预应力混凝土连续梁桥合龙方案对比研究

Comparative study on closure schemes of prestressed concrete continuous girder bridges

为研究合龙段施工时不同施工顺序对桥梁成桥线形和受力的影响,得出最优合龙方案。利用MIDAS CIVIL有限元软件建立四种合龙方案的桥梁模型。通过模型计算出不同合龙方案的主梁上下缘应力、主梁弯矩和挠度,将模型计算结果进行对比分析,结果表明:合龙方案对桥梁线形、弯矩和应力均存在较大影响。由一侧向另一侧逐跨合龙时主梁最大弯矩和下缘最大应力在四种方案中最大。三跨同时合龙的施工方案其主梁各控制截面的上缘应力较大。先中跨合龙后边跨合龙的施工顺序造成的竖向挠度最大,其次是由一侧向另一侧逐跨合龙的方案。三跨同时合龙和先边跨后中跨合龙两种方案下主梁线形变化均较小。考虑施工难度和成本时应首选先边跨后中跨的合龙方案。研究成果可为该类型桥梁的合龙设计提供参考。

In order to study the influence of different construction sequence on bridge alignment and stress during closure section construction,the optimal closure scheme is obtained.Bridge models of four closure schemes are established by using MIDAS CIVIL finite element software.The upper and lower edge stress,bending moment and deflection of girders of different closure schemes are calculated by the model,and the results of model calculation are compared and analyzed.The results show that the closure scheme has a great influence on the alignment,bending moment and stress of bridges.The maximum bending moment and the maximum stress at the lower edge of the girder are the largest of the four schemes when closing one side to the other.In the construction scheme of three-span simultaneous closure,the upper edge stress of each control section of the main girder is larger.The vertical deflection caused by the construction sequence of mid-span closure first and then side-span closure is the largest,followed by the one-side-by-side closure scheme.Under the two schemes of three-span simultaneous closure and side-span first followed by mid-span closure,the change of main girder line shape is small.When considering construction difficulty and cost,the joint plan of side span first and then mid span should be preferred.The research results can provide reference for the closure design of this type of bridge.