Strength and durability assessment of flexure and axial RC members strengthened with carbon fiber polymer

The repair and strengthening of concrete structures is a challenging of the concrete industry for both engineers and contractors. Due to increasing economical constraints, the current trend is to repair/upgrade deteriorated and functionally obsolete structures rather than replacing them with new structures. CFRP has been used previously by air space industries regardless of the high costs. The decrease in the costs of the composite materials, as results of the technology improvement, has made CFRP an alternative to conventional materials for many applications.; In this study, external application of CFRP sheets to reinforced concrete slabs, beams, and columns is examined. A total of 8 reinforced concrete slabs, 8 ft long, strengthened with two types of CFRP systems, 16 reinforced concrete beams 8 ft long, and 10 reinforced concrete beams 10 ft long were subjected to different environmental conditions and sustained load, were tested to failure. In addition fifteen 30 in. long and four 36 in. long, 6 in. in diameter, circular reinforced concrete columns confined with various CFRP sheet configurations were tested to failure under monotonic axial loading. The test results indicated that external strengthening or confinement by means of CFRP composites can significantly enhance the strength, ductility, fatigue performance, and durability.; In addition, a model is proposed to predict the ultimate axial stress and strain of the reinforced concrete columns confined with CFRP sheets. The results from these equations were compared with the experimental test results and the models from the literature.