斜交网格筒体超高层结构DK形混凝土节点试验研究

Experimental research on DK-shaped concrete joints in super high-rise inclined-intersecting grid tube structure

斜交网格筒体结构体系在矩形平面超高层结构中应用较少,其中矩形平面角部混凝土节点（DK形混凝土节点）设计难度较大,为此对其开展模型试验研究,模型相似比为1∶5,同时采用ABAQUS软件对其进行数值模拟对比分析。试验和数值分析结果均表明,DK形混凝土节点总是在加载端和斜柱相交区率先出现裂缝,并逐渐扩展;斜柱相交区间的应力集中现象严重。在极限荷载作用下,DK形混凝土节点具有突然脆性破坏特征,且提高体积配箍率可有效减小其横向膨胀变形。差值加载和等值加载模式下DK形混凝土节点的极限承载力无明显差异,因此设计中可忽略DK形混凝土节点不均匀受力的不利影响。保证DK形混凝土节点区最小体积配箍率大于1.57%的前提下,即使对斜柱适当补强,斜柱仍会先于节点区破坏,可见DK形混凝土节点的设计方案可保证强节点效应。后续工程实践表明,DK形混凝土节点很好地满足了建筑效果和受力要求。

There are few applications of inclined-intersecting grid tube structural system in rectangular planar super high-rise structure,the DK-shaped concrete joint at the corner of the rectangular plane is difficult to design. Therefore,model test study was conducted with a model similarity ratio of 1 ∶ 5,and ABAQUS software was used for numerical simulation and comparative analysis. The experimental and numerical analysis results show that the DK-shaped concrete joints always take the lead in cracks at the intersection of the loading end and inclined column to gradually expand; the stress concentration in the intersecting sections of the inclined columns is serious. Under the action of ultimate load,the DK-shaped concrete joints have sudden brittle failure characteristics,and increasing the volume distribution ratio can effectively reduce the lateral expansion deformation. There is no significant difference in the ultimate bearing capacity of DK-shaped concrete joints under differential loading and equivalent loading modes. Therefore,the adverse effects of DK-shaped concrete joints with uneven loads can be ignored in the design. If the minimum volumetric stirrup ratio of the DK-shaped concrete joint area is greater than 1. 57%,the inclined column will still be destroyed before the joint area even if the oblique column is properly reinforced. It can be seen that the design of the DK-shaped concrete joint can ensure strong joint effect. Follow-up engineering practice shows that the DK-shaped concrete joints well meet the architectural effects and mechanical requirements.