Critical Temperatures for Splitting of FRP-reinforced Concrete with Thermal Expansion

摘要

Fiber reinforced polymer (FRP) bars have been widely used as substitutes for traditional steel barsto prevent reinforced concrete structures from corrosive environments. However, under elevatedtemperatures, the low compatibility of transverse coefficients of thermal expansion between FRPand concrete can cause splitting of the concrete cover. As a result, the bonding of FRP-reinforcedconcrete may not sustain its function to transfer load between the FRP rebar and the surroundingconcrete.The current study investigates the splitting resistance of FRP-reinforced concrete against thethermal expansion based on a mechanical model. The proposed model adopts the thick-wallcylinder theory by subdividing the concrete cover into two zones, i.e. cracked and uncracked. Theconcrete that does not crack is considered to sustain its elastic behaviour whereas the tensilesoftening behavior is employed for cracked concrete. The proposed model is then used to estimatethe critical temperature increment at which the splitting failure of the concrete cover occurs. Thepredicted critical temperature increments are compared with the results obtained from the previousexperiments and formulations. A simplified equation for estimating the critical temperatureincrements is also derived for the design purpose. Based on the critical temperature increments,structural engineers can evaluate the safety of FRP-reinforced concrete members from concretesplitting under elevated temperatures.