焊接钢桥腹板出平面变形疲劳问题的有限元分析

焊接钢桥的腹板在交通荷载作用下产生的出平面变形可以导致腹板空隙处的疲劳开裂，为了分析导致腹板空隙处疲劳开裂的位置、形式以及原因，对一座钢桥的一跨建立了三维有限元模型，并采用了子模型方法对腹板空隙处进行了细致的分析，得到腹板空隙处的应力水平和分布规律。通过分析得到焊接钢桥腹板出平面变形导致腹板空隙处的应力十分复杂，造成多个区域的应力集中。在AASHTO疲劳车的作用下，腹板空隙处的最大应力可以达到200MPa，这样就导致在交通荷栽的反复作用下疲劳裂纹的产生，同时对相应的维修加固策略进行了探讨。研究也显示出了有限元方法分析复杂区域的优越性。

Finite Element Analysis of Out-Plane Distortion Induced Fatigue of Welded Steel Bridge Web

One of the main reasons of fatigue cracks on welded steel bridges is caused by out-plane distortion. In order to analyze the reason that cause web gap fatigue cracks and the type and location of cracks, a finite element model of one span of a steel bridge was constructed, and the sub-model was constructed for the web gap region to get the stress value and distributing rule.According to the analysis, the web gap stress induced by the out-plane distortion of the web is very complex, and a lot of stress concentration points appear. Using AASHTO fatigue truck, the maximum stress of web gap can achieve to 200 MPa, so the fatigue cracks occur under the repetitive loads. The maintenance and reinforce methods were also discussed. The advantages of the finite element method were proved.