Buckling　of　steel　reinforcement　usually　causes　a　sudden　loss　of　the　load-carrying　capacity　and　leads　to　the　ultimate　state　of　conventional　reinforced　concrete　(RC)　columns.　However,　it　behaves　differently　in　fiber-reinforced　polymer　(FRP)-confined　RC　columns　due　to　the　lateral　confinement　effect　of　FRP.　This　paper　presents　a　theoretical　study　into　the　buckling　behavior　of　longitudinal　steel　reinforcing　bars　embedded　in　FRP-confined　concrete　subjected　to　cyclic　axial　compression.　An　empirical　monotonic　compressive　stress-strain　model　for　laterally　supported　reinforcing　bars　considering　the　buckling　effect,　which　was　proposed　in　the　authors’　previous　study,　was　extended　to　a　cyclic　stress-strain　model　following　the　Menegotto-Pinto　model　accounting　for　the　cyclic　loops.　The　cyclic　stress-strain　models　for　laterally　supported　reinforcing　bars　as　well　as　FRP-confined　plain　concrete　were　then　implemented　into　the　OpenSees　platform　to　simulate　the　cyclic　compressive　behaviour　FRP-confined　RC　columns　and　validated　through　comparisons　with　test　results.　The　proposed　cyclic　stress-strain　model　for　laterally　supported　reinforcing　bars　can　serve　as　a　fundamental　law　for　the　modelling　of　seismic　behaviour　of　FRP-strengthened　RC　columns,　especially　for　those　with　sparely-　spaced　transverse　ties　where　buckling　of　reinforcing　bars　becomes　a　significant　concern.　Copyright　©　2016　Department　of　Civil　and　Environmental　Engineering　&　Research　Institute　for　Sustainable　Urban　Development,　The　Hong　Kong　Polytechnic　University.