EFFECT OF CREEP AND COLDNESS-INDUCED SHRINKAGE ON THE PERFORMANCE OF LAMINATED TIMBER BRIDGE DECKS

The purpose of this research was to analyze the effect of creep on stress laminated timber bridges where creep refers to the time-dependent deformational behavior of the wood. Of particular interest was the cause of stress loss in stress laminated bridges. There are two types of creep that are important to bridges. These are perpendicular to grain creep due to the rod stressing and flexural creep from the dead weight load of the bridge. Coldness-induced shrinkage of wood is another important factor which affects the level of rod stress in timber bridges. Studies were conducted to examine all of these variables. Three conclusions were formed. 1. Creep due to mechano-sorptive interaction between wood and water may be an important factor in bridge design as spans are lengthened and as the dead weight of the bridge deck is increased. 2. Coldness-induced shrinkage is an important factor for bridge design due to the effect of this shrinkage on the ability of the stress laminated bridge deck to perform as an orthotropic plate. 3. The results from this study clearly identify the importance of moisture content to the long term durability of the bridge. The results from the analysis of flexural and compressive creep indicate that up to two-thirds of the observed creep takes place during the first desorption. Lumber used for bridge decks should be dried uniformly to 15% moisture content or to a moisture content that is appropriate for the temperature and humidity conditions of the region.

  • Corporate Authors:

    University of Minnesota, Minneapolis

    Center for Transportation Studies, 511 Washington Avenue, SE
    Minneapolis, MN  United States  55455-0375
  • Authors:
    • Steavey, R
    • Erickson, R
  • Publication Date: 1996

Language

  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 30 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00724606
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 20 1996 12:00AM