Abstract
Sea ice is one of the main loads acting on a wind turbine tower in areas prone to icing, and this threatens safe working life of the wind turbine tower. In our study, a simplified calculated model of ice, wind turbine tower, and water dynamic interaction under earthquake action was proposed, which could avoid to solve a large number of nonlinear equations. Then, the seismic behaviour of the wind turbine tower with and without the influence of sea ice was investigated, and we found that the influence of the greater mass of the sea ice on the seismic response of a wind turbine tower should be considered when the wind turbine tower is designed in an area with thick ice. With the influence of the most unfavourable ice mass, the deformation and energy dissipation capacity of the wind turbine tower are decreased, and the wall thickness or stiffening rib thickness should be increased to improve the seismic performance and ductility of the wind turbine tower; the shear force and bending moment increased significantly on the wind turbine tower, and the shear force changes at the bottom of the wind turbine tower and position of action of the sea ice: attention should be paid to the wind turbine tower design at these positions. Finally, we conducted the shaking table test, and verified the rationality of our proposed simplified model.
Highlights
Sea area in north China coincides with seismic activity occurring during the annual fourmonth icing period
>>>>>>>>: Wjk 0 Wu where, subscript i denotes the sea ice term; subscript j refers to the tower; u refers to the superstructure concentration particle; a refers to the added mass; m and n are positions of action of ice and tower before and after motion; xi is the relative displacement of the sea ice; xj is the relative displacement of the tower point-mass; xu is the relative displacement of the superstructure; Wu, Wjm, and Wjk are the equivalent static wind loads corresponding to the top, middle, and bottom parts of the wind turbine tower above the sea ice action position
A simplified model of the water-ice-structure dynamic interaction was proposed to investigate the effect of the sea ice on the seismic behaviour of a wind turbine tower, and the novelties of the study are as follows: 1. A simplified seismic response analysis model of a wind turbine tower, ice, and water under earthquake load was established, and this obviated the need to solve complicated non-linear equations and reduced the computational burden to a significant extent
Summary
Sea area in north China coincides with seismic activity occurring during the annual fourmonth icing period. Sea ice around the pile affects the seismic response of the wind turbine tower above. Japanese codes [5] point out that it is necessary to study the seismic performance of structures under ice load, none of these codes provide a calculation method for the coupling of the structure, ice, and water under earthquake loads. The effect of sea ice on the seismic behaviour of a wind turbine tower is rarely studied. A simplified model, which could be implemented incorporating the interaction of sea ice, water, and structure, was proposed; secondly, the rationality of the simplified model and the accuracy of the calculated results were verified by shaking table test; Seismic performance analysis of a wind turbine tower. The force acting on the top of the tower is shwn in Eq (11)
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