Components of Side-Face Blowout Strengths of Headed Bars in Exterior Beam-Column Joints

摘要

The anchorage strength of a headed bar is provided by the head bearing and bond, and the ratio of the two components are affected by the failure modes and geometric conditions. The head-bearing and bond components are evaluated for headed bars in exterior beam-column joints that fail due to a side-face blowout. The head bearing contribution is not related to the embedment length. After the bond contribution reaches a peak value, the bond is reduced. The bond contribution at failure is linearly proportional to the embedment length with a negative constant that is caused by the bond reduction. As more confinement of the side cover and transverse reinforcement is provided, the head bearing contribution increases more than the bond contribution due to the bond reduction. A model for predicting the anchorage strength of headed bars in exterior beam-column joints is proposed, including the effects of side cover and transverse reinforcement on each component.