In order to establish a rational design method for reinforced concrete (RC) structures against earthquakes, a Finite Element Method (FEM) using "Smeared Crack Model" is considered to be one of the most powerful and effective techniques. The authors are devoting themselves to construct a hysteretic constitutive model of RC under reversed cyclic loads to be used in FEM analysis. At the first step of the research work for establishing a hysteretic constitutive model, the fundamental test series, i. e. the shear test series of RC panels subjected to reversed cyclic in-plane shear stress were conducted by the authors. In the previous paper, the obtained test data of this experiment and the dominant characteristics for the nonlinear analysis of RC panels were presented quantitatively as well as qualitatively. In this paper, a new constitutive model for the analysis of hysteretic behavior of cracked concrete is proposed based on the hysteretic characteristics concerning the folowing items ; 1) cracking stress 2) residual stress and strain caused by alternating shear 3) slip stiffness in low stress state 4) stress-strain relationships of tensile and compressive concrete 5) variation of stress and strain caused by reversal alternating shear The new model was developed by modifying the Collins' theory which was originally derived from monotonic shear tests of RC panels to represent the behavior well under alternated reversal in-plane shear loading. The appropriateness of the proposed constitutive model was shown by applying it to the shear test series of the authors described in the previous paper. Furthermore, the model was also applied to other existing panel tests and torsional cylinder tests. The analytical results grasped well the observed test ones in each case and it is concluded that the proposed constitutive model is adequate.
