Acknowledgement

All praise is to Allah, The Lord of The Creation. Certainly Almighty Allah gave us the strength & courage to make this report.

We are grateful to our teacher Miss Sultana, who gave us the opportunity to implement our skills in making a report which surely was a great experience.

1 | P a g e

TABLE OF CONTENTS

Introduction 3

Name 4

Location 4

Concept, Design and Construction 5

Main Bridge Concepts 6

Pylon 6

Deck 8

Construction and Completion 8

Trouble with Cable Links 9

Monitoring System 9

Records 10

Conclusion 11

Bibliography 12

2 | P a g e

Introduction

The Gulf of Corinth in Greece is deep, wide and long. Great attributes for marine traffic but a nightmare for those travelling by land. The Gulf of Corinth virtually chops Greece in two. The only land route between southern Greece and the Western Europe is 240 km east. Bridging the Gulf is been a goal more than a century but it is never been possible until now.

The water is too deep, the sea bed too soft and an earthquake fault line comes in the middle. Challenges of building bridge here were mind boggling. The biggest problem was Earthquake. Bridges have been built in the earthquake zone before, but this bridge had to cross an active fault line. On top of that the water here is extremely deep i.e. 60 meters. No other bridge has been built with foundations like that.

In April 1996 the only way to cross The Gulf of Corinth was by means of Ferry boat. In a perfect weather the journey would take 45 minutes, a bridge will reduce that to five. So for decades The Greece Government has been looking for new bridge designs, the bridge will have to be extraordinary. The Design of the bridge looks very simple. 368 steel cables, 4 conical towers and a yellow ribbon of roadway that glows at night.

3 | P a g e

Mega Structure – Rio Antirio Bridge

Name

Its official name is the Charilaos Trikoupis Bridge. Charilaos Trikoupis was a 19th century Greek prime minister, and suggested the idea of building a bridge between Rion and Antirion; however, the endeavour was too expensive at the time, when Greece was trying to get a late foot into the Industrial Revolution.

Location

The 2,880 m (9,449 ft) long bridge is located in Greece and it joins southern Greece to the Western Europe, making the journey as short as 5 minutes which used to be 45 minutes in a ferry or via the isthmus of Corinth at its extreme east end.

4 | P a g e

Concept, Design, and Construction

All Bridge designs are based on four types:

Beam Bridges:

The longest bridges in the world are beam bridges but it wouldn’t work here because it will block the way of ship traffic.

Arch Bridges:

An Arch bridge can stay clear of huge ship traffic but a span of Gulf Corinth will require 4 times bigger than any arch bridge built before. This design was too risky

Suspension Bridges:

5 | P a g e

A suspension bridge can be of longest distances, but suspension bridges are too expensive. Greece couldn't afford to build one.

Cable Stayed Bridges:

This left only one possible option, A Cable Stayed Bridge. In this design there are no expensive main cables (unlike Suspension Bridges), instead the smaller cables are directly linked to the towers. It will be able to fulfill the demands of this Bridge.

Main Bridge Concepts:

PylonsFor challenges like these Bridge made of 3 central spans, 560 m in length and 2 side spans, 286 m long was selected. The corresponding four pylons rest on large concrete substructure foundations, 90 m in diameter, 65m high, which distribute all the forces to the soil. Below this substructure, the bearing capacity of the heterogeneous and weak soil was improved by means of inclusions, which consist of 20mm thick steel pipes, 25 to 30 m long and 2m in diameter, driven at a regular spacing of 7 or 8m. The piers are not buried into the seabed, but rather rest on a bed of gravel which was meticulously leveled to an even surface (a difficult endeavor at this depth). During an earthquake, the piers should be allowed to move laterally on the seabed with the gravel bed absorbing the energy.

6 | P a g e

Initially, a concrete block which acts as the base of 4 concrete legs converging at the top of the pylons and giving them the appropriate rigidity was supported by these huge foundations through octagonalpylon shafts, pyramidal capitals and a sophisticated set of bearing devices, post-tensioned tendons and spring dampers. This was absolutely necessary since each pylon supported a symmetrical cantilever 510 m long and each cantilever was connected to the adjacent one or to the approaches by a simply supported deck girder 50m long. Careful analyses of the behavior of the reinforced soil and improvements of this innovative concept led to giving up the initial static scheme of the main bridge and to adopt a much more efficient structure with a continuous pylon (from sea bed to pylon head) and a continuous fully suspended deck isolated as much as possible from the pylons. This allowed the depth of the deck and therefore also the wind effects on the bridge to be reduced.

7 | P a g e

Deck

The deck is a composite steel-concrete structure, 20 m wide, consisting of a concrete slab, 25 to 35 cm thick, connected to twin longitudinal steel I girders, 2,20 m high, braced every 4m by transverse cross beams. It is continuous over its total length of 2252 m, with expansion joints at both ends, and is fully suspended by 8 sets of 23 pairs of cables. In the longitudinal direction the deck is free to accommodate all movements due to thermal and seismic actions and the joints are designed to accommodate 2,5m displacements under service conditions and movements of up to 5,0m in an extreme seismic event. In the transverse direction it is connected to each pylon with 4 hydraulic dampers of 3500 KN capacity each and a horizontal metallic strut of 10 000KN capacity. The stay cables are arranged in two inclined planes in a semi-fan configuration. They are made of 43 to 73 parallel galvanized strands individually protected by an HDPE sheath.

Construction and Completion

The lead architect was Berdj Mikaelian. Site preparation and dredging began in July 1998, and construction of the massive supporting pylons in 2000. With these complete in 2003, work began on the traffic decks and supporting cables. On May 21, 2004, the main construction was completed; only equipment (sidewalks, railings, etc.) and waterproofing remained to be installed. The bridge was finally inaugurated on August 7, 2004, a week before the opening of the 2004 Summer Olympics in Athens. The total cost of the bridge was about € 630,000,000, funded by Greek state funds.

8 | P a g e

Trouble with cable links

On 28 January 2005, six months after the opening of the bridge, one of the cable links of the bridge snapped from the top of the M3 pylon and came crashing down on the deck. Traffic was immediately halted. The first investigation claimed that a fire had broken out on the top of the M3 pylon, after a lightning strike in one of the cables. The cable was immediately restored and the bridge re-opened.

Monitoring System

A structural Health monitoring system was installed during construction on the bridge. It is still in place today and provides a 24/7 surveillance of the structure. The system has more than 100 sensors, including

3D accelerometers on the deck, pylons, stay cables, and on the ground to characterize wind movements and seismic tremors

Strain gauges and load cells on the stay cables and their gussets Displacement sensors on the expansion joints to measure the thermal expansion of the deck Water-level sensors on the pylon bases to detect infiltration Temperature sensors in the deck to detect freezing conditions Linear variable differential transducer (LVDT) sensors on the stay cables to measure movement Load cells on the restrainers for recalibration in the event of an earthquake Two weather stations to measure wind intensity, direction, air temperature, and relative

humidity

One specific element of the system is the ability to detect and specifically treat Earthquake events.

9 | P a g e

Records

This Bridge entered the record books:

It is the longest cable stayed suspension bridge in the world.

It has longest fully suspended continous deck i.e. 2200 meters.

It has the world’s largest bridge foundations and the deepest, sitting 60 meters under the sea.

Innovative engineering allows the Rio Antirio Bridge to survive where the other designs would fail. It

stands as one of the world’s mega bridges.

A beautiful view at night

10 | P a g e

Conclusion

The Rio-Antirio Bridge is a majorand impressive link when compared toother major cable-stayed bridges suchas the second Severn Bridge and evento the Normandy Bridge. The designand construction of this $ 750 millionproject undertaken under a privateBOT (build-operate-transfer) schemecould overcome an exceptional combinationof adverse environmental conditionsthanks to the choice of an appropriateconcept and seismic design philosophy.The pylons are founded directlyon a gravel layer placed on thesea bed allowing them to undergo controlleddisplacements under the mostsevere earthquake and, based on an innovativeconcept, the top 20 m of soillocated under the large diameter bases(90 m) of the pylons are reinforced bymeans of steel inclusions to resist highsoil-structure interaction loads. The2252 m long deck of the cable-stayedbridge is continuous, fully suspendedand therefore isolated as much as possible from the worst seismic motions.

11 | P a g e

Bibliography:

Wikipedia

National Geographic Documentary

Google Images

http://www.iabse.gr/support/LargeProjectsGreece/Bridges/Rio-Antirrio/

12 | P a g e