Durability evaluation of glass fiber reinforced-polymer-concrete bonded interfaces

In this investigation, 90-cm-long plain concrete beam specimens reinforced with externally bonded wet-laid glass fiber reinforced-polymer sheets are investigated. The specimens are precracked with a three point flexural load, subjected to a constant four point flexural load of about 25% of the initial ultimate moment, and placed into different environmental conditions. The four environmental conditions under investigation are indoor laboratory, outdoor, elevated temperature/dry, and freeze/thaw. By varying the exposure time in different environments and using the photoelastic coating method to evaluate strain distributions, the durability of the externally reinforced concrete beams is evaluated. An innovative approach based on fracture mechanics and local bond shear stress-slip relationships is proposed to explain the degradation mechanism. This approach is capable of qualitatively and quantitatively characterizing the environmental effect in terms of the parameters of the shear stress-slip law. Four one-dimensional shear stress-slip relationships are evaluated in terms of their ability to model the environment-dependent strain distribution and debond data obtained in the present investigation.