Bond-slip behavior between concrete and deformed rebar at elevated temperature: Mesoscale simulation and formulation

Abstract

Fire accidents will cause deterioration of the mechanical properties of steel and concrete, which will affect the bond-slip behavior of the interface between steel and concrete. In this work, in order to further understand the relationship between bonding performance of reinforced concrete and temperature, a central pull-out test by the three-dimensional (3D) mesoscale numerical model was established. The surface shape of deformed rebar and the heterogeneity of concrete were considered in the model. The effectiveness of the mesoscale model was verified against with the available test results. Moreover, the bond failure mechanism between deformed rebar and concrete was discussed. Subsequently, the influence of thickness to diameter ratio, elevated temperature and cooling down on the bonding behavior was discussed using the mesoscale numerical model. The results show that the failure mode and the bond stress-slip curve of the specimen are obviously related to the ratio of thickness to diameter. The bond strength, slip and bond stress-slip curve of the specimen at high temperature are significantly different from those after cooling down according to the experimental and numerical results. The influence of temperature on bond strength is greater than that on slip. Finally, on the basis of the existing theoretical model of bonding behavior at room temperature, a calculation method that can predict the bond stress-slip curve at elevated constant temperature is proposed. The calculation results are compared with the simulation and test results to illustrate the validity of the prediction formula.