TIMBER STRUCTURES

This report compares actual with calculated stresses in flexure and in horizontal shear of four 60-ft glued laminated beams used in bridge construction. Information with respect to position of wheel loads for maximum shear is presented. The simultaneous recorded maximum static flexural strains in the beams average 13 percent less than calculated. Maximum live-load tensile stress was 1320 psi, and maximum live-load compression was 1350 psi. The simultaneous recorded maximum static horizontal shear stresses in the two beams measured varied considerably. Maximum live-load horizontal shear stress was 118 psi. Measurements of the shear stress indicated an effective transfer of stress across a glue line. Horizontal shear became a maximum when the first wheel of a truck was 1.7 to 2.0 times the depth of the beam from the bearing as the locomotive moved across the span. Impact tended to increase with speed, with the maximum recorded impact in flexure 12 1/2 percent at a speed of 34 miles per hour. Distribution of maximum simultaneous flexural stress to the four beams was reasonably consistant with the eccentricity of the track. Distribution of the maximum recorded shear stress to the two beams tested was unequal due to a difference in reaction to each beam.

• Corporate Authors:

  American Railway Engineering Association

  59 East Van Buren Street
  Chicago, IL  United States  60605
• Publication Date: 1961-11

Media Info

• Features: Figures; Photos;
• Pagination: p. 164-166
• Serial:
  • AREA BULLETIN
  • Volume: 63 N
  • Issue Number: 567
  • Publisher: American Railway Engineering Association

Subject/Index Terms

• TRT Terms: Girders; Laminated wood; Shear strength; Shear stress; Timber; Wheel loads; Wooden bridges
• Subject Areas: Bridges and other structures; Railroads;

Filing Info

• Accession Number: 00052322
• Record Type: Publication
• Source Agency: Association of American Railroads
• Report/Paper Numbers: Proceeding
• Files: TRIS
• Created Date: Jul 15 1974 12:00AM