Widening ambitions for Derby’s new multi-sports centre created a complex set of demands. A lightweight steel frame was the answer
London may have its Pringle, but Derby will soon have not just a velodrome but a multi-sports centre covered in gold, silver and bronze metal shingles that incorporates a cycling track among its many sports and uses.
Designed by FaulknerBrowns, the 14,500m2 arena is nearing completion at Pride Park on a former car park close to the city’s football stadium. The arena grew out of Derby City Council’s leisure strategy for two major new dry and wet sports centres. After advising on the strategy, FaulknerBrowns was part of the Mace-led team that won an OJEU competition for the dry sports part of the scheme, and was later novated to contractor Bowmer and Kirkland. As the project developed, so did City Council ambitions, leading to the inclusion of a velodrome and scope to host entertainment and conferences, all within the same £26m budget.
With such a complexity of sports and functions, flexibility and cost-effectiveness were essential. Another factor was the site’s landfill past, which meant piled foundations and a relatively lightweight structure were required.
Engineer Arup says a steel frame was the only option to deliver all this with the 85m-wide roof spans needed to create the column-free arena. The 1300t steel structure, delivered by Barnsley-based Billington Structures, is configured using a perimeter column grid of 6.5m, each picking up the huge trusses that support the roof.
‘The aim was to design it as efficiently and rigorously as possible, delivering maximum functionality and operational flexibility. Architecturally, it needed to co-ordinate with the sports overlay so there was no need for additional structure for netting and lighting,’ says FaulknerBrowns director Nigel Tye.
The design team was faced with an extremely tight site sandwiched between two boundary fences and with a car parking requirement for match-day access for the football stadium. As a result, the only set-down area for construction materials was the centre of the arena itself.
‘The key constraint was the tightness of the site with boundary fences on two sides of the arena. So we had to rotate the track by 45 degrees to make it fit, and configure the other accommodation below and around it,’ says Tye.
Unusually, it was decided to lift the 250m cycling track to first floor level to give easy access to the infield, which is the size of 12 badminton courts. Main auditorium seating is to the south, opposite the entrance, with sightlines designed to give good views of the infield courts as well as the cycling.
‘There is completely unimpeded access to the central area – you can even drive vehicles in, which opens up a wealth of opportunities for using the central space,’ says Tye.
The concourse follows the contours of the cycling track to curve up at the north end to meet the hospitality area, where there is additional balcony seating over the arena. In total, the arena can seat 5,000 including 3,500 in temporary infield seating.
Externally, the architect began with a square form, then rounded the corners and pared it back further to reconcile the balance between accommodation and budget. This was then ‘peeled’ up by 4m at front and back to mark the entrance and service point. At the front this creates an imposing entrance, with fitness facilities, hospitality and plant room stacked above. After first considering a cantilever, the engineer came up with columns in ‘V’ pairs to provide structural support and visual interest.
As well as the roof, the perimeter column grid supports the auditorium seating and the track. Columns are 400mm in diameter and spliced at second floor level, giving two 11m stretches. All connections are bolted via short stub plates, pre-welded to take the beams.
Seating is supported off the main columns via steel raker beams that follow the line of the terracing. These support precast concrete terrace units.
One of the main challenges on the project was avoiding the timber structure of the cycling track, which was installed by a velodrome specialist. Below the track, the arena floor – in-situ concrete on a steel deck – supports the 4m wide cantilevered run-off inside the cycling track. Another issue was the dynamics – it was essential, for example, that activity in the fitness suites didn’t transfer through the structure to other areas. Arup ran dynamic analysis modelling tests during design development to establish that the proposed stiffness of beams was sufficient.
A distinctive slash of windows over the entrance emphasises the point of arrival with further slashes at the end of the track. Long aluminium lapped shingles are intended to give an impression of movement, as well as suggesting the cycling track itself.
A secondary steel frame creates the cladding substructure. Anodised metal shingles were fixed to plywood that was attached to curved hot rolled purlins, in turn fixed to the columns.
Tye points out that the arena has been delivered for a fraction of the cost of the Olympic velodrome while providing a wider variety of uses and potential for community participation. ‘We’re on a journey to deliver as much for their money as possible,’ he says.
The arena is being fitted out and is due to open at the start of next year.
See the video case study online at: www.steelconstruction.info/Video_case_studies
Twelve huge roof trusses (above) up to 85m long enabled the design team to achieve the column-free interior essential for sports arena use. The combination of the trusses’ size and their position 22m above the ground created a considerable challenge, according to Billington senior design engineer John Camm, who says the 5m truss depth was at the upper limit of what could be transported on a trailer without a police escort. The trusses have diagonal members at angles of 30-45º between the 305mm open section parallel chords. Each truss weighs 34 tonnes and was formed from four sections, bolt-spliced on site. During erection, the middle two sections were bolted together and lifted into position before being joined by the two end pieces. Hot rolled steel purlins link the trusses at 6m spacings, topped with the profiled roof deck, which naturally adapts to the gentle curve of the roof.
Trusses are deliberately aligned with the three 6.5m wide sports courts to accommodate netting and lighting for each space and so avoid additional secondary members. They also incorporate access walkways.
According to Billington, the eight pairs of feature ground floor columns (above) at the arena entrance were the most challenging part of the structure. Each pair of V-shaped columns, made from 457mm circular hollow sections, required very careful support before being anchored into the floor slab. The columns support the structure from first floor upwards and help provide a focal point for the entrance.
Client Derby City Council
Project manager MACE
Engineer Arup (Structural, Civil, Services, Fire, Acoustic)
Contractor Bowmer and Kirkland
Steelwork contractor Billington Structures