多塔斜拉桥拉索支承刚度系数的求解与分析

Analysis and solution of cable supporting stiffness coefficient of multi-span cable-stayed bridges

为了深入研究多塔斜拉桥刚度过低的本质,基于多塔斜拉桥的结构力学特性,推导了单位荷载作用下多塔斜拉桥的拉索弹性支承刚度系数的解析公式,对其进行了参数敏感性分析。通过算例对推导的公式进行了验证,最后将拉索支承刚度系数公式应用于实际多塔斜拉桥的竖向挠度计算,与嘉兴—绍兴六塔斜拉桥的有限元计算的数值结果进行了对比分析。研究结果表明:多塔斜拉桥刚度过低的本质是主梁对中间塔提供的纵向约束较弱;推导的公式具有较高的计算精度,算例与文献[8]中的单位力作用下主梁的竖向挠度比值仅为1.02;将其应用于嘉兴—绍兴大桥主梁挠度计算时,计算结果误差也较小;此解析公式可通用于各种塔数的斜拉桥,可用于指导多塔斜拉桥结构的概念设计和初步设计工作,有利于提高多塔斜拉桥刚度的计算分析效率。

In order to study thoroughly the low rigidity of multi-span cable-stayed bridges,this paper derived an analytic formula of cable-stayed bridges cable elastic support rigidity coefficient under unit load based on the structure features of the multi-span cable-stayed bridge and conducted parameter sensitivity analysis on it.This formula was verified by an example and was applied to actual bridge vertica deflection calculation.These calculation results were compared with those of Jiaxing—Shaoxing six pylons cable-stayed bridge based on finite element calculation.The results show that the essence of low rigidity of multi-span cable-stayed bridge is weak constraints of the middle pylon.The formula calculation accuracy is relatively high,and the ratio of vertical deflection of beam under the unit load between the example and reference 8counts as 1.02.The error is little when the deflection of Jiaxing—Shaoxing bridge is calculated.The formula can be applied to cable-stayed bridges with various number of towers and can be used on the conceptual design and primary design of cable-stayed structure and make if efficient tocompute the rigidity of cable-stayed bridge.