Air flow around buildings as reflected in failure modes.

The authors have found that recently published scientific literature on the character of air flow around rectangularly shaped objects with flat or gabled tops are particularly accurate, if the accuracy of such formulations can be gauged by the manner in which actual buildings fail when subjected to extreme winds. The paper illustrates current fluid dynamics concepts regarding flow line shapes, flow line separations, and flow line reattachments around idealised structural shapes. These conceptual illustrations are supported by photographs of damaged buildings which confirm the validity of the experimentally (wind tunnel) or theoretically (computed) derived concepts. The state of the art of air flow around buildings is reflected in new wind loads standards which are evolving throughout the world. In addition, several phenomena which are not clearly understood are discussed:- dynamic loadings induced by turbulence downstream from separation points, flow line reattachment phenomena, and interference between multiple structures within the windfield. (A)