Mechanical Anchorage in Exterior Beam-Column Joints Subjected to Cyclic Loading

The effectiveness of headed bars terminating in exterior beam-column joints was assessed. Nine inter-story and five roof-level joint specimens were tested under reversed cyclic loading, where the primary test parameters were the anchorage type, the size and arrangement of the beam bars and the heads, and the detailing provided for roof joints. The test results indicate that hysteric behavior of the exterior joints constructed with headed bars was similar or superior to joints constructed and tested with hooked bars commonly used in Korean practice. Head size with a net area of three to four times the bar area was sufficient to anchor the beam reinforcement effectively within the exterior beam-column joint. The test results also indicate that, in addition to providing vertical U-bars at roof joints, heads on column bars should extend beyond the beam top bars to provide improved behavior.