Structural performance of concrete sandwich panels under fire

Abstract This paper investigates the structural performance of load-bearing precast concrete sandwich panels subjected to one-sided fire. It focuses on panels made with FRP diagonal-bar connectors. Heat transfer analysis is conducted for characterizing the temperature gradient within the panel and a structural model is developed. The model considers the composite action between the reinforced concrete (RC) wythes, the transient creep of concrete under fire, strain softening in compression, cracking and tension stiffening, yielding of the steel reinforcement and geometric nonlinearity. The heat transfer analysis is conducted using a finite element approximation, and the governing differential equations of the structural model are solved using the nonlinear shooting method following an iterative procedure. The model is validated through comparisons with test results and other models in the literature. A numerical example and a parametric study that show the capabilities of the proposed model and clarify the structural behavior are presented. The results reveal progressive failures of the FRP-bar connectors and buckling failures of the panels under fire. It is revealed that the load eccentricity of the applied load greatly affects both the structural performance and the fire resistance of the panels. The diameter of FRP bars, the thickness of insulation layer and the load level are also found to play key roles in the fire resistance of the panels.