Effectiveness of MTMD for jacket offshore platform under wave and earthquake excitations

Jacket offshore platforms are among the most prevalent structural types in ocean engineering. Multiple tuned mass dampers (MTMD) show great potential for mitigating the dynamic responses of these platforms. However, research on the vibration control capabilities of MTMD for jacket offshore platforms, especially considering soil-structure interaction (SSI), remains limited. This study comprehensively investigates the effectiveness of MTMD by modeling the dynamic response of a standard four-legged jacket offshore platform, incorporating SSI effects under both wave and seismic excitations. Firstly, a reliable numerical model of the soil-jacket offshore platform-MTMD system is established, and the total horizontal wave force is validated based on the Morrison equation. Then, the vibration mitigation effects of MTMD with varying frequencies, mass, and numbers of TMDs are compared for both the equivalent pile and SSI cases. Finally, the impacts of MTMD parameters and external load characteristics on the control performance of MTMD are further analyzed. The results demonstrate that MTMD can significantly reduce the dynamic response of the jacket offshore structure. Nevertheless, SSI effects diminish the mitigation performance of MTMD. For the target structure, the optimal frequency bandwidth of MTMD is centered at 0 for the equivalent pile model, while it shifts slightly to 0.1 for the SSI case, and the control effects of MTMD are satisfactory when the number of TMDs is four. Moreover, under SSI conditions, MTMD exhibits superior robustness in vibration control compared to a single tuned mass damper.