Abstract
There are two strength formulae for evaluating the shear strength of R/C members in the AIJ design guideline for earthquake resisting concrete buildings. These two formulae have about same accuracy to predict the shear strength of R/C members, however, the assumptions of the strut angle of the truss mechanism and the effective factor are different in these expressions. In this study, the strut angle and the effective factor are examined by means of FEM and previous experiments. As a result, the strut angle of the truss mechanism is similar to the method B compared with the method A.