In Birmingham the delivery of new Grade A office space for banking giant HSBC underlines the ‘second city’s’ burgeoning commercial clout.
Project: 2 Arena Central
Client: Arena Central Developments
Contract value: £69m
Contract type: NEC Option A – Design and build
Region: West Midlands
Main contractor: Galliford Try
Demolition subcontractor: DSM
Steel frame subcontractor: Frank H Dale
Structural engineer: Mabey
Start date: September 2015
Completion date: November 2017
Birmingham has come a long way in the last 20 years. Take a trip now and you will be greeted by a city that is very different to the down-at-heel place that struggled economically in the latter part of the 20th century.
Birmingham is now proving to be just as innovative as it was in its Industrial Revolution heyday, as well as a destination for those individuals and companies leaving London or expanding beyond it.
The city is also a progressive business start-up hub outside the capital and is attracting major established businesses, including global banking giant HSBC.
And it is HSBC that will eventually occupy the new building that is currently under construction by contractor Galliford Try at the city’s latest development, Arena Central.
Its team is working on the shell and core of the new 2 Arena Central tower, which will feature office accommodation over the ground and 10 upper floors with car parking in the three basement levels and further plant levels above the 10th floor.
Based on the site of the former ATV Television Centre, home of anarchic 1980s Saturday morning children’s show Tiswas, the new structure is hemmed in by two adjacent Grade II-listed buildings, the 1970s-built Alpha Tower and the former headquarters of the Birmingham Municipal Bank, which opened its doors in the 1930s.
Galliford Try started on site in September 2015, taking on the land as a semi-clean site following clearance work by demolition specialist DSM.
“It was quite a quick two-stage tender process,” says Galliford Try project director Mick Butler. “It was only 12 weeks across both phases, stage one took three weeks and then after client Arena Central Developments had taken us through to the next stage we had less than 10 weeks to develop the design and get the contract sorted out.”
“We had less than 10 weeks to develop the design and get the contract sorted out”
Mick Butler, Galliford Try
The building features a reinforced concrete basement tiered over three levels, which will provide parking space for 101 cars as well as bicycle storage and some of the building’s plant.
At podium level the framing material switches to steel with the 350 mm-thick reinforced concrete slab helping carry the loading from the remaining floors of its frame. The structural steel frame itself is supported by two cores, both of which were slip-formed with the larger south core featuring four passenger lifts, four service lifts and a goods lift.
The smaller north core is home to a firefighting and catering lift in addition to a glazed atrium that runs the full height of the building. The structure twists around its central vertical axis at levels seven and 10, reducing the floorplate each time by 9 m and providing two attractive terraces that will overlook nearby Centenary Square.
Across the scheme the project team took the decision to standardise the steel frame as much as possible, helping to simplify the job for the frame contractor. By using just one 600 x 600 x 40 mm steel section size for the beams, the team lessened the number of difficult connection details and also reduced the amount of cutting required on site.
Where the structure steps in to form the terraces at levels seven and 10 the beams have been doubled up to carry the loading. Elsewhere across the site the internal members are punched web beams with the scheme set out across a 9 m standard grid, but the standardisation continues with the size of the windows across the façade.
Galliford Try Arena Central 2
“Standardisation makes more sense from an assembly point of view,” Mr Butler explains. “Everything is the same so we know that it fits and it reduces the amount of cutting work that might need to be done at height.
“We can order from stock that means we don’t have to worry so much about lead-in times. It does mean the frame is slightly over-specified but the cost of that is more than outweighed by the efficiencies we are able to bring to the scheme thanks to that standard steel size,” he says.
Specialist steel frame contractor Frank H Dale has been working on the installation of the steel frame since June 2016 including the huge temporary props, brought in by system specialist Mabey, which support a cantilevered section of the building in its south-east corner.
There is an awkward 18 m fall across the site from north to south. To combat this, the team has installed a contiguous piled wall of 600 mm diameters along its length in the north-west corner of the new structure. This is to protect the Grade II-listed bank building and also provide the basement levels for the development.
Galliford Try Arena Central 8
Over in the north-east corner the mainline railway tunnel in and out of Birmingham New Street station cuts across the site with the new building sitting within 5 m of its crown. To protect the tunnel, the team piled through into the sandstone bedrock either side of it and placed 2 m-deep capping beams over the top of the piles.
“The frame is slightly over-specified but the cost is outweighed by efficiencies we bring to the scheme”
Mick Butler, Galliford Try
Installing these piles and those for the contiguous wall was carried out overnight between 11pm and 4am to avoid any impact on the rail tunnel during operational hours. Given that the site is a neighbour to a host of hotels and residential properties, the team needed to keep a close eye on noise levels.
“We had a series of noise meters set up around the site to monitor levels during the night work,” Mr Butler says. “We did what we could to limit it, but working at night was the only way we could install those piles around the rail tunnel.”
Elsewhere across the site the structure sits on pad foundations rather than deep piles, thanks entirely to the quality of the relatively shallow lying sandstone bedrock.
“It is really good quality sandstone beneath the site so the 1.4 m-deep reinforced concrete pad foundations we installed will be more than adequate,” Mr Butler says. “We have used site-won material as backfill to bring the ground level up beneath the pads where we needed to.”
With time marching on before the completed building is due to be handed over to Arena Developments and occupied by end-user HSBC, work is continuing apace on its façade, which features a signature ‘basket weave’ design (see box).
Soon the team will be working on the extensive public realm and landscaping work that forms part of the contract. This includes a ‘bank court’ – a new public square and ‘urban meadow’ within the development.
Galliford Try Arena Central 7
“We are happy with where we are in the programme,” Mr Butler says. “There have been challenges here; it took us the best part of eight months to get out of the ground, but it has been progressing well and I’m sure we will be meeting our target delivery date.”
With more developments, including an ambitious new private rented sector project that Galliford Try has won, earmarked for this enclave of Birmingham’s bustling centre, the future looks bright for the UK’s second city.
The 2 Arena Central building will be nothing if not distinctive when the Galliford Try team completes its development.
As well as the huge amount of public realm space that will surround the building, it is clad in a variety of eye-catching designs, not least the basket-weave pattern that creates a distinctive façade across its west and south elevations.
Overlapping masonry ‘ribbons’ are colour-matched to the Portland Stone of the neighbouring Municipal Bank building and nearby Baskerville House; the finished effect will certainly be unique.
“The façade is an SFS system with Schuco punch-hole windows and GRC panels which mimic Portland Stone and provide the basket weave pattern,” Mr Butler explains.
Stiffeners are built into the web of the steel frame in order to fix the stainless-steel brackets that hold the GRC panels in position. It is a system that has been tried and tested in a mock-up on site.
The other elevations will be standard glazing and rain clad façade while parts of the double-height reception area and the full-height atrium will feature glazed curtain walling systems.