헤드철근을 사용한 철근콘크리트 모서리 접합부의 이력거동에 관한 연구

The studies of beam-column joint in RC frame structure, generally, have focused on the lowest floor because the plastic hinge initiates and develops in the lowest floor. As geometric limitations, it is often difficult to use of larger diameter reinforcing bars in the top floor, due to the fabrication problems. In case of corner joints, as they connect columns and beams together, reinforcement congestion is likely to occur; thus a detailing can be very useful by using mechanical anchoring. Headed reinforcement is expected to improve the performance in corner joints, but if the concrete is not adequately restrained, it could easily lead to brittle failure. This study offers a various details for corner joint anchored with headed reinforcement, examines their structural properties, and endeavors to provide a database to develop efficient details for the fabrication and construction. To evaluate the performance of the corner joint details that are subjected to cyclic load, five specimens were designed and tested. Main parameter considered in the test is the anchorage detail of reinforcement. Test results shows that when repetitive stress is applied in the beam-column corner joint where head reinforcement was anchored, the exterior joint was exposed to the risk of brittle failure. Especially when the exterior column and the beam were placed with only the head, the structure was subject to low inner strength and rapid brittle failure under opening moment. To prevent this, additional transverse reinforcement is needed within the joint to restrain concrete adequately.