Performance and design of partially CFRP-jacketed circular CFT column under eccentric compression

Abstract

Nowadays, the carbon fibre reinforced polymer (CFRP) strengthening technology that uses the partial wrapping scheme is commonly applied in reinforcement engineering. Nevertheless, related investigations on partially CFRP jacketed concrete-filled steel tubular (CFT) columns under eccentric bearing forces are rarely reported. Herein, a series of experimental and analytical works on the eccentric behaviour of the partially CFRP jacketed circular CFT short and slender columns are presented. The influence of various parameters, in terms of steel yield stress, load eccentricity, number of CFRP layers, CFRP spacing, and column slenderness, on the eccentric compressive response of the specimens were analysed. Mechanical properties were evaluated by discussing the laws of the eccentric pressure (N)-vertical displacement (δ) curves, typical failure modes, strain responses, strength and ductility indexes, etc. Following these, a modified finite element model of the partially CFRP jacketed circular CFT column subjected to an eccentric bearing force was developed and validated against the existing experimental results. The contact stress and the effective jacketing scheme of the composite column were also discussed. Finally, based on an analysis of the confining stress transferring mechanism of the partial wrapping scheme, design formulae were proposed to assess the axial and eccentric load bearing capacity of the partially CFRP jacketed circular CFT column. The observations drawn from this study might provide a good basis for the future applications of CFRP strengthening CFT structures.