Evaluating GFRP bars under axial compression and quantifying load-damage correlation

Abstract

Fiber-Reinforced Polymer (FRP) bars have become widespread in the concrete construction industry because of their superior mechanical, physical, and durability properties. Although the tensile performance of FRP bars has been well studied, only a limited number of research projects have evaluated the compressive behavior of FRP bars due, among other reasons, to the need for a standard test method. This research aims to develop a test method to apply compression at the center of the FRP bar to avoid load eccentricity effects using a steel centering fixture with a plastic 3D-printed plug. To evaluate the ultimate compressive strength and elastic modulus, two different Glass FRP (GFRP) bars, with a 12.7 mm nominal diameter, but with two different length-to-diameter ratios of 2 and 4, were considered. The effect of 3D-printed plugs and cutting surface quality was also evaluated. The main contribution of this research is providing a straightforward test set-up for obtaining the compressive behavior of GFRP bars. The results showed that the compressive strength and elastic modulus of the tested GFRP bars are considerable in a way that the elastic modulus of the G1 bars in compression was equal to the tensile elastic modulus, so neglecting the effects of these bars in designing compressive members is too conservative.