Structural Framing The new swing bridge has a span of 40m . The deck is cable-stayed with a single plane of four locked coil cables connecting to a central , upstand spine beam . The spine beam is a 500mm wide fabricated box with a total depth of 800mm , but only 470mm protrudes above the top of the deck . The reclining pylon is in the continuity of the main central beam and its stiffness transfers the cable loads into the piled substructure . The steel with timber deck is rotated on a slewing bearing , which is stressed down onto a doughnut-shaped pile cap by 34 vertical Freyssibars .
The steel deck comprises cantilevering cross beams that are fabricated I-sections ; a longitudinal edge beam that is a triangular closed section ; and bracing members that are standard angle and T-sections .
The pylon is a fabricated box that has been sculpted to provide strength and stiffness where required . The stay cable anchorages are discretely housed within the top of the pylon with an access panel at the back to allow for stressing and inspection .
Challenges This was a challenging build . The bridge is over 40m long and 3m wide with the mast section extending over 10m into the air . Once completed it weighed more than 40T . In the workshop the eccentric shapes of the individual sections ( some as big as 16T ) created challenges with regards to the moving and rotating for the welding and fabrication .
One of the objectives was to limit disruption to the V & A . Hence , the bridge was assembled on a nearby jetty . Once completed the bridge was carefully craned onto a barge and towed to its position . The bridge was then lifted off the barge and mounted onto the slewing bearing . It was an amazing process that took two days .
The interface between the bridge and the circular slew bearing was a critical joint that required very tight flatness and dimensional tolerances . If not achieved the bearing ’ s working life might be reduced , or worse , the fit-up with the bearing might have been compromised . The bridge 3.5m diameter ring beam that connects it to the bearing was fabricated from heavy plate sections to resist the forces needed to prestress it down onto the bearing . The dimensional control required in fabricating this element was a significant challenge and required all the skills of the welding team .
The architectural intent was for the pylon to be a continuation of the central upstand beam . As such , it is a very slender element . The fit up of the stiffeners and diaphragms as well as the various fabricated pieces of the pylon , ring beam , spine beam and deck elements had to be carefully considered to ensure that the required welding operations were practical .
Client / Developer : Waterfront Properties Architect : Craft of Architecture Engineer : SMEC Engineers Quantity Surveyor : SMEC Engineers Project Manager : Steffanutti Stocks Coastal Main Contractor : Steffanutti Stocks Coastal Steelwork Contractor : Anchor Steel Projects Steel Erector / Project Coordinator : Anchor Steel Projects Galvanising : Advanced Galvanising Corrosion Protection & Paintwork Contractor : MRH Shot Blasting and Corrosion Control
Steel Awards 55