Role of Stirrups and Residual Tensile Strength of Cracked Concrete on Bond

Abstract

The local bond‐slip law of an anchored ribbed bar after the splitting of its surrounding concrete is studied. Particular attention is devoted to understanding the reason why several experimental results show a different variability of this law along the bar. Actually, the bond is governed by the local confining action, which can vary; and its variability depends on both concrete mechanical properties and geometrical characteristics of the specimen. A significant contribution to this action is due to the transverse reinforcement and the residual tensile strength of splitted concrete. Another contribution is due to the structural characteristics, such as the transverse support restraints and possible lateral loads. A refined analytical model involving the local mechanical properties of concrete and the interaction phenomena between the principal and transverse reinforcement is developed. Experimental confirmations of the theoretical results are also presented. Finally, diagrams that are significant for design are shown, giving indications of the minimum transverse reinforcement needed to prevent splitting failure and to limit the opening of the splitting crack.