Experimental Study on Elasto-Plastic Behavior of Concrete-Filled Steel Tubular Space Subassemblages

钢管混凝土结构已被认为是一种抗震结构，研究了轴力比、钢管宽厚比、混凝土强度、钢材应变硬化以及钢与混凝土之间的相互作用等因素对钢管混凝土构件和节点强度和变形能力的影响，即钢管对混凝土的约束作用和混凝土对钢管局部屈曲的抑制作用。然而，目前还没有关于钢管混凝土柱框架在强震作用下的空间受力性能的研究，其中可能出现柱在双向受弯情况下的受力性能和在三维荷载作用下的连接性能。从这一角度出发，进行了由钢管混凝土柱和4根H型梁组成的三维子组合在恒轴向荷载、次方向恒定梁荷载和主方向交替反复剪力作用下模拟地震荷载的试验，研究了以下试验参数对弹塑性性能的影响：试件形状(模拟外柱和角柱周围的组合件的三维和平面框架试件)；破坏类型(面板失效类型和柱失效类型)；以及梁在次要方向上的长期荷载模式。对三维钢管混凝土组合体的弹塑性性能进行了试验研究，得到以下新发现：(1)试件破坏后的最大强度基本相同，没有观察到三维荷载和双向弯曲的影响。另一方面，三维加载和双向弯曲都降低了柱失效试件的最大强度(2)梁柱c

The concrete-filled steel tubular(CFST) structure has been recognized as an earthquake-resistant structure, and the investigation of the effects of several factors on the strength and deformation capacity of CFST members and connections have been investigated : axial force ratio, width-thickness ratio of steel tube, concrete strength, strain-hardening of steel, and interaction between steel and concrete, that is, confining effect on concrete by steel tube, and restraining effect of cencrete on the local buckling of steel tube. However, there have been no research found on the three-dimensional behavior of a frame consisting of CFST columns under the severe earthquake, in which the column behavior under the bi-axial bending and the connection behavior under the three-dimensional loading may appear. From this point of view, three-dimensional subassenblages consisting of a concrete-filled steel tubular column and four H-shaped beams were tested under a constant axial load on the column, constant beam loads in the minor direction, and alternately repeated beam shear in the major direction simulating the earthquake loading, and the effects of the following experimental parameters on the elasto-plastic behavior were investigated : shapes of specimen (three-dimensional and planar frame specimens simulating subassemblages around exterior and corner columns) ; failure types (panel failing type and column failing type) ; and pattern of the long-term loads on the beams in the minor direction. New findings obtained from the experimental study on the elasto-plastic behavaior of three-dimensional concrete-filled steel tubular subassemblages are as followa : (1)The maximum, strengths of panel-failing specimens were almost the same, and the effects of neither the three-dimensional loading nor the biaxial bending were observed. On the other hand, both the three-dimensional loading and the bi-axial bending reduced the maximum strengths of column-failing specimens (2)Beam-to-column c