Steel Box Girder Bridge
Box girder bridge is a bridge in which the main beams comprise girders in the shape of a hollow
box. The box girder normally comprises either prestressed concrete, structural steel, or a
composite of steel and reinforced concrete. The box is typically rectangular or trapezoidal in
cross-section. Box girder bridges are commonly used for highway flyovers and for modern
elevated structures of light rail transport.
Steel box girders are usually adopted in very long span bridges where it is necessary to keep
the self-weight of the structure as minimum as possible. Depending on the width requirements
single and multiple cell girders are selected. Steel Box girders are used for footbridges curved in
plan and also for bridges with longer spans
The lightness of steel construction is considered as an advantage typically in these constructions.
A single box girder as the main longitudinal spine of the bridge is an excellent solution for such
situations. A single box can carry the full width of deck with cantilevers
Fig-1 Ref: -
Google Images
The selection of a steel box girder always needs a consideration of the relative advantages and
disadvantages of box girder elements compared to traditional I girder elements.
Advantages of Steel Box Girders compared to I girders;
High torsional stiffness and strength this enables the use of box girders in
horizontally curved bridges and interchanges;
greater aerodynamic stability;
reduced susceptibility to lateral buckling of flanges in lateral-torsional and
distortional buckling modes;
support point required are less compared to conventional systems;
reduced maintenance of protective coatings since the exposed surface is less
and fewer edges are there and avoidance of exposed horizontal surfaces, no exposed
bracing and stiffeners;
Clean lines of a closed box girder provide better appearance for footbridges where
the visual impact counts.
Disadvantages of Steel Box Girders
Greater design input;
Risks associated with working in enclosed spaces.
Greater fabrication cost due to reduced scope for automated fabrication;
Handling during fabrication and coating is very difficult;
Case Studies
Swanport Bridge
Swanport Bridge is a road bridge on Highway 1 in South Australia, spanning the Murray
River about 4 km southeast of Murray Bridge. Constructed in 1979, the bridge connects the
communities of Murray Bridge and Tailem Bend.
The bridge itself is one kilometre in length with two lanes, one for each direction of traffic,
and no separating median. It is constructed from prestressed concrete. There is a footpath on
the northern side, with no barrier from the roadway
Foyle Bridge
The Foyle Bridge is a bridge in Derry, Northern Ireland. The central cantilever span of
the bridge is the longest in the island of Ireland, at 234 metres (767 ft), and the whole
suspended bridge structure including the approach spans is also the longest in Ireland at
866 metres (2839 ft).
Work on the bridge began in 1980 and it opened in October 1984. The three main river
spans are of steel box construction .The bridge was built for the Roads Service of
Northern Ireland by RDL-Graham Joint Venture, with the consulting engineers being
Ove Arup and Partners. The value of the four-year construction contract was 15,765,000
Europa bridge
The Euro pa
Bridge o r Bridge
of
Europe is a 777-
metre- long
(2,549 ft. The
bridge spans
the Sill River, and forms part of the main
route across the Alps from western Austria
to South Tyrol in Italy. It is also part of the main route between southeaster Germany and
northern Italy.
The longest span between pillars is 198 metres (650 ft). Built between 1959 and 1963 and
standing 190 metres (620 ft) high above the ground, it took the title of Europe's highest
bridge, surpassing the Gueuroz Bridge in Switzerland.
