To　investigate　the　nonlinear　seismic　performance　of　partially　concrete-filled　steel　bridge　piers　with　thin-wall　ribbed　box　sections　during　frequent　and　rare　earthquakes,　three　test　specimens,　one　not　filled　with　concrete,　one　filled　with　concrete　up　to　20%　of　the　height　of　a　bridge　pier,　and　one　filled　with　concrete　up　to　40%　of　the　height　of　a　bridge　pier,　were　produced　and　used　in　the　pseudo-dynamic　tests　using　the　MTS　servo　loading　system.　The　JRT-NS　seismic　wave,　the　same　as　that　in　the　Hanshin　Earthquake　in　Japan,　was　used　in　the　tests,　from　which　the　displacement　time　history　curve,　load-displacement　hysteretic　curve,　and　cumulative　energy　dissipation　time　history　curve　were　obtained.　The　experimental　results　show　the　following:　all　three　specimens　were　in　an　elastic　state　under　frequent　earthquakes;　under　rare　earthquakes,　specimens　filled　with　concrete　at　the　base　were　in　an　elastoplastic　state　and　showed　good　seismic　performance,　without　the　occurrence　of　significant　destruction;　with　the　increase　of　the　filling　ratio　of　concrete　in　the　plastic-hinge　region　at　the　base,　the　constraint　effect　of　concrete　inside　the　thin-wall　steel　tube　on　the　local　buckling　development　of　the　tube　gradually　increased;　and　some　seismic　performance　indexes,　including　the　structural　stiffness,　horizontal　bearing　capacity,　maximum　displacement,　residual　displacement,　and　energy　dissipation　capacity　of　steel　piers,　were　significantly　improved.　©　2016,　Editorial　Board　of　Journal　of　Hohai　University　(Nature　Sciences).　All　right　reserved.