عنوان مقاله [English]
Due to various deficiencies and inadequate lateral stiffness, many reinforced concrete buildings have been highly damaged or collapsed in Iran and throughout the world during the last major earthquakes. In this study, the retrofitting of undamaged infilled reinforced concrete frames using carbon fibre-reinforced polymer (CFRP) is discussed in detail. The main objective of the extensive experimental program is to reinforce the masonry infilled concrete frames, which are known to contribute to the seismic performance of the reinforced concrete structures significantly, and to improve the behavior of such buildings to prevent total collapse. CFRP sheets are wrapped around the top and bottom of the columns to prevent column shear failure, which is known as a catastrophic failure mode. CFRP sheets are also attached to the masonry wall faces and anchored to the concrete frame to carry diagonal tension. The frame of the specimens is designed and detailed in accordance to the Iranian old codes. Four, 1/2 scaled, 1-story, 1-bay, brick infilled concrete frame are tested; namely, a control specimen and three rehabilitated specimens. The specimens are tested under reversed cyclic quasi-dynamic load to failure. The strength, stiffness, and story drifts of the test specimens are determined. The control specimen showed combined brittle column shear and corner crushing infill failure modes, while the rehabilitated specimens showed a more ductile failure mode. CFRP sheets improved the structural integrity and prevented collapse and debris fallout. The experimental results show that CFRP strengthening would not be effective unless CFRP is properly anchored to the infill and the frame members. The maximum increase in initial lateral stiffness due to strengthening was about 10%. But, if the lateral stiffness of the structure, considering that the contribution of the infills is adequate to control the drift of the frames, the increase in strength due to CFRP strengthening, without significant increase in stiffness, can be considered as an advantage. This paper is to discuss the specific design, test setup, and analytical and theoretical background, as well as improved results, that were obtained during testing. Finally, a series of recommendations is proposed for the actual use of CFRPs in ndustry.