The　strengthening　and　retrofitting　technique　with　fiber-reinforced　polymer　(FRP)　composites　on　reinforced　concrete　(RC)　columns　has　been　widely　popular.　Compared　with　concentric　compression　behaviors　of　rectangular　FRP-confined　concrete　columns,　there　are　only　limited　investigations　on　their　eccentric　behaviors.　Additionally,　the　applicability　of　existing　design　codes　obtained　from　tested　small-size　columns　in　calculating　load　capacity　of　large-size　columns　has　not　been　reasonably　explained.　In　view　of　this,　this　paper　developed　a　mesoscale　numerical　analysis　method　using　a　random　aggregate　model　based　on　consideration　of　concrete　heterogeneity.　A　series　of　rectangular　carbon　FRP　(CFRP)-confined　RC　columns　having　different　cross-sectional　heights　were　modelled　to　investigate　the　influences　of　corner　radius　and　size　effect　on　their　eccentric　compression　behaviors.　Simulated　results　showed　that　there　was　a　transformation　of　failure　mode　from　brittle　compression　failure　to　ductile　tensile　failure　with　the　increasing　load　eccentricity.　An　identical　globally　failure　mode　for　rectangular　columns　having　different　cross-sectional　heights　was　observed　whereas　crack　widths　became　larger　obviously　with　the　increasing　cross-sectional　height.　Regarding　the　axial　load　versus　mid-height　deflection　relationship,　the　corner　radius　had　a　significant　influence　on　maximum　axial　load　and　softening　stage,　especially　at　smaller　load　eccentricities.　One　can　see　that　from　nominal　interaction　diagrams,　small-eccentrically-loaded　columns　exhibited　more　obvious　size　effect　than　large-eccentrically-loaded　columns.　The　safety　factor　of　load　capacity　decreased　with　the　increasing　cross-sectional　height　compared　with　existing　design　codes　of　ACI　440.2R-17　and　GB　50608,　illustrating　that　design　codes　appear　to　be　not　conservative　for　large-size　specimens.　Taking　the　influence　of　size　effect　into　account,　the　design　equations　suggested　by　ACI　440.2R-17　were　modified　in　this　study,　and　the　rationality　of　this　correction　methodology　was　verified　against　simulated　data　and　results　of　tested　large-size　rectangular　columns.