Construction methods · Piers, pylons and abutments

Steel and composite pylons

Pylons fabricated as steel boxes in sections of 10-20 m, lifted by tower or floating cranes and bolted or welded, sometimes over a concrete lower part. Faster than concrete above the deck, lighter on the foundation, and dependent on lifting capacity and fabrication precision.

How bridges get built · Piers, pylons and abutments · Steel and composite pylons

Also called: steel tower, composite pylon, stainless-clad pylon

How it is done

Fabricate segments with machined bearing ends so they stack without shims; trial-assemble in the yard.
Lift with a tower crane or a floating crane; bolt splices with pretensioned bolts or weld on site; survey each segment.
Stay anchorages are integral steel boxes; in composite pylons the steel top sits on a concrete shaft with shear connectors.

Where it fits

Suspension bridge towers, cable-stayed pylons where speed or foundation load matters, seismic regions (ductile steel), sites with a fabrication yard and heavy lift.

Where it does not

Sites without heavy lift access; budgets sensitive to steel prices; humid marine sites without a maintenance plan for coatings.

Plant, pace and money

PlantFabrication yard, tower crane 30-100 t or floating crane 1,000-3,000 t, welding and bolting crews.

ProductivityA segment every one to three days; a 200 m tower in 4-8 months.

CostUSD 8,000-15,000 per tonne erected.

Risks and controls

What goes wrong

Fit-up errors between segments, weld defects, wind during lifts, corrosion inside closed boxes.

Quality assurance

Machined end inspection, survey per segment, weld NDT, dehumidification of closed cells.

Examples

Akashi Kaikyo, Golden Gate and most suspension towers; Stonecutters top sections; Japanese cable-stayed bridges with steel pylons.