Alviksbron

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Alviksbron (Swedish: "The Alvik Bridge") is a box girder bridge in central Stockholm, Sweden. Stretching over Oxhålssundet, it connects the island Stora Essingen to the western suburb Bromma. Built 1996-1998 by Nordic Construction Company to a cost of SEK 180 millions, its serves the Tvärbanan light rail system and pedestrians and bicyclists since its inauguration in August 2000.^[1] The name is derived from Alvik, originally a local manor house built in 1819 and demolished in 1930.^[2]

The bridge is 400 metres in length with a 140 metres central span and a horisontal clearance of 24 metres. The underside of the bridge tie forms an arch intended to make the bridge as slender as possible. The two pillars standing in the water, each consists of two thin concrete plates, dressed in two-quarters bricks illuminated during dark hours, with a common concrete foundation.^[1]

The construction is pre-tensioned longitudinally by cables, but non-tensioned across. The upside was stretched as the separate sections were added, while the underside was stretched after all the sections had been cast into a single compact unit.^[3]

Three years after the inauguration crack formations were discovered in the bridge. The shear fissures in the rib had an angle of 25-30° and a length of 0,1-0,3 mm, and were found in greater number on the south side. This is thought to indicate compressive stress from the longitudinal stressing in combination with heat from the sun caused the problem. The bridge was therefore reinforced, first temporarily using outside pre-stressing bars, and then permanently using carbon fibre laminates in sections with minor fissures, and tie struts in the worst affected sections. ^[3]

[edit] References

^ ^a ^b Alviksbron, Stockholm. NCC (2006-10-17). Retrieved on 2007-01-24. (Swedish)
^ (1992) "Västerort: Alvik", Stockholms gatunamn, 2nd ed., Stockholm: Kommittén för Stockholmsforskning, 491. ISBN 91-7031-042-4.
^ ^a ^b Björn Täljsten; Arvid Hejll (2005). Tvärbanebroarna Gröndal och Alviksbron. Luleå tekniska universitet. Retrieved on 2007-01-24. (Swedish)