Structural Performance of Exterior Beam-Column Joints with Large Diameter Headed Bars

Abstract

Generally, a conventional standard hook is used for the reinforcement's anchorage. However, this results in steel congestion, and it makes fabrication and construction difficult. Using a headed bar offers a potential solution for these problems and may also ease fabrication, construction and concrete placement. But, in current design code of the headed bar, it had limitation about the yield strength and the diameter of rebar etc. It hard to use the large diameter headed bar in the reinforced concrete structure. This paper presents the cyclic responses of four reinforced concrete exterior beam-column joints, which are anchored with large diameter headed bars or hooked bars. To evaluate the anchorage capacity of large diameter headed bars, specimen variables were set with anchorage detail, side cover thickness of concrete, and transverse reinforcement. Also, structural performance of beam-column joints is evaluated and compared with each other. The behavior of joints with headed bars are as good as, or better than those companion joints with 90-degree hooked bars. Test results show that the large diameter headed bar has enough anchorage capacity in exterior beam-column joints. Test results show side cover of concrete improved the anchorage capacity of the bars and transverse reinforcement enhanced the anchorage capacity and ductility of joints.