Tuning Structural Properties of High-Rise Buildings to Control Wind Response

Structural design of tall buildings is always driven by forces of nature, such as wind and earthquakes. As buildings get taller, wind-induced dynamic response dictates the design of the lateral system to meet both strength and serviceability requirements. The wind-induced dynamic response depends on geometric properties, such as building shape and height, as well as the structural properties. Building geometry is usually beyond the control of the structural engineer. However, building's structural properties; mass, stiffness and damping, are selected by the structural engineer. This paper discusses the effect of mass, stiffness and damping on dynamic wind forces and floor accelerations in the across-wind direction. Simple charts that relate the change in natural frequency to the base moment are developed. Furthermore, another set of charts showing the relationship between the building's natural frequency, the mass and the top floor acceleration is also presented. The use of these charts is demonstrated through a number of example projects, which describe situations that can face the design engineer after wind loads and accelerations have already been determined by wind tunnel testing. These situations include change of mass, stiffness or performance objectives.