To　explore　the　nonlinear　bond　behavior　between　ribbed　bar　and　concrete,　considering　frictional　resistance　and　the　mechanical　interlocking　between　rebar　and　concrete　as　well　as　the　surface　characteristic　of　crescent　ribbed　bar,　a　3D　meso-scale　modelling　approach　is　established.　Comparisons　between　the　simulation　and　experimental　results　indicate　that　the　meso-scale　method　can　provide　good　predictions　of　the　interface　behavior　between　concrete　and　deformed　steel　bar　under　confinement　conditions.　The　bond　failure　mechanism　and　the　propagation　of　internal　crack　of　specimen　were　clearly　studied　and　revealed　based　on　the　3D　simulations.　Moreover,　the　influences　of　concrete　strength　gradation,　ratio　of　cover　thickness　to　bar　diameter　as　well　as　stirrup　confinement　on　bond　stress-slip　behavior,　concrete　failure　mode　and　rebar　stress　were　explored.　The　simulation　results　indicate　that　the　meso-scale　modelling　method　can　well　describe　the　bond　failure　process　at　the　steel　bar/concrete　interface.　It　is　found　that　increasing　the　concrete　strength　can　delay　the　internal　crack　of　the　specimen　and　may　change　the　failure　mode　of　the　specimen　from　splitting　failure　to　pull-out　failure.　As　concrete　strength　increases,　the　bond　strength　increases　linearly,　whereas　the　peak　slip　decreases　slightly.　The　shape　of　bond　stress-slip　curve　and　the　concrete　failure　modes　are　closely　associated　with　the　lateral　confinements　such　as　concrete　cover　thickness　and　the　stirrup　confinement.　When　the　cover　thickness　and　the　stirrup　confinement　index　reach　a　certain　value,　the　bond　failure　would　no　longer　be　affected.　In　addition,　the　strain　of　stirrups　increases　continuously,　the　bond　stress　provided　by　stirrups　increases　first　and　then　decreases.　©　2020　Elsevier　Ltd