Compressive behavior of double-skin tubular stub columns with recycled aggregate concrete and a PET FRP jacket

Abstract

This paper presents an experimental study on the compressive behavior of hybrid fiber reinforced polymer (FRP)-concrete-steel double-skin tubular stub columns (DSTSCs) with recycled aggregate concrete (RAC) and a polyethylene terephthalate (PET) FRP jacket. RAC is a green, sustainable alternative to natural aggregate concrete (NAC), while its mechanical properties are generally inferior to NAC. Polyethylene terephthalate (PET) FRP is manufactured from recycled plastics and has a large rupture strain (LRS) value of more than 7% compared to pure polyethylene FRP. In this study, a total of 20 DSTSC specimens were tested under axial compression. The main parameters studied were the RAC replacement percent (0, 50 and 100%), the FRP jacket thickness, and steel tube thicknesses (3 and 5 mm). Test results indicated that the compressive behavior of DSTSC specimens with RAC and PET FRP is similar to that of specimens with NAC and PET FRP, and both types of columns exhibit highly ductile compressive behavior. It is also observed that the compressive behavior of DSTSCs is primarily influenced by the confinement stiffness of the FRP jacket and the steel tube, and the replacement percent of RAC has marginal effect. The increase of the FRP jacket or steel tube stiffness can counterbalance the replacement percent effect of RAC on the axial compressive behavior of DSTSCs. Finally, the suitability of the existing ultimate condition models of different types of DSTSCs was investigated based on the experimental results of this study.