An　improvement　to　the　direct　stiffness　calculation　(DSC)　method　for　bending-type　frame　structures　was　proposed　here,　it　could　be　used　to　conduct　damage　assessment.　The　corresponding　system　identification　toolbox　in　the　platform　of　OpenSees　was　expected　to　be　used　in　engineering.　The　proposed　improvement　was　simple,　but　apparently　quite　effective,　the　modification　of　the　DSC　method　for　damage　detection　and　the　system　identification　toolbox　were　applicable　to　practical　bending-type　frame　structures.　Aiming　at　the　benchmark　test　of　a　12-story　reinforced　concrete　frame　model　performed　on　a　shaking　table　in　Tongji　University,　a　simulation　model　for　this　benchmark　test　under　excitation　of　several　seismic　waves　was　evaluated　to　verify　the　modified　DSC　technique　and　the　system　identification　toolbox.　The　results　showed　that　the　preliminary　assessment　using　the　improved　direct　stiffness　method　and　the　corresponding　system　identification　toolbox　is　feasible　and　efficient　for　damage　detection　of　bending-type　structures.