Recently,　large-rupture-strain　fiber-reinforced　polymers　(LRS　FRPs)　has　attracted　great　interest　from　the　research　community　owing　to　its　LRS　characteristic,　which　may　lead　to　relatively　higher　ductility　in　the　seismic　strengthening　of　reinforced　concrete　(RC)　bridge　piers　than　those　retrofitted　by　conventional　FRP　composites.　The　stress-strain　model　of　LRS　FRP-confined　concrete　is　the　basis　for　the　seismic　analysis　of　FRP-strengthened　RC　piers.　Based　on　the　monotonic　axial　compression　test　of　LRS　FRP-confined　concrete,　the　influence　of　confinement　rigidity　on　the　stress-strain　relationship　was　studied.　Unlike　the　strength-based　design　model,　which　determines　the　slope　of　the　second　section　of　the　stress-strain　curve　(that　is,.　the　axial　stiffness)　by　the　FRP　rupture　strain,　the　axial　stiffness　in　this　study　is　determined　by　the　FRP　confinement　rigidity;　thus,　a　stiffness-based　design　model　of　LRS　FRP-confined　concrete　under　uniaxial　compression　is　established.　The　parameters　of　LRS　FRP-confined　concrete　under　cyclic　axial　compression,　such　as　unloading　curve,　reloading　curve,　and　plastic　strain,　were　analyzed.　Plastic　strain　and　stress　degradation　were　found　to　influence　the　cyclic　behavior　of　LRS　FRP-confined　concrete　significantly.　By　redefining　these　two　key　parameters,　an　existing　cyclic　stress-strain　model　was　extended　to　LRS　FRP-concrete　with　good　performance.　Finally,　the　model　was　embedded　in　OpenSees　software　to　simulate　the　quasi-static　test　of　piers　strengthened　by　FRP.　The　simulation　results　are　in　good　agreement　with　the　test　results,　thereby　confirming　the　effectiveness　of　the　stiffness-based　model　in　the　analysis　of　bridge　seismic　reinforcement.　©　2022,　Editorial　Department　of　China　Journal　of　Highway　and　Transport.　All　right　reserved.