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Mon January 25 2021

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Orkney's new flagship

25 Sep 12 A steel frame was specified for the new grammar school in Kirkwall, one of the largest building projects ever undertaken on the Orkney Islands.

A multi-million pound schools investment programme in the Orkney Islands will eventually see main contractor Morrison Construction deliver a new grammar school and arts centre, a halls of residence, and a swimming pool and squash courts, all in Kirkwall, as well as a new primary school in Stromness.    

With a population of just over 8,000, Kirkwall is the biggest town and capital of Orkney. It is a centre of education and a focus for the local arts scene, both of which will be accommodated within the new Kirkwall Grammar School (KGS), the largest component of the overall programme. 

The new school is under construction on land previously occupied by KGS’s playing fields. Once pupils have decamped into the new buildings, the existing school will be demolished to make room for new outdoor sports facilities. 

According to the architect the new school has been designed to create a distinctive focal point, not just for pupils but also for the local community as a whole. 

To this end the school structure includes, within its overall footprint, the 350 seat Orkney Arts Theatre. This will replace an existing theatre and has been designed as a public performance venue as well as a facility for pupils to use during school hours. For security reasons, the design of the theatre and its surrounding rooms incorporates a ‘locked down’ element to allow any outside users access without compromising the privacy of other areas of the school.

The new KGS comprises one large building consisting of three teaching wings connected by an interlinking curved ‘street’ - which also accommodates social and dining spaces - with the oval shaped Arts Theatre located at the head.

Providing 15,000m2 of floor space, the building is large and one of the biggest structures in Kirkwall. It has a curving and irregular shape and so the structural design has incorporated movement joints placed at strategic points to break up the mass of the building. There are five in total, one each where the wings join the main block, one running straight through the middle of the main block, and finally one isolating the theatre.

Designed as a pin jointed steel frame, cross bracing, located in partition walls, cores and risers, provides all of the structural stability.

“Much of the steelwork is quite complex with a lot of curved members in the theatre,” explains David Custer, Morrison Construction design manager.

Steelwork contractor BHC started on site last November and by arranging the job into six phases, it was able to work its way down the structure in a sequential manner, allowing  follow-on trades to get started on areas where the steelwork and metal decking had been completed.

The erection sequence began with the sports hall and BHC then worked its way down the structure completing the three wings and the main teaching block and atrium, before finishing off with the theatre.

“The entire shape of the school presented a challenge as the grid changes constantly, but the final sector - the theatre - was the most complex requiring a thousand individual steel pieces,” says BHC project manager Eddie Brown.

The oval shape of the theatre required a number of curved beams to be supplied to the project. These members not only form the curved perimeter of the venue, but they were also used to construct two-storeys of classrooms that wrap around a portion of the theatre.

The complexity of the steel frame is at its greatest where the theatre joins the main school building. Here a large entrance foyer, which connects into the main central atrium, has curved members adjoining a straighter line of steel columns and beams.

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Forming the open plan column free space of the theatre are two 17m-long trusses, positioned on either end of what will become the main stage. These large steel sections were brought to site fully assembled and erected during one weekend, after getting a police escort through Kirkwall’s narrow streets from the ferry terminal.

Working on the Orkney Islands means all of the project’s materials have to be transported from the mainland, with the steel arriving by ship from Aberdeen. BHC had to limit each load to 25t, with the longest individual load being 24m-long.

“We generally allowed four days for each delivery to arrive after leaving our yard in South Lanarkshire,” says Brown. 

Two locally supplied mobile cranes were utilised during the first stages of the job, when two erection gangs were employed. But as the work came to end and only the theatre remained to be erected, just one 200t capacity crane needed to remain on site.

Elsewhere on the project the steelwork frames follow an irregular grid pattern. For instance, each of the three two-storey teaching wings are different lengths and accommodate classrooms that are based around a 7.1m grid, but get slightly smaller the further away they are from the main building. This design feature creates more circulation and breakout space and is formed by the central dividing corridors in each wing splaying outwards.

The main feature of the school is the centrally positioned and naturally lit three-storey high ‘street’ or atrium. Overlooked by corridors from the adjoining three-storey teaching areas, the ‘street’ is connected to the dining hall and a dance studio. Both of these areas can be opened up into larger spaces by using moveable partitions. Spans across the ‘street’ are a maximum of 24m, and have been formed by a series of cellular beams.

The local authority and client is keen to stress its high sustainability credentials and the new KGS is aiming for a BREEAM ‘Excellent’ rating. It is scheduled to be operational by spring 2013.

Project details

Kirkwall Grammar School, Orkney Islands

Main client: Orkney Islands Council

Architect: Keppie

Main contractor: Morrison Construction, part of the Galliford Try

Structural engineer: A.F. Cruden Associates

Steelwork contractor: BHC

Project value: £35m

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