The fire performance of GFRP-RC beams based on FE thermal analysis

GFRP (glass fiber reinforced polymers) rebars can be used in RC (reinforced concrete) structures as an alternative to conventional steel rebars. Their application offers advantages, especially in chemically aggressive environments, as they can reduce the C (concrete cover) thickness required and also optimize the cross-sectional dimensions of these structures as well as their durability and service life. However, based on FE (finite element) numerical analysis solved by Abaqus software, this research has shown that the reduction in C-thickness promotes a notorious incongruity: an improvement in the fire sensitivity of these structures. The time in which GFRP-RC structures failed in fire can be around 400% lower in relation to identical conventional steel RC structures. In some cases, the fire resistance rate (FRR) of GFRP RC structures can be less than 10 min when the critical temperature of these rebars (around 100 °C) is taken into account. GFRP RC beams with a concrete cover thickness of 20, 30 and 40 mm do not reach the 20 min of the ISO 834 fire. It is to be expected that these beams will fail very quickly when subjected to high temperatures. The interest in structural durability criteria is not sufficient to justify the application of this new type of reinforcement in some concrete buildings.