Behavior of hybrid PET FRP confined concrete-filled high-strength steel tube columns under eccentric compression

Abstract

Fiber-reinforced polymer (FRP) wraps as external confining device have been employed to enhance the performance of concrete-filled steel tube (CFST) columns, and the axial compressive behavior of FRP-confined CFST columns have been intensively investigated. Although FRP confinement could enhance the mechanical performance of CFST columns with a high-strength steel (HSS) tube, they are prone to buckling failure, especially under eccentric compression. The purpose of this study is to experimentally investigate the mechanical performance of polyethylene terephthalate (PET) FRP-confined CFST columns (PFCCFSTs) under eccentric compression. A total of eight circular PFCCFSTs were tested for investigating the effects of a range critical parameters (i.e., column slenderness ratio, eccentricity-to-diameter ratio, and thickness of the PET FRP jacket) on the eccentric compressive behavior of PFCCFSTs. The test results show that the typical load-strain curve of PFCCFSTs generally consists of an initial linear ascending segment, followed by a transition segment and a descending segment. It is demonstrated that the load deterioration of PFCCFSTs is more sensitive to the increase of eccentricity-to-diameter ratio than the slenderness ratio, while the PET FRP thickness has little influence on the load bearing capacity of PFCCFSTs. The predictions from a theoretical model are compared with experimental results, and demonstrate that the model underestimates the ultimate lateral deflections due to the ignorance of the strain gradient effect in eccentrically loaded columns.