考虑材料劣变与损伤累积的既有混凝土斜拉桥抗震性能分析

目前我国多数混凝土斜拉桥因材料劣变而存在结构抗力退化等问题，且主震-余震序列波会使结构损伤积累而更容易破坏。对于材料劣变与损伤积累的桥梁，目前的研究成果和规范尚不能给出合理的地震分析与安全评估方法。而对斜拉桥抗震研究仅局限在主震层面，而在余震作用下的动力响应特点、结构损伤、破坏全过程以及塑性铰产生机制存在研究不足，有关结构的破坏模式与破坏机理尚不明确。为此，本课题针对混凝土斜拉桥，通过在结构的能力与需求模型中体现材料劣变与损伤积累的影响，寿命期内考虑材料劣变与损伤积累分析结构的抗震性能，探讨结构在主震-余震序列波下的响应特点。主要内容包括：（1）材料劣变对结构抗震性能的影响；（2）余震作用下损伤积累的结构抗震性能分析；（3）余震作用下塑性铰产生机制与主震及余震地震动特性的相关性。研究成果可为斜拉桥的全寿命设计、抗震加固以及地震风险评估等提供理论依据。

Nowadays, structural capacities of many cable-stayed 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, especially a sequence of main-shock and after-shock excitations, which always lead to an accumulation of damage in structure. However, our current literatures and design codes have not supplied a reliable method to carry out seismic analysis and assessment of the bridge considering the damage accumulation and the material deterioration. Earlier researches on seismic analysis for cable-stayed bridges mainly focus on the mianshock. The study about dynamic response, structural damage and plastic hinge mechanism under the action of aftershock is not enough. The structural failure mode and failure mechanism are unclear. Therefore, this project focuses on developing a seismic analysis method and discusses the structural response under the mainshock-aftershock sequence wave for cable-stayed bridge systems considering structural material deterioration and damage accumulation. The works mainly include: 1) The influence of material deterioration on seismic performance of cable-stayed bridge. 2) The structural seismic performance under the action of aftershock considering damage accumulation. 3) The plastic hinge mechanism under the action of aftershock and the correlation of mainshock and aftershock. These achievements will provide theoretical basis and analysis support for the life-cycle design, the seismic strengthening, especially the seismic hazard assessment of the existing bridges.