Wind Effects on Structures Modern Structural Design for Wind
The design of buildings and structures for wind depends upon the wind environment, the aerodynamic effects induced by the wind environment in the structural system, the response of the structural system to those effects, and safety requirements based on uncertainty analyses and expressed in terms of wind load factors or design mean recurrence intervals of the response. For certain types of flexible structure (slender structures, suspended-span bridges) aeroelastic effects must be considered in design.
I.1 The Wind Environment and Its Aerodynamic Effects
For structural design purposes the wind environment must be described: (i) in meteorological terms, by specifying the type or types of storm in the region of interest (e.g.,large-scale extratropical storms, hurricanes, thunderstorms, tornadoes); (ii) in micrometeorological terms (i.e., dependence of wind speeds upon averaging time, dependence of wind speeds and turbulent flow fluctuations on surface roughness and height above the surface); and in extreme wind climatological terms (directional extreme wind speed data at the structure’s site, probabilistic modeling based on such data). Such descriptions are provided in Chapters 1–3, respectively.
The description of the wind flows’ micrometeorological features is needed for three main reasons. First, those features directly affect the structure’s aerodynamic and dynamic response. For example, the fact that wind speeds increase with height above
the surface means that wind loads are larger at higher elevations than near the ground.
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The design of buildings and structures for wind depends upon the wind environment, the aerodynamic effects induced by the wind environment in the structural system, the response of the structural system to those effects, and safety requirements based on uncertainty analyses and expressed in terms of wind load factors or design mean recurrence intervals of the response. For certain types of flexible structure (slender structures, suspended-span bridges) aeroelastic effects must be considered in design.
I.1 The Wind Environment and Its Aerodynamic Effects
For structural design purposes the wind environment must be described: (i) in meteorological terms, by specifying the type or types of storm in the region of interest (e.g.,large-scale extratropical storms, hurricanes, thunderstorms, tornadoes); (ii) in micrometeorological terms (i.e., dependence of wind speeds upon averaging time, dependence of wind speeds and turbulent flow fluctuations on surface roughness and height above the surface); and in extreme wind climatological terms (directional extreme wind speed data at the structure’s site, probabilistic modeling based on such data). Such descriptions are provided in Chapters 1–3, respectively.
The description of the wind flows’ micrometeorological features is needed for three main reasons. First, those features directly affect the structure’s aerodynamic and dynamic response. For example, the fact that wind speeds increase with height above
the surface means that wind loads are larger at higher elevations than near the ground.
Download
*