基于增量动力分析方法的独塔斜拉桥地震易损性分析

Seismic Fragility Analysis of Cable-stayed Bridge with Single Pylon Using Incremental Dynamic Analysis Method

斜拉桥是一种多次超静定柔性结构,其动力特性有别于常规桥梁。现行规范针对此类桥梁结构的抗震设计仅给出了基本设计原则。本文以一座混凝土独塔斜拉桥为研究对象,利用有限元软件OpenSees建立了该桥的有限元分析模型,并根据桥梁所处场地条件,从PEER强震数据库中选取16条地震波,基于增量动力分析方法建立了桥墩、主塔及支座的纵桥向地震易损性曲线。采用一阶可靠性方法对斜拉桥进行了整体地震易损性分析,对该桥的抗震性能进行了评估。分析结果表明:在地震作用下,辅助墩、主跨边墩和边跨边墩处支座相比其他构件更易受损,桥梁整体较易发生轻微损伤和中等损伤;斜拉桥整体易损性大于构件易损性;采用整体地震易损性分析结果来评估桥梁整体的抗震性能更加可靠。

The cable-stayed bridge is a kind of multiple hyperstatic and flexible structure.Its dynamic characteristics are different from ordinary bridges. However,current seismic design norms only provide design principles for the seismic design of this kind of bridges.In this paper,a municipal concrete cable-stayed bridge with single pylon was taken as the study object, its elastic-plastic finite element dynamic analysis model was established by using the software of OpenSees platform.According to the site situation of the bridge,16 seismic waves were selected from the PEER strong earthquake database, the seismic fragility curves in longitudinal direction of the piers, the tower and the bearings were established by using incremental dynamic analysis（IDA） method.The global seismic fragility analysis for the bridge was carried out through first-order reliability theory.The anti-seismic performance of the bridge was studied.The results show that the seismic fragility of the auxiliary piers, the side piers of the main span and the bearings at the side piers of side span are relatively higher than other components.Under earthquake action, the whole bridge is prone to suffer slight damage and moderate damage.The global seismic fragility of the bridge is higher than the component fragility.It is more reliable to assess the anti-seismic performance of the bridge by adopting the results of global seismic fragility analysis.