The　paper　reports　the　results　of　a　series　of　tests　of　geometrically　similar　stocky　reinforced　concrete　(RC)　columns　having　different　sizes　with　a　ratio　of　1:1.5:2.25.　The　effects　of　stirrup　ratio,　tie　arrangement　type　and　yield　strength　of　stirrups　on　the　failure　and　size　effect　of　RC　columns　under　axial　compression　were　explored.　Moreover,　a　3D　meso-scale　numerical　method　for　the　simulation　of　failure　of　RC　members　was　developed.　The　test　observations　demonstrate　the　existence　of　size　effect　in　larger-sized　RC　columns,　and　the　failure　is　governed　by　fracture.　With　increasing　the　stirrup　ratio,　the　number　of　stirrups　leg　and　yield　strength　of　stirrups　could　make　the　enhancement　of　nominal　strength　and　improvement　of　ductility　capacity　of　RC　columns.　The　RC　columns　with　a　lower　stirrups　ratio,　a　smaller　number　of　tie　legs,　and　a　lower　yield　strength　of　stirrups　present　much　more　brittle　failure,　exhibiting　much　stronger　size　effect.　The　test　data　illustrates　that　the　nominal　compressive　strengths　are　consistent　with　the　size　effect　law　(SEL)　proposed　by　Bazant.　Moreover,　good　agreements　between　the　simulation　results　and　the　test　observations　illustrate　the　reasonability　of　the　developed　meso-scale　simulation　approach.　(C)　2017　Elsevier　Ltd.　All　rights　reserved.