Boundary layer wind flow characteristics and wind effects on low-rise buildings

Procedures for evaluating design wind loads in terms of the roughness of terrain, average wind velocity, building geometry and desired building safety are available in standard and model building codes. Basic understanding of wind flow characteristics, knowledge of bluff-body aerodynamics and general knowledge of wind climatology are helpful in implementing the provisions of these codes in design practice. Initially, information about the wind climatology of the United States is presented in this paper. Subsequently, the subject of micrometeorology is opened, as it relates to wind engineering. General information about wind tunnel modeling is then presented as a means of more descriptively illustrating the relationships of wind flow and terrain characteristics to the dynamic pressure responses of low buildings. Finally, data used in the development of the ASCE standard's provisions for the calculation of wind loads affecting mono-slope and multi-span gable roofs of low-rise buildings are presented. Additionally, a comparative study of the performance of hip and gable roofs in severe wind events is presented. Based on the descriptions of wind flow characteristics presented in the body of the paper, an interpretation of the gust effect factor model provided in the commentary of the ASCE standard is rendered.