钢箱梁用于公、铁桥梁时正交异性板疲劳敏感部位应力比较

Comparison of Stresses of Fatigue-sensitive Regions in Orthotropic Deck of Steel Box Girder for Highway and Railway Bridges

宁波甬江铁路斜拉桥在设计中采用钢箱梁方案,在铁路桥中为国内首例。铁路桥梁钢轨横向位置固定,桥面铺装也与公路桥梁不同,为研究钢箱梁正交异性板用于铁路桥梁和公路桥梁的区别,在桥面板上分别设置铁路与公路铺装,通过有限元计算,得出设置不同铺装时疲劳敏感部位应力的横向影响线、纵向影响线,研究各部位应力的产生原因,分析钢箱梁正交异性板用于铁路桥梁和公路桥梁的各自特点;选择具有代表性的铁路车辆与公路车辆对钢箱梁正交异性板进行加载,计算各种车辆作用下疲劳敏感部位的应力情况。分析及计算结果表明:公路沥青混凝土铺装对荷载的分散作用有限,铁路铺装对荷载的分散作用较强,与公路桥梁相比,铁路桥梁各疲劳敏感部位应力影响线量值较小,影响线长度较大;在常规铁路车辆作用下,正交异性板在加劲肋与横隔板连接部位及横隔板开口边缘的最不利应力与常规公路车辆作用下的量值相当;与铁路桥梁相比,公路桥梁正交异性板更易在加劲肋与顶板连接处发生疲劳开裂。

The scheme of steel box girder used in the design of Yongjiang Railway Cable-stayed Bridge of Ningbo city is the first case in railway bridges in China.For railway bridges,the transverse position of steel rails is stable,and bridge deck pavement is different from that of highway bridges.In order to study the difference of orthotropic deck used in railway bridge and highway bridge,railway bridge and highway bridge deck pavements were installed on the deck separately.With the finite element method,the transverse and longitudinal influence lines of the stresses in the fatigue-sensitive regions with different bridge deck pavements were calculated.The reason why the stress in each fatigue-sensitive region was studied,and the characteristics of steel box girder orthotropic deck for railway bridge and highway bridge were analyzed.With the representative railway and highway vehicles as the loads,the stresses of steel box girder orthotropic deck in some fatigue-sensitive regions were calculated.The results of analysis and calculation show that（1） The dispersion of asphalt concrete deck pavement for highway bridge is weak,while that of railway bridge deck pavement is strong.Compared with highway bridge,the values of influence lines of the stresses in the fatigue-sensitive regions are smaller,and the lengths of influence lines are longer for railway bridge.（2） Under the load of normal railway vehicle,the largest stresses of rib-to-diaphragm joint and edge of cutout in diaphragm are similar to that under the load of normal highway vehicle.（3） In comparison with railway bridge,fatigue cracks are likely to emerge at the rib-to-deck joint for highway bridge orthotropic deck.