Cantilevered signal, sign, and light support structures are used nationwide on major interstates, national highways, local highways, and at local intersections for traffic control purposes. Recently, there have been a number of failures of these structures that have been characterized as wind-induced fatigue failures. It is widely accepted that there is considerable lack of accuracy in the calculation of wind-induced loads on High Mast Light Pole (HMLP) in both the American Association of State Highway and Transportation (AASHTO) and the Canadian Highway Bridge Design Code (CAN/CSA) provisions. The primary objective of this study was to develop a coupled model for predicting buffeting and vortex shedding induced response for slender support structures. To accomplish this, monitoring of long-term response behavior of a HMLP subjected to wind-induced vibration and wind tunnel experiments were utilized to study global behavior and to extract important parameters. From the long-term field monitoring and wind tunnel experiments, the two critical types of wind vibration (natural wind gusts or buffeting and vortex shedding) were individually extracted for in-depth analysis. Finally, a coupled dynamic model was developed for predicting the wind-excited response and was validated by comparing the simulation results with the field collected data. The fatigue life of a specific HMLP was also estimated with the stress amplitudes predicted by the time-domain model andwas validated with statistical extrapolation of the field data.
Abstract