Investigation on the Pull-out Behavior of Deformed Bars in Cracked Reinforced Concrete

Abstract

Pull-out tests and numerical analyses for deformed bar were performed on test specimens having cracks in concrete along the axial direction of the bar. The parameters for the experiment and analysis were: the maximum width of the initial crack, the presence or absence of a mechanical anchorage, the presence or absence of bond on either side of the deformed bar, and the presence or absence of a transverse bar. In both the experiments and the analyses, the pull-out load was applied at the end of the deformed bar after introducing the initial cracking by means of preloading. The results showed that the pull-out performance was greatly reduced by cracking along the axial direction of the bar. Also, it was seen that cracking along the deformed bar tended to occur only on one side of the bar. In the particular case of mechanical anchorage it was found that bending stresses occurred near the anchorage due to eccentric loading. The transverse bar increases the residual crack width when the same initial crack width was generated before unloading and also inducing spalling of the concrete cover due to cracking of the bond, resulting the reduction in pull-out strength.