大跨度钢箱-混凝土组合系杆拱桥设计

DESIGN OF LONG-SPAN STEEL BOX AND CONCRETE COMPOSITE TIED-ARC BRIDGES

泸溪武水大桥为大跨度钢箱-混凝土组合系杆拱桥,主拱采用钢箱-混凝土组合拱,主梁采用钢管混凝土桁腹与混凝土桥面组合梁。钢箱拱肋的拱脚节段部分采用钢箱内灌注混凝土组合结构、拱肋其他节段部分采用内空钢箱结构。桥梁设计根据组合琴拱桥理论,合理调整拱轴线,改变拱肋截面大小,拱圈灌注混凝土,可减小拱脚水平推力、节省水平系杆;充分发挥组合材料的力学性能,增加拱肋刚度,增强主拱横向稳定性;提高截面的结构效率,有效减轻桥梁自重,提高桥梁结构耐久性。该桥方案设计实现了大跨度异型拱桥力学与美学的统一。针对大跨度拱桥水平推力、横向稳定、施工安装3大关键技术难题,提出新的解决思路和技术方法。对于主桥结构采用MIDAS/Civil空间有限元分析程序进行分析,结果表明:结构整体刚度好、结构稳定性好。

The main arch of a long-span steel box and concrete composite tied-arc bridge was steel box and concrete composite arch,and its main girder was a composite beam which was made of concrete filled steel tubular truss-web and concrete bridge deck. The arch foot parts of rib use steel box with concrete composite structure,and the other parts use inner empty steel box structure. According to the theory of composite arch bridge,the design scheme was made with reasonable adjustment of arch axis and the arch rib section size,and filling concrete into the arch ring. The design could reduce the arch foot horizontal thrust,save horizontal tie bar,give full play to the mechanical properties of composite materials,increase the arch rib rigidity,strengthen the main arch lateral stability,improve the structure efficiency of the cross section,reduce the weight of the bridge,enhance the durability of the bridge structure. The design could achieve the unity of the mechanics and aesthetics for the long-span arch bridge. It also puts forward a new solution method and technology for the horizontal thrust,lateral stability,construction and installation of the long-span arch bridge. The analysis of the main bridge structure was carried out by using MIDAS / Civil analysis program. The results showed excellent overall stiffness and stability of the main bridge structure.