Confinement Effectiveness in Rectangular Concrete Columns with Fiber Reinforced Polymer Wraps

Abstract

An innovative mechanistic based method for passive confinement efficiency estimation is proposed based on the extension to rectangular sections of the pulley model previously proposed by the writers. A refined finite element model was developed using a nonlinear concrete constitutive law in order to analyze stresses in columns passively confined with fiber reinforced polymer wraps. Rectangular and square cross sections of variable corner radii were investigated with reference to a circular cross section. Results showed an increase in corner stresses with sharper corner radii, a localization of failure at the corners, and a decrease in confinement effectiveness with an increase in the rectangularity of the cross section or an increase in corner sharpness. A rigorous numerical method for calculating geometric confinement efficiency factors is proposed and typical factors are calculated and compared with the predictions of the simple pulley model showing good agreement.