UNCERTAINTIES IN WIND LOADS CAUSED BY ADJACENT BUILDINGS.

Mean and fluctuating values of all three moment components caused by wind acting on small-scale models of tall prismatic buildings have been measured. Measurements were made in a boundary-layer wind tunnel for four building shapes with and without a single building placed at different upwind positions. Presence of the upwind building in certain positions was found to cause the rms values for all three load components to be 2 to 2. 5 times the values measured with no upwind building. The propagation of increased loading into the response is demonstrated for specific cases. Accordingly, use of dynamic wind loads specified by codes for an isolated building can result in significant uncertainties relative to actual loading if an upwind building is present. The contribution of these uncertainties to risk assessment for tall buildings is discussed.