Design and Construction of the Rion Antirion Bridge Foundations-PDF

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The Rion–Antirion Bridge in Greece was built across a deep, highly seismic strait with weak alluvial soils, possible liquefaction, and expected tectonic movement. Earthquake forces governed the design of its four main-pier foundations.<br /><br />The adopted solution is a 90 m-wide gravity caisson resting on reinforced natural ground. Beneath three piers, 150–200 steel tubular inclusions per foundation—each about 2 m in diameter and 25–30 m long—were installed on a 7 m grid. A 2.8 m gravel layer separates the inclusions from the foundation raft, with no structural connection between them. The gravel interface permits controlled sliding during extreme shaking, while the inclusions prevent dangerous rotational failure. This capacity-design approach limits forces transmitted to the bridge and accommodates permanent movement.<br /><br />Foundation performance was assessed through limit analysis, nonlinear finite-element modelling, and 100 g centrifuge tests; the methods produced capacity estimates within about 15% of one another. Analyses and tests also indicated that the foundation could withstand repeated cyclic loading without significant degradation. Soil–structure interaction was represented in bridge seismic analyses using a nonlinear macro-element model.<br /><br />Predicted settlements were reduced through construction-stage preloading. For one pier, measured settlement was about 8 cm, compared with an initial estimate of 22 cm, and foundation tilt was negligible. Construction involved assembling the caissons in a dry dock, towing and immersing them, and carrying out seabed preparation and inclusion installation in water depths reaching 65 m.<br /><br />The project’s success depended on extensive investigation, early development of alternatives, and close cooperation among the designers, contractor, concessionaire, and independent checker. The bridge opened in 2004, ahead of schedule.

Keywords

Rion-Antirion Bridge

seismic design

gravity caisson

soil-structure interaction

steel tubular inclusions

liquefaction resistance

capacity design

centrifuge testing

nonlinear finite element analysis

bridge foundations