Buckling　of　steel　reinforcement　usually　causes　a　sudden　loss　of　the　load-carrying　capacity　and　the　ultimate　state　of　conventional　reinforced　concrete　(RC)　cylinders.　However,　reinforcing　bars　behave　differently　in　fiber-reinforced　polymer　(FRP)-confined　RC　cylinders　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　considering　the　buckling　effects　proposed　previously　for　laterally　supported　reinforcing　bars　is　extended　to　a　cyclic　model　by　combining　the　monotonic　envelope　and　the　Menegotto-Pinto　model　accounting　for　the　cyclic　loops.　The　cyclic　stress-strain　models　for　both　laterally　supported　reinforcing　bars　and　FRP-confined　plain　concrete　are　then　implemented　into　the　OpenSees　software　platform　and　validated　through　comparisons　with　compressive　test　results　on　cyclically　loaded　FRP-confined　plain　and　RC　cylinders.　The　proposed　cyclic　stress-strain　model　for　laterally　supported　reinforcing　bars　is　expected　to　serve　as　a　fundamental　model　for　predicting　the　seismic　behavior　of　FRP-strengthened　RC　cylinders　with　widely-spaced　transverse　ties　under　cyclic　axial　compression,　in　which　case　the　local　buckling　of　reinforcing　bars　usually　occurs　between　two　adjacent　transverse　ties.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.