Load distribution in short bridges subjected to oversize vehicles

Trucks that do not satisfy the legal weight and size limits sometimes need to use a transportation network. The effect of such vehicles on a pavement is not as detrimental as on a bridge. In such cases, the bridges along the route shall be checked to see if the imposed loading on them is acceptable from a structural point of view. The girder distribution factors in the AASHTO LRFD bridge design specifications (2017) cannot be used to evaluate the critical live load effect in individual girders if the truck gage width is different from 1830 mm. Consideration of the vehicle’s nonstandard gage width in the structural analysis of an existing bridge can help increase the allowable load. The objective of this study is to develop simple girder distribution factors for shear and flexure for short slab-on-girder bridges subjected to oversize vehicles. To develop the distribution factors, 126 bridges having different girder spacing and span length, and subjected to wide trucks were analyzed by the finite element method. Findings of the study showed that an increase in a truck’s gage width results in lower girder distribution factor, and this is more predominant for shear than for flexure, especially for bridges having large girder spacing. The GDF of bridges having small girder spacing is not affected much by the gage width because only one line of wheels is within the tributary area of the girder under consideration. The derived GDF formulas possess reasonable accuracy; hence, they can be used for evaluating an existing bridge subjected to oversized vehicle in lieu of a 3-dimensional finite element analysis.


  • English

Media Info

  • Pagination: 9p
  • Monograph Title: 9th Australian Small Bridges Conference, Surfers Paradise, Queensland, 1-2 April 2019

Subject/Index Terms

Filing Info

  • Accession Number: 01714765
  • Record Type: Publication
  • Source Agency: ARRB Group Limited
  • Files: ITRD, ATRI
  • Created Date: Aug 26 2019 11:34AM