Local Buckling Restraining Behavior of Thin-Walled Circular CFT Columns under Seismic Loads
Local Buckling Restraining Behavior of Thin-Walled Circular CFT Columns under Seismic Loads
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DOI：
10.1061/(asce)st.1943-541x.0000904
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发表时间：
2014-05-01
影响因子：
4.1
通讯作者：
Lu, Xilin
中科院分区：
文献类型：
--
作者：
Goto, Yoshiaki;Ebisawa, Takemasa;Lu, Xilin
通过双向低周反复荷载试验和双向振动台试验，研究了薄壁圆钢管混凝土柱在地震荷载作用下的局部屈曲约束性能。根据双向循环加载试验中测得的变形和应变的响应，作用在钢管屈曲部分的轴向压力随着其局部屈曲变形的增加而减小，这是因为大部分的轴向压力从钢管传递到填充混凝土。钢管中的压缩轴向力的减小减缓了屈曲变形的进展。此外，在局部屈曲发生后施加的循环荷载下，填充混凝土中发生主要水平裂缝的张开和闭合以及膨胀。结果，主要的拉伸轴向力重复地作用在外钢管的屈曲部分上。该张力通过拉伸局部屈曲变形来抑制或恢复局部屈曲变形。如果在填充混凝土的上表面处的钢管上安装隔膜，则拉力的大小进一步增强。振动台试验结果表明，在地震加速度作用下，两种结构的局部屈曲抑制性能相似。振动台试验和数值分析结果表明，钢管混凝土柱的残余侧移位移δ（r）与最大反应侧移位移δ（m）之比（δ（r）/δ（m））一般比空心柱小得多，这是由于钢管混凝土柱的强度和延性得到了提高。(C)2013年美国土木工程师协会。
The local buckling restraining behavior of thin-walled circular concrete-filled tubular (CFT) columns is examined under seismic loads by conducting a bidirectional cyclic loading and a bidirectional shaking table test. According to the responses of the deformations and strains measured in the bidirectional cyclic loading test, the axial compressive force acting on the buckled part of a steel tube is reduced with the increase in its local buckling deformation because most of the compressive axial force is transferred from the steel tube to the in-filled concrete. The reduction in the compressive axial force in the steel tube slows the progress of the buckling deformation. In addition, under a cyclic load applied after the occurrence of local buckling, the opening and closing of major horizontal cracks and dilation occur in the in-filled concrete. As a result, a predominant tensile axial force acts repeatedly on the buckled part of the outer steel tube. This tensile force restrains or restores the local buckling deformations by stretching them. The magnitude of the tensile force is enhanced further if a diaphragm is installed on the steel tube at the upper surface of the in-filled concrete. The shaking table test confirms that the local buckling restraining behavior is similar under seismic accelerations. The shaking table test together with the numerical analysis illustrates that the ratio between the residual sway displacement delta(r) and the maximum response sway displacement delta(m,), defined as delta(r)/delta(m) for CFT columns, is generally much smaller than that for hollow columns because of the enhanced strength and ductility of CFT columns. (C) 2013 American Society of Civil Engineers.