This　study　investigates　the　dynamic　behavior　of　a　jacket-supported　offshore　wind　turbine　(JOWT)　by　developing　its　substructure　and　controller　tailored　for　the　IEA　15　MW　reference　wind　turbine.　A　fully　coupled　numerical　model　integrating　the　turbine,　jacket,　and　pile　is　established　to　analyze　the　natural　frequencies　and　dynamic　responses　of　the　system　under　wind-wave-current　loading　and　seismic　excitations.　Validation　studies　confirm　that　the　proposed　15　MW　JOWT　configuration　complies　with　international　standards　regarding　natural　frequency　constraints,　bearing　capacity　requirements,　and　serviceability　limit　state　criteria.　Notably,　the　fixed-base　assumption　leads　to　overestimations　of　natural　frequencies　by　32.4%　and　13.9%　in　the　fore-aft　third-　and　fourth-order　modes,　respectively,　highlighting　the　necessity　of　soil-structure　interaction　(SSI)　modeling.　During　both　operational　and　extreme　wind-wave　conditions,　structural　responses　are　governed　by　first-mode　vibrations,　with　the　pile-head　axial　forces　constituting　the　primary　resistance　against　jacket　overturning　moments.　In　contrast,　seismic　excitations　conversely　trigger　significantly　higher-mode　activation　in　the　support　structure,　where　SSI　effects　substantially　influence　response　magnitudes.　Comparative　analysis　demonstrates　that　neglecting　SSI　underestimates　peak　seismic　responses　under　the　BCR　(Bonds　Corner　Record　of　1979　Imperial　Valley　Earthquake)　ground　motion　by　29%　(nacelle　acceleration),　21%　(yaw-bearing　bending　moment),　42%　(yaw-bearing　shear　force),　and　17%　(tower-base　bending　moment).