The proposal for the Commemorative Bridge competition in Dublin centered on applying the principles of craft, timber, sustainable building and the intersection of fabricated elements with simple construction.
Superposition’s interests are very much aligned with ours and so the competition encompassed values we were both keen to advocate and pursue.
We initially brainstormed on various timber construction techniques before settling on a suspended timber deck. The deck is formed using timber elements orientated diagonally which act as a deep beam in plan to resist lateral loads. The layout provides a greater in-plane stiffness compared to typical framing. The timber elements are segmental and allow for simple replacement if required, and ease of construction.
Forming the gateway to the bridge, the piers are one of the key features. They are formed using built-up Irish Oak sections, spliced in the vertical direction using glued finger joints and restrained horizontally together using steel straps. The piers are sized to resist minor axis buckling by cantilevering from ground thus eliminating the need for tying the piers together in the transverse direction.
The piers are founded on piled foundations bearing on the limestone bedrock which is present approximately 11 m below the existing ground level. The back-stays to the main cables are anchored through the use of tension piles anchored into the rock. Anchors are used over a mass concrete ballast to reduce the amount of concrete required.