Failure Investigation of the Steel Strut on the Paseo Suspension Bridge

A vertical strut of the 1,232-ft long, self-anchored Paseo Suspension Bridge fractured when the temperature hit a record low of 9 deg F below zero. During inspection the following day, it was found that its lower pin was frozen and did not allow for free movement of the superstructure. The objective of this study is to pinpoint one of the four reasons for this incidence or their combination: overstressing, thermal contraction, fatigue and reduction in fracture toughness at low temperatures. To achieve this objective, material property and fatigue testing was performed on samples of strut material while the bridge and strut were analyzed under service loading conditions. This study indicated that the strut material practically has an infinite life under normal conditions. The root cause of the failure is overstressing of the vertical strut due to a frozen pin that became frozen because the design of the bridge did not allow the pin to be maintained. The mechanically frozen pin condition was attributable to salt and sand accumulation in the strut housing. To prevent this to the new struts and other similar structures, it is recommended that both upper and lower pins be greased during special inspections and the lower housings be partially sealed to prevent salt and sand accumulation near the pins. Alternatively, a rotation monitoring system can be installed to remotely monitor the rotation of all four vertical struts and alert officials should the pins become mechanically frozen.

  • Record URL:
  • Supplemental Notes:
    • This research was supported by a grant from the U.S. Department of Transportation, University Transportation Centers program.
  • Corporate Authors:

    University of Missouri, Rolla

    University Transportation Center
    1870 Miner Circle
    Rolla, Missouri  United States  65409

    Missouri Department of Transportation

    Research, Development and Technology, 1617 Missouri Boulevard
    P.O. Box 270
    Jefferson City, MO  United States  65102
  • Authors:
    • Chen, G
    • Courtright, C
    • Dharani, L R
    • Xu, B
  • Publication Date: 2005-6-15

Language

  • English

Media Info

  • Media Type: Print
  • Edition: Final Report
  • Features: Appendices; Bibliography; Figures; Tables;
  • Pagination: 86p

Subject/Index Terms

Filing Info

  • Accession Number: 01005798
  • Record Type: Publication
  • Report/Paper Numbers: RDT 05-008, RI03-015
  • Files: TRIS, STATEDOT
  • Created Date: Oct 15 2005 11:44AM