钢悬臂组合桥面板加宽改造箱梁方案研究

Study of Using Steel Cantilever Composite Bridge Deck Plate to Widen Box Girder

为实现对既有箱梁最大限度的保留利用,以某高速公路互通立交匝道桥为背景,对钢悬臂组合桥面板加宽改造箱梁的方案进行研究。该方案通过在原箱梁两侧安装空腹式钢悬臂和钢混组合桥面板的方法,在实现拓宽目标的同时,对原桥的箱梁进行了最大限度的保留利用,并在不设置横向预应力的条件下实现最大悬臂2.875m。通过有限元参数分析确定了该桥钢悬臂的合理布置间距为2m,钢悬臂与混凝土箱梁连接面上锚栓设计时应考虑内力分布不均匀情况。同时,验证了采用带纵肋钢板作为桥面板底模是可行的,但应重视混凝土收缩徐变对组合桥面板的内力重分布的影响。

To maintain and use the existing box girder to the greatest possible extent, an interchange ramp bridge on a highway was taken as the study background.The scheme of using steel cantilever composite bridge deck plate to widen and improve the box girder was studied, in which open-web steel cantilevers and steel-concrete composite bridge deck plates are added to the two sides of the existing box girder.Alongside the realization of the widening targets of the bridge, the scheme kept and made use of the existing box girder to the maximum and achieved the goal of the maximum cantilever length of 2.875 m, without adding transverse prestressing.The rational installation spacing of 2 m for the steel cantilevers was determined by the finite element parametric analysis.In the design of the anchor bolts on the connecting surface of the steel cantilevers and the concrete box girders, the case of uneven internal force distribution should be considered.Meanwhile, the finite element analysis verifies the feasibility of using the steel plates with longitudinal ribs as the bottom formwork of the bridge deck.However, the influences of concrete shrinkage and creep on the internal force redistribution of composite plates should be given enough concern.