Detailed experimental results are given of stresses and deflections at the central section of an elastic single-cell, simply supported box-girder model. The 1:24 scale model had a realistic section shape and was cast from a filled epoxy casting resin. Full details on manufacture and material properties are included. Results are given for prestress, a number of wheel load cases, and types of truck loading, under three different internal diaphragm conditions. Statics checks indicate that experimental accuracy was very good. It is concluded on the basis of experimental results that internal diaphragms did not impact sufficiently beneficial behaviour to warrant inclusion in bridges of this type. Longitudinal stresses are barely influenced, and though distortional stresses can be considerably reduced, at least four internal diaphragms per span would be required. Even then, transverse stresses due to wheel loads, which exceeded distortional stresses, would only be reduced by about 10%. The model was analysed for A number of load cases using (1) three-dimensional finite-element, (2) folded-plate, (3) finite-strip, (4) two-dimensional finite-element plus grid (5) beam-on-elastic foundation analogy and (6) equivalent grillage methods of analysis. It was found that the three-dimensional finite-element gave best results, agreeing closely with experiment in all cases. The folded-plate and finite-strip analyses, using identical grid simulations, gave similar results and predicted experimental behaviour well, except near point loads where stresses were grossly overestimated. The two-dimensional finite-element method, and the beam-on-elastic foundation analogy gave results of adequate accuracy for design purposes, though transverse distortional stresses tended to be overestimated. Results from the equivalent grillage predicted transverse stresses quite well, but underestimated transverse variation of longitudinal stresses. All methods gave satisfactory simulation of the influence of internal diaphragms. ;TRRL;

  • Corporate Authors:

    National Roads Board, New Zealand

    P.O. Box 12-041
    Wellington,   New Zealand 
  • Authors:
    • Priestley, MJN
  • Publication Date: 1974

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 79 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00125585
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Bulletin No. 25 R&D Rept.
  • Files: ITRD, TRIS, ATRI
  • Created Date: Apr 7 1976 12:00AM