Effect of confinement on bond strength between self-compacting concrete and reinforcement

Abstract

Slippage of the beam reinforcement at beam–column connections is an important cause of damage of reinforced frames under static and dynamic loads. This paper presents the effects of confinement in self-compacting concrete (SCC), on the local bond stress vs. slip characteristics of deformed bars in reinforced concrete joints. Prismatic specimens with deformed steel bars embedded for a fixed length equal to three and five equivalent diameters were tested under monotonic loading. The specimens represented the confined region of a beam–column connection. The obtained results indicated that as far as the bond splitting cracks are restrained by reinforcing bars crossing these cracks, confinement of concrete by transverse reinforcement has insignificant effect on the local bond behavior. The specimens having no confining reinforcement failed by splitting of the concrete in the plane of the longitudinal axis of the bar at small bond stress. The failure of specimens with confined concrete was caused by pulling out of the bars at steel stresses below yield strength.