عنوان مقاله [English]
Fiber-reinforced polymer (FRP) composites have been used for structural strengthening in the recent decay and is the appropriate way to increase structural capacity and gaining more popularity among design professionals over conventional strengthening techniques due to its superior mechanical properties and higher tensile strength, stiffness, and durability compared with other techniques. In this paper, the structural behavior of undamaged and damaged reinforced concrete frames strengthened with CFRP composite material was experimentally evaluated. Initially three half-scale reinforcement concrete frames are considered as reference specimens with same beams and columns dimensions and also reinforcement, but different columns stirrup distances 100,200 and 300 mm at the first, second and third specimens respectively. The reference frames were tested under constant axial load and increasing lateral load up to their maximum capacity and failure points, and leaving severe damaged frames. Then, the damaged frames were strengthened with CFRP (Carbon Fiber Reinforced Polymer) composite layers with same arrangement at the critical zones around connections and tested again same as the reference specimens at axial and lateral loadings. The test results indicated that with increasing column stirrup distances of reference specimens, the maximum capacity and ductility and energy absorption were decreased up to 10, 50, and 74%, respectively. And also the maximum capacity and ductility of strengthened specimens were decreased up to 20 and 80% comparing to reference specimens but the energy absorption of strengthened specimens were increased.