Experimental Study of Slender Concrete Columns Strengthened with Longitudinal FRP Laminates and FRP Wrapping System

Khorramian K., Sadeghian P.

10th International Conference on Fibre-Reinforced Polymer (FRP) Composites in Civil Engineering (CICE), İstanbul, Turkey, 8 - 10 December 2021, vol.198, pp.1385-1394 identifier identifier

  • Publication Type: Conference Paper / Full Text
  • Volume: 198
  • Doi Number: 10.1007/978-3-030-88166-5_120
  • City: İstanbul
  • Country: Turkey
  • Page Numbers: pp.1385-1394
  • Keywords: Slender, Concrete columns, FRP, Strengthening, Experimental test, BEAMS, BEHAVIOR
  • Istanbul Technical University Affiliated: No


Strengthening of concrete columns with fiber-reinforced polymer (FRP) wrapping is a very well-known and effective method of strengthening whose function is increasing the confinement of the column. However, the wrapping method for eccentrically loaded concrete columns was not recognized to be as effective as its effect on the concentrically loaded columns. The additional eccentricity causes bending moment which may cause tension in one side of the column while wrapping has its best performance where there is uniform pressure from concrete to wrapping. For slender columns, the effect of eccentricity is even more critical since it is combined with the secondary moment effects. For slender columns, a solution is required to increase the flexural stiffness. Therefore, this study investigates the effects of longitudinal FRP laminates which are supported by FRP wrapping (to prevent buckling of longitudinal FRP laminates) on the strengthening of slender concrete columns using experimental large-scale testing. The tests include three slender concrete columns with length of 3048 mm and a diameter of 260 mm (slenderness ratio of 47) were considered as control (without strengthening), wrapped (only wrapping in hoop direction), and hybrid (wrapping and longitudinal FRPs). The columns were tested under eccentric axial compression loading until failure. The results showed a capacity gain of 44% for the hybrid system in comparison with the wrapping system of strengthening.