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

本文的研究目的是获得钢管混凝土柱在几种材料组合下的极限承载力和塑性变形能力，并寻求最佳的材料组合。普通和/或高强度混凝土（Fc= 240 kg/cm ^2和Fc= 500 kg/cm ^2）用于钢管柱和钢管填充柱。柱为大、小直径圆管或中心宽翼缘截面，试件为十字形柱梁组合体。试验结果表明，钢管混凝土柱的广义附加强度公式可以较好地估算钢管混凝土柱的极限承载力，即使采用高强混凝土也是如此。但对于采用宽翼缘截面的柱，其极限承载力往往过高，箍筋外混凝土的极限承载力应考虑为fc '= 0.2fc。此外，大直径钢管混凝土柱和小直径钢管混凝土柱的塑性变形能力都很高，分别相当于日本建筑标准法中规定的结构等级I的FA和结构等级FB，因此，由此可见，广义附加方程可以较好地估算钢管混凝土柱的极限承载力。这些柱子对地震力有韧性。

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.