PARTITIONED ANALYSIS METHOD FOR SEISMIC RESPONSE OF OFFSHORE FLOATING NUCLEAR POWER PLATFORM

The offshore floating nuclear power platform has emerged as a significant undertaking for China to resolve the energy requirements of remote island or sea-based sites. However, the legitimacy of its seismic safety remains uncertain. A partitioned hybrid analysis method for the interaction between the seabed, seawater, and floating structure under seismic action is developed in this study. The seabed and seawater regions are analyzed using lumped mass-explicit finite elements coupled with transmitting artificial boundaries while the floating structure region is solved using the mode-superposition method. The acoustic-structure coupling between the seawater and the floating structure is implemented through an iterative algorithm. Parallel computation is carried out, and the methodology is verified through a straightforward example. An analysis of the seismic response of a nuclear power platform, represented as a floating barge, to obliquely incident SV waves is performed, and the effects of incident angles of 10°, 20° and 30° on the seismic response are examined for illustration. The results indicate that the conventional view, which suggests that floating structures do not need to consider seismic resistance, is based on the assumption of vertical SV wave incidence. However, when SV waves strike the floating nuclear power platform obliquely, both horizontal and vertical seismic responses are generated, which are dominated by longitudinal rocking and vertical oscillation modes. There is a noticeable trend of increased horizontal and vertical displacements and accelerations in both the containment and appurtenant structures of the floating nuclear power platform with the increasing angle of incidence. The majority of responses occur in the vertical direction, but certain frequency ranges show a higher acceleration response spectrum amplitude in the horizontal direction of the subsidiary structure compared to the vertical direction. This highlights the need to consider seismic design for both the structure and equipment of the offshore floating nuclear power plants.