协作桥合理成桥状态确定方法研究

Research on Method for Determining Reasonable Completion State of a Combined Cable-stayed and Suspension Bridge

对于大跨径斜拉-悬索协作桥,如将斜拉段和悬索段作为独立的体系分别计算其成桥状态,再直接组合,将由于两大体系的相互影响而无法得到理想的成桥状态。以成桥时桥塔和主梁的位移最小为优化目标,以斜拉索初始索力、主梁压重为主要施调变量,提出了一种考虑主要几何非线性效应的协作桥合理成桥状态迭代方法,并以琼州海峡的主跨3 000 m协作桥方案为例进行了验证。结果表明,该方法计算得到的成桥状态中,桥塔竖直、基本处于纯轴压状态,主梁处于刚性支承连续梁状态、弯矩较小且均匀,整体优于直接组合法计算结果,有利于斜拉体系和悬索体系协同受力。

For long-span combined cable-stayed and suspension bridge, the method, which treats the cable- stayed segment and the suspension segment as 2 separate systems and respectively determines their completion states and then combines two results, cannot provide a reasonable completion state of the combined bridge due to the interaction between those 2 subsystems. Considering the main geometric nonlinear factors, a new iterative method for determining the completion state of a combine bridge is proposed, in which the minimum displacements of pylons and girders are taken as the optimization objective, and the initial forces of stay cables and additional weights of girders are taken as the adjustable variables. The method is validated by the application scheme of Qiongzhou Strait combined bridge with a main span of 3 000 m. The result shows that the proposed method gained a reasonable completion state, in which the pylons are straight and essentially axially compressed, and the state of girders coincided with that of a continuous girder on rigid supports in which the bending moments are very small and uniformly distributed. This result is overall better than that of the direct combination method and favors the combined action of the cable-stayed system and the suspension system.