ULTIMATE STRENGTH AND DEFORMABILITY OF CONCRETE FILLED AND COVERED STEEL TUBE COLUMNS WITH SEVERAL MATERIAL COMBINATIONS

本研究的目的是获得几种材料组合下钢管混凝土柱的极限强度和塑性变形能力，并寻求最优的材料组合。覆盖钢管柱和填充钢管柱采用普通和/或高强混凝土（Fc=240kg/cm^2和Fc=500kg/cm^2）。柱分别采用大直径或小直径圆管，或中心宽法兰截面。试验试样是由柱和梁组成的十字形的子组合。它们被反复加载弯矩，这对应于强烈的地震荷载，以及竖向荷载，柱的30%轴力能力同时。试验结果表明，即使采用高强混凝土，广义附加强度方程也能较好地计算钢管混凝土的极限强度。然而，对于采用宽翼缘截面的柱，通常会高估，箍筋外混凝土的极限强度应考虑为fc′=0.2fc。此外，判断直径较大和直径较小的钢管混凝土覆盖柱的塑性变形能力相当高，分别对应于日本建筑标准法定义的结构一级FA和结构板FB。结果表明，采用广义附加方程可以较好地估计钢管混凝土柱的极限强度。这些柱子对地震力是有延展性的。

The purposes of this research are to obtain the ultimate strength and the plastic deformability of concrete filled and covered steel tube columns with several material combinations and to seek the optimum material combinations. Ordinary and/or high strength concrete (Fc=240kg/cm^2 and Fc=500kg/cm^2) are used for covered and filled steel tube columns. And columns have circular tubes with large or small diameter, or wide flange sections at the center respectively.Test specimens are sub-assemblages of cruciform consisted of columns and beams. They are loaded with repeated bending moments, which corresponds to severe seismic loadings, as well as vertical loading, 30% of axial force capcity of the columns simultaneously.It is obtained from the experiment results that the generalized additional strength equations of columns can evaluate the ultimate strength of concrete filled and covered steel tube columns satisfactorily, even using high strength concrete. However, for columns using wide flange sections, it overestimates usually, and the ultimate strength of concrete outside of hoop reinforcement should be considered to be fc'=0.2fc. Moreover, the plstic deformability of columns with concrete filled and covered steel tube with larger diameter and with smaller diameter were judged to be considerably high, which corresponds to FA to the structural rank I and FB to the structural lank respectively defined with Japanese Building Standard Law.Consequently, as the conclusions the ultimate strength of concrete covered and filled steel tube columns can be estimated with the generalized additional equations satisfactorily. And these columns are ductile to seismic forces.