Analysis of joint shear failure of high-strength reinforced concrete interior beam-to-column joint

摘要

The objective of this study is to point out an irrationality of the existing joint shear failure models for reinforced concrete beam-to-column joint. Test results of nine high strength concrete interior beam-to-column-joint subassembledges failed in joint shear are investigated. Joint shear was evaluated from strain in reinforcing bars of the specimens. It is revealed that joint shear had increased in the most specimens, even after apparent increase of joint shear strain and story drift. At the same time, beam moment decreased due to decrease of flexural resistance caused by reduction of distance between stress resultants in beam at column face. So the cause of the deterioration of story shear was identified as the result of softening anchorage of beam reinforcements through the joint core. This investigation reveals the irrationality of hypothesis about joint shear failure models which the current design codes assume.