Vibration mitigation of an integrated structure consisting of a monopile offshore wind turbine and aquaculture cage under earthquake, wind, and wave loads

Abstract

To realize multi-purpose exploration of marine resources, a novel design consisting of a monopile offshore wind turbine and steel aquaculture cage in an integrated structure is proposed in this paper; the structure is denoted as MOWTAC. Based on the theories of the screen model, a hydrodynamic analysis module is developed in the OWT simulation tool FASTv8. Then, in combination with a seismic analysis module, the fully coupled analysis model of the MOWTAC is established in the updated FAST v8. Based on the coupled model, the dynamic characteristics and coupling mechanisms of the MOWTAC under earthquake, wind, and wave loads are investigated. A tuned mass damper (TMD) is applied to the MOWTAC under earthquakes, and the influence of the TMD parameters on the mitigation effects is studied. Furthermore, a multiple tuned mass damper (MTMD) with various tuning frequencies is applied, and comparisons with the TMD are carried out. Based on the reduction of seismic responses using the TMD and MTMD, vibration control methods and related design parameters are recommended for the MOWTAC under earthquake, wind, and wave loads.