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Design Awards: 2005: Commendation

Architects

Feilden Clegg Bradley Architects LLP

Structural Engineer

Buro Happold

Steelwork Contractor

S H Structures Ltd

Main Contractor

Norwest Holst Construction Ltd

Client

The Royal Airforce Museum, Hendon

Feilden Clegg Bradley was appointed in 1999 to consider the phased development of the RAF Museum at Hendon. The Museum needed additional museum space and higher quality accommodation for both permanent and temporary exhibits, and a building that would act as a focus point for the whole site.

The first phase comprises the new “Milestones in Flight” exhibition: a collection of classic aircraft selected from aviation’s 100 year history. This project received a £5.15 million Heritage Lottery award in 1999, went on site in 2002 and was opened to the public on 17 December 2003 on the centenary of the first powered flight by the Wright brothers.

The building bridges the gap between the existing disparate museum buildings. It takes the form of a simple barrel-vaulted structure enclosing the maximum possible volume and providing a structurally efficient frame from which to suspend aircraft.

The barrel vault is clad externally in stainless steel, evoking the sleek fuselages of modern aircraft, and internally in semi-translucent fabric panels which conjure up images of the stick and dope construction of early aircraft. The two ends of the building are entirely glazed in cast glass channels which glow at night and provide diffused light during the day. Internally a series of staggered mezzanine boxes and walkways form a building within a building.
The building form is echoed within the curves of the dramatic steel structure marking the museum entrance. Developed with the Japanese-born sculptor and former architect Kisa Kawakami, ‘Sky Dance’ rises 25 metres into the air, suggesting aspects of aircraft structure, airflow and flight.
Within the building, pollution, temperature and humidity levels are regulated by means of an air-conditioning system. After extensive environmental studies examining the possibility of using passive controls this was seen as the only option given the fragile, and often priceless, nature of the aircraft.

However, unlike all the other museum buildings, which are essentially black box spaces, the building has a strong emphasis on natural light. A continuous roof light at the apex of the barrel vault allows daylight to fall onto the back of the fabric panels, at certain times of day creating huge scalloped shadows. The fabric also acts as an environmental filter preventing harmful UV light from damaging the exhibits.

The Hendon project was severely cash limited but was nevertheless completed both on time and within budget whilst providing a high value for money building of this type and use (in terms of cost/square metre.)

The project value was £7.2 million with a building cost of £5,293,696 (cost per square metre £1,713). Building Area – 3090m2

Judges’ Comment

s:

A crisp solution to provide flexible space to display historic aircraft. The barrel vaulted steel truss structure allows the suspension of aircraft in many different combinations. The incorporation of a membrane inner lining enhances the effectiveness of the space.

Architect

Arup Associates

Structural Engineer

Arup Associates

Steelwork Contractor

William Hare Ltd

Main Contractor

Bovis Lend Lease

Client

The British Land Company PLC

Plantation Place South is the second commercial office building designed by Arup Associates for The British Land Company on a 2.5-acre site in the heart of the City of London. It joins the earlier larger building as part of a strategy to knit the new development into the City’s historical context, including the creation of new through pedestrian routes and views of Wren’s St Margaret Pattens church, while establishing a clear identity for itself on the southeast corner of the site.

The objective of the structural design, beyond satisfying the normal functional aspects, was to enhance the delivery and value of the project, these being the key objectives of a speculative commercial development, as well as to incorporate modern innovations where appropriate.

The plan layout was arranged with a central core and basement to mitigate the impact of perimeter site constraints, which were separately addressed in advance of construction. A substructure ring slab was configured to offer open basement construction and give immediate clear access to a slip form core for an early gain on critical path activity.

The structural frame system was optimised for efficiency and buildability. A detailed comparison with a comparable post-tensioned concrete flat slab, with the same overall structure/services depth, showed that the selected steel framed composite slab construction offered a 10% saving in the cost of foundations, a 6% saving in the frame cost, and a 5% saving on the programme time. Also, by taking into account the space between steel beams for services cross-overs and riser entries, additional services flexibility is in fact offered.

A distinction of the building is that it is the first building in the City of London to have been approved by the District Surveyor without applied fire protection to secondary steelwork. This has been achieved by appreciation of real fire behaviour and by state of the art finite element modelling of the mechanical response of the structure so that appropriate robustness can be designed in. The fire engineering approach has developed previous research into a real world practical application that can be applied to future steel framed buildings. A net reduction in total fire proofing costs was achieved, of the order of £5/m2.
An innovative prefabricated modular load-bearing stone façade was developed as a consequence of the urban context, as well as the new Part L building regulations which limit the potential extent of glass. The solution evolved from a pattern established in the first phase of the project, particularly in the use of projecting stone fins to provide self shading and a desire to exploit the high strength properties of the limestone approved by the Planners. The prefab component and infill window approach, incorporating stainless steel interconnections, offered an economically competitive alternative to the more usual and more limited curtain wall cladding market, as well as giving the building its distinctive character and appearance.

Judges’ Comment

s:

The design of this steel framed commercial office building situated in a prominent conservation area in the City has used innovation to optimise the design solution. The adoption of state-of-the-art thermo-mechanical analysis, justifying leaving the majority of the secondary steelwork unprotected, brought significant costs savings resulting in the first approved use of this approach for a building design in the City of London. The load bearing stone façade avoids column obstructions at the office perimeter.

Structural Engineer

Rowecord Engineering Ltd

Steelwork Contractor

Rowecord Engineering Ltd

Main Contractor

Rowecord Engineering Ltd

Client

Corus Strip Products UK

Rowecord Engineering Ltd completed this major project for Corus in December 2004. The brief required design, manufacture and erection of a total of 6,000t of structural steel in this 50m high facility covering an area of four football pitches. The project involved some very heavy members – such as structures to support 500t capacity cranes.

The project was entirely commercially driven. It was completed on time and within budget. Functional in the extreme, the project has no aesthetic ambitions. But this is a fine example of innovation, problem solving and construction project management.

The challenge was to design and build a three bay extension to the existing caster building including internal process steelwork, a new water treatment plant and move a 300t per hour conveyor. This will increase the plant’s output by some 1m tpa.

The project presented major design challenges. The nature of the existing plant prohibited conventional erection methods. Despite the large plant size and the volume of steel to be erected, the site was small. Rowecord were set a difficult task of tackling fundamental changes to a major industrial process without interrupting continuous production. As a continuously working plant, focus on safety was directed both at the needs of construction and also continuous production.

The project demonstrates the many benefits of offsite modularisation and on-site assembly of steel structures. Quality is maximised through manufacture in a fully equipped engineering workshop. Time spent on site is also minimised – meeting the needs of continuing production. Most important this makes a vital contribution to best possible health and safety management.

Alterations for new facilities demanded innovative engineering solutions. The most significant change was the removal of a key column weighing some 150t to make way for the new caster turret. Its removal presented a problem of supporting the unit’s two 500t capacity cranes.
The solution was to replace the existing 16m span crane-girders with a single 32m equivalent. This girder needed to be a 4.8m deep plate girder weighing some 120t. This “leviathan” was made in two 60t parts at Rowecord’s site in Newport, transported to site and welded together for installation.

In lieu of nine standard 30m roof trusses, erected singly and subsequently clad, Rowecord designed a solution of pairs of trusses which were fully pre-assembled to create roofing modules with all purlins and cladding fitted. This had a major logistical benefit that a roof which might have taken three weeks to build – and then subsequently clad – took a total of just five days to install.

The project involved relocating and reconfiguring a 45m high water storage tower weighing some 270t. This was lifted to its new location in one piece complete with water tanks using a 1,200t capacity crane.

The concast extension required a 30m diversion of a main materials artery, the “633 Conveyor.” This carries some 300t per hour of vital materials – a process requiring minimal interruption. With a shutdown period of just three days, a new conveyor line was created before a last moment diversion of the materials flow and then dismantling the old conveyor structures.

Judges’ Comment

s:

This extension of the Concast facility, in a continuously working steel plant, displays a highly effective structural design which was subject to frequent design changes, with a “construction-led” philosophy.

The logistical challenge was immense on such a confined working site and with continuously evolving requirements.