Barrett Byrd Associates

A tight construction programme, the need to minimise disruption to the local community and some challenging vibration issues led to two hospitals in Glasgow being built with steel. Martin Cooper reports.

The £185M project to construct the new Victoria and Stobhill Hospitals forms Phase 1 of NHS Greater Glasgow & Clyde’s modernisation programme which will radically improve healthcare facilities across Scotland’s largest conurbation.

The hospitals are due to be completed and operational by 2009. The largest is Victoria in the south of Glasgow which is a 41,500m² facility, situated on former playing fields opposite the existing Victoria Infirmary. It will consist of three functioning levels on top of a covered car park.

The slightly smaller new Stobhill Hospital, in the north of the city, is being constructed adjacent to the existing facility on land formerly occupied by a car park. When complete, the three-level 30,000m² facility will also be one of Scotland’s largest hospitals.

As the new buildings at Stobhill are being constructed close to operational hospitals, and in the case of Victoria, near to residential properties, the choice of materials and their environmental impact was a key design criteria.

“We were following our ‘good neighbour’ policy,” explains Stephen Muir, Victoria Hospital Project Director for Balfour Beatty Construction. “With steel there is always less impact on the surrounding area, such as less noise and dirt, and fewer truck movements.”

Both hospitals are consequently steel framed structures as Balfour Beatty wanted to keep deliveries to a minimum and reduce local traffic.

“If we’d have used concrete deliveries would be turning up on site on an hourly basis. Steel also lends itself to off-site fabrication and a relatively short erection period, which reduced pressure on our extremely tight construction programme and meant on average only two steel deliveries a day,” explains Mr Muir.

To emphasis just how tight the programme is he adds: ”We’ve got two and half years to deliver a £100M project and speed is crucial.”

Steelwork erection at Victoria started February this year, seven weeks ahead of the construction programme. Prior to this, Balfour Beatty had undertaken some major preparatory works which included leveling a sloping site by removing 63,000m³ of overburden.

An extensive piling operation also took place with 386 bored piles, each with a pile cap, being installed to accept steel columns.

The works followed a sequential pattern around the site from east to west and then south. The piling programme followed on behind the earthmoving and once an area had been leveled and piled, steelwork contractor Severfield-Reeve was able to begin erecting columns.

The feature element of the project is a 160m-long sweeping crescent facing in a south westerly direction. The facade contains the hospital’s main entrance and an attached 800m² open atrium.

The hospital contains another six open atriums extending upwards from the ground level and these were designed to allow natural daylight to penetrate into the inner wards of building.

Speed of construction is just as important across the city at the Stobhill Hospital project where the entire steel frame was completed in just 15 weeks.

David Cairns, Stobhill Hospital Project Director for Balfour Beatty Construction, said: “By week 34 of our 122 week contract we were already fitting out the building. This is due to the steelwork being so quick to erect.

“The quicker the building is up the faster the other works, such as landscaping the surrounding area, can begin.”

Balfour Beatty started work at Stobhill Hospital in November 2006 and began by clearing the site. By the New Year piling was under way and the reinforced concrete foundations and piles to bedrock were completed towards the end of February.

Steelwork erection was then able to kick off in March and was completed so rapidly because there were no hold-ups, says Andy Burr, Project Manager for Severfield-Reeve. “For us it was a fairly straightforward job and the weather was good which helped.”

Stobhill’s two three-storey rectangular buildings comprise a steel frame construction on reinforced concrete foundations and piles. The simply jointed steel frames with composite concrete floors on Holorib metal decking act with plain UB floor beams.

Vibration can sometimes be an issue on hospital construction, but here again steel played a key role in mitigating any problems. All functional areas of the composite floors were assessed with the methods set out in the Steel Construction Institute (SCI) design guide.

“Response factors at Stobhill were generally found to be acceptable for consulting and examination rooms,” explains John Robson, Technical Director of SKM Anthony Hunts. “The location of operating theatres on the ground floor and the lack of overnight accommodation made the vibration requirements less onerous.”

However, one area on the first floor, which needed to accommodate two MRI scanners, did provide a few challenges to the design team. This part of the steel frame was isolated from the surrounding floor by slab movement joints and rubber bearing under the beams to minimise the risk of structure borne vibration reaching the scanners.

“We employed our Sydney-based specialist structural dynamics team to design a suitable solution,” explains Mr Robson. “A minimum natural frequency of 20 Hz was targeted to ensure the supporting floor was within the range of potential resonance from the MRI scanner.”

To achieve this, plus extremely tight static deflection limits, all within the restrictions on the maximum iron content in proximity to the scanner magnet, a 250mm composite slab on a grillage of 800mm deep beams, at approximately 1,800mm centres, was modelled.

“The beams provided the necessary stiffness within the set steel weight limits and analysis results allowed us to optimise the structural design while achieving the required dynamic response,” explains Mr Robson.

A similar scenario has been played out at the Victoria Hospital project where structural engineers Faber Maunsell, says the pre-construction design was particularly challenging. They say, the design coordination of such a highly serviced building with many rooms, some of which will house specialist equipment such as MRI scanners, has taken a high degree of skill and effort.

According to Mr Muir, vibration could have been an issue at Victoria Hospital and the scanners posed a significant challenge, due to their operational sensitivities. Faber Maunsell and Severfield-Reeve’s diligence produced a design that incorporates all of the Health Board’s specifications.

Fact File
The new Victoria and Stobhill Hospitals, Glasgow
Main client: Glasgow Healthcare Facilities (a special purpose consortium company led by Canmore Partnership and also involving Barclays Capital, Investors in Infrastructure and UME Investments) under a PFI contract with NHS Greater Glasgow & Clyde Health Board
Architect: HLM Architect (Victoria) Reiach & Hall (Stobhill)
Structural engineer: Faber Maunsell (Victoria) SKM Anthony Hunts (Stobhill)
Main contractor: Balfour Beatty Construction
Steelwork contractor: Severfield-Reeve
Steel tonnage: 4,400t
Project value £185M

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