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采用基于微观断裂机制的空穴扩张模型(VGM)和应力修正应变模型(SMCS)对XK型相贯节点进行断裂预测,分析了有限元模型中考虑焊缝构型与否对断裂预测结果的影响。通过与试验结果的对比,证明了合理考虑焊缝构型在相贯节点断裂预测中的重要性,验证了VGM模型用于预测相贯节点在单调荷载作用下延性断裂的适用性。分析了XK型相贯节点在腹杆轴力作用下的破坏模式和极限承载力。结果表明,XK型相贯节点可能在受拉腹杆与弦杆之间的焊缝处发生断裂,这种破坏模式属于强度破坏,节点极限承载力应取该断裂荷载;XK型相贯节点也可能在受压腹杆与弦杆相交处因过大的塑性变形而破坏,此时,节点极限承载力应取荷载-弦杆变形曲线的峰值荷载。XK型相贯节点的破坏模式与节点几何构造和腹杆受力状态有关。
Fracture prediction of XK-type cross-joints was carried out by using VGM and SMCS based on the microscopic fracture mechanism. The influence of weld configuration on fracture prediction was analyzed in the finite element model . By comparing with the experimental results, it is proved that the VGM model is suitable for predicting the ductile fracture under the monotonic load when the joint configuration is reasonably considered. The failure mode and ultimate bearing capacity of XK-type cross-section joints under the action of web axial force are analyzed. The results show that the XK-type cross-section joints may be fractured at the weld joint between the tension web and the chord. The failure mode belongs to the strength failure, and the ultimate bearing capacity of the joints should be taken as the fracture load. May be under pressure at the intersection of the web and chord due to excessive plastic deformation damage, this time, the ultimate bearing capacity of the node should take the load - chord deformation curve peak load. The failure mode of XK-type intersecting nodes is related to the geometry of the nodes and the force state of the webs.