Variable Depth Bridges

Variable Depth Bridges
  • Bridges

Product Description

  • An advanced solution for box girders, achieving longer spans and improved slenderness.
  • Imitates the aesthetics of traditional on-site solutions.
  • 1990s: development of the first single-girder continuous decks with variable depth.
  • 2003: implementation for curved viaducts (radius 200 m).

Main Characteristics

  • This means breaking the span down into sections, with half lap joints and wing-shaped elements on piers.
  • Linear or parabolic variations in depth, with a difference of around 1 m between the pier and the centre of the span (maximum 1.6 m for a pier depth of 3 m).
  • Central span length of over 40 m (up to 60 m).

Types Of Structures Where It Can Be Used

  • Highway viaducts with deck widths of around 12 m, based on a statically indeterminate set-up and large span lengths.
  • Large beams for special building structures (pavilions, for example).


  • Reduced weight in transport due to sectioning of central spans.
  • Facilitates the negative moment of the end restraints on piers by increasing the depth in this section.
  • Reduces the shear force by facilitating the arch effect of the pier concrete.
  • As a result of the above, maximum span lengths using prefabricated components.
  • Highly characteristic aesthetic affect, coming close to the appearance of an arch bridge.

Construction Details

  • Typical continuous span set-up, minimum depth between 1.2 m and 1.5 m and a maximum of around 2 m on pier.
  • Two transverse supports on piers and abutments, with half lap joints in the area where the theoretical moment is zero.
  • Centre span lengths of over 40 m with end spans of around 30 m.
  • Possibility to attach a wing-shaped beam to the side to avoid temporary pier supports.

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