多维地震下钢筋混凝土双曲线冷却塔结构易损性分析

摘要

采用数值模拟方法,对辽宁鞍山某在役钢筋混凝土冷却塔结构的地震易损性进行了评估.应用ABAQUS软件建立了分析模型;根据结构所在的场地条件选择了一系列合理的地震动记录,以考虑地震动的不确定性.选取了材料应变和地面峰值加速度作为结构地震需求参数和强度参数,并将结构的破坏状态划分为五个等级.分别输入单向、水平双向和三向地震作用,结合增量动力时程分析所得结构响应,基于对数正态分布假设,通过回归分析建立结构的概率地震需求模型,最终得到结构的地震易损性曲线;在此基础上对结构的抗倒塌安全储备进行了评估分析.分析结果表明:水平双向地震作用下冷却塔结构的损伤概率比单向地震作用时显著增加,若仅考虑单向地震作用会与实际产生较大偏差;由安全储备分析可知该结构满足“大震不倒”的要求.%Using a numerical simulation method,the vulnerability of a RC cooling tower located in Liaoning Anshan was evaluated.The FE software ABAQUS was adopted to establish its analysis model.According to field conditions of the place where the structure was located,a series of reasonable ground motion records were selected to consider the uncertainty of earthquake.Material strain and peak ground acceleration (PGA) were taken as the structure seismic demand parameter and earthquake intensity parameter,and then the structure's damage state was divided into five levels.Unidirectional,horizontal-bidirectional and three-directional seismic actions were exerted on the structure,respectively.Based on the incremental dynamic analysis and the lognormal distribution hypothesis,the probabilistic seismic demand model of the structure was established by means of the regression analysis,the structure's seismic vulnerability curves were obtained.Furthermore,the structure's anti-collapse security reserve was assessed.The results showed that the damage probability of the cooling tower structure under horizontal-bidirectional seismic action is much larger than that under unidirectional seismic action;vertical seismic action has little effect on the vulnerability of the cooling tower;the structure meets the requirement of "no collapse under strong earthquake" according to its safety margin analysis.