支管缺陷对钢管混凝土空间相贯节点承载能力影响

Influences of Branch Tube Defects on Bearing Capacity of Spatial Intersecting Joint of Concrete-Filled Steel Tube

为确定支管设置切割孔和混凝土亏空的钢管混凝土空间相贯节点的承载力和破坏模式,以某上承式钢管混凝土劲性骨架拱桥为背景,针对其拱肋钢管混凝土空间KK形相贯节点,采用Abaqus软件建立有限元模型,分析带切割孔和混凝土亏空的节点的承载力和破坏模式,并研究切割孔参数对节点承载力的影响。结果表明:支管壁设置切割孔会导致钢管混凝土空间节点的承载力降低,破坏模式由支管屈服变为支管局部屈曲;钢管混凝土空间节点的承载力随切割孔直径的增大而降低,切割孔位置对承载力的影响较小;支管内混凝土亏空会导致钢管混凝土空间节点的承载力降低,破坏模式由支管屈服变为主管壁冲剪破坏。

To determine the bearing capacity and failure modes of the spatial intersecting joint of the concrete-filled steel tube(CFST)with its branch tubes opened with the cutting holes and with the absence of the concrete in the branch tubes,a CFST frame deck arch bridge was taken as an example and for the spatial KK-shape intersecting joint of the arch rib CFST of the bridge,the finite element model was set up,using the software Abaqus,the bearing capacity and failure modes of the joint with the cutting holes and with the absence of the concrete were analyzed and the influences of the parameters of the cutting holes on the bearing capacity of the joint were studied.The results reveal that the opening of the cutting holes in the branch tubes can cause the bearing capacity of the spatial intersecting joint of the CFST to decrease and the failure modes of the joint change from the yielding of the branch tubes to the local buckling of the tubes.The bearing capacity of the joint decreases with the increase of the diameters of the cutting holes while the influences of the positions of the cutting holes on the bearing capacity are slight.The absence of the concrete in the branch tubes can cause the bearing capacity of the joint to decrease and the failure modes of the joint change from the yielding of the branch tubes to the punching shear failure of the main tube.