Development of a Reliability-Based Design Procedure for High-Mast Lighting Structural Supports

摘要

High mast lighting structures are being increasingly used to provide illumination for large intersections, particularly for highways located in rural areas. These structures, ranging from approximately 50 – 130 ft (15 – 40 m) in height, are exposed to high wind forces that in turn produce a tremendous number of loading cycles each year. A recent high mast lighting structural support failure in the high plains of Colorado near Denver International Airport served as the impetus for this study. Specifically, a numerical investigation to determine the nature of the complex dynamic response, estimate the fatigue life, and develop a prescriptive reliability-based selection (design) procedure for high-mast lighting structural supports. Morison’s equation, which provides relative force for slender bodies as a function of flow velocity, was applied within a dynamic finite element framework in order to account for the relative motion between the wind and the motion of the structure. Then, a well-known random vibrations approach was coupled with Miner’s rule to estimate the fatigue life of the structural support. Six different design parameters as well as mean wind velocities were examined.