内压力环索承网格结构环索提升分析

Ring Cable Lifting Analysis of Internal-compression-ring Cable-supported Grid Structure

索承网格结构包括外环、上部网格、径向索、环索和撑杆。环索提升是重要施工步骤之一,现场施工前须分析确定其3个关键问题:环索在地面看台上的铺展位形、在空中与V形撑外肢底端连接的位形、撤除提升工装索后环索与V形撑外肢平衡位形。由于未张拉的环索呈大悬垂状态,上述3个位形与设计位形差异大,且考虑因素不同于常规刚性结构提升。以上海浦东足球场挑篷结构为工程背景,基于非线性动力有限元找形法及各阶段位形控制目标,提出环索提升分析方法,确定其3个关键状态的施工参数。分析结果表明:①提升过程中的环索位形与设计状态差异大;②环索铺展时向场内偏移;③连接V形撑外肢和提升索卸载时,环索存在明显的空间双向偏移,即各环索段在平面上分别向场内和场外偏离,在标高上分别高于和低于设计标高。

Cable-supported grid structure consists of outer ring,upper grid,cable net and brace.The lifting of ring cable is an important construction stage,where three key geometries have to be determined:ring cable unrolled on stand,ring cable connected to the outer branch of V-brace and ring cable hanging freely on the outer branch of V-brace.Due to the large overhanging state of ring cable,the three key geometries have great difference from design configuration and the lifting of ring cable is also different from the lifting of conventional rigid structure.This paper will put forward analyzing method of ring cable lifting and master some construction parameters of the three key state mentioned above.All the work will be based on Shanghai Pudong football field project and according to nonlinear dynamic finite element method and targeting configuration of different construction stage.Analyzing result shows that,the configuration of ring cable has great difference from design geometry in the lifting process.ring cable will offset into the field when unrolled on stand.At the stage of connecting to the outer branch of V-brace and removal of lifting cable,ring cable will have a spatial two-way displacement,which appears as the diviation in plane geometry and elevation.