EXPERIMENTAL STUDY OF SEISMIC PERFORMANCES FOR POST-ANCHORED BEAM-COLUMN JOINTS IN REINFORCED CONCRETE FRAME

Being aimed at the post-anchoring joints of RC beams and columns widely applied in engineering practices of renovation and reinforcement of existing structures，the seismic performance of those post-anchored joints was researched experimentally． The specimens were designed according to the prototype structure with a scale of 1∶ 2． The multiple post-anchored joints in frame structure were considered comprehensively，including the post-cast column on the top of the intermediate frame，the post-cast beam and column on the top of the side frame，and the post-cast beam connected to the intermediate layer． At the same time，several post-anchoring methods were studied，such as reinforcement implanted directly，adding additional reinforcements，and strengthening the main reinforcements by welding steel strip hoop． During the whole experimental process，the laws of the cracks，failure pattern，ductility， energy dissipation capacity and stiffness degradation for different joints were researched carefully． The conclusions were got that the seismic performance of post-anchored joints could be remained by considering the design principle of strong column and weak beam，strong joint and weak member，and anchorage length． The ductility of the whole structure could be improved by strengthening connections． The integrity of the structure should be considered when the new-old beams were connected，so as to ensure the unified strengthening on both sides．