Seismic behaviour analysis of a wind turbine tower affected by sea ice based on a simplified model

Shuai Huang,Wengang Liu,Shufeng Zhai,Qingjie Qi,Jianzhong Liu

doi:10.1038/s41598-021-86142-0

Shuai Huang, Wengang Liu + Show 3 more

Open Access

https://doi.org/10.1038/s41598-021-86142-0

Copy DOI

Abstract

Ice-structure interaction threatens the safety of the offshore structure; however, dynamic seismic action even renders this process more sophisticated. This research constructed a simplified calculation model for the wind turbine tower, ice, and water under seismic loading, which could avoid solving the complex non-linear equations. Then, the seismic behaviour of the structure, i.e. wind turbine tower, in the presence and absence of influences of the sea ice was investigated, and we found the remarkable effect of sea ice upon the wind turbine tower when its mass is within a range; the wind turbine tower is found to have reduced capacity in energy dissipation, and thickness of tower walls or stiffening ribs is supposed to be enlarged for making the structure more ductile. Affected by the sea ice, the shear force and bending moment of the tower showed significant increases, and more attention needs to be paid to the tower bottom and action position of the sea ice. According to the dynamic similarity principle, finally paraffin was used to simulate sea ice, and shaking-table tests were performed for simulating dynamic ice-structure-water interactions. Results of shaking-table tests verified the rationality of our proposed simplified model.

Highlights

Ice-structure interaction threatens the safety of the offshore structure; dynamic seismic action even renders this process more sophisticated
The codes including Canadian Standards Association code (CSA)1, Eurocode[2], American Petroleum Institute code (API)[3], et al only point out that the sea ice load is an essential part to be considered in seismic design of structures, while none of them offers a calculation method to consider the dynamic interplays among ice, structure, and water under seismic actions
Few studies have been conducted into the seismic behaviour of wind turbines affected by sea ice; because such wind turbines are new structural forms, there is a lack of codified seismic design provision governing their analysis, especially for wind turbines located at sea

Summary

Introduction

Ice-structure interaction threatens the safety of the offshore structure; dynamic seismic action even renders this process more sophisticated. Sea ice affects dynamic responses of wind turbine towers to seismic actions; influences of earthquakes and sea ice upon the offshore structures are taken into account separately in most design specifications. Different water depths will directly lead to the different action point of the sea ice upon the wind turbine tower; we investigated effects of ice thickness and water depth upon non-linear seismic behaviours of the structure.

Results

Conclusion