The purpose of this test was to determine the strains and deflections in the 60 ft. beams of the glued laminated, open deck timber bridge built by the Weyerhaeuser Timber Company near Castle Rock, Washington. These beams are the longest timber beams in this country carrying railroad loading. It was concluded that: 1. The simultaneous recorded maximum static flexural strains in the four glulam beams average approximately 13 percent less than calculated. The maximum live load tensile stress was 1,320 psi and the maximum live load compressive stress was 1,350 psi. 2. The simultaneous recorded maximum static horizontal shear stresses in the two beams for which measurements were made varied considerably, being approximately 12.5 percent less and 47.0 percent greater than calculated according to accepted design equation. The maximum live load horizontal shear stress was 118 psi. 3. Measurements of shear stress indicated an effective transfer of stress across a glue line. 4. The study indicated that horizontal shear becomes 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. 5. Impact tended to increase with speed with the maximum recorded impact in flexure 12-1/2 percent at a speed of 34 mph. 6. Distribution of maximum simultaneous flexural stress to the four beams was reasonably consistent with the eccentricity of track. Distribution of maximum recorded shear stress to the two beams tested was unequal due to a difference in reaction to each beam.

Media Info

  • Features: Figures; Tables;
  • Pagination: 17 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00095705
  • Record Type: Publication
  • Source Agency: Association of American Railroads
  • Report/Paper Numbers: ER-1
  • Files: TRIS
  • Created Date: Jul 15 1975 12:00AM