Curve Appeal - continued
The task of producing the curved structure for this project was awarded to expert tube and metal profile bending company Barnshaws
From the outset the engineers from Severfield (UK) consulted with Barnshaws to discuss the best way of creating and manufacturing the design so that it could be installed in the most efficient manner.
As it turned out this would involve two of the largest cranes in the country and some millimetre-perfect construction as well as precise timing.
The second part of the project required steel plate measuring up to 550 mm wide by 50 mm thick to be curved to various radii in order to make the larger sections of each rib.
Each plate section has been curved to a specific set of dimensions to allow it to be assembled into a curved box-section by Severfield (UK).
The largest of the ribs measuring 96 meters in length and weighing nearly 86 tonnes, was installed using a 750 tonne crawler crane
These are then transported to the station site where they are welded together to create the complete rib which is then carefully positioned and installed. Each of these unique ribs has required considerable precision and tight tolerances to ensure the installation process went smoothly.
Greg North, Commercial Director for Barnshaws, comments:
We have worked with Severfields on a large number of projects in the past and we understand each other’s capabilities and strengths. For one particular part of the project we were able to provide 350 mm square hollow section (SHS) steel that was curved to a 7000 mm radius at certain points with no distortion to the section, thanks to our specialised methods of bending.
Most of the curved beams were installed using the UK’s largest telescopic crane, a 1,200 tonne behemoth, while rib 9, the largest of the ribs measuring 96 meters in length and weighing nearly 86 tonnes, was installed using a 750 tonne Liebherr LR 1750 lattice boom crawler crane, supplied by Weldex crawler crane, which is one of Europe’s largest of its type.
This in itself created complications due to the live tracks that run beneath the new roof structure and the whole installation process required close cooperation with Network Rail.
In this way, the short periods during which the tracks can be made safe could be utilised as efficiently as possible, ensuring the roof structure was installed on schedule.
With the main ribs installed, the smaller subsections could be fitted that would support almost 400 ETFE (Ethylene Tetraflouroethylene) panels, similar to those used in the Eden Project and Manchester Piccadilly station. As with the steel sections, each one of the polymer roof panels has a unique shape and relies on the precision of the steelwork to ensure a perfect fit.