钢-混凝土组合梁斜拉桥梁结构的稳定性分析

Analysis of Steel-concrete Composite Beam Cable-stayed Bridge Structure

采用有限元法建立钢-混凝土组合桥梁的结构模型,分析了不同典型施工阶段下桥梁主梁和腹板结构的受力特征,获得了桥梁整体失稳状态。并以桥梁局部失稳状态分析斜拉桥结构的稳定性特征,获得影响斜拉桥稳定性的各影响因素关系。研究结果表明:全桥一阶整体失稳态下的总体稳定系数为7. 7,大于一般计算稳定系数4. 0;桥梁施工状态下,主梁最大应力出现在成桥阶段1 000 d后,桥面板承受最大压应力出现在中跨合拢阶段,均满足规范。对于桥梁主梁腹板,在设计荷载组合作用下,主梁腹板加劲肋局部位置易发生屈曲变形。当轴力/弯矩小于0. 5时,首先在梁段产生横梁侧倾失稳,随着轴力/弯矩比值的增加,由横梁侧倾斜转化为主梁腹板或加劲肋的失稳。

the structural model of steel-concrete composite bridge is established by using finite element method,and the stress characteristics of the main girder and web structure of the bridge under different typical construction stages are analyzed,and the overall instability state of the bridge is obtained.The stability characteristics of cable-stayed bridge structure are analyzed by analyzing the local instability of the bridge,and the influence factors on the stability of cable-stayed bridge are obtained.The results show that the overall stability coefficient of the whole bridge under the first order unsteady state is 7.7,which is larger than that of the general stability calculation,and the maximum stress of the main beam appears 6 000 days after the completion stage of the bridge in the construction state of the bridge.The maximum compressive stress of bridge deck appears in the closing order of middle spanEach section satisfies the standard allowable stress.For the web of the main girder of the bridge, the local position of the stiffened rib of the main girder web is prone to buckle deformation under the action of the design load combination.When the axial force/bending moment is less than 0.5,the lateral instability of the beam first occurs in the beam segment.With the increase of the axial force/moment ratio,the lateral tilt of the beam is transformed into the instability of the main beam web or stiffener.