Remaining Life Assessment of In-Service Luminaire Support Structures

Recent fatigue failures of in-service luminaire support structures in Washington and around the country have prompted concern about their fatigue resistance. Most luminaire support structures in Washington were designed without attention to fatigue or with vague and incomplete fatigue design provisions. Furthermore, most luminaire support structures were installed during the construction of the Interstate system in the 1960s, and as many as half are estimated to have exceeded their 25-year design life. This research was initiated to help the Washington State Department of Transportation (WSDOT) prioritize the inspection and replacement of luminaire support structures throughout the state and to develop rational inspection procedures. The research had four primary components: a literature review, experimental fatigue testing of two in-service luminaire poles, a finite element analysis of the pole base, and development of a framework for estimating remaining life. The extensive literature review found previous experimental studies, which were used to identify details in older WSDOT luminaire support structures that may be critical and to help inform the selection of test specimens. Quasi-static and high cycle fatigue testing were performed on two previously in-service luminaire poles to determine the stress concentration factors (SCF) in critical details and determine fatigue resistance. The results were then compared to the finite element analysis and the fatigue classifications used in design. The finite element model was also used to determine the impact of parameters including base plate thickness, hand hole stiffener thickness, and location of anchor bolts. The individual components of a framework for estimating the remaining life of luminaire support structures in Washington were developed on the basis of a procedure established by Foley et al. (2004) in their study of the remaining life of sign bridge structures. The remaining fatigue life of the critical details in the previously in-service luminaire support structures were found to exceed their design life. Cracking at the stiffened hand hole detail was found to be the ultimate limit state for both specimens but was observed at cycle counts that were well beyond the design life. High SCFs were measured in both compression and tension at the CJP weld toe, indicating the importance of base plate flexibility, anchor bolt layout, and a uniform bearing surface. While it was not possible to know the load history for the selected specimens, it is clear that the number of damaging cycles was low and that the fatigue design life for these details is conservative. Recommendations for luminaire inspection are provided.

  • Record URL:
  • Supplemental Notes:
    • This research was sponsored by the U.S. Department of Transportation, University Transportation Centers Program.
  • Corporate Authors:

    TransNow, Transportation Northwest

    University of Washington, Department of Civil Engineering
    129 More Hall, Box 352700
    Seattle, WA  United States  98195-2700

    Research and Innovative Technology Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Frymoyer, Mark C
    • Berman, Jeffrey W
  • Publication Date: 2010-1


  • English

Media Info

  • Media Type: Web
  • Edition: Final Research Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 198p

Subject/Index Terms

Filing Info

  • Accession Number: 01153226
  • Record Type: Publication
  • Report/Paper Numbers: TNW2010-01, WA-RD 735.1
  • Contract Numbers: DTRT07-G-0010 (Grant)
  • Files: UTC, NTL, TRIS, USDOT
  • Created Date: Mar 24 2010 9:58AM