The　scope　of　the　work　is　to　detect　the　most　appropriate　damage　index,　able　to　provide　a　reliable　description　of　the　structural　damage　level.　This　damage　index　is　used　to　formulate　a　performance-based　design　framework　to　be　used　as　a　design　tool　for　achieving　safer　and　more　economic　designs.　This　objective　is　achieved　by　comparing　alternative　structural　systems　that　comply　with　the　design　demands　in　the　most　cost-efficient　approach,　i.e.,　those　requiring　less　material　volume　for　concrete　and　steel　reinforcement.　In　this　direction,　design　optimization　problems　for　structural　systems　are　defined　for　each　damage　index　under　consideration　and　the　structural　optimization　problems　at　hand　are　solved　by　means　of　a　popular　metaheuristic　search　algorithm.　©　2018　Mitropoulou,　Marano　and　Lagaros.