The　ultimate　rotation　capacity,　depending　on　the　plastic　hinge　length,　is　a　vital　factor　in　the　seismic　design　of　flexural　members.　This　paper　focuses　on　the　investigation　of　the　plastic　hinge　length　and　size　effect　of　rectangular　carbon　fiber-reinforced　polymer　(CFRP)-confined　reinforced　concrete　(RC)　columns.　Firstly,　considerable　scatter　and　evident　bias　of　the　calculation　results　were　found　after　evaluating　existing　models　for　calculating　the　plastic　hinge　length　of　FRP-confined　RC　columns.　Accordingly,　a　meso-scale　numerical　approach　was　developed,　with　concrete　heterogeneity　considered,　to　investigate　the　influences　of　the　confinement　ratio　and　corner　radius　on　the　plastic　hinge　length　and　size　effect　of　rectangular　CFRP-confined　RC　columns.　Results　show　that　columns　having　different　cross-sectional　sizes　exhibit　similar　failure　patterns,　and　the　region　of　lateral　crack　propagation　for　columns　with　lower　confinement　ratios　is　larger　than　that　for　columns　with　higher　confinement　ratios.　The　actual　plastic　hinge　length　is　determined　based　on　the　yielding　zone　of　reinforcement,　the　crushing　zone　of　concrete,　and　the　localization　zone　of　curvature,　while　the　localization　zone　of　curvature　is　employed　to　determine　the　real　plastic　hinge　zone.　The　size　effect　is　found　to　exist　in　the　plastic　hinge　length　ratio,　and　it　is　weakened　with　the　increase　of　the　corner　radius,　which　can　be　attributed　to　the　fact　that　columns　with　higher　corner　ratios　have　more　effective　confinement.　Taking　into　account　the　size　effect,　a　new　model　for　calculating　the　ultimate　drift　ratio　of　CFRP-confined　RC　columns　was　proposed　based　on　an　assumption　of　curvature　distribution　and　presented　accurate　predictions.　©　2024　Elsevier　Ltd