Experimental study on bond behaviour of CFRP sheets externally bonded to reinforced concrete

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University of New Brunswick
Fiber reinforced polymers (FRP) have become widely used in retrofitting existing reinforced concrete (RC) structures because of their high strength and stiffness-to-weight ratio. An important aspect in the design of this composite element is determining the bond behaviour of the FRP sheet-to-concrete interface. Previous studies have involved the use of conventional instrumentation (typically strain gauges) that provide limited data to work with. This study presents an experimental investigation to determine the effect of bond length and stress on the bond behaviour of FRP-to-concrete interface under static loads using a digital image correlation (DIC) technique. Twelve double lap shear specimens bonded with carbon fiber reinforced polymer (CFRP) sheets were tested with varying bond lengths. Development length, longitudinal strains and bond stress and slip relationships were obtained and compared with values computed from existing models. Comprehensive results were obtained from the DIC technique which allowed for proper monitoring of the progression of failure and the effect of shear lag on the distribution of stresses in the FRP sheet.