INVESTIGATING THE AXIAL BEHAVIOR OF CONCRETE COLUMN CONFINEMENT WITH INNER AND OUTER GFRP

The retrofitting of concrete columns by using FRP fiber for strength and ductility is taken into consideration. Recent studies have shown that confined concrete with FRP shows different behavior comparing when confined with steel; therefore, the need for research on concrete columns reinforced with FRP is clear. In this study, finite element analysis and modeling by using finite element software are used to investigate the behavior of columns reinforced with GFRP fibers. Model verification is performed by using the results of laboratory study, and the good agreement between test results and finite element modeling is observed. The next step is to examine the parameters of compressive strength of concrete and column shapes in behavior of reinforced column with FRP. The results in terms of vertical displacement-force Graphs and buckling, are extracted and compared.The deterioration of the nation's infrastructure has been well documented and publicized FRP composites have emerged as a potential solution to the problems associated with the infrastructure. An economic application of FRP materials is in the form of composite construction with concrete, such that FRP can act as a load-carrying partner and protective measure for the structural members. One such application has been demonstrated in fiber jacketing technique, which is now considered as an effective retrofitting tool for the existing columns. By using the principles of fiber-wrapping and steel-jacketing practice, classic steel-concrete composite columns, FRP pressure vessels, and steel-encased plastic piles, a novel type of composite column is proposed that consists of a reinforced concrete core confined in a FRP tubular jacket. The main advantage of FRP-concrete composite construction is the optimal use of materials based on their mechanical properties and resistance to corrosive composite members with pseudo ductile characteristics and high stiffness and strength properties.The composite shell may be a multi-layer FRP tube that consists of at least two plies: an inner ply of longitudinal fibers and an outer ply of circumferential fibers. The longitudinal fibers are inhibited from outward buckling by the outer circumferentially oriented fiber ply and from inward buckling by the concrete core. Similar tubes have been made with a center ply of longitudinal fibers sandwiched between two plies of circumferential fibers.