Numerical models to predict residual adhesion between steel and fiber-reinforced concrete at high temperature

The mechanism of adhesion between corrugated steel and concrete is fundamental in the study of the structural capacity of reinforced concrete. Although this mechanism can be compromised in fire situations, it is probably one of the least studied phenomena in the field of concrete technology and is not contemplated in the design regulations. This paper presents an exhaustive review of the available experimental data, focusing especially on fiber-reinforced concrete. The data allow characterizing the evolution of the adhesion as a function of three variables: the maximum exposure temperature, the type of fiber and its volume fraction. Initially, a linear multiple regression analysis was performed, followed by a series of non-linear numerical models. These models have been constructed using an approach based on the finite element method combined with the Galerkin method formulation. The numerical models have been developed for different degrees of mesh complexity. The error measurements resulting from the application of the above techniques are then compared in order to propose a suitable prediction model. Finally, the selected model is validated for different input values of the independent variables. This last phase serves as a basis for a discussion on how these independent variables affect the evolution of the adhesion between steel and fiber-reinforced concrete after exposure to high temperatures.