Large Diameter Steel Tubular Piles for Optimum Seismic Performance-PDF

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Large-diameter steel tubular piles can provide an efficient, ductile foundation system for major overwater bridges in earthquake-prone regions. Typically 2.5–4 metres in diameter, they can be sized and detailed to balance stiffness, strength and lateral drift. Their flexibility helps limit earthquake forces transmitted to the superstructure, while a smaller footing block reduces seismic mass and the resulting shear demand.<br /><br />Design must account for soil–pile–structure interaction, including layered sediments, pile-group “shadowing,” and moments concentrated just below the footing. Footings must safely transfer large moments, shears and axial forces. Concrete infill in the upper pile section, connected by shear rings, can prevent local buckling and promote ductile behavior. For piles socketed into rock, moments may also peak near the rock surface, so full-length concrete infill and a properly detailed socket may be needed.<br /><br />These piles are often long and rely mainly on skin friction, requiring heavy hammers and crane barges for installation. The Jamuna River Bridge in Bangladesh used piles 2.5–3.15 metres in diameter and up to 80 metres long, driven through deep sands into gravel. For the San Francisco–Oakland East Bay Bridge, tubular piles socketed into rock were selected for the main pylon pier, while long driven piles were planned for the approach viaduct.<br /><br />Overall, tubular piles offer a practical alternative to conventional piers, particularly where deep water, unstable sediments or seismic performance make large cofferdams and massive foundations undesirable.

Keywords

steel tubular piles

overwater bridges

earthquake-resistant foundations

seismic design

soil-pile-structure interaction

pile-group shadowing

concrete infill

rock socketed piles

skin friction

bridge foundation engineering