福州道庆洲大桥总体设计及关键技术

Overall Design and Key Techniques of Daoqingzhou Bridge in Fuzhou

福州道庆洲大桥采用“公路+轨道”双层合建方式,上层为6车道城市主干道兼一级公路和人行非机动车混行通道,下层通行双线地铁。跨江大桥全长2268.5 m,其中主桥为(120+276+120)m变高度连续钢桁结合梁桥,引桥为标准跨径84 m和73 m的等高度钢桁结合梁桥。该桥采用无竖杆变高度双层桥面钢桁梁。主桥上层公路桥面采用大挑臂“密横梁+混凝土板”结合桥面,“体内+体外”预应力混合配索;下层轨道桥面采用“纵、横梁+钢正交异性板”整体钢桥面。为保持跨江桥景观的协调统一,曲线段非通航孔引桥采用变宽桁和折线桁。为解决墩顶负弯矩区桥面板的开裂问题,混凝土桥面板与钢梁结合过程中,采取顶、落梁措施。

The Daoqingzhou Bridge in Fuzhou is a road-rail bridge,with the upper deck accommodating six lanes of urban trunk road/arterial highway and pedestrian/bicycle sidewalks and the lower deck carrying double-track subway.The river-crossing part of the bridge measures 2268.5 m long,of which,the main bridge is a variable-depth continuous steel truss composite girder bridge with three spans of 120,276 and 120 m,and the approach bridges are constant steel truss composite girder bridge with typical spans of 84 m and 73 m.The steel truss girder is variable in depth and has no vertical members,which are designed to bear two layers of decks.The upper deck is formed of densely-distributed cross beams and concrete slabs,reinforced with internal and external prestressing tendons.The lower deck is an integral steel deck composed of orthotropic steel plates strengthened by stringers and cross beams.To enable the bridge to be in harmony with its surroundings,variable-width steel trusses and polyline trusses are used for the curved non-navigational channel approach bridge.To address the cracking issue of deck slabs in pier-top hogging moment zone,measures of jacking up and lowering steel trusses were taken during the connecting process of the concrete slabs and steel trusses.