公铁两用双层钢-混组合梁设计关键技术  

Key Design Techniques for Steel-Concrete Composite Girder of Two-Deck Rail-cum-Road Bridge

作　　者：龚俊[1] 张燕飞[1] GONG Jun;ZHANG Yan-fei(China Railway Major Bridge Reconnaissance&Design Institute Co.,Ltd.,Wuhan 430056,China)

机构地区：[1]中铁大桥勘测设计院集团有限公司,湖北武汉430056

出　　处：《桥梁建设》2020年第S02期88-93,共6页Bridge Construction

基　　金：中国铁路总公司科技研究开发计划课题(2013G001-A-2)。

摘　　要：为选择合理的公铁两用双层钢-混组合梁桥面结构形式,以沪苏通长江公铁大桥跨径112 m简支钢桁梁结构为工程背景,采用有限元软件建立计算模型,对下层桥面槽形梁结构形式和内力计算方法,以及桁梁的“共同作用”施工措施进行研究。结果表明:下层桥面槽形梁采用钢筋混凝土结构能够满足结构受力要求;考虑混凝土开裂影响,下层槽形梁所受拉力仅为线性计算结果的50%左右,槽形梁的开裂对钢桁梁上弦杆影响较小,使下弦杆拉力增大约20%;可按混凝土弹性模量分别折减80%和25%的计算值作为槽形梁和钢桁梁的受力设计值;通过临时连接相邻孔跨,顶(落)不同支点高程的施工方式,可一定程度上消除上层横梁面外附加弯曲应力以及下层混凝土槽形梁的附加轴向拉力的影响。To select rational steel-concrete composite girder structures for rail-cum-road bridge accommodating two layers of decks,the 112 m-long simply-supported steel truss spans in Shanghai-Suzhou-Nantong Changjiang River Bridge are cited as cases.Finite element models were established to analyze the configuration of the trough slabs in the lower deck,to figure out the internal force calculation method and study the measures to control the interaction of deck system and steel trusses.The results indicate that reinforced concrete trough slabs can satisfy the load bearing requirements of the lower deck.Given the influence of concrete cracking,the tensile stress of trough slabs in the lower deck is roughly 50%of the linear calculation value,the cracking of trough slabs has minimal influence on the load bearing performance of the upper chord of the steel truss girder,but can make the tensile force of the lower chord increase by about 20%.The design load bearing capacities of the trough slabs and the steel truss girder can draw the values of concrete elastic modulus with 80%reduction and 25%reduction,respectively.By temporarily connecting the adjacent spans and jacking up/lowering girders at different supports,the influence of out-of-plane additional flexural stresses in the upper cross beams and the additional axial tensile forces of the trough slabs in the lower deck can be removed to a certain degree.

关 键 词：公路铁路两用桥 桁架桥 钢-混组合梁 双层 槽形梁 力学性能 开裂 

分 类 号：U448.216[建筑科学—桥梁与隧道工程] U441[交通运输工程—道路与铁道工程]