Abstract
RC beam-column knee joints are usually the critical section of frame structures where shear load and bending moment are concentrated. But the knowledge on the ultimate strength and ductility of knee joints are not enough to establish rational design method of the joints. In this study, we have carried out loading tests of RC knee joint specimens and have proposed the method to evaluate diagonal cracking strength and yield strength of knee joints under opening moment. We have also discussed on mechanisms of the strength reduction of knee joints under load reversals. We have shown that equivalent dumping coefficient of knee joints become small by the contribution of shear deformation of panel zone of the joint and reduction of compressive force sustained by diagonal compressive strut of concrete is deeply related to strength reduction of knee joint under load reversals.
