Performance in Fire of Fibre Reinforced Polymer Strengthened Concrete Beams Including Embedded Fibre Optic Sensors

Fibre reinforced polymer (FRP) materials are increasingly being applied in many areas of construction, particularly for strengthening of concrete beams. However, concerns associated with fire remain an obstacle to applications of FRP materials in buildings and parking garages due to their susceptibility to degradation at elevated temperatures. For FRP strengthened concrete beams, the bond properties of FRP materials at high temperature are critical. Additionally, in both industrial applications and fire scenarios, sensing may be required at very high temperatures. Such sensing could be used to monitor and control equipment in industrial situations or to provide an emergency management system in a structural fire. Conventional fibre optic sensors (FOS), however, are limited to relatively low temperatures. Thus, this paper also discusses the development of technology for fibre optic sensing at high temperatures. To illustrate the potential application in a structure, two full-scale T-beams (4 m span) are constructed with FOS attached to the internal longitudinal reinforcement. These T-beams are strengthened with external FRP, and fire protection for the FRP is provided by sprayed insulation. These beams will then be exposed to a standard ASTM fire while under sustained loading. This paper also presents an experimental investigation to characterize the bond properties of some currently available FRPs under various loading and thermal regimes ranging from ambient temperature to 200 degrees C. Lap splice tests are conducted under both steady-state and transient temperature conditions, and the results of the two types of testing are compared.