大挑臂下承式连续梁拱组合桥设计

Design of a Combined Tied Arch and Wide-Flange Continuous Girder Bridge

西宁祥瑞大桥为(40+120+40)m大挑臂下承式连续梁拱组合桥。主梁采用大挑臂钢箱组合梁,钢梁采用单箱三室槽形结构,桥面板采用钢筋混凝土结构。主拱采用由2片分离的拱肋及横向风撑组成的组合式拱圈,拱肋呈“纺锤”形。吊杆采用高强度钢绞线整束挤压拉索,索体采用多重防腐层和抗辐射老化措施。系杆由37股∅s 15.2 mm新型高强度钢绞线组成,分布在钢梁中间箱室内。桥墩采用花瓶形钢筋混凝土实体墙式墩,基础采用6根∅2.0 m钻孔灌注桩。彩虹状的拱桥造型极具地域特色,景观效果良好。大挑臂钢箱组合梁结构横向刚度大、抗扭性能好,具有良好的受力性能及经济性能。全桥采用先梁后拱的施工方案,钢梁采用顶推施工,拱肋采用液压提升系统安装,预制桥面板在大挑臂横梁上使用桥面吊机施工。

Arranged in three spans of 40,120,and 40 m,the Xiangrui Bridge in Xining City features the combined tied arch and wide-flange continuous girders.The deck system consists of three-cell open steel box girders and precast reinforced concrete panels.The arch,spatially resembling a spindle,composed of two arch ribs and the in-between wind bracings.The high-strength steel strands in each hanger are integrally compacted,and the hangers are coated for corrosion and radiation aging protection.The ties,consisting of 37,∅s 15.2 mm steel strands each,are arranged in the central cell of the three-cell steel box girders.The piers are vase-shaped,reinforced concrete solid wall piers,resting on pile caps supported by 6,∅2.0 m bored piles.With superior lateral stiffness and torsional resistance,the wide-flange steel box girders are good options in terms of load bearing capacity and economy.The deck system was constructed by an incremental launching method,prior to the installation of the arch ribs using hydraulic lifting system,and the precast concrete panels were installed by the deck cranes that stood on the cross beams of the wide flanges.