悬索桥吊索张拉及索鞍顶推降温法数值分析

摘要

研究目的:当大跨度自锚式悬索桥跨越通航流域不能采用常规支架法施工主跨钢箱梁时,首次应用“先斜拉,后悬索”的总体施工方案,该方案中最重要的过程就是斜拉桥向悬索桥的结构体系转换.针对体系转换中吊索张拉及主索鞍顶推在数值模拟中的实现,本文应用与无应力状态控制法相通的降温法进行分析.以该方法为指导,分析模拟建成后是世界上最大跨度600 m的鹅公岩自锚式悬索桥的体系转换全过程,阐述基于ANSYS的斜拉-悬索两个缆索支撑系统耦合模型中各个关键构件的单元选取及其参数确定的方法和技巧.研究结论:通过数值模拟计算得到体系转换过程中关键构件在整个过程中的变化规律,获得结论如下:(1)利用无应力索长可以将两种独立的斜拉-悬索缆索支撑系统实现耦合模型进行体系转换研究;(2)降温法是将吊索的建模长度降温至其无应力索长来模拟吊索张拉的过程,也可以模拟将主索鞍的预偏量分步降温至接近于零而实现主索鞍的顶推;(3)本文所研究降温法适用于计算大跨径自锚式悬索桥中体系转换过程中吊索张拉和主索鞍顶推分析.%Research purposes:When the long-span self-anchored suspension bridge could not use the general support method to install the steel box girder of main span,the " first cable-stayed,second suspension" overall construction plan was adopted in the world first.The most important process of the scheme was the system transformation from cable-stayed bridge to self-anchored suspension bridge.The suspender cable tension and main cable saddle pushing were realized in the numerical simulation of system transformation.The cooling method similarly with unstressed state control method was applied.Guided by this method,the system transformation whole process of Egongyan selfanchored suspension bridge was analyzed.The Egongyan self-anchored suspension bridge will be the world's largest span of 600 m self-anchored suspension bridge after the completion.The element selection and its parameter determination methods and techniques of the key components of suspension bridges were expounded in the state of two kinds of cable support system coexistence using ANSYS.Research conclusions:Through the numerical simulation,the changing rules of key components in the process of system transformation were analyzed.The conclusions are as follows:(1) All the cable units of the two models used their unstressed length to build the model under unstressed state control method.The coupling analysis model was remodel using the iterative calculation.(2) The cooling method makes the suspender cable cool to its unstressed cable length from modeling length.The cooling method also makes the deviator of main cable saddle cooled to near zero and realize the main cable saddle pushing.(3) The cooling method can be used in the calculation models of the suspension bridges system transformation process at suspension cable tension and main cable saddle pushing.