BREAKOUT CAPACITY OF HEADED ANCHORS IN CONFINED CONCRETE: EXPERIMENTAL EVIDENCE

While provisions are available in the current design codes that account for the presence of tensile fields causing concrete cracking, no provisions are available for anchors embedded in compressively prestressed concrete. Because of this lack of information, a series of experiments were performed to evaluate the tensile breakout capacity of headed anchors embedded in confined and unconfined concrete. To simulate the confinement, uniform biaxial compression (prestress) was applied to concrete specimens in the directions orthogonal to the anchors’ stems. This paper discusses the influence of embedment depth and confinement on the behavior of headed anchors in terms of strength, ductility, and failure pattern. A comparison between actual code provisions for unconfined concrete and the experimental results reported herein is provided. Proposals for the extension of the actual provisions to take into account for the effects of confinement are provided and are contingent upon completion of further investigation.