Effective factors on shear resistance of R/C interior beam-column joints were analyzed by using experimental data including 243 specimens tested in Japan and abroad. A reliable equation to evaluate the joint shear strength was proposed using the regression analysis of the shear strength and three factors : concrete strength, column axial stress and bond index which was consisted of joint reinforcement and beam bar bond stress in the joint. The failure modes in joint shear and in beam/column flexure can be easily distinguished by this equation. On the other hand, the joint shear strength calculated from concrete effective compression strength of diagonal joint strut idealized by the authors and from joint reinforcements, showed good approximation to the experimental values. These results support that shear stress transfer of interior beam-column joints consists of the strut and truss mechanisms.
