Development and experimental investigation of hybrid precast concrete beam-column joints

In this study, an innovative type of hybrid beam-column joint using energy dissipated connection plates and I-shaped steel connectors to connect beams and columns was developed. Five interior beam-column specimens including a monolithic specimen and four hybrid precast joints, were tested under reversed cyclic loading to evaluate the seismic behavior of the connections. Test variables were the hybrid connection forms, flange cover plate, and steel fiber concrete usage. During the test, the hysteresis curves and cracking patterns were recorded. The seismic indicators, such as stiffness degradation, strength, energy dissipation, and ductility were determined. The test results revealed that the hybrid joint with the energy dissipated connection plates and steel fiber concrete failed in a typical flexural mode, exhibited stable hysteretic responses, and showed satisfactory seismic performance. The strength and cumulative energy dissipation of the proposed joint were higher by 46.6% and 230.9%, respectively, when compared with the monolithic specimen. The proposed hybrid connection could effectively transfer the plastic hinges to the connection region, reduce the damage and mitigate the stiffness deterioration due to the energy dissipated connection plates and the tensile deformability of the steel fiber. Therefore, the hybrid beam-column joints had superior performance to resist seismic loading. The developed seismic beam-column joints give a viable alternative for the precast concrete moment-resisting frames due to easy construction.