Interference and Influence of Nearby Buildings: A Discussion of the Design Approach

Local wind effects due to adjacent structures can significantly impact the loading experienced by a building in a developed environment. Phenomena such as buffeting, channeling, and sheltering can have unique, and occasionally unpredictable, effects on the loading and response for a particular building. While sheltering is often beneficial, wake buffeting and channeling may result in increased responses for some wind directions. The consideration of these effects, whether advantageous or disadvantageous, has become a vital component of modern wind tunnel testing procedures. While accepting the influence of general terrain characteristics on wind speed and turbulence profiles many codes and standards, including ASCE 7, mandate that the beneficial effects of sheltering should not be relied upon. This is a conservative and justifiable provision, which grows in importance as an individual building begins to greatly exceed the height of its surroundings. Generally, the removal of an immediately adjacent building is required in order to separate the load reduction (from code-specified values) due to building aerodynamics from that due to sheltering. Building codes, however, do not have specifications targeting interference effects. This paper reviews the relevant underlying mechanisms driving aerodynamic interference in the context of arriving at recommendations of early detection of potential interference effects which should be considered in the wind tunnel testing program. Examples are given which illustrate situations where surrounding buildings significantly alter the mean and dynamic wind loads for a building, which could lead to increased dynamic response for some combinations of structural properties. Discussion of the assessment, treatment and prediction of interference effects is provided in the context of the interaction of the project building with its surroundings. The paper concludes with recommendations on the approach to identifying, dealing with and planning for local wind loading caused by interference effects.