Large-size reinforced concrete columns strengthened with carbon FRP: Experimental evaluation

The use of Fiber Reinforced Polymer wrapping technique has been extensively studied; in particular, the behavior of confined elements of circular cross-sections subjected to pure axial loads has been studied. However, the available models are based on small-scale specimens. Limited studies are found for the cases of prismatic members, especially on large-size ones. To analyze the behavior of axially loaded large-size Reinforced Concrete (RC) columns confined by means of Carbon FRP (CFRP) wrapping, a test matrix was designed to investigate the effect of different variables, such as the geometry of the specimen (circular, square, and rectangular), the area aspect ratio, the side aspect ratio, and a height-to-width aspect ratio. A total of 22 specimens were divided into six series of three specimens each and two series of two specimens. The largest column tested had a cross-sectional area of 0.8 m² (9 ft²) and the smallest one an area of 0.1 m² (1 ft²). The experimental results are compared and contrasted with current available data on reinforced concrete specimens with one minimum dimension of the cross-section of 300 mm (12 in). This evaluation allowed concluding and confirming that among circular and square specimens of the same cross-sectional area, the confinement effect of the FRP is less effective for the latter. It was observed that within specimens of circular and prismatic cross-sections with size-aspect-ratio less or equal than 2.0, the size effect could be negligible.