大跨度系杆拱桥拱梁墩交汇段模型试验研究

Research on the Model Tests of Intersection Section of Arch, Beam and Pier of Large-span Tied Arch Bridge

研究目的:宜宾金沙江公铁两用大桥是成贵线重要控制性工程之一,为公铁两用双层刚架系杆拱桥。本文的研究对象为该桥主拱、立柱、下横梁及桥墩的交汇区域,该交汇段具有受力荷载多、荷载大、受力方向各异等特点,且存在明显的应力集中区域。通过模型试验测试结果与有限元对比分析,对结构的安全性进行评估,并对设计建造提出合理化建议。研究结论:(1)对交汇段进行了细部有限元分析,并设计制作了1∶6的缩尺模型,测试模型在最不利荷载工况下的应力分布与结构变形等受力特性,以及在超载工况下的承载能力,结果表明结构设计合理,具备一定的安全储备;(2)建议在交汇段受拉区增设抗裂钢筋、加强钢混结合面下的混凝土振捣、严格控制钢拱肋与混凝土拱座间锚杆张拉力等措施来提高施工建造质量;(3)本研究结果可为同类型系杆拱桥的施工建造提供借鉴与参考。

Research purposes:Yibin Jinsha River highway-railway dual-purpose bridge is one of the important control projects of Chengdu-Guiyang line,as a highway-railway double-deck rigid frame tied arch bridge.The study object of this paper is the intersection region of the main arch,column,beam and pier of the bridge,the intersection section has the characteristics of many loads,large loads,different stress directions,and there are obvious stress concentration region.Through the comparative analysis of model test results and finite element analysis,the safety of the structure is evaluated,and reasonable suggestions for the design and construction are put forward,which provides reference for the design and construction of this kind of bridge.Research conclusions:(1)The detailed finite element analysis of the intersection section is carried out,and a 1∶6 scale model is designed and made to test the stress distribution,structural deformation and other stress characteristics of the model under the most unfavorable load conditions,as well as the bearing capacity under overload conditions.The results show that the structural design is reasonable and has a certain safety reserve.(2)It is suggested to add crack resistant reinforcement in the tensile area of the intersection section,strengthen the concrete vibration under the steel-concrete joint surface,and strictly control the bolt tension between the steel arch rib and the concrete arch seat to improve the construction quality.(3)The research results can provide reference for the construction of tied arch bridges of the same type.