THE MERLE BRIDGE: RUSTIC AND TIMELESS

This article describes the design and construction of the Merle Bridge, opened in late 1999, which is the largest wooden bridge in France. It spans the 54m wide Maronne Valley in the Correze region of France, and is built from Douglas fir, with a concrete slab forming its deck. It replaces a one-lane suspension bridge which had a 12t weight limit, and has no specified weight limit. Although a wooden structure was more expensive than a traditional solution using twin steel girders on two supports, wood was preferred for both environmental and aesthetic reasons. The architectural requirement was for a simple, rustic, timeless design. The final design was a 57.5m long, 10m wide, 25m high roadway, formed from five identical box beams resting on six crossed supports 12-15m long. The five longitudinal box beams are parallel, spaced every 1.65m, and linked by triangulated braces consisting of two wooden tie beams and two metal tie rods positioned in an X shape. The supports form sloping Z shapes. Douglas fir timber was chosen because of its good mechanical properties and its natural durability. Glue lamination was used in the construction. The deck is a 0.25m thick concrete slab, supported by the longitudinal beams. It includes prefabricated 3.8m wide lateral members and a 2.25m central area cast in situ.

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  • Corporate Authors:

    Institution of Structural Engineers

    11 Upper Belgrave Street
    London,   United Kingdom  SW1X 8BH
  • Publication Date: 2000-8-1

Language

  • English

Media Info

  • Pagination: p. 11-12
  • Serial:
    • Structural Engineer
    • Volume: 78
    • Issue Number: 15
    • Publisher: Institution of Structural Engineers
    • ISSN: 1466-5123

Subject/Index Terms

Filing Info

  • Accession Number: 00799857
  • Record Type: Publication
  • Source Agency: Transport Research Laboratory
  • Files: ITRD
  • Created Date: Oct 6 2000 12:00AM