无铰钢管混凝土拱桥增跨顶升关键技术

为满足交通需求,厦门市某无铰钢管混凝土拱桥桥下道路需从双向6车道拓宽至双向10车道,相应需对原拱桥进行顶升增跨改造。改造需将原拱桥整体提升1.7 m,跨径由43.2 m增加至46 m。改造时首先在原结构上张拉临时系杆,使桥梁由无铰拱变为系杆拱,然后进行拱脚切割、顶升增跨施工,最终形成新的无铰钢管混凝土拱桥并解除临时系杆。为确保各施工阶段结构的安全,采用ANSYS建立拱桥有限元模型,对施工全过程进行仿真分析及位移和应力监测。仿真分析及监测结果表明,结构实际位移及受力与理论分析结果吻合较好;改造全过程中结构位移及受力的变化均在合理范围,不影响改造后的使用安全。

Key Techniques for Jacking-up and Span Lengthening of a Hingeless Concrete-Filled Steel Tube Arch Bridge

To cater for the traffic demand,the road under a hingeless concrete-filled steel tube arch bridge in Xiamen City needed to be widened from dual 3 lanes to dual 5 lanes and accordingly the existing arch bridge over the road had to be rehabilitated by jacking up and span lengthening,i.e.the bridge was to be integrally jacked up 1.7 m and the span of the bridge was to be lengthened from 43.2 m to 46 m.In the rehabilitation process of the bridge,the temporary tie members were firstly added to and tensioned on the existing bridge to make the bridge change from a hingeless arch to a tied arch,then the arch springs of the bridge were cut off,the bridge was jacked up,the span was lengthened and finally a new hingeless bridge was formed and the temporary tie members were released.To ensure the structural safety of various construction stages,the finite element model for the bridge was established,using the ANSYS,the simulation analysis of the whole construction process was made and the displacement and stress were monitored.The results of the simulation analysis and monitoring show that the actual displacement and force conditions of the bridge are in good agreement with those of the theoretic analysis.The changes of the structural displacement and force conditions of the bridge in the whole rehabilitation process are within rational range and the service safety of the bridge has not been adversely affected after rehabilitation.