| A substantial number of metal buildings are damaged or destroyed in extreme winds each year. The damage is primarily attributed to lack of coordination between designer and dealer/contractor, and marginal construction practices.; During the past two decades, research activity in wind engineering has concentrated on defining appropriate values of wind loads on metal buildings. Little has been done to evaluate the resistance (response) of metal building systems subjected to extreme wind loads. This research examines several modes and attempts to reach quantitative conclusions. Low-slope and high-slope gable frames with tapered columns and rafters are designed using an industry quality computer program. The effects of (1) breach of the building envelope, (2) bracing omitted from compression flanges, (3) purlin anchorage failures, (4) unexpected overload due to high winds, and (5) use of tapered members are modelled and studied. These effects are measured in terms of change in moments and unity stress checks along the columns and the rafters. Changes in the horizontal and vertical reactions at the column base are also computed. Costs of designing structural frames to resist these failure modes are also examined.; The main conclusions of the study are: (1) all metal building should be designed to account for the breach in the building envelope, (2) the frames can be designed inexpensively to account for the breach in the building envelope, and (3) purlin anchorage failures and bracing omitted from compression flanges can overstress the frames significantly. Therefore, the utmost care should be exercised in installing connection fasteners and bracing for the compression flanges. |
