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不同材料组合的钢管混凝土柱的极限强度和塑性变形能力，寻求最优的材料组合。普通和/或高强混凝土(FC=240 kg/cm^2和FC=500 kg/cm^2)用于钢管保护柱和钢管柱。试件中心分别为大直径或小直径圆管或宽翼缘截面，试件由柱和梁组成十字形组合。试验结果表明，即使采用高强混凝土，其广义附加强度公式也能较好地评价钢管混凝土和钢管混凝土柱的极限强度。然而，对于宽翼缘截面的柱，通常会高估，箍外混凝土的极限强度应考虑为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较大，分别对应于日本建筑标准法定义的结构等级A和结构等级FB，由此得出的结论是，用广义附加公式可以较好地估算钢管混凝土和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.