Effects of Transverse Reinforcement and Bonded length on the Side-Blowout Capacity of Headed Reinforcement

Pullout tests were conducted on deeply embedded headed reinforcement to determine the effect of transverse reinforcement and bonded length on the side-blowout capacity and load-slip behavior of the anchorage. It was found that transverse ties or stirrups in the anchorage zone had little effect on the ultimate capacity. Increases in anchorage capacity were only observed when the head was positively anchored in contact behind a large crossing bar. Transverse reinforcement also had little effect on the load-slip behavior before failure. However, when large amounts to transverse reinforcement were placed near the head, the amount of load maintained after the blowout failure occurred was increased. Additional bonded length of a preformed reinforcing bar increased the anchorage capacity and reduced the head slip for a given load. The amount of increase in capacity can be predicted using current ACI provisions for development length. Design procedures taking into account the effects of transverse reinforcement and bonded length were developed.