中文摘要：

采用阶段临界强度分枝-约界法对一座斜拉桥模型进行了主要失效模式的搜索，分析了拉索抗力衰减及拉索破断情形下系统主要失效模式和系统可靠度的变化情况．结果表明：未出现断索情形时，结构系统主要失效模式间的相关性很高，但在有拉索破断后，主要失效模式间的相关性出现了明显分组特征；系统可靠度指标随着拉索抗力的衰减而逐渐降低，考虑拉索破断时，外索破断后剩余结构系统可靠度指标降低较多，得到了破断后对剩余结构系统可靠度影响最大的拉索位置，可为斜拉桥结构设计提供参考．

英文摘要：

The is paper employed the stage critical strength-considered branch-bound method to explore the major failure mode of a cable-stayed bridge, and investigated the variations of major failure mode and system reliability in the cases of cable breakage and resistance deterioration. The study indicates that, in the case of without cable breakage, the correlation among the major failure modes of the structure is high, while the correlation appears to clear grouping characteristics in the case of a sudden failure of a cable.The system reliability decreased with the resistance deterioration of the cable. Moreover, the remaining structural system reliability indices decreased remarkably in the ease of the breakage of the outside cable, and the dominant cable that has the greatest impact on the system reliability was captured to guide the fur- ther structural design.