基于疲劳损伤的中、小跨径桥梁限载取值研究

Study on vehicle load limit of medium and small span bridges based on fatigue damage

依托桥址处WIM系统采集的车辆荷载数据,以线路上不同跨径的中、小桥梁为背景展开研究。对车辆数据的车重和轴重等荷载参数进行了统计分析。根据Miner准则和线性累积损伤法,编制了疲劳荷载谱;计算随机车流作用下目标构件的应力时程曲线,得到了应力幅值谱;根据不同跨径桥梁的交通量,得到不同的应力循环次数,计算对应的疲劳寿命并与桥梁的设计使用年限进行了对比;通过试算,不断调整限载取值的大小,求取不同限载取值下桥梁的疲劳寿命。研究结果表明:限载的减小与疲劳寿命的增长呈指数关系;跨径越大,限载对疲劳寿命提升的效果越明显。

The different span of small and medium bridges, which are combined with the vehicle load data collected by WIM system at the bridge site, are studied. Vehicle load parameters such as vehicle weight and axle load are analyzed statistically from vehicle load data, and fatigue load spectrum is compiled according to Miner criterion and linear cumulative damage method. The stress-time history curves of the target component under random traffic flow are calculated to get stress amplitude spectrum.According to traffic volume in different stress cycles of each span bridge, the corresponding fatigue life is calculated and compared with the design life of the bridge. The fatigue life of bridges under different load limits is obtained by adjusting the value of the load limits. The study suggests that the reduction of load limits is exponentially related to the growth of fatigue life. The effect of the load limit on the fatigue life improvement is more obvious with the increase of the span.