中开高速银洲湖特大桥总体设计

Overall Design of Yinzhou Lake Bridge of Zhongshan-Yangchun Expressway

中开高速银洲湖特大桥主桥为主跨530 m混合式组合梁斜拉桥,采用半飘浮结构体系。桥塔为A形塔,斜拉索采用扇形索面布置,全桥共24对斜拉索,采用∅7 mm标准抗拉强度为1860 MPa的镀锌铝平行钢丝,斜拉索在桥塔内采用钢锚梁+钢牛腿+环向预应力方式锚固。桥面全宽36.3 m,外侧设置风嘴;中跨为组合梁,边跨为混凝土梁,均采用PK断面;钢-混结合面设置在中跨距离桥塔中心线7.85 m处,采用“前承压板+钢格室”构造形式。通过精细化设计边跨混凝土梁构造、优化标准节段施工工序,采用“先边后中、多次张拉”,减少双悬臂施工的不平衡力,并设置临时墩改善桥塔受力,实现混合梁斜拉桥“中跨组合梁吊装+边跨混凝土梁牵索挂篮悬浇”的不平衡双悬臂施工。

The Yinzhou Lake Bridge of Zhongshan-Yangchun Expressway is a cable-stayed bridge of a half-floating system.The bridge has two A-shaped pylons and the main span length reaches 530 m.The stay cables consist of the Zn-Al coated parallel steel wires of 7 mm in diameter,each with nominal tensile strength of 1860 MPa,and there are a total of 24 stay cables in the bridge,which are arranged in double cable planes.The stay cables are anchored to the pylons using steel anchor beams,steel corbels and loop prestressing.The deck measures 36.3 m wide(with wind fairings).The steel-concrete composite girders in the central span and the concrete girders in the side spans are all of PK cross-section.The steel-concrete joint sections are set at the locations 7.85 m away from the centerline of the two pylons in the central span,which incorporate the prime components of front load bearing plate and steel lattice chamber.The design of the concrete girders in the side spans was detailed,the construction procedure of the typical girder segments was optimized,and the stay cables in the central span were tensioned ahead of those in the side spans and experienced multiple times of tensioning,aiming to reduce the unbalanced force in the two-way cantilever construction.The prefabricated composite girders in the central span were hoisted into position,the concrete girders in the side spans were cast in situ using form travelers,and temporary piers were built to facilitate the construction.