跨兰西高速公路特大桥主桥连续梁-钢桁组合结构设计

摘要

跨兰西高速特大桥是兰新第二双线的一座跨度最大的桥梁,为跨越兰西高速公路而设,受线路高程的控制,主桥采用一联(80+168+80)m连续梁-钢桁组合结构,即梁部为单箱双室预应力混凝土连续梁,在中跨156 m范围内设置无竖杆三角加劲钢桁,主要承重结构由预应力混凝土连续梁和加劲钢桁梁组合而成,使结构整体刚度大幅提高,结构徐变变形明显减小,同时大大改善了梁端转角.加劲钢桁对连续梁刚度较弱的部位进行了加强,使整个桥梁结构的竖向刚度分布更加均匀,同时有效降低了桥梁建筑高度.%The super-long bridge crossing Lanzhou - Xining highway is the longest-span bridge on Lanzhou-Urumuqi double track line No. 2. Limited by the height clearance of the line, continuous beam-steel truss composite structure (80+168+80) m was adopled for the main bridge. The beams are pre-stressed concrete continuous beams of single box double cell stiffened with triangular steel trusses within the range of 156 m. The main supporting system consists of pre-stressed concrete continuous beam and steel stiffened-truss. The kind of composite structure can make the bridge more stiff, with the creep deformations and turn-angles at beam-end reduced greatly. Since the steel truss stiffens the weak portion of the pre-stressed concrete continuous beam, the vertical stiffness of the bridge becomes more uniformly distributed,and at the same time height of the bridge structure has been reduced.