About this Research Topic
Natural wind can excite the structures into considerable vibrations. The statistics of wind induced damages clearly reveals the fact that even today, structures and their components are not sufficiently wind hazard resistant. There are mainly two excitation phenomena to be considered - one is gust induced vibrations and another is vortex induced vibrations. The gust induced vibrations would lead to forced rupture, whereas vortex induced vibrations would lead to fatigue failure. Therefore, the specification and codification of the design wind load is the need of the hour. Wind load is proportional to the air density, square of the wind speed and aerodynamic coefficient. At least wind speed and aerodynamic coefficient should be treated as random variables. Hence, the specification of the design wind speed as well as the design aerodynamic coefficient are the essential prerequisites for the specification of the design wind load.
Extreme wind climate modelling is required in order to specify design wind speed. Different storms occur due to different geophysical reasons and their turbulent intensities are different. Hence, extreme events from each storm type should be fitted in a separate extreme value distribution and later on a combination of probability distributions should be made in order to specify design wind speed for a target non exceedance probability. The extreme value distributions which may be used include type I (Gumbel), type II (Fre'chet) and type III (Reverse Weibull) distributions. Moreover, slender structures like stacks of power plants, natural draft cooling towers, heavy water drafting towers are often subjected to cross wind vibrations due to Karman's mechanism. Significant cross wind vibrations may occur if the natural frequency of the structure is equal to the frequency of the vortex shedding. The corresponding range of wind velocities is called the lock-in wind speed range. Periodic vortex shedding may lead to fatigue failure, and expected number of stress cycles in the projected working life of a structure is related to the expected number of hours per year in lock-in wind speed range.
The scope of the manuscripts for this Research Topic covers, but is not limited to, the following topics:
• Identification of best extreme value distribution for different storm phenomena and combination of probability densities from different storm types to specify design wind speed;
• Storm simulation in boundary layer wind tunnel and experimental study for the specification of design aerodynamic coefficient;
• Rendering suggestions for the improvement of building codes of different nations;
• Parent and extreme wind climate modelling;
• Wind directional effects for wind load assessment;
• Effects of climate change for the specification of design wind load;
• Corrosion and carbonation of structures;
• Vulnerability curves and retrofitting strategies.
Keywords: wind speed, wind load, aerodynamic coefficient, extreme value distribution, climate change, gust induced vibration, vortex induced vibration
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