A study of the fatigue capacity of a tapered 13 m single davit light pole under vortex shedding loading was conducted. The fatigue capacity of the pole was examined for vortex shedding forces in accordance with the AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals (LTS-5) and the Canadian Highway Bridge Design Code (CAN/CSA S6-06). Fatigue sensitive details examined were the connections between pole segments, hand hole for access into the pole, weld to the base plate and anchor bolts.The vortex shedding forces computed in accordance with both standards were compared. Both codes are applicable to straight or tapered unidirectional poles, resulting in planar vibration modes, perpendicular to the poles. In addition, the AASHTO LTS-5 formulas are intended to consider only the first mode of vibration, though the commentary suggests that higher modes of vibration should be examined. Neither code was sufficiently complete to allow complete calculation of the vortex shedding forces, therefore information was taken from each code in the final calculations.The study resulted in recommendations to improve the CAN/CSA S6-06 section for vortex shedding, including recommended maximum wind velocities, and inclusion of fatigue categories for common details on light poles.
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