Buckling strength and ductility of a metallic cylindrical shell can be enhanced significantly by externally wrapping fiber-reinforced polymer (FRP) composite sheet(s). This paper presents an in-depth numerical study on inelastic buckling of glass FRP (GFRP) strengthened steel tube. The influence of boundary conditions, geometric imperfections, transverse moduli of GFRP, metal-FRP interfacial bond, FRP damage, and other challenges in numerical modeling and computation on buckling behavior are investigated. The predictions demonstrate good agreement with published experiments Teng and Hu [1]. It is shown that accurate prediction of i) post-yield behavior is possible only by the inclusion of metal-FRP interfacial damage, and ii) point of buckling and buckling failure modes require the inclusion of FRP damage as well. Further, this study reveals that i) the metal-FRP interfacial damage happens just before or immediately after the initiation of tube yielding, ii) the axisymmetric buckle initiates at same loading irrespective of amount of FRP strengthening, iii) FRP matrix compression damage and buckle growth aid each other, and iv) an increase in FRP strengthening retards the buckling growth to the point of strain localization. © 2020 Elsevier Ltd