Rion-Antirion Bridge, Greece. Presented by James Mitchell, Dan Bundy and Hung Nguyen.
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Transcript of Rion-Antirion Bridge, Greece. Presented by James Mitchell, Dan Bundy and Hung Nguyen.
Rion-Antirion Bridge, Greece.
Presented by James Mitchell, Dan Bundy and Hung Nguyen
• Spans 2880m across Gulf of Corinth
• Links town of Rion to mainland
Greece
• Previous crossings by boat took 45
minutes, reduced to 5
• Completed August 2004, 4 months
ahead of schedule
• Second longest cable stayed deck in
the world
• Cost €630 million
1. SITE DESCRIPTION1. Introduction
Rio
Antirrio
2. Geology
Geological conditions
1. Subsoil Steep slopes on each side
and long plateau seabed 65m below water surface.
Site investigations found no bedrock at depths of 100m
The weak alluvial deposits of interbeded granular and cohesive layers continue down to a predicted 1000m.
Interspersed with liquefiable sand pockets
2. Geology
Geological conditions
2. Tectonic movement
The Corinth Rift is caused by a geological feature known as a ‘Graben’
The rift is relatively young at 2-5 million years old
North and south sides separating due to tectonic forces by up to ~15 millimetres per year
Uplifting of its southern shore approximately 1mm per year.
2. Geology
Geological conditions
3. Seismic activity
This area is one of the most seismic regions in Europe.
Seismicity lies between antithetic faults, the Alepohori fault dipping north and the Kaparelli fault dipping south
The circle symbols on the map represent historical earthquakes with a magnitude greater than 5.5 Richter.
An exceptional combination of geological conditions present
many challenges in the engineering of The Rion Antirion Bridge:
Creating stable foundations on porous granular soils in deep seabed
Reduced effective strength
Tectonic movement
Possible seismic activity
Isolation of bridge deck to seismic energy- reduce sway
Reduce dynamic response under wind loading
Liquefaction of soil
Movement of foundations
Expansion of rift
Elongation of bridge deck
3. The challenges
Possible Solutions
• Could not tunnel due to seismic activity• Bridge only option• Minimum number of seabed supports
desired• Two choices:
• Suspension• Cable Stayed
• Antirion side of gulf possessed slope stability problem
• Could not install large ground anchors needed for suspension bridge
• Cable stayed bridge only option
4. Engineering solutions
• Soil strengthened with steel inclusions
• 200 Hollow steel tubes 2m in diameter, 25-
30m long driven into soil beneath each
pier
• Covered by 3m thick gravel layer to reduce
shear force transfer to substructure
• 90m diameter footings rest on top
• No connection between footings and gravel
• Pylons are able to lift or slide up to 2m in
an earthquake
Foundation
4. Engineering solutions
• Bridge deck is fully suspended by the cables
• Isolated as much as possible from piers to
reduce seismic impacts
• Longitudinally, expansion joints allow
adjustment to thermal and seismic
movements
• Deck can withstand movements of 2m
between each set of piers
• Fuse restraints installed on pylons, as gulf
expands load cell monitors identify change in
load and dampers can be extended
• Allow for 2-5m expansion over 125 years
Bridge deck
4. Engineering solutions
• 4 Dampers and a fuse restraint at each pylon isolate bridge deck in transverse direction
• 10500kN fuse restraint keeps deck rigid during high winds
• Fails under seismic events allowing bridge to swing with 3500kN dampers
• This is the only connection between pylons and bridge deck
• Deck designed to move 2m in all directions
Bridge deck
4. Engineering solutions
5. Construction methods Construction of the foundation footings in
a dry dock. In parallel, driving steel inclusions is
carried out to strengthen soil. Towing and mooring of these footings to a
wet dock site. Immersion of the foundations at final
position. Erection of the prefabricated bridge deck
using the balanced free-cantilever technique