Construction methods · Steel erection

Crane erection of steel girders

Plate girders, box girder sections or truss members are lifted by mobile or crawler cranes from the ground or a trestle onto the piers and temporary supports, then spliced. With ground access it is the simplest steel method and spans to 90 m with temporary towers or by lifting pre-assembled units.

How bridges get built · Steel erection · Crane erection of steel girders

Also called: piece-by-piece erection, crane placement of steel, girder erection

bolted splice on a temporary towerCrane erection of steel girders
Concept diagram (TheBridgeEng)

How it is done

  1. Fabricate girders in shop lengths of 12-30 m; deliver and stage.
  2. Set the first girder on bearings and hold it with the crane until braced; add the second and cross-frames; continue across the width.
  3. Assemble on the ground in pairs or units where the crane allows, to lift stable frames.
  4. Splice sections in the air on temporary towers or with strongbacks; then place the deck.

Where it fits

  • Overpasses, valley bridges with road access, spans 30-90 m, steel arches and trusses assembled on the ground and lifted as units.

Where it does not

  • Piers in water without a trestle, unstable single girders left unbraced, heavy units beyond crane charts at the required radius.

Plant, pace and money

PlantCrawler cranes 250-1,200 t, tandem lifts, temporary towers, bolting crews.
ProductivityOne to three days per span for plate girders; longer for trusses.
CostErection USD 300-600 per tonne; deck USD 1,400-2,200 per m2 in place.

Risks and controls

What goes wrong

  • Girder lateral-torsional instability before bracing (several collapses), tandem lift coordination, ground failure under outriggers.

Quality assurance

Erection engineering with stability check at every stage, lift plans, bolt tension inspection.

Examples

The game's steel approach spans; most US and European steel overpasses.

In the bridge game

What Bridge Master applies when you pick it

Deck types: Steel plate girder, Steel box girder, Steel truss, Orthotropic steel box, Steel arch, PSC I-girder, PSC U-girder, Spliced PSC girder, Network tied arch. Spans 30-90 m, up to 120 m.

  • +25: Standard steel erection.
  • +20: Light lifts in short windows.
  • -35: Use barges or launching.
  • -20: Reach limits; launching.

Try it in the game →

Related methods

Field splices: bolted and welded connectionsCrane erection of precast girdersTemporary towers and bents for steel erectionTruss assembly and erection

Further reading

AASHTO/NSBA Steel Bridge Erection Guide Specification · AISC Steel Construction Manual

Launching of steel girders and boxes →