- Wind characteristics in atmospheric boundary layer
- Basics of bluff body aerodynamics
- Elements of theory of stochastic processes
- Dynamic response of structures to turbulent wind
- Vortex-induced vibration
- Aeroelastic phenomena
- E. Simiu, R.H. Scanlan, Wind Effects on Structures: Fundamentals and Applications, John Wiley, NY, 1996.
- J. Holmes, Wind Loading on Structures, Spon Press, NY., 2001.
- G. Muscolino, Dinamica delle Strutture, McGraw Hill, 2003.
- C. Borri, S. Pastò, Lezioni di Ingegneria del Vento, Firenze University Press, 2006.
Learning Objectives
At the end of the course, the students are expected to learn the basic concepts concerning turbulent flows in the atmospheric boundary layer and bluff-body aerodynamics, along with the mathematical tools required for the application of these to the analysis of civil engineering structures (stochastic process theory, stochastic dynamics of structures).
The student should be able to identify the main criticalities of structures exposed to the wind action, and to apply consciously the approaches provided by codes and standards. It is also expected that they will be able to interpret and use in a correct way the data of wind tunnel measurements, on-site experimental campaigns, computational fluid dynamic simulations, and technical or scientific literature.
In particular, in the case of structures of great importance and susceptibility to the aerodynamic action, the course aims at providing the tools for advanced dynamic analyses, accounting for possible aeroelastic phenomena.
Prerequisites
- Fundamentals of deterministic structural dynamics (behaviour of a linear oscillator, modal analysis)
- Fundamentals of probability theory (random variables, probability distribution, statistical moments)
Teaching Methods
- Classes
- Visit(s) of the CRIACIV wind tunnel laboratory (Prato)
- Periodic meetings for the review of the exercice assigned to the student
Further information
Meetings with the students will be agreed via e-mail
Type of Assessment
- Exercise on a topic agreed upon with the student, aimed at a practical application of the tools and the theories learned during the course
- Oral examination
Course program
- Wind engineering purview; importance of the wind action for civil engineering structures; "Davenport chain"
- Introduction to stochastic processes; stationarity, ergodicity, gaussianity
- Correlation function and power spectral density; auto- and cross-correlation, auto- and cross-spectrum
- Essentials of extreme value theory of stochastic processes; gust factor and peak factor
- Introduction to atmospheric circulation and origin of several types of winds
- Van der Hoven spectrum and concept of "spectral gap"; statistical analysis of mean wind speed
- Navier-Stokes equations; concept of turbulence; Reynolds-averaged Navier-Stokes equations
- Concept of boundary layer; laminar and turbulent boundary layers
- Atmospheric boundary layer; mean wind speed profile; Ekman spiral; characterization of atmospheric turbulence (turbulence intensities, integral length scales, power spectral densities, coherence function)
- Bluff-body aerodynamics: concepts of stagnation, separation, free-shear layers and wake; meaning and role of the Reynolds number; vortex shedding and Strouhal number
- Definition of pressure coefficient and force coefficients
- Internal pressures in buildings
- Some recalls of deterministic structural dynamics
- Essentials of stochastic structural dynamics
- General principles of the response of structures to the dynamic wind load
- Response of a structure to turbulent wind in the along-wind direction: quasi-steady theory for a body in a turbulent flow; aerodynamic admittance function; joint-acceptance function; resonance and background response; the approach of Eurocode 1 and recommendations CNR-DT 207/2008
- Introduction to the concept of aeroelasticity
- Response of a structure in the across-wind direction: the concept of synchronization with vortex shedding (lock-in); Scruton number; harmonic model and spectral model
- Quasi-steady theory for a body oscillating in a fluid flow; aerodynamic damping
- Galloping instability of slender structures with bluff cross section
- Static instability due to torsional divergence of bridge decks
- Unsteady approaches to the aeroelastic phenomena: flutter of bridges
- Wind tunnel tests; dimensional analysis and Buckingham's theorem; similitude theory for Wind Engineering problems
- Basics of Computational Fluid Dynamics (CFD) and Computational Wind Engineering (CWE)