EXPERIMENTAL BEHAVIOR OF R.C. BEAMS PARTIALLY MAGED IN FLEXURE AND STRENGTHENED WITH CFRP LAMINATES

Abstract

This study presents an experimental investigation on the monotonic flexural behavior and ultimate capacity of reinforced concrete beams partially damaged and cracked in flexure due to applying a 58% of the predicted ultimate flexural load capacity, and then repaired by external strengthening with high strength CFRP (Carbon Fiber Reinforced Polymer) laminates bonded with epoxy resin to the tension face of concrete after doing all the appropriate preparations for the concrete adhesion substrate. Five rectangular reinforced concrete beams were tested to obtain the effect of amount of CFRP laminate on beams cracking behavior, concrete strains, ductility ratios, ultimate loads and failure modes. The results obtained from the adopted repairing and strengthening technique showed a significant effect of external high strength CFRP laminates on improving behavior and capacity of reinforced concrete beams. An increase by 15%- 33% in ultimate load capacities, for the CFRP strengthened beams, was observed over the control beam with conventional reinforcement. This gain in strength was accompanied by a reduction in ductility ratio by 18%- 28% for the CFRP strengthened beams compared with the control R.C. beam. Also, the crack patterns show enhanced performance in crack distribution and propagation for the strengthened beams over the control beam