NORTH QUAY SOUTH QUAY DUBLIN DOCKLANDSLOCATION - The Samuel Beckett Bridge links the north-sideand south-side of the city of Dublin over the River Liffey.To the north is the North Wall Quay and to the South is theSir John Rogersons Quay.(A quay is a structure built parallel to the bank of awaterway for use as a landing place).
CONCEPT - The Bridge was designed with the aim of being a statement of ambition forthe area, rejuvenating the north and south sides of the river as well as forging a new linkbetween the affluent south and less affluent north.It is a landmark, the dramatic shape of the bridge resembles the Irish harp, a symbol forits secularity.TIME FOR CONSTRUCTION - May 2007 to December 2009.DESIGN - The bridge has been designed by Santiago Calatrava who also designed theJames Joyce Bridge which is further upstream.TYPE OF BRIDGE - The bridge is a cable-stayed, steel box girder structure with a span of The design for the bridge was influenced by120 metres between north and south quay walls, and is 48 metres high. the Irish harpSPECIFICATIONS -•The bridge has four traffic lanes, with cycle tracks and footpaths on either side.• It is also be capable of opening through an angle of 90 degrees allowing ships to passthrough.FINANCE - The total cost of the project was estimated at € 60 million, which will alsoinclude a major upgrade of the approach roads.The project is being funded by the Department of the Environment, Heritage and LocalGovernment, the Dublin Docklands Development Authority and Dublin City Council. The Bridge steel superstructure travelled from Rotterdam by barge following its fabrication.
BASIC TYPES OF BRIDGES CABLE-STAYED CANTILEVER BRIDGEBeam Bridge These differ from suspension bridges in the following ways: • There is no single suspender cable • The suspension cables are attached to the tower(s) and to the deck and are not vertical • The deck is attached to the tower(s)Simple Cantilever Bridge • There may be only a single tower or pylon.Suspension Bridge•Used when a large distance, such as a river or estuary, has to bebridged in a single span.• Typically two large supporting cables (called ‘suspenders’) areanchored at each side and fixed to the tops of the towers.• The rest of the structure is suspended from these two cables. Typical Cable-stayed cantilever bridge Samuel Beckett bridgeA typical suspension bridge
BASICS OF THE CABLE-STAYED BRIDGE• A cable-stayed bridge can beconstructed using just one tower.• The tower is usually placed inthe middle of the river Theweight of one side of the bridgewould balance the weight of theother side.• Cables run from the tower tothe road deck.The Samuel Beckett Bridge Forces from the cable transferred downwards, to the support of the bridge. Cantilever bridge The forces on either side of the support are still not balanced The support itself is tilted, and cables are added on the other side to balance the Cable pulls up the cantilever forces.
•The Samuel Beckett Bridge has a span of 120 metres.•Its single support is 28 m from the South quay and the bridge can be turned through 90° to facilitate marine traffic.The Structure of the Samuel Beckett Bridge•The bridge deck has a box-girder structure which provides rigidity.•The load is transferred and dissipated (spread) throughout the structure of the bridge deck and into the cable-stays.•The cable-stays are in tension and the load is transferred to the pylon which in turn transfers the load to the bridge’s foundation, and inturn to the ground.•The pylon is in compression.
CABLE - STAYED SWING BRIDGE Rotating around one end
Balance•In the case of a structure that rotates around a singlesupport it is desirable to eliminate unbalanced forces.•This is usually done by adding a suitable counterweight.The shorter end of the Samuel Beckett Bridge has almost2500 tonnes of steel, lead and heavy concrete added to itso that the centre of gravity of the whole structure isdirectly above the pivot.•The bridge is then in equilibrium.Rotating a Bridge Rotating around one endA swing bridge rotates horizontally about a vertical axis. Abraking system is required to slow the rate of rotation andbring the bridge to rest at specified points.Rotating Balanced StructuresThe structure on top is unbalanced.A balanced structure could be made:• by moving the axis of rotation tothe centre, or• by adding a counterweight whilemaintaining the same overalllength as shown in the diagram.The power required to rotate thesestructures would be considerably Rotating balanced structuresless– and because they are both balanced there would berelatively little rotational force on the bridge support.