有效弹性模量法在大跨斜拉桥稳定计算中应用

为了确立大跨度斜拉桥结构的稳定设计法,提出了按有效弹性模量法计算弹塑性分支失稳方法.通过对跨度1 400 m的斜拉桥模型计算分析,验证了有效弹性模量法在大跨度斜拉桥稳定验算中的适用性及其计算精度.在此基础上进一步讨论了活载布置位置对结构弹塑性稳定强度和失稳特性的影响.结果表明,应用有效弹性模量法能够精确地推算出结构的弹塑性失稳强度;大跨度斜拉桥的轴力由恒载起支配作用,活载分布位置的改变对稳定强度影响十分有限,考虑与不考虑活载分布影响的计算结果相差不到10%,按满布活载的工况可以推算大跨度斜拉桥结构的最小稳定强度.

Applicability of effective tangent modulus method in evaluation of buckling strength of long-span cable-stayed bridges

The effective tangent modulus method was proposed to estimate the elasto-plastic bifurcated stability strength of long-span cable-stayed bridge. The present method was compared with the elasto-plastic large displacement theory by calculating the ultimate strength, buckling mode and the axial force of the girder of a cable-stayed bridge with a span of 1 400 m, and was proved to be applicable and accurate. Besides, effects of live load distribution on the ultimate strength and elasto-plastic stability characteristics of the bridge were discussed. Results for the cases under different load conditions showed that relative deviations are lower than 10%, indicating that the influence of live load distribution is very slight. The stability strength of the bridge can be precisely calculated by considering the case under full-span distributed live load.