考虑节点刚度的钢桁腹连续箱梁桥多尺度分析

Multi-scale analysis of continuous box girder bridge with steel truss webs considering the joint stiffness

为探究某在建4×60 m钢桁腹-混凝土连续箱梁桥新型桥梁结构的工作性能,建立精细化非线性节点模型,求解节点转动刚度曲线,并通过界面连接关系,建立适用于连续组合桥梁腹杆与负弯矩区受力性能研究的多尺度模型。研究结果表明:考虑组合节点初始转动刚度时,成桥状态腹杆受弯矩较小,可采用节点铰接的简化设计方法;负弯矩区腹板在弦杆和腹杆共同作用下,上部受拉下部受压,应力呈阶梯状分布,其中受腹杆轴力影响最大,应沿主拉应力迹线方向配置预应力钢束;竖向荷载作用下顶板存在正剪力滞效应,节点处顶板存在负剪力滞效应。

In order to explore the mechanical performance of the 4×60 m steel truss web-concrete continuous box girder bridge,a refined nonlinear joint model was established.Based on the rotation stiffness curve of the interface connection,a multiscale model was built for the mechanical behavior of the steel truss webs and the negative moment region of the continuous composite bridge.The results shows that the moment in web member are less when considering the initial rotational stiffness.The simplified design method with hinge joint can be adopted through comparison.Under the combined action of the chord and the web member,the upper parts of the web on the support are tensioned and the lower parts are compressed,the stress distribution is like a stairway in the negative moment region.Axis force in the web member influence is greatly on the web.The prestressed tendon can be set along the web’s principal tensile direction.Under vertical load,in the upper plane there is an active shear lag effect,and the negative shear lag in the upper plane near the supports.