Bond-slip model for FRP laminates externally bonded to concrete at elevated temperature

Abstract

This paper presents a nonlinear local bond-slip model for fiber reinforced polymer (FRP) laminates externally bonded to concrete at elevated temperature for future use in the theoretical modeling of fire resistance of FRP-strengthened concrete structures. The model is an extension of an existing two-parameter bond-slip model for FRP-to-concrete interfaces at ambient temperature. The two key parameters employed in the proposed bond-slip model, the interfacial fracture energy G[sub f] and the interfacial brittleness index B, were determined using existing shear test data of FRP-to-concrete bonded joints at elevated temperature. In the interpretation of test data, the influences of temperature-induced thermal stress and temperature-induced bond degradation are properly accounted for. As may be expected, the interfacial fracture energy G[sub f] is found to be almost constant initially and then starts to decrease when the temperature approaches the glass transition temperature of the bonding adhesive; the interfacial brittleness index B exhibits a similar trend. The proposed temperature-dependent bond-slip model is shown to closely represent the test data upon which it is based, despite the large scatter of the test data.