A　series　of　calculation　models　were　designed　and　made　to　analyze　the　energy　dissipation　of　structure　and　floor　damage　under　rare　earthquake,　in　order　to　investigate　the　shear　lag　phenomenon　of　steel　bundled-tube　and　its　effects　on　structure　design.　Based　on　the　finite　elements　analysis　models,　elastic　analysis　under　wind　load　and　frequent　earthquake　and　elasto-plastic　time　history　analysis　under　rare　earthquake　were　used.　The　calculating　data　were　used　to　analyze　distribution　of　plastic　energy　dissipation　along　story　and　influence　of　shear　lag　with　different　depth　of　beams.　Relationship　between　shear　lag　and　floor　damage　was　also　studied.　The　calculation　method　of　floor　damage　degree　was　proposed　by　analysis　of　harmful　displacement　angle　and　plastic　energy　dissipation　of　floors.　The　floor　damage　degree　was　quantitatively　evaluated.　The　results　show　that　the　1/3　height　range　of　the　lower　part　of　steel　bundled-tube　structure　is　shear　sensitive　region.　Increasing　depth　of　spandrel　beams　in　this　region　can　get　the　same　space　working　effect　as　increasing　depth　of　all　spandrel　beams.　It　is　important　to　avoid　stress　mutation　and　severe　shear　lag　in　one　region　during　improving　the　shear　lag　in　another　region.　Representative　value　of　columns　non-uniform　stress　coefficient　which　can　reflect　shear　lag　of　floor　has　similar　distribution　patterns　to　plastic　energy　dissipation　in　the　section　of　vertical　set　back.　The　calculated　floor　damage　factors　agree　with　the　damage　phenomena.　The　proposed　formula　based　on　the　normalized　two　parameter　model　of　displacement　and　plastic　energy　dissipation　can　be　used　to　evaluate　the　floor　damage　degree　of　steel　bundled-tube　structure　quantitatively.　©　2018,　Editorial　Office　of　Journal　of　Building　Structures.　All　right　reserved.