Investigation of the behavior of carbon fiber polymer wrapped reinforced concrete columns under eccentric load effect

High strength reinforced concrete columns have been increasingly used in structural applications. It is known that these columns exhibit brittle behavior under applied loads. Therefore, steel fibers can be added into the core concrete to improve the ductility and deformability of these columns. In addition, high strength reinforced concrete columns can be wrapped with carbon fiber reinforced polymer (CFRP) materials for additional strengthening. In this work, experimental and analytical studies on CFRP confined plain and steel fiber slender high strength columns have been presented. The experimental strength capacities, load-deflection relations and failure modes of the column specimens have been observed. The effects of the parameters of concrete compressive strength, load eccentricity, steel fibers, and carbon fiber polymer material on the structural behavior of high strength reinforced concrete columns have been examined. The experimental study revealed that the CFRP material is significantly effective on reinforced concrete columns with respect to strength, ductility and confinement. In addition, a numerical procedure is presented for the analysis of slender reinforced concrete columns confined with CFRP sheets subjected to combined axial load and biaxial bending. These columns have been analyzed using geometric features and experimental parameters of concrete compressive strength, steel yield strength and CFRP material properties to predict the column structural behavior. It was observed that the analysis results and the experimental results showed good agreement in this study.