In the early
2 0 th
century, high-rise design was focused on strength. Although not accounted for,
the heavy masonry cladding and partitions of the time contributed considerable stiffness and
damping. As a result, building drifts and accelerations were acceptably small. In the mid-20th
century, lightweight curtain wall cladding systems, gypsum board partitions and high strength
steels were introduced. Structures would be less damped than before. Designs with different
building proportions, framing systems and occupancies make wind performance more
challenging. Solutions include stiffness, inherent damping and several types of supplementary
damping [14].