大应变FRP加固连续梁桥地震易损性分析

Seismic fragility of continuous girder bridge reinforced with large rupture strain FRP

摘要:

为评估地震作用下大应变纤维增强聚合物(large rupture strain fiber reinforced polymer, LRS FRP)加固桥梁的抗震性能,以一典型三跨连续梁桥为例进行了研究。目前关于LRS FRP约束混凝土往复轴压模型的研究较少,限制了LRS FRP加固桥梁的抗震分析。因此介绍了作者课题组提出的简化LRS FRP约束混凝土往复轴压模型,根据此模型并结合地震易损性分析理论,基于OpenSees平台,采用增量动力分析(incremental dynamic analysis, IDA)方法,对三跨连续梁桥在LRS FRP加固前后的地震易损性进行了分析。结果表明:轻微损伤和中等损伤状态下桥梁墩柱基本处于未受损坏的线弹性阶段,LRS FRP加固对其地震易损性影响不大；严重破坏和完全倒塌状态下,未加固桥梁的损坏超越概率明显大于LRS FRP加固的桥梁。提出的简化LRS FRP约束混凝土往复轴压模型可为LRS FRP加固桥梁的抗震分析提供参考。

Abstract:

To evaluate the seismic performance of large rupture strain fiber reinforced polymer (LRS FRP)-reinforced bridges under earthquake action, this paper takes a typical three-span continuous girder bridge as the analytical model. There are few studies on LRS FRP-confined concrete models under cyclic axial compression, which limits the seismic analysis of LRS FRP-reinforced bridges. Therefore, the simplified LRS FRP-confined concrete model under cyclic axial compression proposed by the authors’ research group was introduced. According to the simplified model, the seismic fragility of the continuous girder bridge before and after LRS FRP strengthening was analyzed based on the seismic fragility analysis theory and incremental dynamic analysis (IDA) method using OpenSees platform. Results show that the bridge columns were mainly in an undamaged linear elastic state under slight damage and moderate damage, and LRS FRP reinforcement had little effect on the seismic fragility. In extensive damage and complete collapse states, the exceedance probability of damage of unreinforced bridge was significantly greater than that of LRS FRP-reinforced bridge. The proposed simplified LRS FRP-confined concrete model can provide reference for seismic analysis of LRS FRP-reinforced bridges.