Experimental Study on Shear Behavior of Reinforced-Concrete Members Fully Wrapped with Large Rupture-Strain FRP Composites

Abstract

This paper presents an experimental study on the shear behavior of RC members fully wrapped with polyethylene terephthalate (PET) fiber-reinforced polymer (FRP) composites, which are a new type of FRP material characterized by a much larger rupture strain (LRS) compared with conventional FRPs (i.e., made of carbon, glass, and aramid fibers). A total of 10 PET fully-wrapped RC beams, which were designed to fail in shear and with different shear-span to effective-depth ratios, transverse reinforcement ratios and shear strengthening ratios, were tested under 4-point bending loads. The overall load-deflection responses and the shear deformation of the beams as well as the strain development of the transverse steel reinforcement and the FRP jackets were carefully observed. Based upon the extensive strain measurements, the shear contributions by concrete, FRPs, and transverse reinforcement are differentiated. It was found that the use of PET FRP composites as the jacket material of RC members could shift the mode of shear failure from a brittle one to an ideal ductile one whereas the ultimate state of the members is no longer caused by FRP fracture. In order to efficiently predict the shear strength of RC members wrapped by LRS FRPs, the effective strain in LRS FRPs and the degradation of concrete at the peak member shear strength should be appropriately considered.