Practical Strategies for Enhancing Fire Resistance of FRP-strengthened Reinforced Concrete Beams

A macroscopic finite element based computer model is developed and verified that accounts for constitutive material properties at elevated temperatures, temperature induced bond degradation (slip) at the interface of FRP and concrete, and realistic load and restraint conditions. This model is used to conduct a set of parametric studies to establish and quantify influence of different parameters such as fire scenario, insulation scheme, anchorages, bond degradation, axial restraint force and load level on the fire response of FRP-RC beams. In addition, comprehensive experimental studies are conducted on insulated FRP-strengthened RC beams under standard and realistic fires. Five different supplemental fire insulation schemes, four insulation thicknesses and different configuration of end zone anchorages of FRP are examined. Based on test results, as well as the parametric studies, practical strategies including different insulation schemes/configurations, its thicknesses and end anchorages (to reduce debonding mechanism) are presented in this paper to enhance fire response of FRP-strengthened RC beams. Results demonstrate that beyond an optimum insulation thickness, fire resistance does not increase considerably. Moreover, appropriate insulation scheme and effective anchorage towards the end of FRP zone (at terminating points) significantly enhances fire resistance of FRP-RC beam under fire.