The main bridge of Xitiaoxi right line extra-long bridge on Shangqiu-Hangzhou-Hefei high-speed railway is a tied arch bridge with 140 m span. It is a concrete filled steel tubular arch bridge with prestressed concrete tie beam, and the construction method of arch-before-beam is used. The finite element model calculation and analysis is employed to determine the reasonable structure forms and the process of arch prior to beam and define the design parameters related to the stress, stiffness and stability of tie beam, arch rib and hanger. Analysis results show that (1) the main bridge structure of stress and deformation meet the requirements of the code;(2) when the tied arch bridge use ballastless track, the track's up and down displacement caused by the rotation angle at bridge end should be controlled by 1 mm limit; ( 3 ) stretching steel strand tie-bar by steps with arch-before-beam construction without support meet the requirement of uninterrupted navigation.%新建商合杭铁路西苕溪右线特大桥跨越长兴港采用1-140 m系杆拱方案,为预应力混凝土平行钢管混凝土拱桥,采用先拱后梁方法施工.介绍采用无砟轨道时系杆拱设计方案,并根据实际施工阶段建立有限元模型计算分析,确定结构的合理形式及先拱后梁施工工序,计算拱肋、系梁、吊杆等结构应力、刚度、稳定性等设计参数.分析结果表明:(1)该桥主体结构应力、变形等均满足规范要求;(2)系杆拱应用于无砟轨道时,静活载梁端转角引起钢轨上拨及下压量宜按1 mm限值控制;(3)先拱后梁系杆拱采用施工阶段分批张拉钢绞线系杆形式,实现无支架施工,满足不中断通航要求.
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