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Wind and Structures
  Volume 8, Number 5, September 2005, pages 343-356
DOI: http://dx.doi.org/10.12989/was.2005.8.5.343
 


Practical fatigue/cost assessment of steel overhead sign support structures subjected to wind load
John W. van de Lindt and Theresa M. Ahlborn

 
Abstract
    Overhead sign support structures number in the tens of thousands throughout the trunk-line roadways in the United States. A recent two-phase study sponsored by the National Cooperative Highway Research Program resulted in the most significant changes to the AASHTO design specifications for sign support structures to date. The driving factor for these substantial changes was fatigue related cracks and some recent failures. This paper presents the method and results of a subsequent study sponsored by the Michigan Department of Transportation (MDOT) to develop a relative performance-based procedure to rank overhead sign support structures around the United States based on a linear combination of their expected fatigue life and an approximate measure of cost. This was accomplished by coupling a random vibrations approach with six degree-of-freedom linear dynamic models for fatigue life estimation. Approximate cost was modeled as the product of the steel weight and a constructability factor. An objective function was developed and used to rank selected steel sign support structures from around the country with the goal of maximizing the objective function. Although a purely relative approach, the ranking procedure was found to be efficient and provided the decision support necessary to MDOT.
 
Key Words
    overhead sign support; cantilever; fatigue; wind load; steel design.
 
Address
John W. van de Lindt; Department of Civil Engineering, Colorado State University, Fort Collins, CO 80523-1372, USArnTheresa M. Ahlborn; Civil and Environmental Engineering, Michigan Technological University, Houghton Michigan 49931-1295, USA
 

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