Bond properties for deformed steel bar in frost-damaged concrete under monotonic and reversed cyclic loading

This study presented a systemic research to investigate the bond properties for deformed steel bar in frost-damaged concrete under monotonic and reversed cyclic loading. Specimens of three kinds of concrete strength grade and four kinds of frost damage level were tested and the primary bond response indications were analyzed. Results showed that accompanied by the increasing number of freezing and -thawing cycles, the initial bond stiffness, the maximum bond resistance and the remaining bond strength decreased whereas the slip at peak bond stress increased, moreover, the progressive acceleration of bond stiffness degeneration as well as the more obvious bond strength decay and the worse energy dissipation capacity were also observed for the specimens of the same concrete strength grade. Results also indicated that with regard to the specimens exposed to the same freezing-and-thawing cycles, the initial bond stiffness, the slip at peak bond stress, the maximum bond resistance and the remaining bond strength increased with the increasing concrete strength grade. Thereafter, the analytical local bond stress-slip models for deformed steel bar in frost-damaged concrete under monotonic and reversed cyclic loading were presented to reproduce the bond degradation caused by loading and freezing-and-thawing. (C) 2017 Elsevier Ltd. All rights reserved.