Q1100　refers　to　ultra-high　strength　steel　(UHSS)　with　a　nominal　yield　strength　of　1100　MPa.　Hysteretic　tests　were　conducted　on　seven　Q1100　UHSS　H-section　welded　columns　to　assess　their　hysteretic　performance.　The　hysteretic　performance　was　evaluated　through　hysteresis　curves,　damage　phenomena,　energy　dissipation,　ductility,　and　load-carrying　capacity.　The　impact　of　the　width-to-thickness　ratio　and　axial　pressure　ratio　on　the　hysteretic　behavior　was　also　investigated.　A　validated　finite　element　model　was　utilized　to　analyze　the　hysteresis　behavior,　influencing　factors,　and　the　applicability　of　Eurocode　3　width-to-thickness　ratio　limits,　resulting　in　proposed　seismic　design　recommendations.