孟加拉帕德玛大桥主桥钢桁梁预拱度设置

Pre-camber Setting of Steel Truss Girder of Main Bridge of Padama Bridge in Bangladesh

孟加拉帕德玛大桥主桥由41孔跨度为150 m钢桁梁组成,由于钢梁为全焊接结构,采用浮吊与桥面吊机配合整孔安装的施工方案,钢桁梁吊装上桥后不具备线形调整的条件。钢梁竖向线形误差要求控制在±20 mm以内,对比国内同类桥梁,线形控制要求高;且支座下摆允许偏离设计位置±10 mm,整孔钢桁梁纵向制造长度控制难度大,通过研究影响预拱度理论计算的因素,以及预拱度的设置方法,为工程的顺利实施提供理论依据。其成果对同类国际工程具有参考意义。

The main bridge of Padama Bridge in Bangladesh is composed of 41-span 150-meter steel truss girder.Due to the steel beam is an all-welded structure,the construction scheme of the whole span installation with the floating crane and the deck crane is adopted.There is no condition for alignment adjustment after the steel truss girder is hoisted on bridge.The vertical alignment error of the steel girder must be controlled within±20 mm.Compared with similar bridges in China,the linear control requirements are high,and the bottom hem of support is allowed to deviate from the design position±10 mm.It is greatly difficult to control the longitudinal manufacture length of the integrated-span steel truss girder.Through the analysis on the factors influencing the pre-camber theoretical calculation and the method of pre-camber setting,the theoretical basis is provided for the smooth implementation of the project.Its achievements have the referring significance for the similar international projects.