The effect of wind on Tall Buildings - Tall Buildings: Structural Systems and Aerodynamic Form - page 150

The eFFecT oF wind on Tall
Buildings
The history of skyscrapers, which epitomizes the twentieth century, begins in 1885
with the Home Insurance Building . Reaching a new and important point in 1931 with
the Empire State Building and gathering speed in 1972 with the World Trade Center
Twin Towers, this process is unfolding at an even greater rate today.
Since the weight of the structural system in the first skyscrapers made vertical
forces more critical than lateral forces, wind loads were not considered important. In
time, with developments and innovations in structural systems and the increase in the
strength-to-weight ratio of the structural elements, the weight of buildings decreased
and wind loads began to be important. Consequently, because the tall buildings being
constructed today are lighter, more slender and more flexible than their predecessors,
they are more prone to lateral drift with low damping, and wind-induced building
sway has been transformed into one of the most important problems encountered by
tall building designers, becoming a basic input to the design.
The wind loads affecting the building and the response of the building depend on
the following factors:
• the characteristics of the wind
• the building size and geometry
• the stiffness of the building and the distribution of the building mass
• the inherent damping characteristics of the structural system and of the construction
material, which dissipates wind-induced building sway
• the surrounding topography (issues with neighbouring buildings, etc.)
• the orientation (position) of the building with respect to the prevailing wind
direction.
The determination of the acceptable sway limits of tall buildings is an important topic
that has been extensively researched. Since wind speed and wind pressure increase
according to the building height, wind loads become important as the building height