LABORATORY INVESTIGATION OF PRESTRESSED CONCRETE RAILWAY BRIDGE BEAMS

This report contains a description and analysis of laboratory tests made during 1960, 1961, and 1962 on 23 full-size prestressed concrete beams. These beams are 18 in. deep, 15 in, wide, and 19 ft. long and were patterned after the full-size slabs reported in AREA Proc. Vol. 59, p. 133. This investigation was directed toward a study of the effect of size of strand and level of prestress on their static and fatigue strength, and is an extension of one conducted at Lehigh University on similar beams, and reported in AREA Proc. Vol. 60, p. 1. From this tests, it can be concluded that: 1. In the static tests, the cracking loads and the deflection were affected by the level of prestress but not by the size of strand. Taking into consideration the difference in concrete strength the ultimate strength apparently is not affected by level of prestress or by size of strand. 2. Fatigue strength was influenced by the level of prestress. 3. The test results were inconclusive with regard to the relationship between fatigue strength and size of strand. 4. The mode of failure in the static tests was by crushing of the concrete accompanied by large strains of steel strands, while breakage of the steel strands caused failure in the fatigue tests. 5. The ultimate load varied from 2.5 to 3.0 times design load for static tests and from 1.3 to 1.8 times design load for fatigue tests. 6. Fatigue life decreased as the cycling load increased. 7. Strains and deflections changed only slightly for those beams which did not fail for 2,000,000 cycles of repetitive loading. 8. There was no evidence of strand slip. 9. Recorded ultimate static moments compared favorably with values computed by using the formula given in the current AREA Specifications. 10. The fatigue strength of beams could be predicted by using an idealized stress-moment diagram combined with a failure envelope for the steel strands.

Media Info

  • Features: Figures;
  • Pagination: 17 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00095684
  • Record Type: Publication
  • Source Agency: Association of American Railroads
  • Report/Paper Numbers: No. ER-36
  • Files: TRIS
  • Created Date: Jul 15 1976 12:00AM