FATIGUE LOADING OF CANTILEVER SIGN STRUCTURES FROM TRUCK WIND GUSTS

This is the final report of an experimental and analytical study to determine the fatigue loading on cantilever highway signs from gusts produced by trucks passing under the sign. Three sign structures were instrumented in the field to determine their response from truck gusts. These signs were then analyzed using a three-dimensional dynamic analysis computer program. A loading was developed from the computer analysis which produced a response which simulated the response measured in the field study. A matrix of standard Texas State Department of Highways and Public Transportation standard sign structures was analyzed using the same computer program and the simulated loading. The result of this analysis was the development of dynamic load factors for these signs. A simple method of estimating the three primary modal frequencies of typical signs was developed using single degree of freedom models. Means of correcting the results of these simple models to agree with the computer analysis was developed. The resulting frequencies allow the dynamic load factor to be calculated without the use of the complex three-dimensional computer analysis. A method of analyzing the anchor bolts of the signs for fatigue is presented. The analysis uses the loading developed in this study amplified using the dynamic loading factors calculated from the modal frequencies estimated from the single degree of freedom models. The low measured stresses in the superstructure did not indicate any potential fatigue problems. The anchor bolt fatigue stresses are primarily caused by bending of the bolt between the base plate and the foundation. (FHWA)

  • Supplemental Notes:
    • Study conducted in cooperation with the Department of Transportation, Federal Highway Administration. Research Study Title: "Fatigue Loading in Sign Structures".
  • Corporate Authors:

    University of Texas, Austin

    Center for Highway Research, 200 West 21st Street
    Austin, TX  USA  78712

    Texas State Department of Highways & Public Transp

    Transportation Planning Division, P.O. Box 5051
    Austin, TX  USA  78763
  • Authors:
    • Creamer, B M
    • Frank, K H
    • Klingner, R E
  • Publication Date: 1979-4

Media Info

  • Pagination: 114 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00319104
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: FHWA/TX-79/10+209-1FIntrm Rpt., FCP 45A1-082
  • Contract Numbers: Res Stdy 3-5-77-209
  • Files: TRIS, STATEDOT
  • Created Date: Nov 19 1980 12:00AM