STUDY ON DYNAMIC HYSTERESIS OF REINFORCED CONCRETE AND STEEL MEMBERS SUBJECTED TO COMBINED STRESSES AND NONLINEAR DYNAMIC ANALYSIS

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During 2002 to 2004, we conducted the experimental research to clarify the hysteresis of reinforced concrete members subjected to axial forces, bending and torsional moments. Experimental parameters are initial axial forces, pitch of hoop lateral ties, and ratios of bending loads and torsional loads. The following new conclusion is obtained by experimental results for 20 models.About restoring characteristics,1)The pitch of hoop lateral tie(HLT) remarkably affect for hysteresis loop for torsion, but not for bending.2)In torsional load surpass type, energy absorption is also carried out by bending for poor HLT models (ctc=60mm), but is not carried out by bending for sufficient HLT models (ctc=30mm).3)In case of sufficient HLT, amount of energy absorption for combined loading type is largest, but in case of poor HLT largest energy absorption member vary in accordance with surpass loading.About interaction curves of bending and torsion,1)Interaction curves become larger according to the increasing of the initial axial forces. The effect of pitch of HLT is few for crack and yield interaction curves, but it remarkably affect for ultimate strength interaction curves especially in torsion surpass region.2)For normalized interaction relations, safety side interaction curves are proposed. Interaction curves for maximum strength of the member depend on the pitch of HLT.3)The boundary of torsion surpass region and bending surpass region depend on the pitch of HLT. Therefore the further investigation to clarify the boundary is necessary.