超大跨度斜拉桥的安装构形与无应力构形

Assembled geometry and unstrained geometry of super long span cable-stayed bridges

节段施工桥梁的安装构形与无应力构形是现场施工和工厂预制的重要信息,而工程中对此存在一些误解。论述了安装构形与预制构形的联系与区别。根据力与变形的协调原理,提出求安装构形的大循环迭代法和求无应力构形的单元CR(随转坐标系)位移法。对苏州—南通大桥的计算结果表明:结构整体无应力构形与设计构形相差较大,但由于密索体系斜拉桥的恒载弯矩较小,短线法预制只需考虑单元长度修正,无需考虑梁端角度修正;切线拼装的误差随悬臂拼装急剧放大,完全按无应力控制法进行斜拉桥施工控制需慎重。

Assembled geometry and unstrained geometry of segmental bridge provide important information for fabrication and site construction, but there is some mistake about itin practice. The relation and difference between assembled geometry and unstrained geometry an discussed. Based on the compatibility between force and deformation, an approach to solving asembled geometry by iterating of construction sequence and to solving unstrained geometry by CR displacement was put forward. According to the result of Suzhou-Nantong Bridge, although the difference between unstrained geometry and design geometry is significant, the dead loadmoment of cable-stayed bridges with multi-cable systems is small, unstrained geometry of elenent without considering angle adjustment is permitted, only if shortening is considered. Tangent cantilever erection method is very sensitive to error including unstrained geometry, and the error is magnified rapidly with the increasing of cantilever length, so attention should be paid to the unstressed construction control. 7 figs, 8 refs.