FATIGUE DAMAGE IN THE LEHIGH CANAL BRIDGE FROM DISPLACEMENT-INDUCED SECONDARY STRESSES

Strains were measured at several structural steel details on one of the Lehigh Canal bridges under normal traffic. Inasmuch as these bridges have several fatigue cracks in the tie plates connecting the floor beams to the outrigger cantilever brackets, the primary focus was on the tie plates and the case of fatigue cracking. Strain gauges were mounted on five tie plates, on a stringer, and on the longitudinal girders. An automatic computer-controlled data acquisition system was used to record the strain range occurrences. In addition, an analog trace recorder was used to determine the live load strain variations with time. Stress ranges in the stringer and girders were comparable to those observed by others in girder bridges. However, the horizontal in-plane bending stresses in the tie plates were found to be two to three times as high. The higher stress range was attributed to differential displacements between the deck-stringer system and the girder, which were transmitted through the tie plates. The strain measurements on the tie plates and the volume of truck traffic during the structure's life were used to estimate the cumulative damage in several tie plates. Good correlation was obtained with the root mean square stress range and constant cycle laboratory fatigue test results. Miner's rule was also found to provide a good correlation. /Author/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/trr/1976/607/607-011.pdf
• Record URL:
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• Supplemental Notes:
  • Publication of this paper sponsored by Committee on Dynamics and Field Testing of Bridges. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved
• Authors:
  • Fisher, John W
  • Yen, Ben T
  • Daniels, J Hartley
• Publication Date: 1976

Media Info

• Media Type: Print
• Features: Figures; Photos; References; Tables;
• Pagination: pp 56-62
• Monograph Title: Bridge design, testing, and evaluation
• Serial:
  • Transportation Research Record
  • Issue Number: 607
  • Publisher: Transportation Research Board
  • ISSN: 0361-1981

Subject/Index Terms

• TRT Terms: Analog computers; Bridges; Cantilevers; Computer programs; Cracking; Data collection; Dislocation (Geology); Fatigue (Mechanics); Girder bridges; Loads; Railroad ties; Strain gages; Stresses; Stringers; Structural steel; Trucks
• Old TRIS Terms: Analog systems; Secondary stresses
• Subject Areas: Bridges and other structures; Highways; Motor Carriers;

Filing Info

• Accession Number: 00157815
• Record Type: Publication
• ISBN: 0309025826
• Files: TRIS, TRB
• Created Date: Sep 28 1977 12:00AM