The report describes three pendulum tests and four static tests conducted on box and H-shaped sign supports built up from Micro-Lam. Micro-Lam, is a laminated wood product with the grain in all the wood veneers running in the same direction. Different cutout patterns in the webs of the box and H-sections near the ground were used to improve the breakaway chracteristics. The pendulum tests simulated an impact by a lightweight passenger car. The pendulum mass weighed 2250 lbs, was equipped with a crushable nose simulating a pre-1974 Chevrolet Vega, and had an impact speed of 20 mph. The static tests Chevrolet Vega, and had an impact speed of 20 mph. The static tests were used to simulate wind loading forces on the sign supports, and the load was increased until the supports failed. The box and H-shaped membes hold promise as effective breakaway supports. The change of momentum for the pendulum mass varied from 299 to 573 lb-sec, well below the preferred maximum value of 750 lb-sec. The failure moments at the based of the supports varied from 23,200 to 42,580 ft-lbs in the first three static tests. Design wind load moments were 38,200 ft-lbs; hence, the utlimate strength was low. In Test 4, two horizontal sawcuts were used in the box section webs instead of rectangular cutouts, and the failure moment was 52,900 ft-lbs. This moment should increase for supports embedded in the ground. (FHWA)

  • Corporate Authors:

    Southwest Research Institute

    6220 Culebra Road, P.O. Drawer 28510
    San Antonio, TX  United States  78228-0510

    California Department of Transportation

    1120 N Street
    Sacramento, CA  United States  95814

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590
  • Authors:
    • Kimball, C E
    • Deel, G W
  • Publication Date: 1980-7

Media Info

  • Pagination: 35 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00331206
  • Record Type: Publication
  • Report/Paper Numbers: FHWA/SWRI-80/02 Intrm Rpt., FCP 41V3-134
  • Contract Numbers: F78TL02
  • Created Date: Aug 15 1981 12:00AM