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在一超高层结构工程中,外框架采用了焊接钢管混凝土边柱和夹角为12°的斜柱交叉形成高达6层且与6层楼面梁相接的巨型交叉节点,该节点构造复杂。节点边柱的轴向荷载不平衡在节点处产生剪力,同时,由于斜柱承受的轴向荷载巨大,该巨型节点受力复杂。为研究该节点的受力性能,对其进行了大比例模型加载试验。试验在最不利工况(1.2×重力荷载+1.3×设防地震作用)下:1)在设计荷载作用下节点试件整体仍然处于弹性工作状态;2)增大边柱不平衡力,对节点试件的平面内侧移有一定的影响,而对平面外变形基本没影响;3)对斜柱轴向荷载进行卸载,将节点由压剪转换至更不利的拉剪受力状态,节点未破坏;4)施加斜柱轴向荷载超过设计承载力的2倍,节点试件最终在斜柱两端出现局部鼓起而发生破坏,说明该交叉节点的设计符合我国规范“强节点弱构件”的设计原则。在整个加载过程中,节点区域并未产生剪切破坏面,钢管内部设置的纵向内隔板和加劲环板使得钢管与混凝土协同工作,节点构造合理。通过合理的简化,对该节点试件进行了三维非线性有限元分析,其荷载-变形曲线以及破坏模式与试验结果吻合良好。
In a super high-rise structural project, the outer frame uses a welded steel tube concrete column and the angle of 12 ° inclined column intersect to form up to 6 layers and connected with the six-story floor of the giant cross-node, the node structure is complex. The unbalanced axial load of the side columns of the node produces shear force at the node, and at the same time, the giant node is subjected to complicated forces due to the huge axial load on the inclined column. In order to study the mechanical behavior of this joint, a large-scale model loading test was carried out. Test Under the most unfavorable conditions (1.2 × gravity load + 1.3 × fortification earthquake effect): 1) Under the design load, the joint specimen is still in elastic working state; 2) Increasing the unbalanced force of the side columns, The in-plane displacement of the part has a certain influence, but has no effect on the out-of-plane deformation; 3) Unloading the axial load of the inclined column and transferring the node from the pressure-shear to the more unfavorable tensile- 4) The axial load applied to the inclined column exceeds 2 times of the designed bearing capacity, and finally the specimen of the node appears partially bulged and damaged at both ends of the inclined column, indicating that the design of the crossed node conforms to the Chinese standard of “strong node weak component” Design principles. During the whole loading process, the shear failure surface is not produced in the node area. The longitudinal internal partition plate and stiffener ring plate inside the steel pipe make the steel pipe and concrete work together and the node structure is reasonable. Through reasonable simplification, the three-dimensional nonlinear finite element analysis of the joint specimen was carried out. The load-deformation curve and failure mode agree well with the experimental results.