Abstract:To investigate the influence of different experimental methods on the bond performance between corroded rebars and concrete, numerical simulations were conducted on pull-out tests and beam tests. Corresponding pull-out and beam models were established, and the effects of non-uniform corrosion of tensile rebars and confinement conditions (thickness-diameter ratio and stirrup confinement) on bond performance were analyzed. In the numerical models, mechanical interlocking forces were simulated by fine modeling of the tensile rebar and the surrounding concrete, while frictional forces were reflected through face-to-face contact ignoring chemical bond forces. The corrosion heterogeneity within the cross-section of tensile rebar was also considered. A two-stage numerical analysis method was adopted, in which the influence of corrosion on the bond behavior between the rebars and the concrete interface was simulated by applying enforced displacements and then the bond performance of corroded specimens was analyzed. The results show that the experimental methods have a significant impact on the failure mode and bond stress-slip curve of the corroded specimens. The existing corrosion-induced cracks are deepened and widened in both the beam and pull-out models when the bond failure occurs, but the beam model also generates diagonally traversing cracks throughout the bond area. The bond strength and descending segment slope in the pull-out model are significantly greater than those in the beam model. Stirrups barely influence the bond strength. As the thickness-diameter ratio increases from 2.0 to 3.5, the bond strength in the beam model and pull-out model increases by 16% and 32% respectively at 3% corrosion rate. After demonstrating the validity of the aforementioned numerical model through comparing numerical results with experimental results, a normalized model was established for bond strength applicable to different test methods. Subsequently, comparison between the results calculated by this normalized bond strength model and those obtained from numerical simulations reveals good agreement, thereby confirming the reliability of the proposed normalized model.
