Effect of load eccentricity on the stress-strain relationship of FRP-confined concrete columns

Although fiber reinforced polymer (FRP) confined concrete columns have been extensively investigated, a satisfactory stress-strain model for the columns under eccentric loading has not been developed because of the complications of the problem. The analytical study in this paper indicates that even the key factors that affect the stress-strain relationship have not been correctly identified so far. This paper presents an experimental and analytical study of FRP confined circular concrete columns under eccentric loading. Thirty-six short concrete cylinders were tested under varying levels of load eccentricity and FRP jacket stiffness. Based on analyses of the test results, a new model for the stress-strain relationship of FRP-confined columns under eccentric loading is developed. It is concluded from this work that the stress-strain models previously developed for concentrically loaded columns are inadequate for predicting column response under eccentric loading. The stress-strain curve shows a significant stiffening trend when load eccentricity increases.