The　influences　of　opening　and　closing　of　contactable　joints　of　arch　dam　and　arch　dam-foundation　rock　dynamic　interaction　on　the　seismic　response　analysis　of　arch　dams　under　strong　earthquake　are　all　very　obvious.　The　present　some　models　simulating　the　contact　process　of　contactable　joints　used　in　the　seismic　response　analysis　of　arch　dams,　such　as　Fenves＇　model　and　Dowlings＇　model,　are　also　based　on　the　penalty　parameter　method,　it　is　trouble　that　the　penalty　parameters　are　determined.　In　addition,　the　two　effects　mentioned　above　have　not　yet　been　considered　together　in　the　present　seismic　response　analysis　of　arch　dams,　and　it　is　difficult　to　consider　the　two　effects　together　by　the　methods　in　the　frequency　domain.　Therefore,　a　combination　method　in　the　time　domain　of　the　explicit　FEM　and　a　transmitting　boundary　have　been　proposed　for　the　analysis　of　the　seismic　response　of　arch　dams　by　X.L.　Du　et　al　(2000).　In　this　paper,　the　first　effect　stated　above　is　studied　by　introducing　a　contact　force　model　into　the　combination　method.　Through　comparing　with　the　results　obtained　by　the　model　tests　on　vibration　table,　the　simulation　accuracy　for　contact　state　between　the　interfaces　of　contactable　joints　by　the　contact　force　model　is　verified.　By　using　a　dynamic　analysis　method　the　static　responses　of　arch　dams　is　solved,　and　a　combination　method　is　also　proposed　to　calculate　the　nonlinear　responses　of　arch　dams　under　the　actions　of　static　and　dynamic　load.　Finally,　some　results　have　been　obtained　by　using　this　approach　for　the　designed　Xiaowan　arch　dam　with　maximum　height　of　292m　in　china.　©　2004　Taylor　&　Francis　Group,　London.