要理论意义和工程价值。本文收集了国内外广泛用于结构地震反应分析的地震动记录,以典型RC框架结构为例,研究了两次地震作用下结构的抗震分析方法;探讨了两次地震作用时设计PGA调整系数的确定方法;当设防烈度、场地条件以及输入地震动特征不同时,分析了单次与两次地震作用下结构损伤状态的差别,确定了设计PGA的调整系数。主要内容包括以下几部分:1.选取了损伤指标及强度折减系数模型。从加速度时程、反应谱、傅立叶谱及对结构的损伤四个方面分析了两次地震与单次地震的联系和区别;通过分析不同损伤指标的适用情况,确定了损伤指标;通过对三种强度折减系数模型的比较,选取了 Vidic模型。2.提出了考虑两次地震作用的抗震分析方法。以典型结构为例,比较了目前用于单次地震作用结构抗震分析的常用方法。在分析各类方法的优点和不足的基础上,给出了结合动力时程分析、静力往复加载分析与Pushover分析的考虑两次地震作用的结构抗震分析方法;并以3层典型RC框架为例,验证了方法的可行性。3.基于损伤相等的原理,提出了考虑两次地震作用的设计加速度峰值的调整系数的确定方法。通过选取、构造序列型地震动,对某3层典型RC框架结构进行了 600次单一地震和3600次连续两次地震的动力弹塑性时程分析,统计了结构整体损伤指数特征,定义了整体损伤指数(DI)的放大系数和PGA的等效调整系数两个参数,给出了考虑两次地震作用时的结构设计加速度峰值的调整系数建议值。4.建立了考虑两次地震作用时DI的放大系数和PGA的等效调整系数的经验公式。对不同典型RC框架结构进行了动力弹塑性时程分析,并统计了结构整体损伤指数特征,得到了放大系数、等效调整系数与结构自振周期之间成正比的结论。5.研究了设防烈度、场地条件和输入地震动对放大系数和等效调整系数的影响。通过研究4层RC框架结构在设防烈度、场地条件和输入地震动等因素影响下的动力时程分析,根据整体损伤指数统计分析,得到放大系数和等效调整系数与设防烈度成正比,与输入地震动场地Vs30均值成反比的结论,给出了输入地震动对放大系数和等效调整系数的影响的建议值。
[Abstract]:A large number of earthquakes show that there are few single earthquakes in the process of earthquakes, that is, the probability of isolated earthquakes is relatively low, which is generally 11.The occurrence of strong earthquakes is usually accompanied by multiple aftershocks, and the time between most aftershocks and the main shock is relatively short. The damaged structure is subjected to earthquake action again without reinforcement, which results in more serious damage or even collapse of the structure. At present, the design methods of seismic code at home and abroad only consider the action of single earthquake. Therefore, it is of great theoretical significance and engineering value to explore a suitable way to consider the influence of multiple earthquakes on the structure. In this paper, the records of ground motion which are widely used in structural seismic response analysis at home and abroad are collected. Taking the typical RC frame structure as an example, the seismic analysis method of the structure under two earthquakes is studied, and the method of determining the PGA adjustment coefficient of the design under the action of two earthquakes is discussed, when the intensity of fortification, site conditions and the characteristics of the input ground motion are different, The difference of structural damage state between single earthquake and two earthquakes is analyzed, and the adjustment coefficient of design PGA is determined. The main contents include the following parts: 1. The damage index and strength reduction coefficient model are selected. From the acceleration time history, the response spectrum, The relation and difference between the two earthquakes and the single earthquake are analyzed in four aspects of Fourier spectrum and damage to the structure, the damage index is determined by analyzing the application of different damage indexes, and the comparison of the three models of strength reduction coefficient is made. The Vidic model. 2. A seismic analysis method considering the action of two earthquakes is proposed. Taking typical structures as an example, The methods commonly used in seismic analysis of single seismic structures are compared. On the basis of analyzing the advantages and disadvantages of various methods, the combined dynamic time-history analysis is given. Static reciprocating load analysis and Pushover analysis are applied to seismic analysis of structures considering the effects of two earthquakes, and the feasibility of the method is verified by taking a typical three-story RC frame as an example. 3. Based on the principle of equal damage, A method for determining the adjustment coefficient of the peak value of design acceleration considering the action of two earthquakes is presented. Dynamic elastic-plastic time history analysis of a typical RC frame structure with three layers is carried out for 600 single earthquakes and 3600 successive earthquakes, and the damage index characteristics of the whole structure are calculated. The magnification factor of the whole damage index and the equivalent adjustment coefficient of PGA are defined. The suggested value of adjustment coefficient for the peak acceleration of structural design considering two earthquakes is given. The empirical formulas of the magnification factor of DI and the equivalent adjustment coefficient of PGA when considering the action of two earthquakes are established, and the empirical formulas for different typical RC are established. The dynamic elastic-plastic time history analysis of frame structure is carried out. At the same time, the damage index characteristics of the whole structure are calculated, and the magnification factor, the equivalent adjustment factor and the natural vibration period of the structure are obtained. 5. The fortification intensity is studied. The influence of site condition and input ground motion on magnification factor and equivalent adjustment coefficient is studied. The dynamic time history analysis of four-story RC frame structure under the influence of fortification intensity, site condition and input ground motion is studied. According to the statistical analysis of the whole damage index, it is concluded that the magnification factor and the equivalent adjustment coefficient are directly proportional to the fortification intensity and inversely proportional to the Vs30 mean value of the input ground motion. The effect of input ground motion on magnification factor and equivalent adjustment factor is given.
【学位授予单位】：中国地震局工程力学研究所
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU375.4

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