This study aims at proposing a simulation method for an offshore converter station platform (OCS) under dynamic loading. A user-defined in-house FORTRAN code was developed based on the Vector Form Intrinsic Finite Element (VFIFE) method, and the numerical model was validated by test data. After model validation, the dynamic behavior of the OCS was carefully studied and the effect of different loading conditions, including seismic, hydrodynamic and wind load, on the dynamic behavior of OCS was investigated. The time history of the structural response was obtained, and the relationship between the structural peak response and the peak value of the seismic load was also shown. It indicated that water damping accelerates energy consumption, while the effect of hydrodynamic and wind load has little influence on the cases studied in this work. Generally, the peak response increases almost linearly with the increase in the peak acceleration of the ground, and the seismic propagating direction has a great impact. In addition, both a whipping effect and stretching-squeezing effect were observed, and the vertical acceleration response of the valve hall deck is much higher than other structures, which is caused by the relatively lower local rigidity of the large-span structure and the inertia force caused by the valve tower.

Converter valves are the core equipment of offshore wind power structures. However, they are highly vulnerable to vibration under strong earthquakes, which will affect normal operation of the offshore wind farm. Converter station is an axisymmetric structure with obvious asymmetry in its internal configuration of the superstructure. This study aimed to analyze the dynamic response of a supported converter valve in an offshore converter station under seismic excitation. The coupling model of the supported valve tower group and the converter station were established, and the distribution law of the valve tower dynamic response and foundation settlement were investigated. The dynamic response effect of the modal truncation, valve tower stiffness, and basic size on different areas and foundations of the valve towers were studied. The findings were as follows: (i) the effect of local vibration of the valve tower should not be simplified by using equivalent mass and node condensation; (ii) the structure–equipment coupling analysis method should be used to review the structural design scheme of the offshore converter station in the intensity VII region; (iii) the vertical higher-order modes should be considered during the vibration response calculation and its participation ratio in mass should not be lower than 90%; (iv) the frequency range that minimizes the vibration response is the characteristic frequency range of horizontal vibration, while the best vibration suppression effect cannot be obtained in both the horizontal and vertical directions; and (v) the stiffness of the valve tower itself should be adjusted and different stiffness designs of the valve tower in different positions should be adopted to realize effective vibration response control.