A multi-mechanical bond-slip model for bar-concrete interface under confinement-corrosion coupling conditions

Abstract

The use of stirrup/FRP confinement significantly contributes to the mechanical performance of corroded reinforced concrete (RC) members, the evolution of bond behavior of bars, however, is unclear for the confinement-corrosion coupling conditions. To address this issue, a new bond-slip model was established within the framework of multi-mechanical theory, which can accurately capture the bond-slip response of specimens subjected to such coupled conditions. Taking the independent evolution of bond stress and slip into consideration, the bond stress of the new model was determined by the thick-walled model and fictitious crack model based on elastic-plastic mechanics. The additional effects of confinement and corrosion on bond were incorporated through an optimization algorithm-modified thick-walled cylinder model. Based on the damage mechanics, the elastic-plastic evolution of slip was developed within the thermodynamic framework. The final bond-slip response was reproduced by superimposing an infinite number of characteristic points, where the bond stress and slip were independently determined by their corresponding functions. The proposed model can not only exhibit good agreement compared with test results but also provide a phenomenological insight into the underlying mechanisms governing the bond-slip response under coupled confinement-corrosion conditions.