Clyde Arc Bridge, Glasgow

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CLYDE ARC BRIDGE, GLASGOW •AWARD Tmajor addition to the Glasgow skyline. included the use of tubular piles and pre-cast concrete setMinimising the environmental impact was a key factorin the development of the conceptual detailed design. Thishe judges say this eye-catching structure is thoroughlyprofessional, meets the aspirations of the client and is a They went on to add that the single arch has a diamond- above river bed level to lessen disturbance of sediments. shaped profile, giving a slender appearance enhanced Making full use of off-site fabrication in terms of steel and by reflections of light from the sky and the river surface, pre-cast concrete also minimised the duration of on-site strikingly augmented at night by architectural illumination. The works. design of the arch, the hangers and deck, is satisfyingly and Considerable cost savings were made by integrating the effectively resolved with clear expression of their functions. construction of the abutments, piles, composite deck and The 96m single span structure crosses the River Clyde and steelwork. An example of this was highlighted by a large was constructed to improve access to the rapidly expanding floating crane which was used for the installation of the steel Pacific Quay area of the city. piles and the steel deck girders. Consequently, the pre-cast A couple of firsts are also associated with the project: the units were sized around the lifting capacity of this crane. single arch rib straddling the deck is the first such structure in For the construction of the bridge, four temporary trestles the UK to be tied to the deck, while the diamond shaped arch were installed in the river to support the deck. Every lift was section is also unique. planned in detail and in order to save hook time a hinged Ian Salisbury, Halcrow Project Director, says the diamond detail was developed so that all the splice plates could be shape offers both an aesthetically pleasing structure and an fixed to the beams on the shore with a small crane. Once efficient design. in position, the splice plates could be manually swung into “The shape enhances the slenderness of the arch while place. also providing significant visual interest from the constantly The nine arch sections were delivered, assembled and changing reflection of sunlight and from the projection of the welded on the deck into three large sections each weighing architectural lighting,” he adds. 150t. Two 500t capacity cranes were then used to tandem lift The structural relevance of the diamond shape is also the sections onto temporary trestles. The two joints in the demonstrated by the fact that in cross section the hangers arch were then butt welded in situ. intersect the arch rib at angles approaching 90-degrees. The support trestles were then un-jacked and removed and The arch is 130m-long around the curve and was fabricated the hangers installed. Finally the deck weight was transferred by Watson Steel Structures in sections each weighing to the hangers and the temporary supports in the river approximately 50t. removed. This elegant bridge will aid development of a fast growing area of Glasgow. FACT FILE CLYDE ARC BRIDGE, GLASGOW Architect: Gillespie Architects Structural engineer: Halcrow Steelwork Contractor: Watson Steel Structures Main contractor: Edmund Nuttall Client: Glasgow City Council NSC July/August 2007 17


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