How can you reduce wind vibrations on structures?

1 What are wind vibrations?

Wind vibrations are oscillations or movements of structures caused by the interaction of wind forces and structural properties. Wind forces can vary in magnitude, direction, and frequency, depending on the wind speed, turbulence, topography, and shape of the structure. Structural properties, such as stiffness, mass, damping, and natural frequency, determine how the structure responds to the wind forces. When the wind frequency matches or is close to the natural frequency of the structure, a phenomenon called resonance occurs, which can amplify the vibrations and cause excessive deflections, stresses, and strains.

2 How to analyze wind vibrations?

To analyze wind vibrations on structures, you need to use structural dynamics and vibrations principles and tools. Structural dynamics is the branch of engineering that deals with the behavior of structures under time-varying loads, such as wind, earthquakes, and traffic. Vibrations is the study of the oscillatory motion of structures and its effects on the structure and its surroundings. To analyze wind vibrations, you can use mathematical models, computational methods, and experimental methods. Mathematical models are equations or formulas that describe the relationship between the wind forces and the structural response. Computational methods are numerical techniques that solve the mathematical models using computers. Experimental methods are physical tests that measure the wind forces and the structural response using instruments. Different types of models, methods, and instruments can be used depending on the complexity and accuracy of the analysis, as well as the computational resources available. Experimental methods can also be used to validate or calibrate the mathematical models and computational methods, or to obtain data that is difficult or impossible to obtain otherwise.

3 How to reduce wind vibrations?

In order to reduce wind vibrations on structures, you can modify either the wind forces or the structural properties, or both. Aerodynamic modifications, such as tapered or twisted shapes, corner modifications, spoilers, or porous materials, can be used to reduce drag or lift forces and disrupt the formation of vortices or gusts. Structural modifications like bracing, prestressing, mass reduction, or tuning can be employed to increase stiffness or decrease mass of the structure and shift its natural frequency away from the wind frequency. Vibration control devices such as tuned mass dampers, active or passive dampers, base isolation, or active or passive control systems can be attached to the structure to dissipate or cancel the wind energy and change its dynamic characteristics.

4 How to choose the best method?

When selecting the best method to reduce wind vibrations on structures, you need to consider the type and magnitude of the wind vibrations, the design and retrofit objectives, and the available data and analysis tools. For example, you must distinguish between buffeting, flutter, galloping, or vortex shedding vibrations and how they cause stress, fatigue, or serviceability problems. Additionally, you should define criteria and constraints that guide the design and retrofit of the structure such as cost, feasibility, aesthetics, and functionality. Lastly, you must evaluate the quality and quantity of data and analysis tools that you have or can access to support the design and retrofit of the structure. This includes considering the reliability and accuracy of mathematical models, computational methods, and experimental methods to affect confidence and robustness of solutions.

5 How to learn more?

To learn more about how to reduce wind vibrations on structures, you may want to explore books such as Structural Dynamics and Vibration in Practice by Douglas Thorby, Wind Effects on Structures by Emil Simiu and Robert H. Scanlan, and Vibration of Structures and Machines by Giancarlo Genta. Additionally, there are courses that teach the fundamentals and applications of structural dynamics and vibrations, such as Structural Dynamics by MIT OpenCourseWare, Structural Dynamics and Earthquake Engineering by NPTEL, and Vibration Control by edX. Furthermore, journals like Journal of Sound and Vibration, Engineering Structures, and Journal of Wind Engineering and Industrial Aerodynamics publish the latest research and developments in structural dynamics and vibrations.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?