O’Connor Sutton Cronin have designed a number of attractive footbridges with the best known being the Sean O’Casey Bridge over the River Liffey in Dublin.
The structural design evolved on the basic principle of a “balanced cantilever” which is to function both in the in use condition and must remain stable in the bridge open or out of use condition. The two central opening sections are approximately 44m in overall length and each rotates on plan about a central pier to allow a free 33m open width. Two profiled cantilever abutments complete the transition with the quay side. The balanced cantilever achieves its support via a cradle, comprised of four tapered steel sections, profiled to allow the flow of maximum load transfer. The bridge deck is directly supported on continuous longitudinal circular sections and these in turn are supported at their extreme end via tension rods saddled over the cradle tips and tensioned down to the support pivot.
We have recently completed the design for Dublin City Council of the replacement for the footbridge in Fairview which is designed as a tied bowstring arch.