索道桥竖向刚度控制的虚拟恒载法  

Virtual Dead Load Method for Controlling Vertical Rigidity of Cableway Bridge

作　　者：景天虎[1,2] 李青宁[1] 

机构地区：[1]西安建筑科技大学土木工程学院,陕西西安710055 [2]桂林理工大学土木与建筑工程学院,广西桂林541004

出　　处：《公路交通科技》2010年第4期78-83,127,共7页Journal of Highway and Transportation Research and Development

基　　金：陕西省自然科学基础研究计划项目(2005E236);陕西省重点学科建设专项基金资助项目(E1004)

摘　　要：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。Based on the principle that virtual dead load can increase gravity rigidity and vertical rigidity of cableway bridge as same as the actual one,the problem of too large vertical deformation of cableway bridge under static load was investigated.By virtue of the principle above,determining method of initial pre-tension for main cables and the virtual dead load method for controlling vertical deflection during service period were put forward,and the operation method of applying virtual dead load（i.e.,pre-tensioning the main cables after their initial cable curve forming due to the whole dead loads and in ahead of live loads acting）was given.According to the calculation theory for flexible cables with small sags,the formula to compute virtual dead load and the equation to determine initial sags of main cables were derived,considering the influence of temperature change and different elevation of two bearings on cableway bridge.Moreover,reasonable range of the ratio of deflection to span due to live loads was obtained after the analysis of a cableway bridge.The result of the computation also indicates that the virtual dead load method is economical and its effect to control vertical stiffness is significant.

关 键 词：桥梁工程 竖向刚度 虚拟恒载 索道桥 承重索 

分 类 号：U448.25[建筑科学—桥梁与隧道工程]