- مبلغ: ۸۶,۰۰۰ تومان
- مبلغ: ۹۱,۰۰۰ تومان
Interest in renewable and clean energy over the past decade has motivated immense research on wind energy. The main issues in design of offshore wind turbines in regions of recent development have been aero- and hydrodynamic loads; however, earthquake is a design concern in seismic areas such as East Asia and Western United states. This paper reviews the state of practice in seismic design of offshore wind turbines. It is demonstrated that wind turbines are in particular vulnerable to vertical earthquake excitation due to their rather high natural frequencies in vertical direction; however, inclusion of the radiation damping could contribute considerably reduce the earthquake loads. Moreover, it is demonstrated how soil nonlinearity could lead to settlement and permanent tilting of offshore wind turbines on caisson foundations or tripods. Using these cases, the paper demonstrates that the design of offshore wind turbines for earthquake loading is driven by performance-based considerations.
Summary and conclusions
This paper has presented a brief history of the development and growth of wind turbines and OWTs. It has also presented the state of practice in seismic design of offshore wind turbines and existing design cods. In addition, the paper has addressed, among others, the use of foundation macro-elements for earthquake response of wind turbines under lateral earthquake excitation and has highlighted the vulnerability of wind turbines to vertical earthquake excitations due to their high vertical natural frequencies. It has also been shown that for such loading conditions, use of radiation damping is a key to a more economical design. Moreover, the paper has demonstrated how soil nonlinearity and pore-pressure generation could lead to settlement and permanent tilting of offshore wind turbines on mono-bucket foundations. Using these cases, the paper has clearly highlighted the importance of performance-based analyses in seismic design of OWTs.