J. Morales, J. Sánchez, S. Jesús, J. Caraballo
A large number of breakaway-type highway signs toppled over during hurricane María in Puerto Rico. The cause was the unintended rupture of the fuse plates, a key component of the breakaway system. The design of fuse plates is unusual because two opposing constraints must be precisely balanced: 1. they must be weak enough to rupture during collision of an errant vehicle, thus minimizing injuries to passengers and damage to the vehicle, but 2. strong enough to resist wind loads. These uncommon constraints attracted the interest of the authors. The following question guided the research: Could classical stress analysis, in conjunction with established failure theories, predict the failure of an actual fuse plate that fractured during hurricane María? This investigation fills a gap in the literature by examining a more refined classical model of the stresses than previously considered. A wind gust speed of 155 mph at the top of the sign was assumed. The yield and ultimate strengths were obtained experimentally with one tensile specimen machined from a failed fuse plate. The classical stress analysis, in conjunction with the von Mises yield failure criterion, accurately predicted yielding of the fuse plate; however, higher wind speeds would have been required to reach fracture. It was concluded that the simplified model available in the literature is adequate to predict yielding. Its error was less than 1% when compared to the more refined model developed in this study.
Published on 17/02/21Accepted on 17/02/21Submitted on 17/02/21
Volume 19-20, 2021Licence: CC BY-NC-SA license
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