Experimental investigation on rectangular RC columns strengthened with CFRP composites under axial load and biaxial bending

This paper presents the results of an experimental study on rectangular RC columns strengthened with carbon fiber-reinforced polymer (CFRP) composites under axial load and biaxial bending moment. A total of 8 large-scale RC columns with rectangular cross-section were cast and tested under bi-eccentric compressive loading up to failure. In this investigation, several parameters like CFRP thickness of one, two, three, and four layers, fiber orientations of ±45°, 0°, 90° and their combination, and eccentricities in the direction of both weak and main axis were studied. The effects of these parameters on the moment–curvature relationship, and load–longitudinal displacement relationship were investigated. In general, increasing longitudinal layers rather than transverse layers led to a greater load carrying and displacement capacity of the specimens, because of the overall behavior of RC wall-like columns. The results of these experimental and numerical studies showed a great improvement on the strength and ductility of confined RC columns.