既有公路桥梁抗震性能快速评价方法

Rapid evaluation of seismic performance for existing highway bridges

为了保证既有桥梁地震安全,在广泛参考前人研究经验并借鉴我国公路桥梁抗震相关规范的基础上,提出了一套系统性的既有公路桥梁抗震性能快速评价方法。该方法适用于良好场地上跨径不超过150 m且不含高墩的梁式桥,其内容主要包括落梁风险评价、桥墩细部构造评价以及桥墩延性性能评价三个方面。对于抗震设防不满足现行区划图要求或满足要求但按“89规范”设计或未考虑抗震设计的桥梁,对其桥墩进行E1地震作用下强度要求和E2地震作用下变形能力的补充验算。继而提出了公路桥梁抗震性能快速评价的系统流程,并完成了“08细则”施行前设计的5座桥梁的示范性研究及应用。结果表明仅1座桥梁存在落梁风险;桥墩的细部构造大多不满足要求,延性低,容易发生弯剪甚至剪切破坏;桥墩在E1地震下的强度基本满足要求,E2地震下则需提升其变形能力。提出的方法能够以尽可能简单的方式在大量(多个线路)的桥梁中科学、快速地识别出地震易损性高的桥梁结构及其抗震薄弱环节,可直接服务于地震高风险区既有公路桥梁抗震加固决策。

In order to ensure the seismic safety of existing bridges,a systematic rapid evaluation method for the seismic performance of existing highway bridges is proposed based on the previous researches and the seismic codes or standards of highway bridges in China.This method is applicable to the girder bridges with span less than 150 m and without high piers on good sites.It mainly includes three aspects:the risk assessments of deck falling,pier details and pier ductility.For the bridges whose seismic fortification does not meet the requirements of the current zoning map or meets the requirements but are designed according to the“89 Specification”or without considering the seismic design,the strength requirements under E1 seismic effect and the deformation capacity under E2 seismic effect for the piers are complementally checked.Then the system process of rapid seismic performance evaluation for highway bridges is proposed,and the demonstration study and application of five bridges built before the implementation of'08 Guidelines'are carried out.The results indicate that only one bridge has the risk of deck falling;most piers have the details do not meet the requirements and have low ductility,which are prone to occurring flexural-shear even shear failure.The strengths of piers under E1 seismic effect basically meet the requirements,while the deformation capacity under E2 seismic effect need to be improved.The proposed method enables the identification of the bridge structures with high seismic fragility and their weakness scientifically and quickly in the simplest way possible,which can serve the decision of seismic strengthening for existing highway bridges in seismic high-risk areas directly.