Design Awards: 2015: Award

Derby Arena

Derby Arena 1

Architect
FaulknerBrowns

Structural Engineer
Arup

Steelwork Contractor
Billington Structures Ltd

Main Contractor
Bowmer & Kirkland

Client
Derby City Council

Derby’s multi-sports Arena is a key legacy project that draws on sporting enthusiasm following the 2012 Olympics. The first new-build velodrome constructed in England since the London Olympics, the iconic 14,500m2 building features a 250m Siberian timber Olympic-sized velodrome track.

In addition to the cycling facilities, the Arena allows provision for a large number of community sport and fitness activities, including a large fitness suite and aerobic studios. The main Arena space accommodates 12 badminton courts or three volleyball courts. The Arena has been designed for a range of sporting and non-sporting events and can hold up to 5,000 spectators.

Structural steelwork was used for the majority of the key elements of the project due to its strength allied to its relative lightness, aesthetic appeal and speed of erection. Steel was the ideal material for the large spans of up to 85m that were part of the design concept.

The innovative facility raises the track to allow greater flexibility of the infield for other uses, including court sports activity, events, exhibitions and concerts. The level access for day-to-day use and event logistics, rather than usual ramps and tunnels, makes this particularly attractive from an operational perspective.

The Arena building is diamond-shaped with chamfered corners. Its main entrance is on the western corner and the oval cycling track sits east-west across opposite diagonals of the building at the first floor level.

The geometry created between the curving roof profile and the lifting of the building front and back has been deliberate to create a consistent height to the upper façade. This consistency allows a horizontal strip cladding to be used akin to the boarding of the velodrome track. Whilst the height of the strips is consistent, the vertical jointing is random.

The cladding system is a metal long strip aluminium ‘shingle’ system. The ‘shingle’ system is a ‘soft metal’ rainscreen adopting the building curvature which tapers to create window ‘eye-lids’ and integrated louvres. As a ‘soft metal’ system there will be a subtle and effective distortion and rippling appearance to the sheets which create a shimmering surface.

Three effective ‘eye-lids’ feature on the outside of the Arena building, which provided the challenge of accommodating twisted glazing with the frame. Due to the shape, this proved to be a complex element in the overall production, one which required optimum coordination between the steelwork contractor, glazier and architect to ensure a smooth and accurate execution.

Corrosion protection was achieved through combining offsite applied corrosion primer protection and onsite finishing coats, including intumescent paint as necessary.

Durable cladding systems to minimise materials consumption and waste generation were used to maintain a low environmental impact. Site materials were re-used in situ or sourced from a local supplier to minimise road transport to and from the site as far as possible. Sustainable urban drainage was used throughout the project to limit the impact of the new surface water drainage. Lined gravel filled trenches were used to provide conveyance and storage, and to keep excavations to a minimum within the landfill material. These were combined with large diameter storage pipes and a hydrobrake/surface water pump to control offsite surface water flows.

In terms of energy and carbon reduction, the strategy focussed primarily on the building fabric and achieving a well-insulated and airtight construction. In addition, the high efficiency central heating and hot water plant is supplemented with a combined heat and power (CHP) unit. It has achieved a BREEAM rating of ‘Very Good’.

By working together the design team was able to bring an innovative and futuristic design to life with an ambitious steel structure. With the selection of structural steel as the main construction material the building will stand the test of time, remaining aesthetically pleasing for generations to come.

The project was completed within budget and handed over earlier than the planned construction completion date.

Judges’ comment

A very well-executed project for a new velodrome that challenges the normal configuration by lifting the track to free-up the ground floor for a multi- use sports facility. The highly efficient steel-framed structure, with its 85m spans, exposes the steelwork where appropriate.

The building’s success owes much to careful integration of the architecture and engineering.

First World War Galleries, Imperial War Museum, London

Imperial War Museum 1

Architect
Foster + Partners

Structural Engineer
BuroHappold Engineering

Steelwork Contractor
Bourne Steel Ltd

Main Contractor
Lend Lease

Client
The Trustees of the Imperial War Museum

The Imperial War Museum (IWM) was founded in 1917 and moved to the site in Lambeth on 7 July 1936. Since then it has been refurbished on numerous occasions over its history.

On 19 July 2014 – to mark the start of the Centenary of the First World War – a transformed IWM London re-opened with groundbreaking new First World War Galleries and a dramatic new atrium displaying iconic large objects and terraces featuring key stories from the museum collections.

Refurbishment of this heritage building uses structural steelwork once again to reinvigorate this British national museum. IWM London’s atrium houses rockets, planes, tanks and other military hardware as a reminder of the weapons of war developed to protect the nation in times of conflict.

The refurbishment project required the cutting-out and removal of existing concrete floors and steelwork to create an extended atrium space for the large hanging exhibits. The removal of all materials and the introduction of new materials inside the enclosed atrium area was through the constraints of the existing entrance and access ways, and often material was manhandled when mechanical means was not possible. The access way into the main atrium was complicated by having a 90 degree turn from the access way between the existing concrete columns and the atrium space. This limited the new steelwork to a maximum length of approximately 8m. Trusses, stair frames, link bridges and long columns all had to be spliced to get them in the building, which also meant substantial temporary support frames were needed to erect the individual pieces.

To add to the challenges, the project commenced before the museum underwent a temporary closure period to allow for the most invasive works to be completed.

Therefore, removal of the existing hanging exhibits from the barrel vault roof and the survey of the existing structure had to be carried out simultaneously as night-time working.

Twenty tapered Vierendeel columns connect back to the existing steel frame, holding up a high level flying steel exhibition gallery including trusses and floor beams, above which sits the magnificent retained barrel vault steel roof structure. These new intricate column structures now support the fair-faced precast concrete cladding, as well as the hung exhibits, to complete a crisp structural elevation to the atrium space. Floating steel staircase structures, infill floor structures to match and extend the existing floors, a corridor structure in the existing loading bay and two new lift structures with a triangular truss link bridge to the high level flying gallery complete this 370t of new structural steelwork on the five storey internal structure, all of which had to match the existing floor levels.

The majority of the steelwork was finished with intumescent paint, with areas that are visible in the final condition being matched to the finish of the existing steelwork. The feature stair structure up to the link bridge was finished with a hot zinc spray sealed with a renaissance wax to the underside of the trusses and treads. The top of the treads were covered with a precast concrete nosing sat on the steel plates and the side trusses were finished with thin steel sheet wrapped tightly around the supporting steel members.

On the high level flying steel ‘Roof Terrace’, there were 12 specialist lifting lugs welded to the underside of the trusses and beams to support the aircraft hung from the flying gallery.

The erection of the high level flying steel required a load transfer operation to remove the existing columns supporting the barrel vault glazed end gable which was to be supported by the high level flying steel truss. The barrel vault glazing remained in place throughout the construction, so there could be no movement of the existing structure during the load transfer.

Due to the tight confines of the atrium area, the steel construction process had to be coordinated with numerous other trades to enable the final structure to come together.

HRH the Duke of Cambridge and the Prime Minister, David Cameron MP, officially opened the IWM London’s new First World War Galleries following the refurbishment in July 2014.

Judges’ Comment

A dramatic new atrium has been built within the transformed museum. Angular and robust structures frame new galleries and support war machines in a cathedral-like space. Steel construction uniquely allowed constraints of access and time to be well-answered. The visitor route is now clear and exciting.

A strong sign of success is that visitor numbers have doubled in the year.

Island Pavilion and Footbridge, Wormsley

Island Pavilion and footbridge 2

Architect
Robin Snell and Partners

Structural Engineer
Momentum

Steelwork Contractor
Sheetfabs (Nottm) Ltd

Main Contractor
Mace Ltd

Client
Wormsley Estate

Conceived in the English classical tradition of a pavilion in the landscape, the project re-interprets the 18th Century tradition for the 21st Century. The Island Pavilion, Wormsley House and Garsington Opera House form a landscape group of ‘Pavilions in the Park’.

The Island Pavilion will be used for entertaining during the summer months of opera, including dining, receptions, art exhibition and musical recitals and has been designed as a container to house a stainless steel sculpture by Jeff Koons entitled ‘Cracked Egg (Blue)’.

The single storey pavilion measures approximately 8m by 15m on plan and is 4m high, situated on the east side of the island. The structure is generally open plan, with cellular accommodation to the rear housing kitchen and washroom facilities. The primary space is a single room with glazed walls. None of the walls contribute to the structural system in order to allow the pavilion to be constructed quickly and easily onsite.

The pavilion is formed from three-pin portal frames at 3m centres, made from bespoke stainless steel sections for the rear and top elements. The columns supporting the frames at the front of the building are pin-ended stainless steel CHS posts. The frames sit on a galvanized steel structure set approximately 0.75m from the ground level. The floor construction consists of galvanized channel sections which support secondary steel members and a structural steel weldmesh floor upon which the architectural finishes are applied. The floor structure is connected to structural steel supports at the front and back of the building which also form the supports for the roof frames.

The roof of the pavilion is formed by a series of trusses which carry both the ceiling and roof covering. A profiled metal insulated decking is used to support the finishes and acts to create a diaphragm which carries elevational wind loads to the supporting elements of the stability system.

The structure is stabilised by the three-pin portal frames in the transverse direction. Longitudinally the vertical legs of the portal frames at the rear of the building are portalised together with a circular hollow steel member at the eaves.

The foundations for the building consist of driven steel tube piles founded in the competent chalk at depth. These in turn support a grillage of reinforced concrete ground beams which carry the loads from the superstructure.

The pavilion was constructed using a series of prefabricated components which were delivered to the island on a barge. The key components were:

8m by 3m floor ‘cassettes’ consisting of galvanized steel perimeter channels, with secondary steel beam elements spanning in between at 1m centres. A steel grating is fixed to the tops of the secondary steels to form the support of the floor and provide racking strength to the ‘cassettes’ during the erection sequence.
3.5m by 10m portal frames – the bespoke stainless steel elements that make up the top and rear of the three- pin portals were fully welded offsite.
7.5m by 0.5m (max) secondary roof support frames.
The bridge is approximately 42m long by 2.1m wide with a series of intermediate supports to carry the bridge deck.

The bridge is formed by a single 355 by 16 CHS spanning between foundations at 10.5m intervals. Tapered ‘I’ beams are welded through the CHS at 2m centres to support the structural ‘T’ edge members. A profiled aluminium deck spans between the edge members, perpendicular to the span of the bridge. The deck cantilevers 300mm over the structural ‘T’ edge members. The CHS member carries both the vertical bending forces when the bridge is fully loaded and also the induced torsion when the deck is loaded on one side only.

The bridge is stabilised laterally by pairs of inclined CHS sections bolted down to the foundations.

The project took six months to complete and was a lesson in teamwork, integrated design and working directly with steelwork contractors, resulting in a crafted product utilising contemporary materials and technologies.

Judges’ comment

In rolling parkland set with architectural ‘gems’, this small pavilion and its access bridge are exquisite. The detailing and fabrication of the partly tapered, and partly stainless, plated steel members are exemplary. As the site was effectively in a swamp, the whole team worked hard to achieve timely results.

The project is a testament to the pursuit of technical refinement when economy is not key.

Merchant Square Footbridge, London

Merchant Square Footbridge 1

Architect
Knight Architects

Structural Engineer
AKT II

Steelwork Contractor
S H Structures Ltd

Main Contractor
Mace Ltd

Client
European Land & Property Ltd

The new moving footbridge at Merchant Square in Paddington is a 3m wide cantilevered structure which spans 20m across the Grand Union Canal, and is divided into five slender ‘fingers’ which are raised using hydraulic jacks with an action similar to that of a traditional Japanese hand fan.

The fabricated steel beams forming the deck open in sequence, with the first rising to an angle of 70 degrees and the last achieving the required clearance over the canal of 2.5m tall by 5.5m wide at mid- channel. Shaped counterweights assist the hydraulic mechanism and reduce the energy required to move the structure. The bridge balustrades are formed from twin rows of inclined stainless steel rods overlapping to form a robust, yet filigree and highly transparent, structure. The handrail houses a continuous low energy LED downlight which provides excellent and uniform functional illumination of the walking surface and the edge, as well as offering an attractive lighting feature.

The relatively modest span suggested that only vertical movement would offer the drama sought in the brief. Constraints on land ownership dictated the bridge structure should be supported primarily from the north end, with only limited support provided on the south bank. Simplifying maintenance was a key driver – by dividing the beam into five discrete ‘fingers’ the duty on the hydraulics required to raise the beam is significantly reduced.

The design of the footbridge structure relied very much on the steelwork contractor’s ability to manufacture the five ‘fingers’ to exacting tolerances. When in its lowered position the five slender steel ‘fingers’ had to effectively create a flat, almost seamless, walking surface. The five ‘fingers’ were set up in bespoke jigs which were used to control the critical dimensions and limit distortion caused by the welding process. Each ‘finger’ also had a sculptured blade at each end, which not only held the ballast needed to balance the bridge but also formed a vital component in the overall aesthetics of the bridge. Each blade tip was formed from profiled pressed plate which was carefully ‘puddle’ welded onto the internal stiffeners. The finished welds were ground flush to give a sharp seamless finish to the blades.

The fabricated steel beams received a high quality paint finish to provide a highly durable protective coating. The top surface of the beams is finished in a similarly durable epoxy and aggregate non-slip finish. The counterweights are formed from fabricated flat steel plates and the finish on the sculpted counterweights matches that of the beams.

Each of the five beams forming the bridge is activated with a small single-acting hydraulic cylinder driven from a single power pack located in the basement of the adjoining building. At around 6t and slender in shape each beam is a modest weight and experiences little windage, so the size of mechanism and power requirements are relatively low. The counterweights have been sized to aid the system while ensuring the bridge can always be closed under gravity.

The hydraulic cylinders and rotational bearings are housed in a concrete substructure beneath ground level, protected from the canal water by a drained sump and connected to the power pack by hydraulic pipework. Access to the hydraulic cylinders can be gained without closing the bridge to pedestrians and the bridge beams can be raised to provide ready access for inspection, cleaning and maintenance.

Fabrication of the steel superstructure and mechanical, hydraulic and electrical components commenced early in 2014 and construction began with site clearance. The head of the canal basin was drained to allow access for other parts of the development and the bridgework took advantage of this for both the basement works and the installation of the beams themselves. Instead of delivering the structure direct to the site and lifting it into place with a mobile crane, the bridge ‘fingers’ had to be delivered to a wharf upstream to be offloaded onto a barge to be towed to the site with a canal tug.

The built-up nature of the surrounding development and the ground conditions immediately next to the canal meant that the ‘fingers’ had to be lifted into place with a barge mounted hiab-type crane.

Bridges are a crucial element of the built environment at Merchant Square and, therefore, it was important for the new footbridge crossing the Grand Union Canal to enhance the public realm, not only practically but visually. This has been achieved by introducing vertical movement to the design to create a bridge that is highly visible and dramatic.

Judges’ comment

The new footbridge over Paddington Basin is formed of five ‘fingers’ which are each raised by hydraulic rams, and rotate about an axis on one side of the basin.

The erection of this novel structure was solved imaginatively by the contractor, as were the extreme requirements for accuracy.

This is in the tradition of exciting sculptural bridges in steelwork at this development.

Moorgate Exchange, London

Moorgate Exchange - London - 3

Architect
HKR Architects

Structural Engineer
Ramboll

Steelwork Contractor
Severfield

Main Contractor
Skanska UK Ltd

Client
Blackrock

The brief was to provide a dynamic and high quality office and headquarters building, a modern architectural statement that maximised lettable area and provided efficient and flexible floor plates.

In order to achieve this, a steel frame was utilised to enable large column-free spans on a 15.5m by 7.5m structural grid. The structural floor zone itself was made the minimum depth possible to accommodate the required services openings, which allowed an additional floor to be introduced at the top of the building.

The building’s west facing wedge-like form responds to the rights to light of the residents in the Barbican. Its height is limited by the St Paul’s viewing corridor and the choice of structural strategy was influenced by the need to avoid conflicts with Crossrail tunnelling that partially overlaps the site’s footprint.

The design team used these constraints to achieve a distinct architecture. The wedge has been creatively used to provide landscaped terraces at the upper levels. These are highly visible from the surrounding streets and notionally extend the greenery of the Barbican terraces eastwards.

The profile negotiates the step change in scale between the Barbican and Moor House to the east of the site. The double- height main entrance space on this corner creates a statement, providing maximum views from London Wall between Moor House and St Alphage, and creates a real sense of arrival through the use of a glass façade to the bright reception area and gently LED-illuminated glass fins that rise vertically across the full height of the building over the main entrance.

Internally, the large central atrium draws natural light into the adjacent office accommodation. A combination of high- specification glazing and external shading prevents overheating on sunny days. Energy-efficient LED light fittings, with daylight sensor control, will ensure that lights are switched off when adequate daylighting is available and the building fabric u-values and infiltration exceed Part L 2006 requirements.

Rainwater harvesting coupled with an onsite attenuation tank and a greywater recycling plant reduces stormwater run-off and mains water consumption.

By utilising steel rather than concrete, the building was able to achieve long column- free spans as well as reducing the overall floor zone, increasing the maximum number of storeys, and increasing the net lettable space for the client due to fewer and smaller columns.

The speed of construction for the frame was quicker compared to concrete frame options and, in addition, the lightweight superstructure frame allowed a raft foundation to be used. This would not have been possible with a concrete superstructure which would have needed a piled foundation solution, increasing construction time and cost.

The complex terrace transfer system also would not have been anywhere near as efficient without the use of steel, while the structure is also far more adaptable to future tenant changes than a concrete equivalent would be.

The steel frame was designed and rationalised to allow easier fabrication of the elements. This included using standard plate thicknesses which could be used to fabricate a number of different beams.

The steel frame was designed to be erected close behind the slip formed cores, which provided stability to the structure. Provision for a tower crane through the floor plates was included in the base floor design, and the design of the columns was closely coordinated with the steelwork contractor’s preferred splice connections.

The steelwork contractor had a highly skilled set of workers onsite who erected the steel frame efficiently and on programme, with a minimal number of snags. The ‘V’ columns in particular required very tight control of site tolerances, and were delivered to site with the GRC cladding already installed to guarantee quality of finish.

Cellular beams were used to allow integration of the services within the structural zone, increasing floor-to-ceiling heights. The building itself was fully modelled in 3D from an early stage to maintain high levels of coordination throughout the project.

Concrete filled CHS columns were utilised to provide 90 minutes’ fire protection without the need for any external fire protection on all of the internal and perimeter columns. This, coupled with a structural fire engineering analysis on the floor plates, allowed intumescent paint to be removed from a significant proportion of the steelwork.

Corrosion protection was provided through galvanized steel members in the externally exposed structure, helping the building to achieve a 50-year design life. The building has fulfilled the client brief and achieved a BREEAM ‘Excellent’ rating.

Judges’ Comment

The team maximised the net lettable space by exploiting the great benefits of a steel frame – long clear spans with minimal fire-engineered columns, and with a reduced overall floor depth that enabled the incorporation of an additional storey. Level access to external balconies was a clever bonus. The lightweight superstructure permitted a raft foundation, impossible with other solutions.

A commercial success thanks to intelligent steelwork.