近断层地震动作用下钢筋混凝土桥墩易损性评价

发布时间：2018-10-10 14:29

【摘要】：近断层地震动相比于远场地震动有着较为明显的速度脉冲波段,并且伴有强烈地竖向地震动,导致桥梁结构的严重震害。为了合理评估近断层地震动作用下典型钢筋混凝土桥墩地震易损性,现以一我国常见公路中等跨径钢筋混凝土桥墩为研究对象,基于OpenSees抗震分析软件,考虑材料强度的不确定性,采用拉丁超立方抽样建立了13个钢筋混凝土桥墩模型,随机与从PEER地震数据库中挑选的13条具有明显速度脉冲的近断层地震记录组合成“地震动-桥墩”样本。首先通过推导分析,确定了桥墩在完好、基本完好、轻微破坏、中等损伤和严重损伤状态下的位移延性系数、曲率延性系数和位移转角等损伤参数的取值;然后选取8条远场地震动对桥墩进行非线性时程分析,分别计算小震、中震和大震下桥墩响应,并与近断层地震动计算结果相比较,结果证明近断层地震动下桥墩损伤明显大于远场地震动作用;最后对13个分析样本进行水平和竖向地震动联合作用下的增量动力分析,其中竖向地震动峰值和水平地震动峰值按照等比例增加,建立了墩顶位移延性系数、墩低控制截面曲率延性系数和位移角等参数的易损性曲线,并与远场地震动作用下易损性曲线进行了比较。结果表明:近断层地震动作用下的钢筋混凝土桥墩相比远场地震动的作用下呈现出更为剧烈的地震响应。论文主要包括以下几方面内容:(1)确定了本文所选模型在不同损伤状态下的损伤参数取值;本文选取墩顶水平位移、墩底控制截面曲率和位移角作为描述桥墩在地震动作用下达到完好、基本完好、轻微破坏、中等破坏以及倒塌五种破坏状态的损伤参数,并分别根据公式推导、静力弹塑性推覆分析、相关统计结果,确定了上述三种损伤参数在不同破坏状态的取值。(2)对远场地震动作用和近断层地震动作用下钢筋混凝土桥墩的损伤参数进行了比较;根据增量动力分析方法的特点,分别对选取的近断层地震动记录与远场地震动记录进行峰值调整,对比验证钢筋混凝土桥墩在小震(0.1g)、中震(0.2g)、大震(0.4g)三级抗震设防标准下的参数变化,给出对比分析的结论。(3)建立了近断层地震动作用下钢筋混凝土桥墩的易损性曲线基于理论易损性分析方法的概念,给出了近断层地震动作用下的上述三种损伤参数的易损性曲线,对钢筋混凝土桥墩做易损性评估,为了更好的说明结果,同样给出远场地震动作用下的易损性曲线做对比验证。
[Abstract]:Compared with far field ground motion, near-fault ground motion has obvious velocity pulse band and strong vertical ground motion, which results in serious earthquake damage of bridge structure. In order to reasonably evaluate the seismic vulnerability of typical reinforced concrete pier used in near-fault seismic action, this paper takes the reinforced concrete pier of a common highway in China as the research object, based on the OpenSees seismic analysis software. Considering the uncertainty of material strength, 13 models of reinforced concrete pier are established by Latin hypercube sampling. Random and 13 near-fault seismic records with obvious velocity pulses selected from the PEER seismic database are combined to form a sample of "ground motion and bridge pier". Firstly, the damage parameters such as displacement ductility coefficient, curvature ductility coefficient and displacement angle are determined under the condition of intact, basic intact, slight damage, moderate damage and serious damage. Then eight far-field ground motions are selected to carry out nonlinear time-history analysis of bridge piers, and the pier responses under small, moderate and large earthquakes are calculated, respectively, and compared with the results of near-fault ground earthquake. The results show that the pier damage caused by near-fault earthquake is obviously greater than that of far-field ground motion, and the incremental dynamic analysis of 13 analysis samples under the combined action of horizontal and vertical ground motion is carried out. The peak value of vertical ground motion and the peak value of horizontal ground motion increase according to the equal proportion. The ductility coefficient of pier top displacement, the ductility coefficient of low controlled section curvature of pier and the vulnerable curve of displacement angle are established. It is compared with the vulnerability curve under the action of far-field ground motion. The results show that the reinforced concrete pier used in near-fault seismic action presents a more severe seismic response than that under the action of far-field ground motion. The main contents of this paper are as follows: (1) the damage parameters of the selected model under different damage states are determined, and the horizontal displacement of the pier top is selected in this paper. The curvature and displacement angle of the control section at the bottom of the pier are used to describe the damage parameters of the pier under the action of ground motion, such as intact, basic intact, slight damage, moderate failure and collapse. The values of the above three damage parameters in different failure states are determined by static elastic-plastic nappe analysis and correlation statistical results. (2) the damage parameters of reinforced concrete pier under the action of near-fault earthquake and far field ground motion are compared; According to the characteristics of incremental dynamic analysis method, the peak values of selected near-fault ground motion records and far-field ground motion records are adjusted respectively. The parameter changes of reinforced concrete pier under the seismic fortification standards of small earthquake (0.1g), moderate earthquake (0.2g) and large earthquake (0.4g) are compared and verified. The conclusion of comparative analysis is given. (3) based on the concept of theoretical vulnerability analysis, the vulnerability curve of reinforced concrete pier for near-fault seismic action is established. The vulnerability curves of the above three damage parameters used in near-fault seismic action are given, and the vulnerability of reinforced concrete pier is evaluated. In order to better explain the results, the vulnerability curves under the action of far-field ground motion are also compared and verified.
【学位授予单位】：石家庄铁道大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U442.55;U448.34

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