Load ratio effects on the structural fire behaviour of glass fibre‐reinforced polymer‐reinforced concrete beams with mid‐span bar lap splices – Experimental study

Fibre‐reinforced polymer (FRP)‐reinforced concrete members have been gaining attention as an alternative to conventional steel‐reinforced concrete members due to their advantageous characteristics. A few to mention are excellent resistance to corrosion, high strength‐to‐weight ratio, and reduced maintenance cost in the long term. Nevertheless, FRPs are often limited in use mainly due to fire safety considerations since they can encounter significant deprivation of strength and bond with concrete in fire conditions. This paper presents the results of an experimental study aimed to investigate the effects of the applied load level on the structural behaviour of glass fibre‐reinforced polymer (GFRP)‐reinforced concrete beams having mid‐span bar lap splices when exposed to standard fire. Two 2750‐mm long beams with cross‐sectional dimensions of 300 mm wide × 350 mm high were exposed to elevated temperatures that followed the CAN/ULC‐S101 standard fire time–temperature curve while being subjected to a load level equivalent to 85% of the beam ultimate design load. The experimental results of the two beams were compared to those obtained for identical beams but subjected to a lower load level that is equivalent to only 40% of the beam's ultimate design load. Results show that the increased load level (slightly more than double the load ratio) unexpectedly did not impact the fire resistance time of the GFRP‐reinforced concrete beams but affected other structural responses of the beam, such as its midspan deflections and cracking patterns.