There are many arch bridges in Iceland, but this is probably one of the more unusual ones.
Built in 1994, this bridge is 125.5m long, with a main span of 70m. The steel-concrete composite road deck is supported on the arch via slender piers at 14m spacing.
The bridge was designed by Línuhönnun Consulting Engineers, who became part of EFLA Consulting Engineers in 2008. Swiss engineer Christian Menn was involved as a consultant.
The bridge is unusual for the arch being of composite construction, with a concrete slab supported on two steel box girders, and for its angular form. In the UK, we'd describe it as a "thrupenny-bit" profile. This solution was chosen over girder and framed options for aesthetic reasons, although studies showed a steel frame bridge to be slightly less expensive.
The composite form was chosen to eliminate the need for falsework as far as possible. The steel girders were erected first, and used to support 150mm thick prefabricated concrete panels. A further layer of in-situ concrete was then poured to create an arch 300mm thick in total. The width of the arch varies from 4.4m at the crown to 6.4m at its springings.
The bending stiffness of the arch and deck are similar, so in the finished bridge, they both resist asymmetrical bending equally.
The construction sequence had to be considered very carefully to ensure that the very slender arch remained stable at all stages - the construction photo below (taken from a technical paper describing the bridge's design and construction) shows quite how slender it appeared.
Further information:
- Google maps
- Structurae
- A Composite Arch Bridge, Iceland (Kristjánsson, Hjálmarsson, Einarsson and Haflidason, Structural Engineering International, 1996)
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