无索区长度对矮塔斜拉桥活载效应的影响

Influence of no-cable segment length on live load effect of extradosed cable stayed bridge

矮塔斜拉桥在梁段内存在无索区,怎样设置这些无索区合理地布置斜拉索,使斜拉索结构与连续体系梁结构协调地工作,是设计人员关心的问题。基于此,将典型的3跨矮塔斜拉桥梁段内无索区的分布以主塔附近无索区长度、中跨跨中无索区长度以及边跨端部无索区长度3个参数表示,并以此3个参数为研究对象进行结构行为的影响分析。以某大跨度矮塔斜拉桥方案的结构数据为基础,建立(ANSYS)结构有限元模型。在此模型的基础上,设置3个参数可能的合理变化范围,构造其他工况的结构有限元模型。利用参数化设计语言(APDL)编制计算程序,分析参数变化对车辆荷载作用下主梁内力和变形的影响,从而得出主梁在活载作用下合理的无索区长度及分布的范围,为矮塔斜拉索立面布置的优化设计提供参考。

There are no-cable segments along the girders of extradosed cable stayed bridge. How to set up these no-cable segments to optimize the cable layout so that the cable structure and the continuous girder structure can work in harmony is a big issue to the designers. The distribution of no-cable segments in a typical 3-span extradosed cable stayed bridge was represented in this paper by 3 parameters: no-cable segment length near the main tower, no-cable segment length across the middle span, and no-cable segment length at the end of side span. The 3 parameters were used to analyze the influence on structural behavior. The FEM model(ANSYS)was established mainly from the structural data of a real long-span extradosed cable-stayed bridge. Based on this model, the reasonable and possible variation ranges of the three parameters were set up, and the structural FEM models under other working conditions were also built. The influence of parameter changes on inner forces and deflections of girders with live vehicle loads was analyzed by using computer program that was coded by APDL(ANSYS parametric design language), and the reasonable no-cable segment lengths and distribution ranges of the girders with live vehicle loads were obtained. The results could provide references for the optimal layout of stay cables for extradosed cable-stayed bridges.