LABORATORY INVESTIGATION TO DETERMINE STATIC AND REPEATED LOAD STRENGTH OF FULL SIZE SOUTHERN PINE SOLID SAWN STRINGERS

This report contains a description and analysis of data recorded during the laboratory investigation of twenty four full-size, solid-sawn, treated southern pine stringers at the Association of American Railroads in cooperation with the Forest Products Laboratory, Madison, Wisconsin. The purpose of the investigation was to determine the static and the repeated load shear strength of full-size, treated southern pine stringers and the effect of load placement. The test specimens were divided in three groups, six were loaded with the first load point 1-1/2d stringer depths from the the support, eleven at 2-1/4d and seven at 3d stringer depths from the support, respectively. The two load points were 4 ft-8 in apart in each case. The stringers were loaded in increaments of the shear design load. Design load was that which produced allowable design shear stress of 125 psi. The following observations may be made from the recorded data: Static Loading; 1. The three stringers loaded statically 1-1/2d, 2-1/4d and 3d failed at shear stresses of 727 psi, 580 psi and 513 psi, respectively. Failure was in tension for 1-1/2d and 3d, and was in compression for 2-1/4d type loading. 2. Eleven stringers which did not fail after 2,000,000 cycles were later tested statically. One stringer loaded at 1-1/2d failed in horizintal shear at shear stress of 852 psi. Of eight stringers loaded at 2-1/4d, five failed in tension at shear stresses from 488 psi to 679 psi, two failed due to horizontal shear at shear stresses of 644 and 649 psi, and one failed in compression at shear stress of 620 psi. Two stringers were loaded at 3d, one sustained a bearing failure at 555 psi while the other failed in tension at 520 psi. 3. Inspection for Decay: A visual inspection of each specimen was made to determine any evidence of decay. A pick test also was made on each specimen. From these evaluations, no decay was found.

Media Info

  • Features: Figures; Photos; Tables;
  • Pagination: 15 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00095706
  • Record Type: Publication
  • Source Agency: Association of American Railroads
  • Report/Paper Numbers: ER-76
  • Files: TRIS
  • Created Date: Jul 15 1975 12:00AM