镇江体育会展馆张弦桁架施工张拉分析与监测

Construction Analysis and Field Monitoring on Cable of Truss String of Zhenjiang Sports Conference Exhibition Pavilion

镇江体育会展馆屋盖为大跨度对称张弦桁架结构,张弦桁架的张拉为施工中的重点和难点。本文首先通过三种张拉方案的比选,得出采用分批对称张拉是一种比较合理的施工方案;并采用ANSYS和ADINA有限元软件对张弦桁架的施工全过程进行了模拟,为张拉施工提供了理论数据。通过对桁架关键部位监测点的布置,开展了全部10榀桁架施工过程的实时监测。监测结果与计算结果比较后发现,两者的跨中竖向位移、杆件应力及支座位移均符合较好,模拟计算结果是可信的。最后分析得出了跨度变化且对称张弦桁架结构在张拉中的一些特点:单榀张弦桁架在张拉过程中,其跨中竖向位移和滑动支座位移在张弦桁架完全脱离支撑胎架后增长迅速,而其跨中轴向应力随索力增加而增长较为均匀。最后张拉完成后,各榀张弦桁架跨中竖向位移、滑动支座位移跨中轴向应力随跨度的增加而增大。

The roof of Zhenjiang sports conference exhibition pavilion is a large span symmetrical truss string structure.The emphasis and difficulty in construction are cable stretching of the truss string.Three methods of cable stretching are compared in this paper;as a result,symmetrical stretching in batches is the best one for the symmetrical truss string.Numerical assessment with FEM software of ANSYS and ADINA is achieved,which provide theoretic data for cable stretching.Isochronous field monitoring is done on the key points,whose data fully accord with theoretic data.So the theoretic data is believable.At last,some feature in cable stretching like this project are found： in cable stretching of a single truss string,its middle vertical displacement and displacement of support abutment increase rapidly after the single truss string absolutely leave its tension bed,but its middle axial stress increases equably.After all cables are stretched,their middle vertical displacement,displacement of support abutment and their middle axial stress increase along with their span increasing.