Steel pipe piles (open- and closed-ended)

How bridges get built · Driven piles · Steel pipe piles (open- and closed-ended)

Also called: tubular steel pile, steel pipe pile, plugged pile

How it is done

Specify diameter, wall thickness, grade and seam type, the toe reinforcement or shoe, and the corrosion allowance; run a wave equation driveability study that includes plugged and unplugged behaviour.
Set up the pile barge or jack-up with a template or pile gate that holds position and rake, and survey each pile before and during driving.
Drive the upper part by vibro-hammer where allowed, then by impact hammer; record blows, energy and penetration continuously.
Splice with full-penetration girth welds after checking fit-up and alignment, and test them ultrasonically before driving resumes; keep splices out of the zone of maximum bending.
Open-ended piles: measure the soil plug; where it does not form or soft soil fills the tube, clean out and cast a concrete plug or close the toe. Closed-ended piles: check for water ingress.
Drive to the required set and penetration; test dynamically at end of driving and on restrike, and by static or bi-directional load test where the design requires.
Cut off to level, clean out the head and cast a reinforced concrete plug for the cap connection (or weld a head plate), then repair coatings in the splash zone.

Key numbers

Diameter400-2,500 mm for bridge piles; minimum wall t = 6.35 + D/100 mm (API RP 2A), D/t usually 40-100.
Length30-100 m; spliced on site to any length.
Axial resistanceroughly 2-20 MN per pile for 0.6-2.5 m diameters.
Driving stress limit0.9 fy (AASHTO).
Corrosion allowance in temperate seawater (EN 1993-5, per exposed face): about 3.5 mm per 100 years immersed or intertidal, about 7.5 mm in the splash and low-water zone.

Where it fits

River, estuary and sea piers; long piles through soft clay to a deep layer; pylon foundations in sand; sites with lateral load from ships, ice or earthquakes.

Where it does not

Rock at the tip without a socket (use PRD or bored piles), highly corrosive ground without protection.

Choosing it

Choose steel pipe over concrete piles where ship impact, waves, earthquake, liquefaction, great length or hard driving demand bending capacity, ductility and easy splicing.
Prefer large bored piles where the bearing layer is rock or very deep and capacity per pile must exceed what can be driven, or where noise rules out impact driving.
Prefer PHC or square prestressed piles for moderate loads in easily driven, non-corrosive ground: cheaper per MN.
Open-ended piles drive more easily and are the norm above about 600 mm; close the toe only where end bearing must be assured and driving resistance allows.

Plant, pace and money

PlantBarge with template, hydraulic hammer 15-40 t, welding crews, ultrasonic testing.

Productivity2-6 piles of 40-60 m per barge per shift including splices.

CostUSD 250-600 per metre for 1,000-1,200 mm including driving; steel price dominates.

Risks and controls

What goes wrong

Buckling or tearing of the toe on boulders, running in soft layers, and corrosion: allow a sacrificial thickness from EN 1993-5 or the local port standard (in temperate seawater about 3.5 mm per 100 years where permanently immersed and about 7.5 mm in the splash and low-water zone), and add coatings and cathodic protection in the splash zone.

Quality assurance

Weld inspection, driving records and PDA, verticality survey by template, plug measurement.

Origins

Steel pipe piles became the standard marine foundation with offshore oil platforms in the Gulf of Mexico from the late 1940s and with Japanese port and bridge works from the 1960s, as large hammers and spiral-welded pipe made long, large-diameter piles economic.

Examples

Long marine viaducts in China (Donghai, Hangzhou Bay), seismic bay crossings (San Francisco-Oakland Bay Bridge Skyway) and soil reinforcement under gravity foundations (Rion-Antirion); the reference uses open-ended pipes for water piers over sand.

Case studies

San Francisco-Oakland Bay Bridge East Span (Skyway)USA · 2013Piers on raked steel pipe piles 2.5 m in diameter and up to about 100 m long, driven at a batter of about 1:6 through soft Bay mud with a hydraulic hammer of about 1,700 kJ.

Rion-Antirion BridgeGreece · 2004Steel pipes 2 m in diameter and 25-30 m long were driven at 7-8 m spacing under the 90 m pier footings as soil-reinforcing inclusions, deliberately not connected to the footings, to strengthen weak seismic seabed soils.

Donghai BridgeChina · 2005The 20 km deep-sea section rests on groups of raked steel pipe piles driven from piling barges and capped by precast concrete boxes.

Hangzhou Bay BridgeChina · 2008Steel pipe piles with precast piers carry the approach spans, about 95 % of the 36 km crossing, in strong tidal currents.