Traditional　control　algorithms　have　difficulty　handling　nonlinear　behavior　of　structures,　time　variable　features　and　parameter　uncertainties　of　structural　control　systems　under　seismic　excitation.　A　direct　method　based　on　the　Off-and-Towards-Equilibrium　(OTE)　strategy　was　presented　in　this　paper　to　overcome　these　difficulties.　According　to　the　proposed　method,　the　control　force　can　be　designed　by　dividing　the　phase　plane　into　mesh　regions.　Its　advantage　is　that　it　can　be　used　for　a　variety　of　control　systems.　In　order　to　evaluate　the　performance　of　the　method,　the　seismic　performance　of　a　three-storey　shear　building　with　an　active　tendon　system　was　studied.　The　results　show　that　the　proposed　method　performs　slightly　better　than　the　linear　quadratic　regulator　(LQR)　algorithm,　while　possessing　several　advantages　over　the　LQR　controller.　Consequently,　the　feasibility　and　effectiveness　of　the　proposed　method　are　verified.