American Society of Civil Engineers

Slip between Glue-Laminated Beams in Stress-Laminated Timber Bridges: Finite-Element Model and Full-Scale Destructive Test

by Mats Ekevad, (Associate Professor, Division of Wood Science and Technology, Luleå Univ. of Technology, SE-931 87 Skellefteå, Sweden. E-mail:, Peter Jacobsson, (M.S., Martinsons Träbroar AB, Kroksjön 230, SE-93195 Skellefteå, Sweden.), and Göran Forsberg, (Lab. Engineer, Wood Technology, SP Technical Research Institute of Sweden, Skeria 2, SE-931 77 Skellefteå, Sweden.)

Journal of Bridge Engineering, Vol. 16, No. 2, March/April 2011, pp. 188-196, (doi:

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Document type: Journal Paper
Abstract: Stress-laminated timber bridge decks consist of several sawn timber beams or glue-laminated (glulam) beams held together with prestressed steel bars. Frictional shear stresses between the beams transfer loads between individual beams. Because the vertical (transverse) shear stress component has been extensively discussed, this paper considers the horizontal shear stress. A full-scale test and corresponding finite element simulations for a specific load case confirmed that horizontal slip occurred between beams. Using an elastic-plastic material model, the finite element model handled both vertical and horizontal frictional slip. The results showed that the finite element model gives reliable results and that slip in general leads to permanent deformations, which may increase with load cycling. Horizontal slip between beams over a large area of the bridge deck begins at a low load, resulting in a redistribution of load between beams, but does not lead to immediate failure. Vertical slip between beams starts at a high load close to the load application point and leads to failure.

ASCE Subject Headings:
Laminated materials
Wooden bridges
Full-scale tests
Finite element method

Author Keywords:
Timber bridge
Wooden bridge
Full-scale tests
Finite-element method