福厦高铁泉州湾跨海大桥主桥钢-混结合梁设计

Design of Steel-Concrete Composite Girder of Main Bridge of Quanzhou Bay Sea-Crossing Bridge on Fuzhou-Xiamen High-Speed Railway

福厦高铁泉州湾跨海大桥主桥采用主跨400m双塔双索面钢-混结合梁斜拉桥,为半飘浮体系。针对并行公路桥和海湾深水强风环境的建设条件,主梁采用混凝土桥面板+槽形钢箱梁的封闭式箱形结合梁,梁高4.25 m,梁宽21m,标准节段长10.5m。槽形钢箱梁(不含风嘴)采用单箱三室等高截面,底板及纵腹板加劲肋采用直板肋,节段断面连接采用栓焊混合连接方式,索梁锚固采用锚拉板结构。混凝土桥面板标准厚30cm,分块预制,在桥位与钢梁结合。墩(塔)区域的主梁采用浮吊整体吊装,其余梁段利用桥面吊机悬臂吊装。针对海洋大气腐蚀环境,预制桥面板采用C55高性能混凝土,桥面板湿接缝采用粗、细合成纤维混掺的补偿收缩混凝土,钢梁底漆采用石墨烯纳米材料改性鳞片型醇溶无机富锌涂料。

The main bridge of Quanzhou Bay Sea-Crossing Bridge on newly-built Fuzhou-Xiamen High-speed Railway,which has a main span of 400 m and two pylons,is a steel-concrete composite girder cable-stayed bridge of semi-floating system,with stay cables fanned out in double cable planes.The construction of the bridge is restricted by the nearby parallel highway bridge,and also faces the challenges of the deep water and harsh winds in the bay.The main girder,which is a closed box composite structure comprising concrete slabs and open-top steel boxes,measures 4.25 m high and 21 m wide,with typical segment length of 10.5 m.The open-top steel box girder(involving the wind fairings)contains five cells and is constant in depth.Flat stiffeners are added to the base plates and longitudinal webs.The girder segments are connected by the combination of welding and bolting.The stay cables are anchored with the main girder via steel anchor plates.The concrete slabs,with typical thickness of 30 cm,are precast panel by panel and fixed with the steel boxes at the bridge site.The girder segments at the locations of piers(pylons)were monolithically erected into position by floating crane,and the remaining segments were installed in cantilevers using launching crane.To address the durability issue in the marine environment,the concrete slabs are cast by C55 high-performance concrete,with stitches on the deck filled with supplementary shrinkage concrete mixed with coarse and fine synthetic fibers.The steel girder is coated with grapheme-based inorganic zinc-rich primer that is alcohol soluble and flaky.