Masonry　structures　often　exhibit　poor　seismic　performance　during　earthquakes　owing　to　their　low　material　strength,　structural　integrity,　and　ductility.　To　address　the　mechanism　of　in　-plane　damage　and　collapse　of　masonry　walls　subjected　to　earthquake　ground　motion,　three　full-size　brick　walls,　one　with　structural　columns　and　two　without　structural　columns,　were　designed　and　constructed　in　this　experimental　study　to　quantitatively　investigate　the　effect　of　structural　columns　on　the　seismic　performance　of　masonry　walls.　Quasi　-static　tests　of　masonry　walls　subjected　to　cyclic　lateral　loading　were　conducted　using　electrohydraulic　servo　actuators.　The　inplane　damage　evolution　and　failure　mode　of　the　masonry　walls　under　lateral　loading　were　investigated.　A　numerical　model　with　a　novel　plastic　damage　constitutive　model　of　masonry　was　established.　The　accuracy　of　this　model　and　the　calculation　results　were　verified　by　comparing　them　with　the　crack　development　and　mechanical　property　curves　obtained　from　the　experiments.　Based　on　the　numerical　model,　a　parametric　analysis　was　conducted　to　investigate　the　influence　of　critical　factors,　such　as　mortar　strength,　vertical　load,　and　height　-to　-width　ratio,　on　the　seismic　performance　of　masonry　structures.　The　test　results　showed　that　structural　columns　can　effectively　improve　the　performance　of　masonry　structures.　Properly　installed　structural　columns　can　improve　the　peak　load　-bearing　capacity,　ductility,　and　energy　dissipation　of　masonry　structures.　The　masonry　damage　constitutive　model　used　in　this　study　could　simulate　the　damage　to　masonry　wall　specimens　well　and　reflect　the　hysteretic　curves　of　the　specimens　within　an　acceptable　range　of　accuracy.　Thus,　it　provides　a　valuable　reference　for　physical　experiments.　An　appropriate　mortar　strength　and　vertical　compressive　stress　can　effectively　enhance　the　loadbearing　capacity　of　masonry　structures　within　a　certain　range.　For　structural　column　walls.　Walls　with　mortar　strengths　(average　compressive　strength)　of　12.5　MPa,　10　MPa,　7.5　MPa,　and　5　MPa　showed　an　increase　in　peak　bearing　capacity　of　26.2　%,　23.9　%,　18.5　%,　and　9.4　%,　respectively,　compared　to　walls　with　mortar　strengths　(average　compressive　strength)　of　2.5　Mpa.　The　aspect　ratio　had　a　significant　impact　on　the　shear　load　-bearing　capacity　of　the　masonry　walls.　An　increase　in　the　aspect　ratio　led　to　a　transition　from　shear　failure　to　flexural　failure　and　a　subsequent　decrease　in　shear　load　-bearing　capacity.　For　masonry　walls　with　structural　columns,　increasing　the　diameter　of　the　longitudinal　steel　in　the　structural　columns　can　enhance　the　load　bearing　capacity　of　the　masonry　wall,　resulting　in　a　significant　improvement　in　its　overall　performance.