Over the years, a number of cantilevered traffic signal support structures (traffic poles) havecollapsed as a result of fatigue failure of the mast arm and vertical pole connection. Due todynamic wind loading, excessive and sustained vibrations have led to the fatigue cracking andsubsequent collapse. A number of different methods have been suggested to reduce theexcessive wind induced vibration of traffic poles, including struts and vibration absorbers. TheSignal Head Vibration Absorber (SHVA), developed at the University of Connecticut, is apromising type of vibration absorber for traffic signal support structures. This device hasexperimentally shown to increase the critical damping of the traffic signal structures to 10.1%,eliminating any steady state deflection, and protecting the structure from fatigue damage. InSouth Korea, where the cantilevered traffic poles are shorter and lighter, struts connected at anangle between the pole and mast arm are used exclusively throughout the country to reducevibrations. The shorter mast arm length, coupled with the use of a strut, made the structureslighter than average poles in the United States. This paper explores the potential benefits of usinga SHVA versus a strut to control the vibration of traffic signal support structures. A 55 footAmerican pole is evaluated against a 17 foot Korean pole to examine the potential benefits andrelative merits of these two methods of reducing excessive wind induced vibration of trafficpoles over various traffic pole configurations.
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