Three-Dimensional Finite-Element Modeling of the Thermomechanical Response of GFRP-Reinforced Concrete Slab Strips Subjected to Fire

Abstract

The fire design of reinforced concrete (RC) members with glass fiber–reinforced polymer (GFRP) bars comprising lap splices and cold anchoring zones requires the explicit consideration of the GFRP–concrete bond degradation with temperature; however, few studies in the literature have addressed this issue. This paper presents numerical investigations in which three-dimensional finite-element models were developed to simulate fire resistance tests performed in GFRP-RC slab strips subjected to a fire load and current standards. The slabs comprised continuous and spliced reinforcements, as well as different concrete cover thicknesses and concrete strengths. In the models, the GFRP–concrete interaction was simulated by means of previously calibrated local bond stress–slip laws at different temperatures. This study provided new insights into the fire behavior of GFRP-RC flexural members, confirming that their fire resistance can be drastically reduced when lap splices, designed for ambient temperature conditions, are directly exposed to heat and that even adopting relatively low concrete cover, fire endurances above 120 min can be attained provided that the bars’ anchors remain sufficiently cold.