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无背索斜拉桥在理想的成桥状态下,面内失稳模态为主梁屈曲。将主梁简化成弹性地基梁计算模型,选用正弦级数作位移函数,运用能量方法,提出了主梁屈曲临界荷载的计算公式。结合该类桥梁的结构布置特点,用简洁的连续函数描述主梁轴压力和拉索弹性支承刚度的变化,同时用简单的线形折减系数反映斜塔变形对拉索弹性支承刚度的影响。最后以长沙市洪山大桥为例,用该方法计算了其成桥状态屈曲临界荷载,其结果与有限元解对比具有很好的精度。
Without backslip cable-stayed bridge in the ideal state of the bridge, the in-plane instability mode buckling of the main beam. The main girder is simplified as the elastic foundation girder calculation model. The sine series is chosen as the displacement function and the buckling critical load formula of the main girder is proposed by energy method. Based on the structural arrangement characteristics of such bridges, the simple continuous function is used to describe the variation of the axial stress of the main beam and the elastic support stiffness of the cable, and the simple linear reduction coefficient is used to reflect the influence of the deformation of the inclined tower on the elastic support stiffness of the cable. Finally, taking Hongshan Bridge in Changsha City as an example, the critical load of the bridge in flexed condition is calculated by this method. The result is in good agreement with the finite element method.