Structural Engineering

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Browsing Structural Engineering by Subject "Aerodynamic, Seismic Load, Land-Based Wind Turbine Towers, Numerical Investigation"

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    Numerical Investigation of the Effect of Aerodynamic and Seismic Load Interaction on the Stability of Land-Based Wind Turbine Towers
    (Addis Ababa University, 2023-06-13) Gossaye Mathewos; Bedilu Habte (PhD)
    Wind energy is one form of renewable energy and the utilization of wind energy is rapidly growing worldwide due to its a bundance. Wind turbines are a feasible, cost effective, and durable source of wind energy, and ensuring their safety is essential for proper service life operation to protect the investment. The installation of wind turbines in seismic regions is growing t o meet renewable energy demand around the world, and analyzing the stability of wind turbines in these regions is critical. This research analyzes the effect of aerodynamic and seismic load interaction on the stability of land based horizontal axis wind tu rbine towers built in seismic areas. The methodology implemented to conduct this study is a decoupling approach to analyze the effect of wind loads and seismic loads independently and combine results obtained from ANSYS Workbench 2022. A reliable finite el ement model is established by validating modal analysis results with experimental values. Then, global responses such as top tower displacement and second order (P Δ) effect, and local responses such as maximum Von Mises stress and eigenvalue buckling anal ysis of wind turbine towers were conducted. Earthquake loads are found to be dominant loads compared to wind loads for all wind turbines and earthquake induced emergency shutdown condition is found to be the most critical operation condition for all wind t urbines. In addition, the second order (P Δ) effect from analysis of wind turbine towers shows that 1.5MW and 5MW wind turbine towers are significantly affected, but P Δ is negligible for 65kW wind turbine. Moreover, a 1.5MW wind turbine has higher top tow er displacement and maximum Von Mises stress compared to a 5MW wind turbine which is due to the effect of the shell property of the tower and the weight of wind turbines. Furthermore, the characteristics of the acceleration vs time records are also found t o have a significant effect on the response behavior of the turbines rather than the magnitude and distance earthquake records are measured from the source alone. This study emphasizes the need to consider the impact of the second order (P Δ) effect for th e design of 1.5MW and 5MW wind turbines to avoid structural stability failure.