变曲率竖曲线顶推施工钢箱梁局部受力分析

现今大跨径桥梁的钢箱主梁无应力线形一般为单一半径竖曲线,杭州江东大桥的钢箱梁无应力线形为连续变曲率竖曲线,变曲率特征不仅使得顶推竖曲线的顶推半径变化,也使得滑道处钢箱梁的转角位移变化十分明显。进而对顶推滑道的构造提出了新的要求:滑道顶面线形需能自动适应梁体线形的变化。滑道处钢箱梁的局部受力的安全,关系着顶推施工的成败。运用大型通用有限元软件ANSYS对滑道处钢箱梁局部进行三维有限元分析,对比7种典型工况下钢箱梁各个构件的应力分布情况,指出临时墩支反力和滑道处钢箱梁转角位移是影响钢箱梁局部受力的关键因素。

Local Force Analysis of Steel-Box Girder Bridge with Incremental Launching Construction by Vertical Curve of Variable Curvature

The non-stress alignment of present long-span steel box girder bridges is generally a single radius of vertical curve.The non-stress alignment of steel box girder of Hangzhou Jiangdong Bridge is a continous variablely curved vertical curve.The feature of variable curvature not only changes the incremental launching radius of vertical curve,but also makes the displacement of steel box girder at slide path corner obvious.Therefore,the new requirement to construct the incremental launching slide path is put forward: the alignment of rubber surface should automatically adapt to the changes of grider.The security of steel box girder forcing is essential to the success of the incremental launching.3D finite element analysis on local steel box girder of the slide path is carried out by ANSYS,and stress distributions of various components of steel box girder under seven typical operation conditions are comparied.The analysis draws a conclusion that the counterforce of temporary pier and the corner displacement of the steel box girder on the slide are critical factors to affect the local stress of the steel box girder.