Development of Mixed Column Base of Square CFT Structures Considering Constractability

本文提出了一种新型的柱脚，并对其结构性能进行了试验研究，讨论了柱脚最大强度和初始刚度的估算方法。建议柱脚的想法已经从两个传统的方法发展而来。另一种是裸露式，柱以一定的长度埋入钢筋混凝土基础梁中。另一种是裸式，柱通过锚栓和底板与基础梁连接。前者刚度和强度较大，结构性能较好，但施工工序较复杂，必须先安装钢筋，再浇筑基础梁混凝土。与预埋式相比，半预埋式钢管混凝土柱脚的刚度和强度较小，但施工方便，造价较低，本文提出了半预埋式钢管混凝土柱脚，研究结果表明，半预埋式钢管混凝土柱脚的刚度和强度比预埋式钢管混凝土柱脚小，且施工方便，施工成本低 关于我们 结果表明：柱管的局部屈曲对柱脚的滞回曲线影响不大;柱管嵌固长度较长的柱脚滞回曲线表现为稳定的纺锤形，而嵌固长度较短的柱脚滞回曲线表现为收缩形;柱脚极限承载力的计算结果与试验值吻合较好;柱脚的初始刚度分为两种抗力机制：（1）柱脚的转动刚度为1.锚栓和底板。前者刚度和强度较大，结构性能较好，但施工工序较复杂，必须先安装钢筋，再浇筑基础梁混凝土。与预埋式相比，半预埋式钢管混凝土柱脚刚度和强度较小，但施工方便，造价较低。本文提出了半预埋式钢管混凝土柱脚，研究结果如下：1）柱管的局部屈曲对试件的滞回曲线影响不大; 2）柱管埋置长度越长，滞回曲线越接近稳定的纺锤形;而长度较短的则呈捏缩状。将半埋式柱脚的初始刚度分解为两种抗力机制;（1）由锚栓和底板提供的转动刚度;（2）钢筋混凝土基础梁的抗弯刚度和抗撬刚度之和;（5）由4）中提到的机构提供的初始刚度很好地估计了试验值。少

In this paper, a new type of column base is produced of which the structural performance have been investigated experimentally, and the estimation of the maximum strength and initial stiffness is discussed. The idea of the proposed column base has been developed from the two conventional methods. The other is the bare type; the column is embedded into the reinforced concrete foundation beam with a certain length. The other is the bare type; the column is connected to the foundation beam by the anchor bolts and a base plate. The former shows the larger stiffness and strength, and the better structural performance, but the procedure of the construction is rather complicated ; the erection of the steel must be done before the concrete casting of the foundation beams. The latter has smaller stiffness and strength compared to the embedded type, but it is easy to construct, and the cost of construction is less. The semi-embedded type of CFT column base proposed in this paper.The research fin … More dings are as follows :1) Local buckling of the column tube did not much affect the behavior2) The hysteresis loops of specimens with longer embedded length showed the stable spindle shapes, but those with shorter length showed the pinched shape.3) The proposed calculation for the ultimate strength showed a good evaluation to the experimental values.4) The initial stiffness of a semi-embedded column base was provided into two resisting mechanisms; i) rotational stiffness by. the anchor bolts and base plate. The former shows the larger stiffness and strength, and the better structural performance, but the procedure of the construction is rather complicated; the erection of the steel must be done before the concrete casting of the foundation beams. The latter has smaller stiffness and strength compared to the embedded type, but it is easy to construct, and the cost of construction is less. The semi-embedded type of CFT column base proposed in this paper.The research findings are as follows :1) Local buckling of the column tube did not much affect the behavior2) The hysteresis loops of specimens with longer embedded length showed the stable spindle shapes, but those with shorter length showed the pinched shape.3) The proposed calculation for the ultimate strength showed a good evaluation to the experimental values.4) The initial stiffness of a semi-embedded column base was provided into two resisting mechanisms; i) rotational stiffness by the anchor bolts and base plate, ii) the sum of bending stiffness and prying resistance of reinforced concrete foundation beam.5) The initial stiffness provided by the mechanisms mentioned in 4) well estimated the experimental values. Less