Effect of corner radius and aspect ratio on compressive behavior of rectangular concrete columns confined with CFRP

This paper investigates the behavior of rectangular concrete columns confined with carbon fiber reinforced polymer (CFRP) composites, considering the effect of corner radius and cross section aspect ratio. Nonlinear behavior of confined concrete and orthotropic behavior of fiber-reinforced polymer (FRP) composite have been incorporated in the finite element modeling. The CFRP rupture was modeled in the state of biaxial stresses by using Tsai-Wu's failure criterion. Therefore, the effects of axial stresses on rupture of FRP as well as the effects of hoop stresses were taken into consideration. Furthermore, to provide more precise modeling and analysis, Tsai-Wu's criterion and a modified Drucker-Prager plasticity model were applied concurrently in simulating. The finite element analysis was verified by simulating CFRP confined cylindrical and rectangular columns. Concrete columns with cross section aspect ratios of 1.00, 1.25, 1.54 and 2.00, and different corner radii including 5, 15, 25 and 38 mm were modeled. Corner radii of 45, 60 and 75 mm were also modeled in square sections. Results showed that both decreasing the corner radius and increasing the aspect ratio, decrease the compressive strength and ductility enhancement of the confined column. Results of simulating rectangular confined columns led to a design-oriented model for predicting the compressive strength of these sections with different corner radii. The proposed simple model is shown to be in good agreement with the existing test results in the literature, showing the applicability of the model for design purposes for FRP-confined concrete columns.