The　nonlinear　unified　strength　criterion　proposed　by　authors　in　2010　is　adopted　as　the　yield　function　and　the　plastic　potential　function　for　concrete.　Four　original　material　parameters　of　the　nonlinear　unified　strength　criterion　are　derived　as　functions　of　four　conventional　strength　indexes　of　concrete.　A　three-dimensional　elastoplastic　constitutive　model　for　concrete　is　then　developed　by　using　hardening　and　softening　functions　that　are　determined　from　the　uniaxial　compressive　stress-strain　relationship.　The　performance　of　the　constitutive　model　is　evaluated　by　comparing　prediction　and　experimental　data　from　literatures.　The　comparison　shows　the　model　is　able　to　reasonably　describe　the　three-dimensional　strength　characteristics,　strain　softening　behavior　after　the　peak　stress　and　the　dilatancy　of　various　concretes.　Moreover,　the　proposed　model　is　integrated　in　the　general　finite　element　package　ABAQUS　via　UMAT　to　simulate　the　deformation　process　of　reinforced　concrete　columns　under　eccentric　compression.　The　simulations　show　that　the　proposed　constitutive　model　is　able　to　describe　the　nonlinear　mechanical　behavior　under　complex　stress　states　with　high　computational　efficiency.　(C)　2015　Elsevier　Ltd.　All　rights　reserved.