A 1/20 scale-model study of simple-span girders was undertaken to examine the effect of a typical construction loading on both single open-section and quasi-closed-section girders and interconnected girders. Deflections, distortion, and stresses resulting from the torsional loading on these girder systems were observed. The response of a open, simple-span girder braced to minimize distortion, can be predicted with available theories for mixed torsion. A quais-closed girder generally behaves as a closed section and St. Venant shear stresses resist applied torsional loadings. However, the quasi-closed girder was found to have only 40 percent of the theoretical torsional stiffness value. Studies of interconnected boxes with end diaphragms and simple tie bracing at the one-third span points indicate that simple tie bracing significantly reduces the torsional rotation of open sections. This bracing can remain in place without affecting the appearance of the girder system. Bracing is necessary to maintain the stability of open sections during construction. Considering symmetry can help to minimize torsional construction loads on individual girders. Geometrically and structurally stable configurations can be designed for construction loadings by using simple bracing schemes. /Author/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 1-6
  • Monograph Title: Bridge tests
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00179372
  • Record Type: Publication
  • ISBN: 0309026741
  • Files: TRIS, TRB
  • Created Date: Aug 27 1978 12:00AM