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研究了荷载作用下索道桥的竖向变位太大的问题。依据虚拟恒载同样能增加承重索的重力刚度、从而提高索道桥竖向刚度的基本原理。提出了虚拟恒载法控制竖向挠度的方法和初始预张力的确定方法,并给出了虚拟恒载的施加方法,即在主索因全部恒载作用而形成初始线形之后、承受活载之前,对其进行预拉。并运用小垂度柔索的索力转换方程,推导出了虚拟恒载的计算公式和初始垂度的确定方程,并考虑了温度变化和索道桥两支点高程差异的影响。通过对算例的计算结果分析,得出了活载挠跨比较合理的取值区间;虚拟恒载法控制竖向刚度的措施比较经济,且效果十分明显。
The problem of vertical displacement of cable bridge under load is studied. Based on the virtual dead load can also increase the gravity stiffness of the load-bearing cable, thereby enhancing the vertical stiffness of the ropeway bridge the basic principles. A method of controlling the vertical deflection by the virtual dead load method and the method of determining the initial pretension are proposed. The method of applying the virtual dead load is given, that is, after the initial line shape is formed by the full dead load of the main rope and before the live load , Its pre-pull. The formula of the virtual dead load and the initial equation of the initial sag are deduced by using the cable force conversion equation of the small sag cable, and the influence of the temperature variation and the elevation difference of the two fulcrums of the cable bridge is considered. Through the analysis of the calculation results of the example, the reasonable value interval of the live load-bearing flexible span is obtained. The method of controlling the vertical stiffness by the virtual dead load method is more economical and the effect is obvious.