平潭海峡公铁大桥钢桁梁预压主桁减小桥面系与主桁共同作用技术  

Technique to Mitigate Deck-Main Truss Interaction of Steel Truss Girder by Preloading Main Truss for Pingtan Straits Rail-cum-Road Bridge

作　　者：王东辉 何华武[3] 韩冰[1] 雷俊卿[1] WANG Dong-hui;HE Hua-wu;HAN Bing;LEI Jun-qing(School of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China;China Railway Major Bridge Engineering Group Co.,Ltd.,Wuhan 430050,China;Chinese Academy of Engineering,Beijing 100088,China)

机构地区：[1]北京交通大学土木建筑工程学院,北京100044 [2]中国中铁大桥局集团有限公司,湖北武汉430050 [3]中国工程院,北京100088

出　　处：《桥梁建设》2020年第5期107-112,共6页Bridge Construction

基　　金：国家自然科学基金项目(51778043,51578047);中国铁路总公司科技研究开发计划课题(2014G004-D)。

摘　　要：平潭海峡公铁大桥深水高墩区非通航孔桥采用跨径为80(88)m的双层钢-混结合简支钢桁梁结构。为减小简支钢桁梁桥面系与主桁的共同作用,改善公路横梁面外受力,针对传统方案的不足,提出了预压主桁上弦、缩短并滞后安装公路纵梁和副桁弦杆的方案。通过对3种预压方案比选,采用平行钢丝索预压主桁上弦方案。在主桁上弦两端设置张拉锚箱(锚箱间设置平行钢丝索,共8根),采用梁端对称张拉钢丝索的方式,分2个阶段(端部节间预压和中间节间预压)进行主桁上弦预压;在完成主桁上弦预压以及公路纵、横梁与副桁弦杆的组焊后,释放预压力,在公路横梁形成面外预反变形,从而抵消桥面系与主桁共同作用在公路横梁形成的面外弯曲。The non-navigational channel bridge that is located in the deep water area and has high piers adopts the simply-supported steel truss structure of a steel-concrete composite system.The bridge accommodates separated upper and lower decks,with spans of 80(88)m in length.To mitigate the main truss-deck interaction of the simply-supported steel truss girder and improve the out-of-plane load bearing condition of the cross beams in vehicle deck,a scheme of preloading the upper chords of main truss,shortening the installation time and delaying the installation of the stringers and members of the subsidiary truss was selected,to overcome the disadvantages of the traditional methods.A number of three schemes were compared,and the one suggesting preloading the upper chord of the main truss by using parallel steel wire cables was employed.The anchor boxes for cable tensioning were installed on the two ends of the upper chord of the main truss,between which the parallel steel wire cables were installed and a total of 8 cables were used.The steel wire cables were symmetrically tensioned at the girder ends to preload the upper chord of the main truss in two phases,including preloading the end truss panels and preloading the central truss panel.After the completion of upper chord preloading for the main truss and the assembly and welding of stringers,cross beams and subsidiary truss members of the vehicle deck,the preloading pressure was released to force the cross beam to generate out-of-plane counter camber,so as to counterbalance the out-of-plane bending of the cross beams in vehicle deck induced by the main truss-deck interaction.

关 键 词：跨海大桥 公路铁路两用桥 钢-混结合梁 钢桁梁 共同作用 主桁预压 施工技术 

分 类 号：U448.121[建筑科学—桥梁与隧道工程] U445.4[交通运输工程—道路与铁道工程]