Bearing angle model for bond of reinforcing bars to concrete

Abstract

The rib geometry of deformed bars governs bond behavior and is instrumental in guaranteeing adequate bond resistance. The ribs of bars can split the concrete cover and shear off the concrete key by wedging action. This study is intended to explain the nature of the wedging action of ribbed bars as they interact with concrete during bond failure. Analytical expressions to predict bond resistances for splitting and shearing are derived, in which the bearing angle is a key variable. As the bearing angle is decreased, the splitting bond resistance decreases while the shearing bond resistance increases. In the case of bars at a moderate level of confinement, the bearing angle is decreased to decrease the splitting resistance and to increase the shearing resistance, and then the concrete key is sheared off. The bearing angle is determined so that the splitting resistance can be equal to the shearing resistance. The bearing angle model is proposed to better understand bond mechanisms between ribbed reinforcing bars and concrete.