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以某主跨为800m的钢桁梁斜拉桥为工程背景,依据承载能力极限状态下主梁应力相似原则比较了钢箱梁斜拉桥设计方案,对两桥的力学性能、施工方案、钢混结合段构造和材料经济性进行对比。结果表明,钢桁梁和钢箱梁活载挠度与跨径之比分别为1/1 171和1/712;最小整体弹性稳定系数分别为6.622和7.188;前者用钢量比后者多32.2%;钢桁梁方案钢混结合段更适合采用无格室构造。钢桁梁结构刚度较钢箱梁大,施工中对桥位处交通条件要求低,但是稳定性不如钢箱梁,在设计中要注意索塔附近局部稳定和钢混结合段应力集中问题。分析结果可为超大跨度斜拉桥主梁方案设计提供参考。
Taking the steel truss cable-stayed bridge with a main span of 800m as the engineering background, the design scheme of the cable-stayed bridge with steel box girders is compared according to the principle of the stress of the main girder under the ultimate load carrying capacity. The mechanical properties, construction schemes, Mixing section construction and material economy are compared. The results show that the ratio of live load deflection to span of steel truss girders and steel box girders is 1/1 171 and 1/712 respectively; the minimum overall elastic stability coefficients are 6.622 and 7.188 respectively; the former uses 32.2% more steel than the latter; Truss girder steel mixing project is more suitable for the use of non-grid structure. Steel truss girder structure stiffness than the steel box girder, the construction of the bridge at the traffic conditions at the request of low, but not as good as steel box girder stability in the design should pay attention to local stability near the tower and steel mixing section stress concentration problems. The results of the analysis can provide reference for the design of girder of super-long span cable-stayed bridge.