大跨度组合梁斜拉桥极限承载力影响因素

为探讨斜拉索断裂、组合梁界面相对滑移和桥面板剪力滞效应对结构极限承载力的影响,以在建的重庆江津观音岩组合梁斜拉桥为工程背景,考虑结构的几何非线性、材料非线性、体系转换、位移和应力的累积效应,按第二类稳定理论对桥梁全过程极限承载力进行了研究.结果表明,考虑斜拉索断裂、组合梁界面相对滑移和桥面板剪力滞效应的影响后,结构承载力安全系数最大变化分别达23.0%,19.0%和42.4%;斜拉索断裂对极限承载力的影响是一个先增大再逐渐减小的过程,而界面滑移和桥面板剪力滞效应对结构极限承载力的影响主要表现在短悬臂阶段.

Influencing Factors of Ultimate Load-Bearing Capacity of Long-Span Composite Girder Cable-Stayed Bridge

In order to deeply research the effects of stay cable breaking, relative interface slip of composite girder and deck shear-lag effect on structural ultimate load-bearing capacity, Guanyinyan composite girder cable-stayed bridge in Jiangjin in Chongqing, as the engineering background, was investigated by considering geometrical nonlinearity, material nonlinearity, system transition and cumulative effect of displacements and stresses and adopting the theory of second kind static stability.The research results show that stay cable breaking, relative interface slip of composite girder and deck shear-lag effect have great influences on safety factor for the ultimate bearing-capacity of a long-span composite girder cable-stayed bridge, and the maximum variation of the safety factor resulted from them are respectively 23.0%, 19.0% and 42.4%. The effect of stay cable breaking on the ultimate loadbearing capacity increases firstly and then decreases gradually, while the influences of the relative interface slip and the deck shear-lag effect behave mainly at the stage of short cantilever.