Abstract
Cyclic loading tests of composite short colunns with the ratio of the shear span equals 1.5 were carried out. The steel sections of specimens were H shapes and cross-H shapes. There were six specimens with three kinds of the ratio of steel area to steel and reinforcement area, SP/(SP+RP), : 30, 60 and 90%. The inelastic hysteretic behavior and the shares of the steel and the reinforcement in sustaining the in tennal force were compared among the three SP/(SP+RP) ratios and following conclusions weve obtained. (1) The area of the hysteresis loops of the column yielded under bending moment increased stabely with the increase of deformation even for the column with SP/(SP+RP)=30%. (2) It is considered that the excess amount of hoops had the effect of maintaining the bending strength of the concrete section. (3) The ratios of internal bending moment sustained by the steel section and the reinforcement section to the external force reached those of respective bending strengths to the external force in the final state of stress. (4) The ratio of internal shear force sustained by the steel section and the reiaforcement section to the external fore was the same as the above flexural behavior in case of the encased H-shaped steel, but was in excess of that in case of the encased cross H-shaped steel. It is considered that the steel web and hoops contributed to take up a part of interral bending moment sustained by the concrete section. (5) The value of internal axial force sustained by the steel shifted from compression to tension with the progress of tension cracks of the concrete.
