考虑材料劣变过程的桥梁地震易损性分析

Stochastic Fragility Analysis of Bridges Considering the Material Deterioration

摘要:

目前我国多数桥梁因材料劣变而存在结构能力退化等问题，使其容易在地震中受到损伤。为此，本文建立了一套基于概率和非线性有限元的桥梁结构地震性能演变分析方法，分析了材料劣变过程；且结合人工神经网络（ANN）与蒙特卡罗方法（MC），建立了结构随机能力模型；在能力模型的基础上，通过IDA分析，建立了考虑材料劣变过程的需求模型，从而形成地震易损性曲线；并以一座斜拉桥的主塔为例，利用所建立的方法研究了随着服役年限增加结构易损性的变化规律。研究成果可为桥梁的全寿命设计、既有桥梁的运营以及地震风险评估等提供理论依据。

Abstract:

Nowadays, structural capacities of many bridges in China degrade due to material deterioration and other reasons. It increases the possibility of fracture or even collapse of these bridges under action of earthquake. Therefore, this project focuses on developing a seismic fragility method and proposes a fragility assessment procedure for typical highway bridge systems considering structural material deterioration. In this study, a material deterioration model is developed. And a structural capacity and demand model considering material deterioration using ANN-MC method is developed. Based on the capacity and demand model, fragility curves are formed. Moverever, a case study of the main tower of cable-stayed bridge using the proposed method is provided to illustrate the details and structural vulnerlability. These achievements will provide theoretical basis and analysis support for the life-cycle design, the operation and management, especially the seismic hazard assessment of the existing bridges.