Experimental investigation of shear stress distribution between concrete and CFRP straps

Bonding of carbon fiber reinforced polymer composites (CFRP) has become a popular technique for strengthening concrete structures in recent years. The bond stress between concrete and CFRP is the main factor that was determining the strength, rigidity, failure mode and behavior of the reinforced concrete member strengthening with CFRP. The accurate evaluation of the stress is required for analytical calculations and design process. In this study, the stress between concrete and bonded CFRP straps across the notch is tested. Indirect axial tension is applied to CFRP bond by four point bending tests. The variables studied in this research are CFRP strap width, bonding length and the concrete compression strength. Furthermore the effect of a crack- modeled as a notch- on the stress distribution is studied. It is observed that the stress in the CFRP to concrete interface reaches its maximum values near the crack tips. It is also observed that lengthening the CFRP strap more than a certain value does not affect the strength and the stress distribution of the bonding. The stress distributions obtained from experiments are compared to Chen and Teng?s analytical model.