Wind tunnel studies of cantilever traffic signal structures

Hector J. Cruzado, Chris Letchford and Gregory A. Kopp

Abstract

The wind-induced vibrations of the mast arm of cantilever traffic signal structures can lead to the fatigue failure of these structures. Wind tunnel tests were conducted on an aeroelastic model of this type of structure. Results of these experiments indicated that when the signals have backplates, vortex shedding causes large-amplitude vibrations that could lead to fatigue failure. Vibrations caused by galloping were only observed for one particular angle of attack with the signals having backplates. No evidence for galloping, previously thought to be the dominant cause of fatigue failures in these structures, was observed.

Key Words

cantilevered traffic signal structures; fatigue; wind-induced vibrations; galloping; vortex shedding

Address

Hector J. Cruzado : Department of Civil and Environmental Engineering, Polytechnic University of Puerto Rico, San Juan, USA Chris Letchford : Department of Civil and Environmental Engineering, Rensselaer Polytechnic Institute, Troy, NY, USA Gregory A. Kopp : 3Boundary Layer Wind Tunnel Laboratory, Faculty of Engineering, University of Western Ontario London, Ontario, Canada

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