典型矮塔斜拉桥地震风险概率评估方法研究

鉴于矮塔斜拉桥受力性能的特殊性，引入增量动力分析（IDA）和拉丁超立方体抽样（LHS）评估该结构在地震激励下发生损伤的风险概率。首先采用LHS考虑桥梁构件材料的随机性，与事先选取的地震波相结合形成桥梁-地震动样本集合；其次在确定桥梁有限元模型主要构件损伤指标的基础上采用基于蒙特卡罗（MC）抽样的IDA进行地震易损性分析和地震风险概率评估。为验证方法的正确性和有效性，对一预应力混凝土独塔双索面矮塔斜拉桥结构模型进行地震风险概率评估，结果表明:该方法既充分考虑了材料和地震输入双重随机性又避免了繁琐的积分过程，同时也提高了工程计算的效率及精度。

Assessment of the seismic risk probability of a typical lower-tower cable-stayed bridge

Due to the particular mechanical properties of lower-tower cable-stayed bridge, incremental dynamic analysis (IDA) and Latin Hypercube Sampling (LHS) method were combined to evaluate the risk probability of damage to bridge structures under earthquake excitation. In this method, the LHS was first introduced to consider the randomness of structural materials, and hence they are combined with pre-selected seismic waves to produce a sample set of ground motion-bridge combination. Then, on the basis of determining the damage index of the key components in the bridge’s finite element model, Monte Carlo (MC) sampling based IDA was used to perform seismic vulnerability analysis and seismic risk probability assessment. The accuracy and effectiveness of the proposed method is illustrated via the evaluation of the seismic risk probability of a prestressed concrete cable-stayed bridge model with a single low tower and double cable planes. Results show that the proposed method not only takes into account the randomness of materials and earthquake excitation, but also avoids the cumbersome integration and improves computational efficiency and accuracy.