Low　cyclic　loading　tests　with　lateral　restraint　were　carried　out　using　a　110　scale　model　to　investigate　the　seismic　performance　of　the　steel　frame-bent　structures　with　braces　in　domestic　large-capacity　and　thermal　power　plants.　The　transverse　roof　trusses　from　the　main　building　of　a　thermal　power　plant　are　utilized　as　the　research　object.　The　seismic　performance　is　evaluated　according　to　the　observed　experimental　phenomena　and　the　obtained　hysterics　loops,　skeleton　curves,　stiffness　degradation　curves,　ductility　index,　and　the　effective　viscous　damping　coefficient.　The　research　results　show　that　the　steel　frame-bent　structure　with　braces　has　good　seismic　performance,　with　a　plump　load-displacement　curve　as　well　as　good　ductility　and　energy　dissipation　capacity.　The　initial　structural　failure　first　appeared　in　the　bottom-bracing　part　and　the　sequence　of　articulation　development　moved　from　the　hinge　beam　to　the　hinge　column.　The　failure　mode　of　the　frame-structuring　columns　was　compression　bending　deformation,　while　the　bent-structuring　showed　flexural-torsional　deformation.　The　maximum　bearing　capacity　in　the　positive　loading　was　approximately　11.3%higher　than　that　in　the　negative　loading　by　under　unidirectional　loading　within　the　frame　plane,　so　the　seismic　performance　was　asymmetric.　The　weak　story　should　be　strengthened　in　the　design　because　the　inter-story　drift　angle　of　the　second　floor　reaches　1/22.　The　buckling　of　braces　is　the　main　reason　for　the　out-of-plane　distortion,　joint　deformation,　and　the　residual　deformation.　©　2017,　Editorial　Office　of　China　Civil　Engineering　Journal.　All　right　reserved.