Behavior and new strength model of FRP square columns based on the FRP effective circumferential failure and the effective lateral confining pressure

Abstract

This paper presents an experimental investigation of the effect of concrete compressive strength, strengthening ratio and corner radius on the behavior of small-scale square columns wrapped with carbon fiber-reinforced plastic (CFRP) materials. A total of 39 specimens (150 × 150 × 300 mm) wrapped with one, two, and three plies of CFRP wraps were tested. In addition to the FRP jacket thickness, the effect of three different concrete mixes and four cases of corner radius were examined. The effective circumferential CFRP failure strain and the effect of the effective lateral confining pressure were investigated. The obtained results show that the CFRP reinforced columns provide a significant increase in ultimate conditions (strength and ductility) compared to the case of the unconfined specimens. It can be seen that higher concrete compressive strength and lower strengthening ratio reduce the effect of confinement with CFRP material. The test results demonstrated that the corner radius ratio is in direct proportion to the increase in confined concrete strength. A new model is presented to predict the compressive axial strength and corresponding strain of CFRP-confined columns based on the effective lateral strain of FRP material.

Keywords:

• CFRP
• compressive strength
• ductility
• effective circumferential failure
• effective lateral confining

Disclosure statement

No potential conflict of interest was reported by the authors.