It mushroomed at the top to accommodate a restaurant with a view. Below the restaurant, the developers had expanded the tower to create office space. In the wind tunnel, winds coming off opposite sides of the tower collided and made the model vibrate. Combined with the natural frequency of the tower's vibration, there was potential for disastrous oscillation in high, steady wind. The developers ultimately scrapped the office-bulge portion of the building.
Wind tunnels provide vital information for a variety of structural designs.
Even on more modest buildings, those of 10 to 20 stories, wind tunnel testing is becoming common. On all floors, edges at all four corners are found, which is very beneficial from a wind forces standpoint. We have three sets of slots, two stories tall, that allow wind to pass through the building. As building heights continue to increase and designs become more sculptural, wind testing will remain a vital part of the engineering and design process. Dirk Sutro is a freelancer writer based in Leucadia, California.