The increased demand in energy and the need for sustainable and renewable sources of electricity in hazardous environments with a significantly growing population yields the installation of more wind turbines in these areas. The technological development in material and construction methods has led to the building of taller and more flexible wind turbines, with inherent low structural damping. Installing modern wind turbines in offshore harsh environments or seismic prone areas can cause an increment in the probability of failure due to excessive vibrations. We evaluate the performance of onshore and offshore wind turbines under multiple hazards, including wind, wave, earthquake, and mass and aerodynamic imbalances for both parked and operating conditions. The Lagrangian approach is employed to model the wind turbine considering the blade/tower coupling. To reduce the vibrations induced by multihazard loads, external smart dampers are used and a novel energy‐based probabilistic approach is employed to tune the semiactive controllers. The results show the effectiveness of the approach for the design of semiactive controllers in vibration mitigation of a wind turbine subjected to multiple hazards.
In the past few decades, high-rise buildings have received a renewed interest in many city business locations, where land is scarce, as per their economics, sustainability, and other benefits. Taller and taller towers are being built everywhere in the world. However, the increased frequency of multihazard disasters makes it challenging to balance between resilient and sustainable construction. Accordingly, it is essential to understand the behavior of such structures under multihazard loadings, to apply such knowledge to design. Earthquake loads excite higher modes that produce lower inter-story drift, compared to wind loads, but higher accelerations that occur for a shorter time. Wind-induced accelerations may have comfort and serviceability concerns, while excessive inter-story drifts can cause safety issues. High-rise and slender buildings designed for wind may be safe under moderate earthquake loads, regarding the main force resisting system. Nevertheless, nonstructural components may present a significant percentage of loss exposure of buildings to earthquakes due to higher floor acceleration.
To alleviate these issues, fluid viscous dampers are employed under both wind and earthquake loads. The optimum number and location of dampers are selected based on modal drifts and targeted values of the response. Displacement, acceleration, inter-story drift ratio, shear force, and base bending moment are considered along with other concise sets of system-level performance criteria that are easily understood by decision-makers and/or stakeholders of diverse technical backgrounds. Placement of viscous dampers with a lever mechanism shows that higher reductions in responses can be achieved with smaller damping devices. Stiffness uncertainty and damper failure are considered to check the robustness of the mitigation system. Viscous dampers are a viable solution for vibration attenuation in high-rise buildings susceptible to wind and earthquake loads, which permits the minimization of structural and nonstructural damage by counteracting multi-hazard forces in real-time. Viscous dampers show their potential to enhance the dynamic performance of buildings under multiple hazards and can directly promote community resiliency.
- Xie, F., Aly, A.M. (2020), “Structural Control and Vibration Issues in Wind Turbines: A Review,” Engineering Structures, 210(May), 110087. DOI: 10.1016/j.engstruct.2019.110087
- Chapain, S., Aly, A.M. (2019), "Vibration Attenuation in High-Rise Buildings to Achieve System-Level Performance under Multiple Hazards," Engineering Structures," Engineering Structures, Volume 197, 15 October 2019, 109352. DOI: 10.1016/j.engstruct.2019.109352
- Rezaee, M., Aly, A.M. (2018), "Vibration Control in Wind Turbines to Achieve Desired System-Level Performance under Single and Multiple Hazard Loadings," Structural Control and Health Monitoring, DOI:10.1002/stc.2261.
- Longarini, N., Cabras, L., Zucca, M., Chapain, S., Aly, A.M. (2017), "Structural Improvements for Tall Buildings under Wind Loads: Comparative Study," Shock and Vibration, 2017, Article ID 2031248, 19 pages. doi:10.1155/2017/2031248
- Abdelkader, A.M., Aly, A.M., Rezaee, M., et al. (2017), "On the Evaluation of Wind Loads for Wind Turbines’ Foundation Design: Experimental and Numerical Investigations," The Structural Design of Tall and Special Buildings, 26(9), 14 pages. doi: 10.1002/tal.1362.
- Rosa, L., Tomasini, G., Zasso, A. and Aly, A.M. "Wind-induced dynamics and loads in a prismatic slender building: modal approach based on unsteady pressure measures," Journal of Wind Engineering and Industrial Aerodynamics, 107-108, 118-130, 2012.
- Aly, A.M. "Pressure Integration Technique for Predicting Wind-Induced Response in High-Rise Buildings," Alexandria Engineering Journal, Elsevier, Volume 52, Issue 4, December 2013, Pages 717-731. DOI: https://doi.org/10.1016/j.aej.2013.08.006