大跨度公铁两用斜拉桥板桁主梁受力特性研究

Study of Mechanical Characteristics of Plate and Truss Main Girder of Long Span Rail-cum-Road Cable-Stayed Bridge

为研究大跨度公铁两用斜拉桥板桁主梁整体受力性能和铁路桥面系局部受力性能,以(84+196+532+196+84)m平潭海峡公铁两用大桥主桥为背景进行分析。采用ANSYS建立全桥和不同节段长度主梁的三维板桁结构精细化有限元模型,对板桁主梁的整体刚度和桥面板局部刚度进行计算,并对比分析铁路桥面系构件参数(板桁连接方式、桥面板厚度、横梁刚度、纵梁及U肋厚度)对主梁刚度的影响。分析结果表明,板桁主梁中横梁位置处钢轨的竖向线刚度较大,两横梁之间竖向线刚度较小,钢轨的竖向线刚度沿纵向周期性波动。铁路桥面板厚度对桥梁整体扭转刚度影响明显,铁路桥面板局部刚度与横梁、纵梁和U肋密切相关。

To study the global mechanical behavior of the plate and truss mare gtrcler and the local mechanical behavior of the railway floor system of long span rail-cum-road cable-stayed bridge, the main bridge of the Pingtan Strait Rail-cum-Road Bridge with span arrangement （84＋ 196＋532＋196＋84） m was cited as an example and was analyzed. The ANSYS was used to es- tablish the refined three-dimensional plate and truss finite element models for the whole bridge and for the main girder of different segment length, the global stiffness of the plate and truss main girder and the local stiffness of the deck plates were calculated and the influences of the component parameters （the plate and truss connection, deck plate thickness, eross beam stiffness and stringer and U rib thickness） of the railway floor system on the stiffness of the main girder were comparatively analyzed. The results of the analysis demonstrate that the vertical linear stiff- ness of the rails at the middle cross beam of the plate and truss main girder is great, the vertical linear stiffness in between the two cross beams is little and the vertical linear stiffness of the rails cyclically fluctuates along the longitudinal direction. The influences of the railway deck plate thickness on the global torsional stiffness of the bridge are significant and the local stiffness of the deck plate is closely related to the cross beams, stringers and U ribs of the bridge.