偏压修正法在斜拉桥荷载横向分布计算中的应用

对于斜拉桥的荷载横向分布计算,当前国内外通用的方法是偏压法加主梁抗扭验算,即索面承担竖向荷载,箱梁承担扭矩,开口截面主梁假定其抗扭刚度为零,不承担扭矩。本文结合斜拉桥受力特点,进一步改进了偏压修正法在斜拉桥上的应用,充分考虑了桥跨结构的横向弯扭耦合效应。本文还应用SAP有限元分析程序对桥例建立空间模型进行了分析,并与偏压修正法和改进后的偏压修正法的计算值进行了对比,证明改进偏压修正法用于斜拉桥计算是完全可行的,并由此得出几点结论。

APPLICATION OF MODIFIED ECCENTRIC -COMPRESSIVE METHOD IN THE TRANSVERSAL DISTRIBUTION OF LOADING OF CABLE-STAYED BRIDGE

The cable-stayed bridge, an indeterminate structure with more degrees of redundancy, consists of towers, cables and girders. Under loading, towers, cables and girders take part in working in cooperation with each other. Currently, the method of loading transversal distribution of cable-stayed bridge is the eccentric-compressive method. It means that cables sustain vertical forces and box girder sustains torsion moment. The torsion stiffness of girder with open cross section is assumed to be zero. So, the girder with open cross section can't sustain torsion. Based on the analysis of cables and girders working cooperation with each other, loading transversal distribution of girder mostly depends on the coupling of bending and torsion. In this paper the application of modified eccentric-compressive method has been discussed and some improvement on it has been also done. At the end of this paper, some results of examples obtained from SAP, a large finite element program, are given. Compared with the values obtained from the modified eccentric-compressive method and the improved method, it can be seen that the improved eccentric-compressive method is suitable for the cable-stayed bridge.