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考虑到火车、汽车与风荷载的长期作用以及多荷载的随机性,评估大跨多荷载桥梁的疲劳可靠度是一项富有挑战的任务。该研究基于健康监测系统提出了大跨多荷载悬索桥的疲劳可靠度分析框架,并应用到香港青马大桥。首先,定义了疲劳可靠度的极限状态函数,基于监测数据建立火车、汽车与风荷载的概率模型。基于概率模型和蒙特卡洛模拟方法,利用疲劳关键位置上多荷载的每日随机应力响应,估计每日应力幅m次方之和的概率分布。假设交通保持不变,可确定在给定时段内应力幅m次方之和的概率分布。最终得到桥梁不同疲劳关键位置不同时间点的疲劳失效概率。结果表明,在目前的交通状态下,青马大桥的疲劳健康状况可保持良好。
Taking into account the long-term effects of trains, wind and wind loads and the randomness of multiple loads, assessing the fatigue reliability of long-span, multi-load bridges is a challenging task. Based on the health monitoring system, this study proposed the fatigue reliability analysis framework of long-span multi-load suspension bridge and applied it to Tsing Ma Bridge in Hong Kong. First, the limit state function of fatigue reliability is defined, and the probability model of train, vehicle and wind loads is established based on the monitoring data. Based on the probabilistic model and the Monte Carlo simulation method, the probability distribution of the sum of the mth power of daily stress amplitude was estimated by using the daily random stress response of multiple loads at the critical fatigue location. Assuming traffic remains the same, the probability distribution of the sum of the m-th magnitude of stress in a given time period can be determined. Finally, the probability of fatigue failure at different time points of different fatigue critical locations of the bridge is obtained. The results show that under the current traffic conditions, the fatigue state of health of the Tsing Ma Bridge can be maintained well.