基于IDA的渡槽结构地震易损性分析

Seismic Fragility Analysis of Aqueduct Structure Based on IDA Method

渡槽结构是由槽身、槽墩和支座等相互关联的构件组成的结构系统。强震作用下,仅用单一构件的地震易损性来评价渡槽结构系统的地震易损性,往往会高估渡槽的抗震能力。为研究渡槽结构系统的地震易损性,以一座三跨等距简支梁式渡槽为研究对象,基于Open SEES平台建立了有限元动力分析模型,采用增量动力分析法(IDA)计算了槽墩、盖梁处板式橡胶支座以及槽台处聚四氟滑板支座三种构件的横槽向地震易损性;然后,分别通过一阶界限法和二阶界限法,建立了渡槽结构系统地震易损性曲线,并进行了对比分析。结果表明,地震作用下,渡槽结构的板式橡胶支座与聚四氟滑板支座相比槽墩更容易发生损伤;渡槽结构的系统易损性大于单一构件的易损性;二阶界限法所得结构失效概率区间均位于一阶界限法上下界之间,相比一阶界限法,采用二阶界限法建立的系统易损性曲线来评估渡槽结构的抗震性能更为合理。

The aqueduct structure is a structural system composed of the aqueduct body,piers and bearing. Under earthquake action,evaluating the system seismic fragility of the aqueduct structure only by the seismic fragility of a single component will overestimate the seismic capability of the aqueduct. In order to analyze the systematic seismic fragility of aqueduct structure,a three-span equidistance simply supported beam aqueduct was taken as the research object and a finite element dynamic analysis model has been established based on OpenSEES platform. The transverse seismic fragility of pier,plate rubber bearing at cover beam and PTFE slide bearing at abutment has been calculated by incremental dynamic analysis( IDA). Then,the seismic fragility curves of aqueduct structure system are established by the first-order and second-order boundary methods respectively,and are compared and analyzed. The results show that the rubber plate bearing and PTFE slide bearing of aqueduct structure are more likely to be damaged than the pier under earthquake action. The system fragility of aqueduct structure is greater than that of single component. The structural failure probability intervals obtained by the second-order boundary method are between the upper and lower bounds of the first-order boundary method. Compared with the first-order boundary method,the system fragility curve established by the second-order boundary method is more reasonable to evaluate the seismic performance of aqueduct structures.