Fiber-reinforced　polymer　(FRP)　confining　jackets　offer　an　attractive　solution　for　the　seismic　retrofit　of　RC　columns.　For　the　accurate　prediction　of　strength　and　ductility　of　FRP-confined　RC　columns,　it　is　necessary　to　understand　interactions　between　the　FRP　jacket　and　the　RC　column　at　all　deformation　levels　under　seismic　loading.　In　particular,　when　the　transverse　steel　reinforcement　consists　of　widely　spaced　steel　stirrups　or　spirals,　the　longitudinal　steel　reinforcing　bars　(rebars)　are　likely　to　develop　buckling　deformations　despite　the　lateral　support　provided　by　the　FRP-confined　concrete.　This　paper　presents　a　theoretical　study　into　the　buckling　behavior　of　longitudinal　steel　rebars　embedded　in　FRP-confined　concrete　subjected　to　monotonic　axial　compression.　In　the　theoretical　model,　a　beam-on-elastic　foundation　idealization　is　used,　where　the　steel　rebars　are　laterally　supported　by　elastic　springs　representing　the　FRP-confined　cover　concrete.　To　evaluate　the　stiffness　of　the　elastic　springs,　a　curved　beam　model　is　proposed.　Predictions　from　the　theoretical　model　are　compared　with　test　results,　demonstrating　the　reliability　of　the　theoretical　model.　A　parametric　study　is　then　presented　to　examine　the　influence　of　three　key　factors　(i.e.,　spring　stiffness,　yield　strength　of　steel,　and　slenderness　ratio　of　rebar)　on　the　overall　compressive　stress-strain　response　of　laterally　supported　steel　rebars.　Finally,　an　empirical　compressive　stress-strain　model　considering　the　effect　of　buckling　deformation　is　proposed　for　steel　rebars　embedded　in　FRP-confined　concrete　subjected　to　monotonic　axial　compression　and　validated　through　comparisons　with　the　test　results.　©　2017　American　Society　of　Civil　Engineers.