FIELD INVESTIGATION OF TWO CONCRETE BRIDGES ON SEABOARD AIRLINE RAILROAD

This report contains a description and analysis of data on two concrete bridges. One bridge, 401.9, consists of solid concrete slabs, 15 ft--6 in long and 21 ft long, reinforced in the conventional manner with bars. The other bridge, 402.5, consists of prestressed, hollow, rectangular slabs 24 ft long and prestressed, octagonal piles. The purpose of the investigation was to obtain static and dynamic stresses in the slab spans permitting a comparison of the two design types and to obtain stresses in the piles of bridge 402.5 under vertical loads and from longitudinal forces of braking and traction. All data was obtained with 2-unit diesel locomotive and a test train. A brief summary of the data follows: Loading effects of the prestressed piling in two bents of the prestressed bridge were also investigated. The analysis indicated that: 1. Longitudinal forces due to braking and traction were predominately carried through the rails, with the resulting stresses to the piling being considerably less than that which would occur from forces of the magnitude recommended in the current AREA specifications; 2. Higher bending stresses occured in the higher bent with the greatest influences being, respectively, (a) vertical loads moving across the bridge, (b) braking, and (c) traction. Static and dynamic effects of a train operating over two bridges having similar length spans -- one bridge of conventional reinforced concrete and the other of prestressed concrete were analyzed for the purpose of comparing the different types of construction. From the test data, it can be concluded that: 1. With few exceptions, all recorded stresses were less than calculated for both bridges. 2. Transverse load distribution was nearly uniform across the decks of both bridges. 3. Impact increased slightly with speed for the conventionally reinforced spans, but remained nearly constant for the prestressed span. 4. The recorded impacts were considerably less in the prestressed span than in the conventional spans. 5. Maximum impacts occurred predominantely under the locomotive, but maximum live load plus impact stresses occurred under the cars. 6. Wheel irregularities caused high impacts of very short duration in both bridges. 7. A rail joint on one of the conventional spans influenced total impact values.

  • Supplemental Notes:
    • Conducted under sponsorship of AREA Committee 30 - Impact and Bridge Stresses.
  • Corporate Authors:

    Association of American Railroads Research Center

    3140 South Federal Street
    Chicago, IL  USA  60616
  • Publication Date: 1964-8

Media Info

  • Features: Figures; Tables;
  • Pagination: 19 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00095878
  • Record Type: Publication
  • Source Agency: Association of American Railroads
  • Report/Paper Numbers: ER-48
  • Files: TRIS
  • Created Date: Jul 24 1975 12:00AM