设置U肋内隔板的钢桥面板疲劳性能研究

摘要

为研究U肋内隔板及其参数对正交异性钢桥面板疲劳性能的影响,以某钢桁梁柔性拱铁路桥为背景,针对其钢桥面板制作2个足尺模型(试件1无内隔板,试件2设置内隔板)进行疲劳试验,研究疲劳裂纹的产生情况,采用ANSYS软件建立有限元模型,分析产生裂纹处纵肋腹板的应力分布情况,应用断裂力学方法评估钢桥面板的疲劳寿命,并分析内隔板参数对钢桥面板应力的影响.结果表明:纵肋腹板与横梁帽孔交汇处易发生疲劳裂纹,2个试件均在此处出现疲劳裂纹;设置纵肋内隔板能改善纵肋腹板与横梁帽孔交汇处的应力集中现象,有效提高纵肋腹板和横梁帽孔处的疲劳强度;内隔板厚度对钢桥面板的应力影响不大,适当增加内隔板高度差可减小纵肋腹板处主应力.%To study the influences of the U rib inner diaphragms and their parameters on the fatigue performance of the orthotropic steel bridge deck plate, a railway bridge of the rigid steel truss girder and flexible arch was cited as an example, 2 full-scale models (the specimen 1 of the models had no inner diaphragms while the specimen 2 had) for the deck plate of the bridge were fabricated, the fatigue tests were carried out and the occurrence of the fatigue cracks was studied.The finite element models were also set up, using the software ANSYS and the stress distribution at the longitudinal rib webs where the cracks occurred was analyzed.The fatigue life of the deck plate was assessed, using the fracture mechanics method and the influences of the parameters of the inner diaphragms on the stresses of the deck plate were analyzed.The results demonstrate that at the junctures of the longitudinal rib webs and the cross beam cap holes, the fatigue cracks are prone to occurring and the cracks of the 2 specimens all occur at such junctures.The arrangement of the longitudinal rib inner diaphragms can improve the stress concentration and effectively enhance the fatigue strength at the junctures.The influences of the thickness of the inner diaphragms on the stresses of the deck plate are not great and the appropriate increase of the height differences of the inner diaphragms can reduce the principal stresses at the longitudinal rib webs.