中文摘要：

在桥梁耦合抖振谱分析的基础上，采用谐波合成技术，依据Monte Carlo思想大量模拟位移谱时程，由此便可以方便、快捷地计算桥梁抖振响应首次超越失效概率，克服传统Monte Carlo方法时域内再现桥梁抖振首次超越小失效概率事件效率偏低的问题。采用江阴长江大桥和上海杨浦大桥作为算例，比较了抖振首次超越响应谱Monte Carlo模拟结果与目前广泛使用的基于Poisson、Poisson包络、Markov过程三种假定的近似解析算法结果差异，表明由于考虑大气紊流环境下桥梁抖振背景分量，在较高阈值情况下，近似解析算法不再适用，而本文方法具有更高的精度。

英文摘要：

Buffeting response spectrum of long-span bridges is calculated by coupled spectrum analysis in the frequency domain, and the time history of structural responses induced by buffeting is simulated by trigonometric sery composition approach. While a large amount of samples about buffeting time history are generated with Monte Carlo simulation technique, it is relatively easier to numerically solve the probability of first passage failure of long-span bridges. Two numerical examples referring to buffeting deflections of the Jiangyin Suspension Bridge and the Shanghai Yangpu Cable-stayed Bridge have been considered. The numerical results are also compared with those obtained from three semi-analytical approaches, namely Poisson process, Poisson envelope process and Markov process. The results show that by considering the background component of the atmosphere turbulence, the proposed numerical method is very precise and effective, especially in the case of higher threshold values.