摘要
广西滨海公路长坜桥主桥为2×79 m连续刚构桥,桥宽39.4 m,主梁为双幅单箱三室箱梁,左、右幅箱梁共用一个箱式双肢薄壁墩,墩高5.22 m。该桥采用先平行铁路双幅整体支架现浇后转体跨越铁路的施工方法,转体重量3.6万吨,球铰直径6.0 m。根据桥墩较矮、桥宽较宽、转体T构悬臂较大、转体吨位大、上承台受力较大的构造和结构受力特点,提出双肢薄壁墩、墙式墩、箱形空心墩3种主墩方案,从构造、结构受力、抗推刚度等方面进行综合比选。结果表明:双肢薄壁墩抗弯刚度大,可提高大悬臂转体施工状态下的结构安全性,对梁体主墩处的负弯矩起削峰作用;其抗推刚度小,可降低墩梁刚度比,改善梁体和桥墩的受力,故选择双肢薄壁墩方案。为进一步减小上承台厚度,解决矮墩身、分幅梁体、中心转铰带来的墩身受力问题,在常规整体式双肢薄壁墩的墩顶设置预应力混凝土系梁,形成箱式双肢薄壁墩。经计算,相较于整体式双肢薄壁墩,箱式双肢薄壁墩能有效减小上承台厚度,且能极大地降低主墩和上承台的应力,使结构受力更优,因此该桥最终采用箱式双肢薄壁墩方案。
The main bridge of Changli Bridge carrying a section of Guangxi Binhai Highway is a continuous rigid-frame bridge with two equal spans of 79 m.With a deck width of 39.4 m,the bridge has double superstructures that consist of three-cell box girders,the left and right superstructures share the 5.22 m-high,box-type,double-thin-walled piers(with extra cap beams compared with traditional double-thin-walled piers).The two superstructures were cast in situ on scaffolds parallel the railway,and then integrally rotated to span over the railways,using a spherical hinge that measured 6.0 m,and the weight of the rotated structures reached 36000 t.Given the characteristics of the bridge,three types of piers,including the double-thin-walled piers,wall piers and hollow box piers,were recommended and compared from aspects of structural configuration,load bearing behavior and thrust stiffness,and the double-thin-walled piers were finally selected,which was considered the best solution to accommodate the characteristics of the bridge,specifically the low piers,wide deck,long cantilevers of the rigid T frame,massive rotation tonnage and heavy-loaded pile caps.The double-thin-walled piers exhibit great flexural stiffness,which is beneficial to improve the safety of the structure at the long-cantilever rotation stage and alleviate the peaks of negative bending moments of the superstructures at the main piers,due to the small thrust stiffness,the stiffness ratios of the piers and superstructures are relatively reduced,and the load bearing conditions of the two get improved.To further reduce the thickness and enhance the loaded condition of the pile cap restricted by the short pier column,separated left and right superstructures and the spherical hinge,the double-thin-walled piers are fitted with extra prestressed concrete cap beams on top of the thin walls,becoming box structures that are different from the traditional double-thin-walled piers,as a result,the pile caps are made thinner,the stresses in the main piers and the pile caps are remarkably reduced,and the load bearing performance of the bridge is better.
作者
迟德有
CHI Deyou(Nanning Survey and Design Institute Co.,Ltd.,of China Railway Siyuan Group,Nanning 530003,China)
出处
《桥梁建设》
EI
CSCD
北大核心
2024年第3期123-128,共6页
Bridge Construction
基金
中铁四院集团南宁勘察设计院有限公司科技开发课题(2015K01)~~。
关键词
连续刚构桥
转体施工
双肢薄壁墩
墙式墩
箱形空心墩
结构受力
抗推刚度
方案比选
continuous rigid-frame bridge
rotation construction
double-thin-walled pier
wall pier
hollow box pier
load bearing behavior of structure
thrust stiffness
scheme selection
