This　paper　discusses　three　hardening　modes　of　a　shear-type　yield　surface　and　proposes　a　true　three-dimensional　(3D)　frictional　hardening　method　using　the　transformed　stress.　The　proposed　method　reasonably　reflects　the　stress-induced　anisotropy　of　concrete　for　a　wide　range　of　hydrostatic　pressures.　A　unified　hardening/softening　function　is　proposed　based　on　the　uniaxial　compressive　stress-strain　relationship.　The　plastic　potential　function　is　obtained　by　studying　the　influence　of　linear　and　nonlinear　plastic　potential　function　on　the　dilatancy,　and　the　relationship　between　the　yield　surface　and　plastic　potential　surface　is　analyzed.　The　loading-unloading　criterion　suitable　for　the　softening　behavior　is　obtained　by　transforming　the　yield　function　expressed　by　stress　into　the　one　expressed　by　strain.　Furthermore,　a　true　3D　frictional　hardening　elastoplastic　constitutive　model　is　established.　The　explicit　stress　integral　algorithm　and　semi-implicit　stress　integral　algorithm　are　used　to　implement　the　numerical　computation.　Finally,　five　sets　of　biaxial　and　triaxial　test　results　of　high-strength　and　normal-strength　concrete　are　used　to　verify　the　established　constitutive　model.　(C)　2018　Elsevier　Ltd.　All　rights　reserved.