Structural Steel Design Awards
Battersea Arts Centre
Following a fire, the parameters of the original ceiling and roof finishes were set. However, the need to meet current regulations and improve plant provisions resulted in the roof truss needing to be slimmed down at its pinch point. An elegant solution of doubling up new trusses and linking them to form a boxed section allowed that to happen.
Heyne Tillett Steel
Battersea Arts Centre
Upgrade works to refurbish and extend the Grade II listed Battersea Arts Centre in London were nearing completion in March 2015 when a tragic fire broke out in the northern half of the building, destroying the roof of the Grand Hall. While this was heart-breaking it presented an opportunity to create something special and enhance the current use of the building.
The brief was to create a flexible space that is not just used for performances, but also ceremonies, debates, gatherings, food shows, fashion shows, community use and more.
The new roof needed to provide enough flexibility to support a large number of rigging point configurations for technical equipment and lighting and incorporate walkways to provide easy access for technical crew along its length. It also had to support plant, acoustic attenuators and an ornate lattice plywood ceiling.
Other upgrades to the space included demountable side galleries, modifications to the balcony to support an organ, rebuilt dressing rooms to the sides of the stage and a new stage roof, again built for flexibility to support a combination of rigging points.
An early decision was to provide two lines of walkways along the length of the hall. This drove the form of the roof trusses into ‘space-frames’ using RSA and PFC members.
The curvature of the original arched ceiling was still visible in the surviving plaster relief on the north buttress wall. This curve was surveyed and is incorporated in the lower chords of the new trusses and ceiling.
The original roof trusses had deep, plated haunches which were built into brickwork buttresses. The proposed design required a significant increase of load and therefore thrust on the buttresses, and with the increased build-up of finishes there was a subsequent decrease in available depth, and hence stiffness, of the truss haunches. To overcome this, a design was developed utilising elastomeric bearing pads on one side of each truss that allowed the truss to ‘relax’ during the initial loading of the roof.
These movements were monitored during construction and the bearings locked in place once 50% of the roof build-up was installed. This ensured the thrust on the buttresses would not exceed the original loading and minimised live-load deflections. Using this technique avoided any strengthening works to the original masonry structure.
The trusses were fabricated offsite, delivered in three sections and installed through removable sections in the temporary scaffold roof using a mobile crane.
Fen Court, London
Fen Court is a 15-storey commercial and retail development that includes a public roof garden offering 360-degree views of London’s Square Mile and a public right of way passage through the centre of the site. A challenging construction sequence was required to accommodate the relocation of a high street bank that was operational on site throughout the works.
Eric Parry Architects
Sir Robert McAlpine
Generali Real Estate
Fen Court is a 39,000m2, 15-storey office and retail project that includes a 2,200m2 roof terrace with 360-degree views of London’s Square Mile. Located within London’s expanding financial district, Fen Court is a notable addition to the London skyline. Towering 65m above street level, the distinctive crown-shaped design on the 10th floor, along with spacious offices, rooftop restaurant and London’s first publicly accessible roof garden, make this project truly unique.
The minimal, yet sharp, geometries of the building’s façade were part of the initial vision for Fen Court. The constantly-changing crystalline appearance of the upper floors is determined by daylight and the weather, making the top floors reflect light differently depending on the conditions. The modern steel and glass design, combined with the natural green space of the roof garden, provides a welcome contrast to the imposing city environment.
The upper office floors have a doubleskin passive façade, with dichroic glass in the outer panes, giving this section of the building its changeable appearance. The high-performance façade also includes motorized blinds, giving occupants the option to easily reduce solar gain during summer.
A key requirement on Fen Court was to keep an existing high street bank on the site in operation, whilst demolition and construction works took place. So, the previous building was demolished around the existing bank, and their new premises had to be constructed in advance of the rest of the structure.
The challenging build of the high street bank premises involved a top-down construction sequence for a small portion of the site, in which plunge columns were driven into the ground and a small area of the B1 slab was cast. Excavation down to B3 level could then be done underneath the B1 slab, while steelwork was being erected above. Steelwork and metal decking were installed at ground floor and mezzanine levels for the south west corner of the site, where the new bank was situated. This was then made watertight, and handed over to the bank for fit-out and, finally, occupation.
To achieve the tight programme of 23 weeks for the erection of 6,500 tonnes of steel, a series of welded frames around the perimeter, comprising two two-storey columns and two perimeter floor beams, were used. Effectively, this turned four lifts into only one lift, saving precious time.
The project’s design and environmental requirements were successfully met, helping Fen Court to achieve a BREEAM ‘Excellent’ rating
Chiswick Park Footbridge
The mutual resolution of architectural form and innovative structural design conceals the complexity of the technical and geometrical constraints these bridges had to address. Brilliantly conceived, beautifully made and ingeniously erected, this project provides not only a much-needed physical link for the community, but also a remarkable local landmark.
Chiswick Park Footbridge is a three-span arched structure providing a new pedestrian link between a successful business park and an underground station, both called Chiswick Park. Providing a safer route than the current railway level crossing, the footbridge spans landscaping, a bus route, and railway lines.
The challenging site posed numerous constraints including a 45m span over Network Rail lines, a restricted landing site at one end including a 4.5m drop in level, a minimum road height clearance for buses in the central span, a set podium launch level at Chiswick Park, and a curved horizontal alignment, all set within a complex urban environment hemmed in by railway lines, roads, residences, a business park and a nature reserve.
A key feature of the structural design was minimum self-weight, so the 45m Network Rail span could be lifted from Chiswick Park while fully fitted out. As such, the use of steel was instrumental in the successful delivery of this bridge, not only for the main arches, but also for the deck itself. The arch was designed as a network arch with close centred crossed cables, which act as a stiff mesh to control pedestrian dynamic effects.
Durability and minimum maintenance requirements led to the use of weathering steel for the primary structure and stainless steel for the hanger cables and architectural metalwork.
The curved geometry of the deck and arches required parametric modelling to create geometry and analysis models. These were used to create the geometric definition of every steel plate in a format suitable for the steelwork contractor’s fabrication model, which avoided the need for 2D fabrication drawings and potential errors. These geometry models were also used to perform checks against the as-built 3D site surveyed data. A series of bespoke error checking tools were developed to assess the deviation from perfect form, which facilitated rapid geometry agreement on site for the critical arch sections.
An ambitious construction programme was based around a ‘kit of parts’, maximising offsite fabrication and minimising the extent of complex on-site works. Each span was assembled in a separate compound and the three spans were then lifted into place during 2 weekends with road closures and a rail possession.
The construction of the UK’s first network arch footbridge built around a curve, in a challenging urban site, using bespoke surveying and control processes and an innovative cable stressing sequence, to budget and programme was a stunning success.
Ingenuity House, Birmingham
The central location for this regional hub ideally connects and consolidates previously dispersed departments under one roof. Efficient offices surround a grand central social space which greatly benefits departmental collaboration. Intelligent use of steel has delivered a triangular building, reflecting site constraints, stepped to give environmental benefits to the offices within and a cohesive grandeur to the whole.
Billington Structures Ltd
Interserve Construction Ltd
Interserve Construction Ltd
Ingenuity House is a new 5-storey regional headquarters for the support services and construction firm, Interserve. Located next to Birmingham International Airport, Birmingham International Railway Station and the proposed HS2 Interchange Station, it is a key element of ‘UK Central’ which forms a catalyst for the regeneration strategy of the area.
The 12,000m2 energy-efficient building will bring together circa 1,200 Interserve and RMD Kwikform staff, who are currently spread across five regional offices. The intention is for staff to benefit from modern and flexible ways of working, to promote enhanced open communication and collaboration.
The building layout has been designed to optimise the space planning, orientation and form to reduce energy consumption, minimise overheating and maximise natural daylighting, thus achieving a BREEAM ‘Excellent’ rating. The stepped façade creates shelter to glazed elevations, with narrow floorplates and a terraced internal atrium enabling maximum daylight penetration into the space. The terraces promote enhanced interaction of staff through visible connections, and provide vibrant collaboration spaces arranged around the atrium. The atrium roof itself is an elegant and stunning centrepiece to crown a building designed to inspire.
The architectural form presented some distinct structural challenges, each requiring creative solutions from the stepped floorplates and column-free entrance to the 38m spanning atrium roof. Raking columns with external cantilevers and internal transfer beams supporting stepped vertical columns, were found to provide the optimal balance of structural efficiency and spatial planning.
The stepping floorplates are all constructed using cellular beams allowing the horizontal distribution of services within the depth of structure, which delivers a clean ceiling plane and maximises clear height.
A scheme to hang the perimeter curtain walling from a support beam above, closer to the root of the floor beam cantilever, was developed to ensure compatibility of movements between the primary frame and cladding system. Significant lateral forces were induced into the floorplates to restrain each wing of the building as it tries to ‘lean’ out.
One of Interserve’s principle requirements was for a building that could adapt and flex over time in response to changing business needs, with each floorplate having the ability to accommodate a variety of working modes. Whilst being primarily a bespoke building for Interserve, the design does allow for potential future subdivision both vertically and horizontally with services in each core serving particular areas of floorplate.
A collaborative approach throughout design and construction was key to the overall success of this project.
Neuron Pod, London
The Neuron Pod, the latest addition to Queen Mary University of London Cell Education Centre, surprises in its animal form, is fun and colourful. These qualities meet the brief of inspiring and hopefully attracting future scientists. This contemporary work of craftsmanship in weathering steel succeeds in striking a whimsical note with serious scientific educational intent.
Queen Mary University of London
The Neuron Pod is a new addition to Centre of the Cell, an award-winning science education centre at Queen Mary University of London’s Whitechapel campus. To address ever-increasing demand, the Neuron Pod will help increase visitor numbers and provide a multi-functional space for live science shows, hands-on workshops, experiments, debates, films and exhibitions.
Made out of weathering steel, the Pod consists of an external structural skin stiffened by internal steel ribs. These internal ribs run in both directions to provide stiffness and rigidity to the structural skin. Inspired by a Zeppelin shape, both in plan and elevations, it is supported by three legs. The overall shape presents a curved surface, resembling the central part of a neuron, while the dendrites are shaped in the form of numerous spikes scattered along the external surface of the Pod.
Constructed following a process similar to the construction of a ship’s hull, the structure comprises 8mm thick precise lasercut flat metal sheets, curved in place using the vertical ribs as an embedded structural formwork and then welded.
This project was designed, analysed and produced using a bespoke workflow to generate the surface, implement the structural ribbing and splicing following the overall stress patterns, and then produce a full set of construction drawings. The smooth surface obtained with a computer generated algorithm was envisaged as a starting point.
A subsequent step was to study a subdivision pattern to discretise the overall shape into developable strips. This allowed a quick generation of various options for the ribs, and once the loading criteria were set, it allowed fine-tuning of the pattern to balance the target of limiting the self-weight (and therefore material) with the needs of strength and stiffness.
The workflow output was then used by the steelwork contractor to cut, assemble and weld the pieces. The various pieces were temporarily bolted together on-site in order to minimise the temporary props required. Once the jigsaw was complete, the bolted interfaces were welded to create the final structural continuity, allowing the temporary props to be removed.
With a weathering steel Pod and galvanized steel connecting bridge, the materials used provide a lasting durability to the structure, whilst retaining the aesthetic quality the architect envisioned and providing the ‘wow’ factor the client wanted. Without adding to the structural elements, this piece provides an art installation as well as a functional teaching space increasing the capacity of facilities available in the university.
Royal Academy of Music, London
A remarkably collaborative team of client, designers and contractors has delivered a spectacular new auditorium theatre in the heart of the listed campus building, and within the most constrained of live sites. A highly integrated design of the steel roof trusses has allowed the team to squeeze in a rooftop recital space without compromise to the auditorium below.
Ian Ritchie Architects
Geoffrey Osborne Ltd
Royal Academy of Music
This redevelopment of the world-renowned Royal Academy of Music (RAM) has totally transformed its existing theatre and back of-house facilities.
Structural interventions in the historic Grade II listed buildings included the demolition and replacement of the existing theatre superstructure, the addition of new cantilevered balcony seating, two substantial box frames through significant masonry walls, the introduction of a flytower (with main plant room above), an enlarged orchestra pit, insertion of new vertical circulation routes, and a box-in-box rooftop recital hall with its own glazed foyer.
All of this was achieved during a threeyear demolition and construction period without significant disruption to the life of the Academy which completely surrounds the site.
The ill-equipped and badly shaped existing auditorium theatre has been remodelled to provide a 40% increase in seating capacity in a contemporary, warm and inviting space optimised for musical and opera acoustics.
A slender cantilevered horseshoe 100- seat balcony has been introduced into the theatre, the structure of which mainly consists of an ingenious system of steel beams cantilevering off hidden two-storey steel columns which, in turn, sit on the existing stalls concrete bowl slab and are only laterally restrained at roof level to avoid overloading the slab below.
A striking feature ‘Mercator’ auditorium ceiling has been introduced to provide a visual focus and to maximise the acoustic volume of the theatre.
The Mercator roof and flytower are supported by a deep upstand plate girder to the rear of the balcony, and two novel hybrid storey-height combined steel trusses and plate girders. These give space at the edges of the spans at rooftop level for the circulation space and a plant room.
Above the redeveloped theatre, the opportunity was taken to add a new, partially exposed, steel-framed 100-seat flexible recital hall, entirely isolated acoustically from the surrounding structure. An attractive and unique system of exposed tension cables connected to steel moment frames are joined together at a torsionally stiff central round oculus, which transfers moment from one side of the centre of the roof to the other. The lateral thrusts of this semi-arching roof structure are resisted by 400mm SHS beams around the perimeter at eaves level.
The final piece of this complex structural jigsaw at roof level is the glazed-roof circulation space adjacent to the recital hall and flytower. Elegant tapered twin steel fins are supported by closely spaced stainless steel cables inspired by the aesthetics of string instruments.