ASCE MOP 67

Abstract

Although wind tunnel model testing has gained wide acceptance, it is important to stress that the action of wind in many cases is adequately dealt with in existing building codes. It is therefore important to identify situations in which wind tunnel studies are desirable or necessary. The primary reasons for carrying out such studies are to improve the reliability of structural performance and to achieve cost effectiveness&#8212;both of the final structure and during the period of construction. Wind tunnel derived wind loads can, in many circumstances, fall below code prescribed values. Wind tunnel model studies, therefore, frequently lead to cost savings. <br>Other candidates for wind tunnel tests are buildings and structures that have an unusual sensitivity to the action of wind or that fall outside existing experience. This is particularly true when a significant part of the windinduced response is dynamic. Examples are tall, slender, and flexible buildings, observation towers, masts and chimneys, intermediate and long-span bridges, pedestrian bridges, transmission line systems, and various special structures, such as large-span flexible roofs, cooling towers, large cranes, etc. Buildings and structures of unusual aerodynamic shape, which may experience large wind-induced overall forces or local pressures, also warrant special attention. Other areas of potential concern include the presence of unusual terrain and surroundings, and close proximity to major buildings and structures or prominent topographic features. In all situations, buildings and structures located in areas of high incidence of significant wind speeds are more likely to be in need of wind tunnel testing than those constructed in areas where winds are generally benign. <br>Wind tunnel tests are not always prompted by concerns for structural integrity. Such tests can also provide information on serviceability related questions, such as wind-induced drift or horizontal accelerations which, if excessive, may adversely affect occupant comfort. The effects of wind on pedestrians and the environment of built-up urban areas, including the dispersion of pollutants and the resulting air quality, are other questions that wind tunnel model studies can address. Such tests are particularly valuable if they are carried out at an early stage when design adjustments can still be made.