不同加载方向下五边形截面钢管混凝土巨型柱抗震性能试验研究

Seismic behavior of pentagonal cross-section CFST mega-columns under horizontal loading in different directions

为研究五边形钢管混凝土巨型柱不同加载方向的抗震性能,设计了6个1/7.5缩尺的巨型柱模型试件,试件截面构造包括单腔体腔内配置钢筋、4腔体腔内未配置钢筋和4腔体每腔体内配置钢筋。进行了两种不同加载方向的拟静力研究,一种沿截面对称轴方向加载,另一种沿垂直截面对称轴方向加载。分析了各试件的破坏特征、滞回特性、承载力、延性、刚度退化和耗能性能。结果表明:五边形截面钢管混凝土巨型柱三种截面构造中,4腔体每腔体内配置钢筋的试件抗震能力较强;不同加载方向五边形截面钢管混凝土巨型柱受力性能有明显差异,设计中应考虑两个方向抗震能力的均衡性;五边形截面钢管混凝土巨型柱,屈服位移角均值为1/75,最大弹塑性位移角均值达1/24,具有良好的延性。

In order to study seismic behavior of the pentagonal cross-section concrete filled steel tube （CFST） megacolumn under horizontal loading in different directions, six 1/7.5 scaled mega-column specimens were designed. The section constructional details of the specimens are divided into three types, including one cavity with steel bars inside, four cavities without steel bars inside and four cavities with steel bars inside. The test was conducted under two kinds of low cyclic loading in different directions. One loading direction was along the axis of symmetry and the other perpendicular to axis of symmetry. The failure modes, hysteresis behavior, bearing-capacity, ductility, stiffness degradation, and energy dissipation were analyzed. Research result shows： among the three different cross-section types, the seismic behavior of the specimens with four cavities and inner steel bars are the best; the mechanical property of pentagonal cross-section CFST mega-columns varies obviously in different directions, hence, the balance of the seismic behavior in the two directions should be considered; as the yielding story drift ratio is 1/75 and the maximum elasto-plastic story drift ratio reaches 1/24, the ductility of the mega-columns are proved to be perfect.