Construction methods · Piers, pylons and abutments

Pier heads, hammerheads and pier caps

The widened top of a pier that carries the bearings. A hammerhead cantilevers out on both sides and is cast on brackets or a shored platform; a cap on a multi-column bent spans between columns on falsework. Post-tensioning is common in wide hammerheads.

How bridges get built · Piers, pylons and abutments · Pier heads, hammerheads and pier caps

Also called: hammerhead cap, pier cap construction, cantilever pier head

Pier heads, hammerheads and pier caps — concept diagram — Concept diagram (TheBridgeEng)

How it is done

Cast the column to the soffit level; install bracket frames bolted through the column or a shored platform from the ground.
Fix the reinforcement and post-tensioning ducts, form the head, pour in one operation, cure, stress the tendons, strip.
Set bearing plinths to level with a laser survey; grout the bearings.

Where it fits

Every pier with bearings; hammerheads for single columns under 12-25 m wide decks; multi-column caps on wide urban viaducts.

Where it does not

Over-wide hammerheads without post-tensioning; brackets on slender columns without a check.

Plant, pace and money

PlantBracket system or falsework, crane, stressing jacks.

ProductivityTwo to three weeks per head.

CostUSD 600-1,000 per m3, higher than the column.

Risks and controls

What goes wrong

Bracket collapse during the pour, cracking at the column junction, bearing plinth levels out of tolerance.

Quality assurance

Bracket design check, plinth survey, tendon stressing records.

Examples

Standard on the game's hammerhead piers under I-girder approaches.