Experimental studies on bond capacity of grid system for UCCF cables

Abstract

UCCF (Unresin Continuous Carbon Fiber) cable is a reinforcing material made of carbon fibers without impregnation into the resin matrix. As tensile reinforcement for concrete structures, the reinforcement must have enough bond capacity to concrete inorder to achieve an effective reinforcing action. The bond capacity of UCCF cables is very low, approximately 1/10 to 1/15 comparingwith that of the steel reinforcement. Although it is difficult to develop full bond action on UCCF cables, it is considered that the partial bond system can offer good effect to the flexural behavior of a concrete beam reinforced by UCCF cables. The partial mechanical bond effect on cable is achieved by constructing the grids along the reinforcing cables by connecting the longitudinal cables with the transversal cables by epoxy. Pullout test indicated that the grids have bond capacity approximately ten times higher than that of the cable itself. For design purposes, a model of the grid system is proposed. By this model, the grid bond capacity of the cross section of the grids could be predicted. Comparing to the experimental results of pullout test, the model results showed a good agreement.