五边形截面钢管混凝土巨型柱受压性能试验研究

为研究某超高层结构中五边形截面钢管混凝土巨型柱的受压性能，设计了6个1/5缩尺的柱模型试件，试件分为钢管内不分腔体仅配钢筋、钢管内分腔体不配钢筋、钢管内分腔体配置钢筋、钢管内分腔体配置钢筋且分腔隔板及竖向肋板在柱中部断开4种类型，对试件进行轴压和偏压试验。为研究试件刚度随加载循环次数的退化，采用单向重复荷载加载，对比研究了各试件的承载力、刚度及退化过程、破坏特征和平截面假定的适用性。试验表明：五边形截面钢管混凝土柱，钢管内不分腔体仅配钢筋的试件承载力较差；钢管内分腔体不配钢筋的试件与配钢筋的试件相比，虽承载力相差不大，但后期承载力下降较快；偏压试件与等截面轴压试件相比，承载力相对小，刚度退化速度较慢；腔体的分腔隔板及竖向肋板若在中部断开，造成刚度突变；腔体内设置竖向和水平肋板，对提高外壁钢板的稳定性有明显的作用；截面变形基本符合平截面假定。

Experimental research on compression behavior of pentagonal cross-section CFST mega-columns

In order to study the compression behavior of pentagonal shaped CFST mega-columns in a high-rise building, experiments on six 1/5 scaled specimens were carried out. There were four different types of specimens, including the specimen with reinforcements but without cavities, the specimen with cavities but without reinforcements, the specimen with both cavities and reinforcements, the specimen with reinforcements, cavities and division plates and vertical ribs which were cut in the middle of the column. The specimens were tested under axial compression or eccentric compression. In order to study the effect of the repeat loading on the stiffness degradation, one-way repeated loading test was adopted. The bearing capacity, stiffness and failure characteristics were studied, and applicability of the plane-section assumption was analyzed. Test results show, with regard to the pentagonal shaped CFST columns, the bearing capacity of specimens with reinforcements but without cavities are comparatively poor; compared with the specimens with both cavities and reinforcements, the bearing capacity of specimens without reinforcements is almost the same, but the bearing capacity decreases rapidly after the peak load; as to the eccentric compression specimens, compared with the axial compression specimens with same section, the bearing capacity is lower and stiffness degradation is slower; as to the specimen where the cavity plates and vertical rib are cut in the middle, the stiffness mutation is confirmed. The horizontal and vertical division plates can improve the stability of the outer plate significantly. The section deformation essentially agrees with the plane-section assumption.