Fiber reinforced polymer (FRP) has been applied to many purposes for civil engineering structures not only for new structures but also for strengthening of the deteriorated structures. The application of FRPs in various forms such as rod, grid and sheet are widely accepted solution due to its corrosion resistance as well as high tensile strength to weight ratio. The application has been done on many purposes including strengthening of damaged reinforced concrete structures. Depend on the level of the damage of the concrete beams, it may be restored or repaired. In other to study the application of FRP sheet for the strengthening of the damaged concrete beams, a series of experimental programs has been done. This paper describes the effect of the GFRP belt to the failure mode of the cracked concrete beams strengthened using GFRP sheet. Specimens of reinforced concrete beams with dimension of 15 cm x 20 cm x 270 cm were casted. The specimens were the uncracked beams as control specimens and the cracked beams strengthened by GFRP sheet with parameter of GFRP belt width. Before the application of GFRP sheet, beams were loaded up to the yielding point of tensile steel reinforcement. The results indicated that GFRP belt on the strengthened beams changed the failure mode. The beams without belts failed due debonding of GFRP sheet. While, the strengthened beams with GFRP belts failed due to the rupture of the GFRP sheet. As the results, the maximum flexural capacity increased
