Beam-column connections in a ductile RC frame is a critical region, especially under the action of earthquake loading. The parameters affecting the problem are numerous and not yet completely defined. For this reason a lot of researchers have experimentally investigated and analytically studied the connection under simulated seismic forces. Nevertheless no simple design tool has yet been found.
For both interior and exterior beam-column joints the core is affected by a biaxial stress state of tension and compression which causes failure. An analytical expression, which takes into account this stress state, is here presented to estimate the shear strength of interior and exterior RC joints under seismic loading. This expression is based on the superposition of three resisting contributions to shear strength: the concrete, the longitudinal reinforcement and the stirrup ones.
The reliability of the here obtained expression is compared with those obtained by means of some analytical expressions recently proposed by other authors, and it has found to be the best.
From this optimizing expression a design formula for calculating the joint shear strength is also obtained and its results are compared with those obtained by means of American, New Zealand and European Code formulas. Also from this comparison the proposed formula is found to most adequately predict the shear strength of the joint and to give the best correlation with the test results (more than 300 interior and exte- rior RC beam-column joints) found in the literature. This is the most numerous specimen of RC joint nowadays collected.
