Fire Survivability of Externally Bonded FRP Strengthening Systems

The use of externally-bonded fiber-reinforced polymers (FRPs) to strengthen reinforced concrete (RC) structures is now widely recognized. However, a concern that continues to discourage the use of FRPs in many applications is their susceptibility to high temperature and fire. Although recent studies have shown that the fire endurance of appropriately designed and insulated FRP strengthened RC members is satisfactory, the specific performance of FRP systems at, and after exposure to, high temperature remains largely unknown. The results of tests on the residual properties after high-temperature exposure of various available FRP strengthening systems for concrete are reported; these include: tension coupon tests, single-lap FRP-to-FRP bond tests, direct tension FRP-to-concrete bond tests, and pull-apart FRP-to-concrete shear bond tests after exposure to temperatures up to 400°C . The data show that the allowable exposure temperatures for residual performance of externally bonded FRP systems lie between the glass transition temperature (Tg) and the thermal decomposition temperature of the resin systems used. The potential consequences for fire-safe design of FRP strengthened RC members are discussed. Material properties during a fire event are not specifically addressed.