随机车流作用下悬索桥钢桥面板疲劳损伤与寿命评估

Fatigue damage and life assessment for steel decks of suspension bridge under stochastic traffic flow

为了评估大跨度悬索桥钢桥面板在车流荷载作用下疲劳安全性,在实测车流数据的基础上,采用有限元数值模拟方法对某主跨为820 m的悬索桥钢箱梁顶板-U型肋构造细的疲劳损伤及寿命进行研究。通过对动态称重(WIM)实测车流数据的统计分析建立随机车流模型,基于应力-寿命(S-N)曲线和线性累积损伤准则分析运营状态和交通量增长对悬索桥钢桥面板构造细节疲劳损伤及寿命的影响。研究结果表明:随着密集运行车辆占有率的增加,疲劳损伤呈较缓增长趋势;随着交通量系数的增长,疲劳损伤呈加速增长趋势。与密集运行车辆占有率相比,交通量增长系数对疲劳损伤有较大的影响。在交通量增长系数达到6%时,钢桥面板细节疲劳寿命小于设计基准期,基于实测车流数据的疲劳性能评估对确保钢桥面板在运营期的安全性尤为重要。

In order to assess fatigue safety of steel decks of long-span suspension bridges, the fatigue damage and life for steel decks of a suspension bridge with 820 m mid-span were investigated based on finite element analysis （FEA） and test traffic data. The random traffic flow was established based on test data on the basis of weigh-in-motion （WIM） system. Parameters were analyzed for influence of vehicle operating states and increment of traffic on fatigue damage and life for steel deck details of the suspension bridge, based on stress-life （S-N） curves and linear cumulative rule. The results show that the fatigue damage increases slowly with the increase of occupancy of heavy traffic flow. The fatigue damage increases rapidly with the growth of traffic volume. Traffic increment has a considerable effect on structural fatigue damage than the occupancy of heavy traffic flow. When the traffic increment reaches 6%, fatigue life of steel deck details will be lower than the design life. Fatigue property assessment ultilizing actual traffic data are especially important for ensuring safety of steel decks during service life.