Use of structural damping for wind and seismic control of tall buildings

The increase in construction of high rise and super high rise buildings in high wind and seismic areas throughout the Pacific Rim has led designers to search for more economical and effective means of controlling building drift under lateral loads. Traditionally, engineers have approached this problem by adding stiffness to the building frame itself, however this approach, while effective for resisting forces, does not directly address the dynamic and vibrational behavior of tall structures. In addition, frame systems, particularly steel frames, have very little inherent damping. More recently, attention has been paid to reducing vibrations by augmenting the building frame with various types of damping systems, and a number of buildings have been constructed or retrofitted to take advantage of these systems. This paper will review the different methods of vibration damping available to the tall building designer to control building movement under wind and seismic loads. Included are active mass damping, in which heavy masses, usually at roof level, are manipulated mechanically to provide a countering force to the building movement; viscous and viscoelastic damping, which involve smaller energy-absorbing devices inserted into the frame at various locations; friction damping, which can take the form of either discrete devices or modified frame connections; and other systems.