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Steel Bridges

Modern steel bridges taking advantage of thelatest advances in automated fabrication andconstruction techniques are able to provideeconomic solutions to the demands of safety,rapid construction, aesthetic appearance,shallow construction depth, minimalmaintenance and flexibility in future use.

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High Strength to Weight Ratio

Leads to :

* Reduce weight and cost of superstructure and substructure

* Shallow construction depth

* Low transport cost

Moving a bowstring bridge at Hale - UK

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High Quality Material

eadily available worldwide in various certified grades,shapes and si#es

High quality control in manufacturing

$refabrication in controlled shop conditions leads tohigh quality work at minimum cost.

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Speed of construction%he prefabrication of components means that

construction time on site in hostile environments isminimised. %he speed of steel bridge constructionreduces the durations of rail possessions and roadclosures, which minimises disruption to the public usingthose networks.

he !ewar" #$"e rail bridge

%ust slid into position

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Versatility

Steel suits a range of construction &ethods and se'uences(five t$pical ones are:

)sse&bl$ in situ

Launching

Lifting

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antilevering

Sliding or rolling in

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Modification & Repair

Steel bridges are adaptable and can readily be

altered for a change in use. %hey can be widenedto accommodate extra lanes of traffic, andstrengthened to carry heavier traffic loads.

a&ar suspension bridge: before and after widening

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Rec$cling

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!urability

&y proper inspection and maintenance steel

bridges may last for several '(( years.%ake measures to protect from corrosion

)se weathering steel

"estheticsSteel has broad architectural possibilities.

Modern fabrication methods have removedrestrictions on curvature in both plan andelevation. The painting of steelworkintroduces colour and contrast, and repainting

can change or refresh the appearance of the

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S$dne$ harbour bridge +ateshead &illenniu& bridge

)la&illo Bridge Spain

,orth

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lassification of steel Bridges

Steel bridges can be classi ed under thefollowing groups:

Beam bridges late girder bridges

Bo! girder bridges Truss bridges "rch bridges

#able sta$ed bridges #antilever bridges Suspension bridges Movable bridges

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Bea& bridges and late girder bridges

#epending on the spans involved. the loading intensit$. costs

of steelwor" fabrication and an$ particular geo&etric and /oraesthetic re'uire&ents of the structure. a decision &ust beta"en as to whether co&&erciall$ available rolled bea&sections or fabricated girders are to be used

here is usuall$ a choice available between 0a1 using twowidel$ spaced longitudinal girders. with the cross girders$ste& supporting the dec". and 0b1 providing &ultiple

longitudinal girders with s&all spacing2

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3 bea& bridge late girder bridge

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Si&ple and is widel$ used2Much &ore shear capacit$than is re'uired2

4cono&$ in shear has i&provedHaunched to increase transverse

bending resistance

)t larger girder spacingscross girders are introducedto "eep the re'uired slabthic"ness s&all

the twin girders withinter&ediate stringer

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$pical span / depth proportions

Modes of instabilit$ in plategirders