Skip to page content
USDA Forest Service

Research & Development Treesearch

Treesearch Home
About Treesearch
Contact Us
Research & Development
Forest Products Lab
International Institute of Tropical Forestry
Pacific Northwest
Pacific Southwest
Rocky Mountain
Southern Research Station
Help - We Participate  Government Made Easy

Global Forest Information Service

US Forest Service
P.O. Box 96090
Washington, D.C.

(202) 205-8333

You are here: Home / Search / Publication Information
Bookmark and Share

Publication Information

View PDF (3.8 MB)

Title: Live-load distribution on glued-laminated timber girder bridges : final report : conclusions and recommendations

Author: Fanous, Fouad; May, Jeremy; Wipf, Terry; Ritter, Michael;

Date: 2011

Source: USDA Forest Service, Forest Products Laboratory, General Technical Report, FPL-GTR-197, 2011: 23 p.

Publication Series: General Technical Report (GTR)

Description: Increased use of timber bridges in the U.S. transportation system has required additional research to improve the current design methodology of these bridges. For this reason, the U.S. Forest Service, Forest Products Laboratory (FPL), and the Federal Highway Administration have supported several research programs to attain the objective listed above. This report is a result of a study sponsored by the FPL, with the objective of determining how highway truckloads are distributed to girders of a glued-laminated timber bridge. The American Association of State Highway and Transportation Official (AASHTO) load and resistance factor design (LRFD) Bridge Design Specification provides live-load distribution provisions for glued-laminated girder timber bridges that were used in previous AASHTO Specifications. The AASHTO live-load distribution provisions were reviewed in this report. Field-test results were used to review the current AASHTO LRFD glued-laminated timber girder bridge-design specifications and to validate analytical results obtained by finite-element analyses. With the validated analytical models, parametric studies were performed to determine the worst-case live-load distribution factors that can be used to calculate the design moment and shear for glued-laminated timber girders. Simplified live-load distribution equations that can be used to determine these distribution factors were developed and are provided in this report. These equations take into account how load is distributed to the bridge girders, considering the effects of span length, girder spacing, and clear width of the bridge.

Keywords: Timber, wood, bridges, girders, loads, load distribution, live loads, wooden bridges, testing, evaluation, load factor design, laminated wood, dynamic loads, structural timbers, construction, specifcations, finite element method

Publication Notes:

  • We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
  • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.



Fanous, Fouad; May, Jeremy; Wipf, Terry; Ritter, Michael. 2011. Live-load distribution on glued-laminated timber girder bridges--Final report: conclusions and recommendations. General Technical Report FPL-GTR-197. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory. 23 p.


 [ Get Acrobat ]  Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

USDA logo which links to the department's national site. Forest Service logo which links to the agency's national site.