斜拉桥调索时索的拔出量计算精度分析

为寻找简便、精确的拉索拔出量计算方法,利用弹性悬链线精确解推导了张拉刚度和拉索沿两端点连线的轴向刚度计算式,对Ernst等效弹性模量法、割线模量法、精确等效弹性模量法等的计算原理进行了阐述。并通过算例对各种方法计算的索长拔出量进行了对比分析。分析结果表明,对成桥状态,各种方法都具有很高的精度;对施工状态,各种方法也都能满足工程中的精度要求;精度最高的3种方法依次为精确等效弹性模量法、割线摸量法和轴向刚度法,其中前2种方法的误差不超过0.6%。因此,推荐使用割线模量法和精确等效弹性模量法进行斜拉桥调索计算。

Precision Comparison of Cable Pull-out Length of Cable-stayed Bridge Calculated by Different Methods

In order to simply and accurately calculate cable pull-out length in cable tension adjusting of cable-stayed bridges with about 1 000 m main span,during construction and in service,formula of axial stiffness and tension stiffness are derived based on analytical solutions of elastic catenary,other different methods,such as Ernst equivalent elastic modulus method,secant elastic modulus method and accurate equivalent elastic modulus method,are collected to calculate cable stiffness.Several cables with different lengthes are taken as example to test errors of different formulas.It indicates that all the methods are accurate enough in service state,and have satisfying precision during construction.The three most accurate formulas are accurate equivalent elastic modulus method,secant elastic modulus method and axial stiffness method.Secant elastic modulus method and accurate equivalent elastic modulus method are proposed to be used in cable adjusting.