Simplified methods to determine shear strength in reinforced concrete beams with fiber-reinforced polymers exposed to fire

Abstract

The importance of structural design under fire conditions, together with the uncertainty in the behavior and resistance of reinforced concrete structures with fiber-reinforced polymer bars (FRP) at high temperatures, reveal the need for more research along these lines. Although there are studies evaluating the flexural and shear strength of elements exposed to fire, there are no standards nor regulations specifying the procedures thereto. This work proposes methods to calculate shear strength in FRP-reinforced concrete beams, with rectangular cross-section, based on the degradation of the properties of the materials and/or the reduced concrete cross-section, as recommended by (Diab, 2014), Eurocode 2 (EN-1992-1-2, 2004) and (Saafi, 2002). In accordance with the thermal analysis executed with the Super Tempcalc software, these procedures were applied to 13 beams of different dimensions and reinforcements, subjected to standard fire of the ISO-834 standard on three sides, thereby obtaining the shear capacity degradation curves for each case. The results show that the differences between the shear strength values were very small throughout the total fire exposure time.