Sponsored by: The British Constructional Steelwork Association Ltd and Steel for Life

Structural Steel Design Awards 2017

The British Constructional Steelwork Association Ltd4 Whitehall Court, Westminster, London SW1A 2ES

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As at September 2017 | www.steelforlife.org

BARRETTBARRETTSTEEL LIMITED

This year’s entries demonstrate that steel is, as always, thestructural material of choice across the complete range of buildings,infrastructure projects and other structures.

The high quality and effectiveness of the entries to the Awardsscheme is genuinely impressive and demonstrates the resilience andresponsiveness of the constructional steelwork sector. They alsoillustrate admirably the versatility of steel, in providing designerswith an effective means of satisfying the widely different andexacting requirements of their clients.

It is hoped that the high quality, visually stimulating, yet cost-effective projects presented here will provide inspiration andgenerate interest in steel construction and all that it has to offer.

D W Lazenby CBE DIC FCGI FICE FIStructE – Chairman of the PanelRepresenting the Institution of Civil Engineers

R B Barrett MA (Cantab)Representing the Steelwork Contracting industry

J Locke MBE FREng DEng MSc CEng FIStructE FWeldIRepresenting the Steelwork Contracting industry

C A Nash BA (Hons) DipArch RIBA FRSARepresenting the Royal Institute of British Architects

Professor R J Plank PhD BSc CEng FIStructE MICERepresenting the Institution of Structural Engineers

W Taylor BA (Hons) DipArch MA RIBA FRSARepresenting the Royal Institute of British Architects

O Tyler BA (Hons) DipArch RIBARepresenting the Royal Institute of British Architects

…to recognise the high standard of

structural and architectural design

attainable in the use of steel and its

potential in terms of efficiency, cost-

effectiveness, aesthetics and innovation

THE JUDGES

OBJECTIVES OF THE SCHEME

INTRODUCTION

The Leadenhall Building, London

The Leadenhall Building is a 224m highsteel-framed commercial office tower in theCity of London. In order to meet theclient’s aspiration for a landmark tower onthis sensitive site, the architects proposed awedge-shaped building. This produced thehighest office floors in the City, whileminimising the impact on a cherished viewof St Paul’s Cathedral.

The use of steel is fundamental to the valueof this building. It is visibly integrated intothe architecture to an extent that is highlyunusual for a skyscraper, creating apowerful tectonic quality which enables

people to appreciate and take delight in theway that the building is constructed.

Panoramic lifts were placed on the verticalnorth elevation so they could serve all theoffice levels. As a result there is no centralcore, and stability is provided by theperimeter braced steel ‘megaframe’ placedoutside of the building envelope.

This steel design allows the floors to beexceptionally open, with views in everydirection and spans of up to 16m, so thatthere are only up to six internal columnswithin floorplates of up to 43m x 48m,

making them very flexible and attractive totenants.

At the bottom of the building, floors arecut away and hang from the levels above,creating a vast open space, the ‘galleria’,which connects and relates directly to thesurrounding public realm, regenerating thelocal environment and creating newpedestrian routes.

The architects wanted the building toexpress its engineering systems whereverpossible. This significant challengedemanded a holistic and creative approach,

AWARD

Architect: Rogers Stirk Harbour + Partners

Structural Engineer: Ove Arup & Partners Ltd

Steelwork Contractor: Severfield

Main Contractor: Laing O’Rourke

Client: C C LandPROJECT TEAM

© Paul Carstairs/Arup

with the engineers and architects workingclosely together from the outset. The moststriking example of this is in the‘megaframe’. Alternative bracingarrangements were proposed, studied andthen optimised, leading to an arrangementthat is both structurally efficient andarchitecturally coherent. Vertical columnsare provided where they are most needed,on the east, west and north faces, and adiagrid structure on the more lightly-loaded south face. Connections are madethrough a family of separate fabricatednode pieces. This ensures that the complexgeometrical relationships between membersare always resolved within welded jointsand the site connections remain simple and standardised.

Within the ‘galleria’, floor beams areexposed, enhancing the character of thespace. At level 5 these project beyond the‘megaframe’ to form a canopy overLeadenhall Street. The levels below aresuspended via hangers whose bespoke endconnections provide a seamless transitionbetween the rods and the supporting steel beams.

The ‘megaframe’ columns and bracesaround the ‘galleria’ are unrestrained over a height of 28m. Standard ‘megaframe’sections are therefore subtly adapted, withtapering webs and additional stiffeningplates, to significantly increase theirbuckling resistance without underminingthe node connection principles or aesthetic proportions.

Steelwork is corrosion protected and fireprotected where required. In externalareas, epoxy intumescent coatings areemployed for durability. Cast intumescentcaps were placed over the ends of the‘megaframe’ fasteners to preserve the ‘nutsand bolts’ aesthetic.

The most complex steelwork details weredeveloped in workshops based aroundArup’s Tekla BIM model. The model feddirectly into the procurement processwhere it was used to explore theconstruction methodology and co-ordinatethe temporary works. It also fed directlyinto the steel fabrication models, drivingautomated shop processes.

80% of the building was constructedoffsite, reducing waste and improvingquality, safety and programme.

All wet concrete was eliminated above level5 by replacing conventional compositefloor slabs with an innovative precastconcrete panel system. The panels havepockets which enable dowels to be installedinto the neighbouring units via cast-incouplers to provide diaphragm action.These dowels pass through circularopenings in shear tabs pre-welded to thetops of the steel beams, to provide therequired shear connection.

The primary steel system within the northcore was built as a series of storey-hightables, with the services and concrete floorslabs pre-attached to them, minimising thenumber of crane lifts required.

The building was predicted to movesideways to the north during construction.An innovative approach was deployed tocounter this, known as ‘active alignment’.The structure was initially erected straightand movements regularly monitored. At alater point, adjustments were made to the‘megaframe’ diagonals which pulled thebuilding back sideways, reversing thegravity sway. This allowed the ‘megaframe’nodes to be fabricated with a simpleorthogonal geometry and improved theoverall accuracy of construction.

The Leadenhall Building provides thepublic with a unique and dramatic newspace at ground level, offers tenants someof the most desirable office spaces in theCity, and forms a sensitive and elegantaddition to London’s skyline.

This project had a committed client, architectural and engineering excellence,fabrication precision and construction ingenuity and innovation. They all combinedto make a project whose achievements are even greater than the sum of the parts.

Structural steel is rigorously controlled to generate an architecture that is clear andlegible throughout the building. Like most ground-breaking projects there werelessons to be learned, but the client and the team persevered to achieve final success.

This world-class project is an exemplar for large commercial buildings.

JUDGES’ COMMENT

© Thomas Graham/Arup © Arup

The T-Pylon is a structure of only few partsthat can be erected quickly and requiresvirtually no maintenance. It is designed tocarry 2 x 400kV, but can be modified toalternative specifications, and is the result ofa design competition in 2011 to find a 21stCentury power pylon design forNationalgrid UK. The challenge was to findan alternative to conventional lattice towersthat minimised the visual impact on thelandscape, whilst being cost-effective andfunctionally superior.

The use of steel for the T-Pylon has allowedfor unique geometries. Contrary toconventional lattice tower designs, the arms

of the T-Pylon are slightly raised, which givesthe pylon a more optimistic and positiveappearance. The few parts making up thepylon have been welded together andsubsequently painted white. The towerdesign is shorter and leaner than traditionallattice towers resulting in improved aestheticsand reduced environmental impact. The useof a monopile foundation also minimises theoverall cost, installation time andenvironmental impact of the T-Pylon.

The alternative design using steel has madeit possible to obtain the aesthetic andfunctional goal, which is to minimise thevisual impact on the surrounding landscape,

while also providing an economic anddurable solution.

The steel structure is designed inaccordance with Eurocode 3 and fabricatedin accordance with BS EN 1090-2 toExecution Class 3. The structural steelspecification for the flanges, monopole and transition piece is for S355J2 to BS EN 10025-2 for thicknesses up to and including 50mm, and either S355NL to BS EN 10025-3 or S355ML to BS EN 10025-4 for thicknesses over 50mm.The steel plate also has to be accompaniedby a Type 3.1 specific inspection certificateaccording to BS EN 10204.

AWARD

T-Pylon

Architect: Bystrup

Structural Engineer: Bystrup

Main Contractor: Balfour Beatty Power Networks

Client: Nationalgrid UK

PROJECT TEAM

A radical innovation is the re-assessment ofthe conductor/cable arrangement. Theprismatic configuration of the cables allowsa reduction in the pylon's height of morethan 30%. The footprint of the powerlines, as well as the electro-magnetic field(EMF) radiation, is thus reduced.

The most remarkable characteristic of theT-Pylon design is that all conductors arecarried by a single attachment point.Traditionally, such a structure would havethree separate arms - each carrying anindividual conductor.

This unique attachment point was studiedclosely to ensure its robustness andresistance to fatigue. Complex analysis andphysical loading tests were carried out tosimulate climatic conditions such asextreme winds and ice loads. Investigationswere made into the dynamic performanceof the structure under simulated vibrations.

The pylon is made from S355 steel platesthat are curved and welded to formcylindrical sections. The shaft is fabricatedin either one or two pieces according to thelength needed, the requirements for hot dipgalvanizing, and transport limitations. Thesteel plate thickness used for the shaft isoptimised according to the design loadcases and varies from 22mm at groundlevel to 14mm at the top.

At the top of the shaft a cast node connectsthe shaft to the two arms. The node is cast inone piece to ensure the optimal load transferfrom the arms to the shaft. The result is a

highly effective and smooth node thattransfers the shape and forces from the armsto the shaft. The node is connected to thearms and shaft by non-visible internal bolts.

Dynamic external wind loads experiencedon the pylon arms result in a bendingmoment at the pylon foundation. However,the cast node must withstand the transfer ofinternal stress from compression andtension at the node due to the pylon armdistributed load case. The cast node isdesigned to withstand both the magnitudeand the dynamic behaviour of the load case.

At the end of the arms another nodeconnects the insulator configuration to thearm in an aesthetically pleasing way. Again,the node is connected to the arms by non-visible internal bolts.

For the UK market the pylon is hot-dipgalvanized and painted light grey. Thisduplex coating system gives the pylon anexpected lifespan of at least 80 years. For

other markets the pylon can be produced instainless steel or weathering steel.

The design of the shaft is similar to thedesign of towers for wind turbines.Consequently, it was possible for thesteelwork contractor to use the experiencefrom wind turbine towers to produce theshaft using automated processes in controlledfactory conditions. Maximising the offsitefabrication simplified on-site operations andreduced the number of operatives requiredfor the installation process.

The new designs have significantly reducedmaintenance requirements compared totraditional lattice towers. The durablecoating system and lack of edges andbolted connections increases the futuremaintenance intervals and makes re-painting the towers much faster. Also, noanti-climbing devices are needed for themonopole shaft, which would otherwiserequire frequent replacement.

The T-Pylon represents a generational step change in power transmissionhardware. Analytical design from first principles included re-examination ofarrangements for insulation and maintenance.

The result is a family of compact pylons which can be deployed in sensitivelandscapes, with prefabrication enabling consistent finish, smaller land take andspeedy erection. This is a steelwork design classic.

JUDGES’ COMMENT

LSQ London is a Grade II listed buildingrefurbishment, which required over 2,000tonnes of structural steel and metal deckingto be installed within what is thought to beEurope’s largest retained façade. Situated inLondon’s busiest tourist area, this projectrequired meticulous planning andorganisation to ensure the most efficientuse of time and craneage without bringingthe surrounding streets to a standstill.

The completed building was erected to therequired tolerance of 15mm over the fullheight, making this project challenging forthe engineering and delivery teams, but was

completed on time, to budget and to theclient’s satisfaction.

The existing building envelope is partiallyretained with new upper storeys ofcommercial floor space being provided. Thedesign delivers two basements, two floorsof retail space and seven floors of highquality office space with a new entrance onWhitcomb Street. Upper floors are enclosedby a new curved mansard roof. On thelower floors, new retail space has createdactive frontages at street level with new,clearly defined entrances.

The contemporary roof design is supportedby a structural steel-framed central core andnew perimeter stanchions, with completecolumn-free office space and spans of up to12m providing very efficient floor space toappropriate market standards.

A new two-storey basement was created bythe installation of a secant piled wall insidethe retained façade profile. Shallow floorconstruction was used for the B1 andground floor slabs to maximise headroomin below ground spaces, whilst minimisingexcavation depths.

Architect: make

Structural Engineer: Waterman Structures

Steelwork Contractor: Bourne Steel Ltd

Main Contractor: Multiplex Construction Europe Ltd

Client: Linseed Assets LtdPROJECT TEAM

AWARD

LSQ London

© www.commissionair.co.uk

The project was designed using Revit 3Dmodelling techniques to capture theintegration and interfaces of botharchitecture and building services. This assisted the design and constructionactivities, but also provides full integratedmodels for future use.

The design of the building naturally leantitself to using steel for the primarystructural elements. The design of the newsteel structure introduced a new centralcore, and enabled clear, open-planfloorplates improving the office spaceswithin the building. One of the key aspectsof the façade retention scheme was thealignment of new floors with existingwindow openings. This was assisted byintegrating the suspended services withinthe structural downstand beam zone, suchthat the depth of floor zone against thefaçade was minimised. The use of a steelframe offered the flexibility needed to suitthe various interfaces that occur with theexisting façade.

The steel-framed façade dates from the1920s and 1930s, however some areaswere added during the 1960s. The steelcolumns are all encased in Portland stoneand consequently in good condition.However, steelwork originating fromvarious decades required extensivelaboratory tests to determine its make-upand suitability prior to making the weldedconnections for 250 new façade retentionbrackets. This demonstrates theadaptability of steel-framed structures bothold and new.

The new fifth floor is clad with Portlandstone to integrate with the retained façadebelow. This floor level’s steelwork istopped with a ring beam that goes aroundthe entire perimeter of the building.

The ring beam is formed from jumbo boxsections measuring 650mm × 450mm witha 25mm thickness. The sections werebrought to site in 3.5m long sections eachweighing three tonnes. The box section ringbeam performs two functions, one is tosupport the columns for the feature roof asthese are not aligned with the maincolumns for the rest of the building, andthe second function is for the stonecladding panels for the sixth floor as theyare hung from the beam.

The steel feature roof slopes outwards fromthe two centrally positioned cores and isformed with a cranked steel frame, whichin turn supports a lightweight aluminiumframe and glazing. This new and elegantcurved mansard roof encloses the buildingand offers a modern interpretation of thetraditional mansard style where archgeometry sits atop a classical base. Thisrespectful, contemporary addition to thebuilding composition reduces the existingtop-heavy visual mass of the building and,with the curved design, also seeks to ensurethe building blends in seamlessly with thesurrounding iconic buildings of Leicester Square.

The use of structural steel for the newinternal structure, including cores, enablednew clear-span floorplates to be achieved,whilst respecting the existing listed façade.It minimised disruption during constructionin London’s busiest tourist area.

With its graceful three-storey ‘top-knot’, thebuilding has a new lease of life as a strikingyet respectful landmark in the West End.

This project showcases the role steelworkcan play in the extension and re-purposingof historic buildings.

JUDGES’ COMMENT

The Duke Street phase of theredevelopment project included forming anew staff entrance into the building belowEdwards Mews and realignment of theHGV entrance ramp to the loading bays.However, the primary feature of the firstphase of works was the insertion of a new50m long 165 tonne steel-framed bridgestructure, through the existing store, toimprove HGV egress from the basementloading bays. This new structure is abraced steel tube linking the loading baywithin the basement to Duke Street.

The structural works were designed tokeep the loading bay active throughout the

works, while staff access was maintainedand retail operations continued within 1mto 2m of the structural works.

Design and execution of the structuralinterventions was made more complex bythe limited existing building information,and numerous historical alterations thatwere discovered during the build, requiringmodifications to be made to the newconstruction as it progressed on-site.

To maximise retail space for the client, thepreferred routing of the egress ramp wastight to the perimeter of the building. Thisrouting allowed the ramp to be partially

supported on the existing steel structure,but necessitated the partial removal ofthree existing columns that then had to be re-supported on bespoke steel transfergirders integrated into the new rampstructure.

The routing of the ramp meant it wouldspan over an occupied three-storeybasement. To minimise disruption to thesebasement spaces, and to minimise the needfor new foundations, support was takenfrom the existing 1920s steel structurealong the northern edge of the ramp. Onthe southern edge of the ramp verticalsupport was limited to two new columns

Architect: Gensler

Structural Engineer: Expedition Engineering

Steelwork Contractor: William Hare

Main Contractors: Blue Sky Building and SRM JV

Client: SelfridgesPROJECT TEAM

AWARD

HGV Egress Ramp, Selfridges, London

© Kevin Sansbury 2015

between which a new steel truss wouldspan. The new columns were threadeddown through the existing building andsupported on new hand dug padfoundations.

Reuse of the existing 1920s steel frame onthe northern edge of the ramp provided aneconomic solution. The existing steelworkcomprised of built-up riveted sections,which geometrically added complexity tothe connections, formed to the existingstructure. However, the existing steelproved to be of a weldable nature and sosite welded connections were adopted.

Where the new ramp is supported onexisting steel columns, these were checkedfor a change in loading and restraintcondition due to the removal of the groundfloor beams. Some of the columns requiredstrengthening but, as this was governed bybuckling capacity, the columns could bestrengthened relatively simply via theaddition of welded plates to the existingsections to increase their stiffness. The sizeof the strengthening plates could be easilytailored to suit constraints on site andmanual installation.

To allow the ramp to connect betweenroad level and the loading bay within thebasement a large slot was cut into theexisting ground floor slab. The stability ofthe building is likely to be provided by acombination of frame action and somecontribution from the masonry infilledbuilding cores. The unquantifiable natureof the system meant the diaphragm actionof the ground floor had to be maintained.

This was achieved in the temporarycondition via a temporary proppingarrangement, and in the permanentcondition by making connections betweenthe existing ground floor frame and newramp. The new ramp structure was thendesigned to transfer any diaphragm loadsback to the existing retaining wall, withsteel members being tuned to provide anappropriate stiffness.

The two transfer structures used to re-support the columns above the ramp weredeemed to experience vertical deflectionsexceeding acceptable limits for an occupiedbuilding. However, to negate the existingstructure above experiencing thesemovements, an erection approach utilisingjacking was adopted. This allowed theload from the existing column sections tobe transferred into the new transferstructures in advance of the lower columnsections being removed. The jacks wereused to push the transfer structures down,

realising the anticipated deflections beforeconnections were made to the existingcolumns.

A key challenge in the construction of thenew steel ramp structure was the fact thatit was to be constructed within a liveexisting building. As the structure was tosupport HGV vehicles the steel forming thestructure was of a scale that, althoughlighter than other forms of construction,could not be manhandled. The contractorteam therefore developed a series oftemporary works that spread the load of aspider crane across the existing suspendedbasement floor. The crane could then besafely driven into the space via the existingloading bay entrance without backpropping through the levels below.

The creation of the new egress ramp was ahighly complex piece of engineering designand construction successfully delivered byclose collaboration between the whole team.

The creation of this new egress ramp within an existing steel structure washighly complex, yet successful. A key challenge for the engineering design andconstruction was that the work was to be carried out in a live and busy existingbuilding, with ongoing high-end retail operations being immediately adjacent tothe work zone.

The outstanding success of this complex project was achieved through very closecollaboration between the whole design and construction team.

JUDGES’ COMMENT

© David Lankester

Architect: Reiach and Hall Architects

Structural Engineer: Engenuiti

Steelwork Contractor: J & D Pierce (Contracts) Ltd

Main Contractor: Bowmer & Kirkland

Client: Heriot-Watt UniversityPROJECT TEAM

AWARD

Oriam, Heriot-Watt University, Edinburgh

Oriam, Scotland’s new Sports PerformanceCentre, comprises a full size indoor 3Gsynthetic pitch for football and rugby withspectator seating for 500 people, a nine-court sports hall, a 100-station fitness suite,as well as a high performance wing thatincludes areas for hydrotherapy, strengthand conditioning, rehabilitation, offices anda classroom.

Oriam presented truly fantasticopportunities to be creative. With longspans and a simple but elegant diagram, the cross section forms the principalstructural concept. Steel arches at 7mcentres span over the football hall andsports hall from buttresses on each sideonto a central street of piers.

The arch profile for the football hall roofoffers a high rise : span ratio andconsiderable curvature, giving rise to ahighly efficient structure with acomparatively low overall weight. The archis a naturally efficient form allowing thestructure to work primarily as axiallyloaded, with relatively small bendingmoments generated.

Tensioned PVC fabric was chosen to cladthe football hall roof as it offered thenecessary light transmission properties so asto limit the need for artificial lighting of thepitch space, whilst managing heat gain. Itwas also preferable in the structural design,given that the fabric is lightweight andforgiving to structural movements and

deflections. The diagonal arrangement ofarched secondary CHS members ensuredthat the fabric shape could be preventedfrom flattening under heavy imposedloading, whilst also creating interest to theroof form itself.

The sports hall roof comprises steel archeson a 7m grid, with straight secondary steelmembers spanning between the arches, andcurved tertiary steel members spanningbetween secondary beams to provideintermediate support for the roof cladding.In this case, the original trapezoidal sectionwas re-engineered to work as a standardUB section, further increasing the materialand prefabrication savings.

© Reiach and Hall Architects

Central piers support the ends of thefootball hall and sports hall arches, whichconverge at a single point behind the listedwall in an area known as the Street. Initiallythese piers were conceived as reinforcedconcrete elements. However, the overallprogramme advantages of bringing thiselement within the steel package wereexplored and, following this review, thesteelwork option was selected giving bothprogramme and cost advantages.

The roof structure acts as an umbrella overthe public fitness area and high performancewing, which are both constructed asconventional steel-framed structures andaccommodate the high performance spacesand the public fitness suite, café andaccommodation. In the public area the tightlimitations on available floor depths meantthat cellular floor beams were needed tospan the full width of the structure withoutintermediate columns, leaving the gym andcafé spaces completely column-free. Thesame was needed in the high performancewing in order to maximise the column gridspacing and minimise the disruption to thefloor layouts.

The roof arch is formed from three curvesmeeting at tangents and, whilst this is stableonce vertical, it has little structural strengthin its minor axis. This meant that buildingthe trusses flat on the ground and thenlifting them vertically would requireextensive temporary works, which with 13to lift would have substantially increasedthe build costs. Building the trussesvertically on the ground was ruled out dueto the height of any temporary frameswhich would have been required fortemporary stability during assembly.

The solution was to utilise the permanentdesign for the temporary works. Simplestubs were designed to transfer the loadfrom truss to truss with chord ties, and thenmatch all these stubs at each truss so trusscomponents could be connected directly tothe previous truss; this allowed a full trussto be built in the air. The challenge wasthen how to erect the first truss! As this wasat a gable the slender gable posts, whichwere themselves trussed, could be proppedfirst and then roof truss segments landed ontop and joined together to form onecomplete arched truss.

All the steel structural elements were veryprecisely fabricated to tight tolerancesbefore delivery to site, which enabled arapid waste-free assembly and acomparatively quiet construction process.

This was important as the existing Centreand Academy buildings needed to remainopen during the construction work. Erectionprocedures were planned in detail using 3D models.

The steel-framed structures and regularcolumn grid arrangement for the office, caféand elite sports areas are all adaptable forfuture changes of use.

The structural steel was efficientlyengineered for fire resistance with thestructural elements supporting floorsrequired to achieve a 60 minutes' fire rating.For exposed elements this was achievedthrough the use of high visual qualityintumescent paint. For those which are notexposed, intumescent paint with a basicfinish was used.

The project team has delivered a world-classfacility that also provides extensive accessfor the local community.

Two parallel vaulted forms spring froma central spine; the larger one covers afootball pitch, whilst the smaller covers a sports hall. The elegant lightweightsteel trusses resulted from a collaborativeeffort by the designers and contractor,with the construction methodologyinforming the roof structure andsupports from which it springs.

Striking and effective steelwork.

JUDGES’ COMMENT

© Reiach and Hall Architects

© J & D Pierce (Contracts) Ltd

The Curve initiative is a major developmentcomprising a mixed-use, vibrant communityfacility with multi-functional spaces andwider cultural offerings, based around thearts with opportunities for performance and exhibitions.

The 90m long x 15m high building's form,a curved 'tube,' features fully glazed entryfaçades, and opens onto two new publicsquares created at each end of the building.

A heavily serviced building with a singletwo-storey enclosed plant area presentedparticular challenges in incorporatinghorizontal distribution routes within thebuilding. The composite steel frameallowed floor depths to be kept within astringent floor zone, whilst allowing for theservices’ distribution.

The composite steel solution allowed forfull flexibility in the design of an irregularcolumn grid, and provided minimumdepth cantilever façade support sections.The aesthetic of the circular hollowsection columns has been retained andexpressed throughout. The double height

performance space required columnremoval, for which composite universalcolumn sections were able to achieve thespans in the shallowest depth possible. The constrained site utilised a singlemobile crane to perform all liftingoperations in a carefully planned threephase construction sequence, allowing free site areas open to other trades.

Detailed 3D modelling allowedefficiencies to be gained in specifying aconstant bend radius for the façademembers, and limiting the supportingtubular transfer beam to three discretebend radii. This 45m curved CHS beamwas then spliced using carefully detailednon-visible connections. Curved edges tothe internal atrium required cantileverdecking sections to arrive at site with thebend radii pre-cut. Staircases, both frontand back-of-house, were formed offsite insteel and installed quickly and prop-freeto open up the site to the follow-ontrades. Detailed 3D model coordinationallowed for accurate placement of pre-applied cladding fixings and secondary support steelwork.

A shop applied painted system provided thecorrosion resistance to the members. Fireresistance throughout was provided byintumescent painting of the main structuralmembers up to the 120 minutes’ periodrequired in some areas. The designmethodology to use bolted connectionsreduced the risk of compromising steel coatingsthat can occur when site welding is required.

The Curve, Slough

COMMENDATION

Part of the implementation of themasterplan for the regeneration ofSlough Town Centre, The Curveprovides popular and accessiblecommunity facilities. Its strikingcurved form arose from its proximityto a church and probably could onlyhave been achieved by an integratedteam using coordinated BIM design,analysis, fabrication and erection.

Elegant and effective steelwork meetsunusual demands.

Architects: BBLUR architecture and CZWG architects

Structural Engineer: Peter Brett Associates

Steelwork Contractor: Caunton Engineering Ltd

Main Contractor: Morgan Sindall

Client: Slough Borough CouncilPROJECT TEAM

JUDGES’ COMMENT

© David Butler

West Croydon Bus Station has beentransformed from an unsightly, uninvitingand poorly functioning 1980s ‘shed’ into acustomer-friendly landmark that supportsthe regeneration of Croydon. The oldbuilding has been replaced by an openconcourse under an elegant weathering steelcanopy. The canopy wraps around andconnects two small buildings – a retail unitand a bus operations building.

The choice of materials was carefullyconsidered to reduce whole life costs. Theprimary material of the project is weatheringsteel, and is used throughout the canopystructure in combination with translucentKalwall panels, creating a structure requiringminimal ongoing maintenance.

The weathering steel canopy wraps aroundthe two brick clad buildings, tying thestation architecture together on the linearsite. The brick and weathering steel werechosen to complement the surroundings.The style and natural flow of the stationachieves this while also providing aninteresting play of light, shadow andtexture. Timber seating and planters arefully integrated into the steel canopystructure, along with customer informationand lighting to minimise visual clutter.

The canopy is based around a repeatingmodule where canopy and supportingcolumns are linked by a curved haunch.This haunch is perforated with variablesized holes to both create interesting visualeffects and demonstrate the changing stressintensity across the haunch.

Guttering, downpipes and lighting have allbeen integrated into the structure to ensureservices are not visible nor impact on thefinal impression of the structure.

The buildings are highly sustainable andenvironmentally friendly - with solar panels,air source heat pumps, LED lighting andbuilding materials that maximise thebuildings’ performance. A buildingmanagement system ensures energyefficiency and reduces light pollution.

The opaque canopy provides naturallighting and manages glare and heat

transfer. Night lighting on the canopycreates an attractive and safe environment.

The whole life value of all aspects of thedesign was assessed to inform designdecisions, such that:

• The weathering steel of the canopy reducesmaintenance and future carbon impact.

• The design modelled different climatescenarios and was carefully detailed tominimise waste during the build.

• Prefabricated insulated timber panelsreduced on-site labour and the energyrequired to mechanically condition thebuildings throughout their lifetime.

Anti-social behaviour was a significant issueat the old bus station. The new improvedopen layout, architectural lighting and softlandscaping tackle this issue and create asafer, more socially sustainable,environment.

Architect: Transport for London

Structural Engineer: Price & Myers

Steelwork Contractor: B&W Engineering Services Ltd

Main Contractor: Quinn London Ltd

Client: Transport for LondonPROJECT TEAM

High quality design and careful selection of materials, with low maintenance amajor objective, are evident in this project. The lightweight canopy is framed inweathering steel, carefully prepared and detailed, to provide visual interest.

This is a facility which has transformed passenger experience and provided asignificant contribution to the environment.

COMMENDATION

West Croydon Bus Station

JUDGES’ COMMENT

© Alex Upton

© Alex Upton

Central Square is a 20,400m2

development, providing 18,700m2 ofGrade ‘A’ offices with 1,700m2 of retail,leisure and health/fitness.

The scheme provides officeaccommodation on 10 floor levels and issaid to have the largest floorplatesavailable in the city. These are arranged sothat they can be subdivided, providing theoccupier with both flexible and highlyefficient floor space. The developmentoffers an outdoor Sky Garden on the levelnine, providing entertainmentopportunities and views across the city. Inaddition, a stunning seven-storey fullyglazed atrium houses Central Square’sWinter Garden, where the createdcontemporary square offers a mixed-usedestination for members of the publicthroughout the day and evening to enjoythe high quality public realm, retail andleisure facilities on offer.

Sitting above a two-level concretebasement, the steel frame forms a U-shaped structure with the central voidoccupied by the fully glazed WinterGarden created by the glazing slopingdown from the underside of level eightwithin this central void.

In total five 27m long tubular ‘vertical’bowstring trusses, which were delivered tosite in two pieces, form this indoor zone.These trusses, carrying heavy dead loadfrom the attached glazing, are pinconnected at the base to architecturallyexposed fabricated base assemblies.

The heaviest steel assembly on the projectwas the 43 tonne, storey-high, Vierendeeltruss that supports level eight’s balconythat overlooks the Winter Garden. TheVierendeel truss, comprising heavy UCmembers, was brought to site in individualsections that were then assembled on theground before being lifted into place by a300 tonne capacity mobile crane.

The majority of the steelwork was erectedusing the site’s tower cranes, with twoerection teams being employed thatdivided the structure in half and erectedthe frame three levels at time,incorporating placing and subsequentlyfixing of the metal deck flooring. Each ofthe U-shaped structure’s tips contains oneof the building’s three cores, and thisprovided each erection team with an idealand stable starting point. From these outerconcrete cores each of the teams workedits way to the centre of the structure,

meeting up at the third centrallypositioned core.

Above the lower levels of retail andleisure, the offices begin at level two andextend upwards to level 12. Levels two upto seven are identical, with a centralportion positioned inside the WinterGarden. The reception for the offices ispositioned at level one and accessed via afeature escalator, with the upper levelsbeing accessed by a number of liftsincluding two glass-clad wall climber lifts.

Central Square is a landmark officeand leisure complex within twominutes of Leeds City Station. In thisBREEAM ‘Outstanding’ development,the floors are supported on long-spanbeams enabling 25,000ft2 floorplates,the largest in the city.

The ground and first floors areaccessed through a large atrium ‘wintergarden’, forming a new and excitingpart of the public realm in the area.

Architect: DLA Design

Structural Engineer: WSP

Steelwork Contractor: Elland Steel Structures Ltd

Main Contractor: Wates Construction

Client: M&G Real EstatePROJECT TEAM

COMMENDATION

Central Square, Leeds

JUDGES’ COMMENT

Architect: Glenn Howells Architects

Structural Engineer: BuroHappold Engineering

Steelwork Contractor: S H Structures Ltd

Main Contractor: Speller Metcalfe

Client: Forestry Commission, Westonbirt, the National ArboretumPROJECT TEAM

Owing much to the romantic tradition ofgreat English landscapes this sinuouswalkway carefully winds through thecanopy of ancient working woodland, whilst avoiding the precious root zones. A ‘tuneable’ structural system addresses thevarying dynamics and geometrical restraints.

The curvilinear route, which heightens thesense of drama and discovery, was facilitatedby the use of steel. Apparent simplicityconceals sophistication in this project.

COMMENDATION

STIHL Treetop Walkway, Westonbirt, the National Arboretum

JUDGES’ COMMENT

The STIHL Treetop Walkway is the longeststructure of its kind in the UK. Reachingheights of up to 13m, the walkwaytransports visitors effortlessly on a journeythrough the park’s Silk Wood.

The structural solution that developed is ahybrid timber and steel structure. The basicstructure is a simple arrangement of twoperimeter beams supporting the 1.8m widedeck and the balustrades. These beams areformed from curved galvanized steel RHSsections which, with the CHS cross beam,create a laterally stiff structure to transferloads back to the supports. The use ofgalvanized steel provided the requiredstiffness and allowed a shallower deckprofile to be created with something thatwas durable and maintenance-free.

Building the walkway using smallassemblies and single elements enabled the size of the construction equipment to be reduced and allowed the use of bolted connections throughout, meaningthat future dismantling would bestraightforward.

Various support solutions were considereddue to the unique constraints of the site.The chosen solution was to use shallowreinforced concrete pads supporting pairs

of inclined timber legs at 10.5m centres.The inclined columns provided a morenatural feel and allowed the base positionsto be easily moved in plan to avoid areas ofheavy root coverage.

The client was keen to accentuate thetreetop experience by having a degree ofmovement, and the use of a non-lineardynamic model of the structure enabled anacceptable behaviour to be achieved.

The walkway is punctuated by a number ofindependent platforms, such as the Crow’sNest, which serve as educational areas.The ability to curve the hollow steelsections to a very tight radius enabled thearchitect’s requirements to be achieved.Whilst the main walkway is inherentlystable, the cantilevered Crow’s Nest issomewhat more lively, providing visitorswith the more dynamic experiencerequested by the client.

Four different capacity cranes were usedduring construction, including a mobiletower crane which provided the requiredreach over the trees. Mobile cranes of upto 350 tonne capacity were used in otherlocations where prepared bases wereconstructed in areas that would cause theminimum impact.

The construction followed a repetitivesequence with the pairs of columns beinginstalled first. The columns weretemporarily supported with guy lines fixedto concrete kentledge blocks. Thismethodology enabled the column heads tobe positioned correctly whilst causing nodamage to the trees and their roots.

© Paul Box/Forestry Commission

© S H Structures

Architect: David Morley Architects

Structural Engineer: Price & Myers

Steelwork Contractor: Tubecon

Main Contractor: ISG

Client: The Hurlingham ClubPROJECT TEAM

A detailed, yet compact, building adds generous newindoor play areas, whilst meeting the requirement fora low profile at the edge of the Club grounds. Thestringent dimensional and technical constraints wereanswered by well-coordinated structure, services,equipment and enclosure.

Steelwork again enables elegance and efficiency inmodern sports facilities.

The state-of-the-art Racquet Centrereplaces an existing marquee structure andhas modern functionality practical to itspurpose. Designed to meet high standardsof sustainability, it fits sympathetically intoits rural surroundings. The Centre is hometo four indoor and two outdoor tenniscourts, four squash courts, a multi-usegames area and changing facilities.

Steelwork was the natural and most cost-effective material, due to the long spansneeded by the large 38m x 70m column-free space required by the tennis hall.

A series of tied-arched steel frames, tiedwith large diameter bespoke tensionbars, at 16.5m centres form the primaryroof structure. These purpose-engineeredwelded box sections were paired togetherto also act as Vierendeel trusses to helpdistribute horizontal forces back tovertical bracing systems. Furtherefficiencies of the arch were gained byportalising the structure and providingraking ties at the roof ends, which helpminimise the depth and weight of thebox sections.

COMMENDATION

The Hurlingham Club Racquet Centre

JUDGES’ COMMENT

These arches support timber stress-skinpanels which span between the arches. The structure is predominantly internal;however, where the structure becomesexternal, an offsite painted protectionsystem with a life to first maintenance of20 years has been used and, wherenecessary, with a decorative top coat. By using steel, the main elements could befabricated offsite while the groundworkswere completed. This prefabrication meanta fast erection process on-site and alsoassured a high quality finish – imperativeas the majority of steelwork is leftarchitecturally exposed.

A key consideration was how the timberpanels would bear and tie to the steelframe without visible fixings, and whattolerances would be needed. Creating theprimary arches from welded plates allowedthe bottom plate to provide a bearingledge for the timber panels, which weretied to the tops of the steel with steelstraps and self-tapping screws to allowthem to be completely concealed. Designedto be transportable, the trusses had to befabricated in three sections with boltedsplices connected on-site using a seatingjig. Once connected, a tandem lift thenraised the 40-45 tonne trusses into place,which cantilevered approximately 2m-3m.

With architecturally exposed steel, allprocesses required acute accuracy andhighly skilled workmanship, from detailingand connection design through to thefabrication and erection process.

© Price & Myers

© Metsä Wood

The footbridge provides enclosed pedestrianaccess from an existing car park that servesthe old West Quay shopping centrecomplex in Southampton over HarbourParade and directly into the newWatermark retail centre.

The bridge is a box truss cross braced oneach face which is an efficient structuralapproach to both giving an enclosure, andachieving the spans of 30m between columnsupports and a 10m cantilever at theexisting car park end.

For the truss sidewall bracing, RHSdiagonal bracing elements are used in theidealised compression direction withpaired plates lapping these in the idealisedtension direction.

The challenge with the detailing was toachieve a uniform appearance throughoutthe length of the bridge. Thicker RHSbracing elements are used at the supportlocations with subtle local stiffening.Narrow and thick-walled chords (200 x200 SHS) were used to give a visuallyshallow profile. The bottom chord isinternally stiffened at the support cross

beams to ensure the line of the chords is notvisually broken.

The horizontal bracing to the box truss’roof and floor is in a similar, but less dense,pattern to the sidewalls and is formed withRHS elements of equal size to the RHS wallbracing. A steel deck floor is employed withan anti-slip deck treatment applied.

The vertical supports to the structure are500 x 250 RHS steel hoop frames, whichare independent of the existing car park andnew shopping centre structures at each end,and are located to minimise disturbance tothe considerable amount of undergroundservice routes in the vicinity.

The footbridge was fabricated and trialassembled within the factory before beingseparated into two sections for delivery tosite. Installation took place during a closureof Harbour Parade enabling a 500 tonnecapacity mobile crane to be positioned closeto the bridge position.

To facilitate securing the first bridge sectionin its temporary condition a temporarytrestle was installed on the bridge centreline.

The top of the trestle was fitted withhydraulic jacks to enable the final loweringof the bridge to be carefully controlled.

With the first section in place the secondsection was lifted into place. A temporaryconnection was integrated into the trussmembers that aligned the two sections,holding them in place until the joint wasfully welded.

The use of steel resulted in a lightweightstructure that could be quickly erectedfrom prefabricated component parts,minimising the need for temporary worksand road closures.

The pedestrian link from parking into theshopping centre was necessarily economical. This latticed box girder bridge does the jobwithout fuss. The diagonal geometry of the facesis composed of both welded flats and tubes,reflecting the forces carried. These support theglass cladding and filter sunlight most elegantly.

A simple and economical concept has beenbeautifully executed.

COMMENDATION

JUDGES’ COMMENT

Watermark Westquay Footbridge,Southampton

Architect: ACME

Structural Engineer: David Dexter Associates

Steelwork Contractor: S H Structures Ltd

Main Contractor: Sir Robert McAlpine Ltd

Client: Hammerson plcPROJECT TEAM

Architect: AWW Architects

Structural Engineer: Arup

Steelwork Contractor: Billington Structures Ltd

Main Contractor: Balfour Beatty

Client: Defence Infrastructure Organisation

This 22,000m2 three-bay maintenance hangar was built toservice specific military transport aircraft, with the roofhaving main girders spanning 67m. The design andconstruction were heavily constrained by the operationaldemands of the airbase, particularly avoiding interferenceto radar and aircraft guidance systems.

Satisfying the constraints and the client was a noteworthysuccess for large steelwork.

The 22,000m2 three-bay maintenancehangar based at RAF Brize Norton inOxfordshire was built to service A400Mand C17 military transport aircraft. Inaddition to housing three aircraft in baysequipped with overhead cranes, thebuilding contains specialist workshopstogether with parts stores, offices, welfareand mission planning functions. Thedesign and build was heavily constrainedby the demands of the airbase, inparticular the need to avoid interferencewith radar and aircraft guidance systems.

A metallic blue colour was chosen for thebuilding to reflect the colour of the skyand complement the natural surroundings.

A large rounded cladding profile waschosen to soften the building’s form tohelp break down the hard edges of thebuilding. The building has an A ratedEPC, BREEAM ‘Excellent’ rating, andachieved an air pressure test rating on firstpass of 1.98m3/h/m2, which is all the moreremarkable bearing in mind the size of thehangar doors which are up to 64m wideand 20m high.

The impact of the building on theoperational environment of the airbasewas carefully considered. A radar impactassessment indicated the need for radardiffusing cladding at high level on thesides of the building facing the runway.

Modelling was necessary to prove that PVpanels on the roof would not cause glareto pilots from reflected sunlight.

The main building’s structure is a steel-framed construction with the roofconsisting of primary girders spanning upto 67m supporting secondary trusses. This allows the hangars, stores andworkshops to remain column-free spaces.The roof supports the rails of a number oftravelling cranes. Supporting the cranesdirectly from the roof structure avoided theneed to provide additional steel columns forcrane runway beam support, thus increasingthe usable ground floor area. The design ofthe roof was carefully developed to ensurethat the deflection of the primary roofstructure would be compatible with thedeflection limitations of the cranes.

The use of a 3D BIM model was especiallybeneficial in the complex 3,000 tonne frameas it allowed the structural engineeringteam to rapidly assess coordination areas,such as secondary cladding support andcrane runway beam setting out. The 3Dstructural model was issued to thesteelwork contractor, where it wasinvaluable in early tonnage take-offs andconstruction programming and phasing.

This functional building at RAF BrizeNorton is also aesthetically pleasing andsympathetic to its surroundings.

MERIT

A400M MRO Facility, RAF Brize Norton

JUDGES’ COMMENT

PROJECT TEAM

© Balfour Beatty

© Billington Structures

MERIT

Architect: WilkinsonEyre

Structural Engineer: AKT II

Architectural Metalworker: Clifford Chapman Staircases Ltd

Main Contractor: Overbury

Client: Wellcome TrustPROJECT TEAM

This finely crafted staircase winds its waythrough two floors, with a changinggeometry to fit the tight constraints of theexisting floor structures. The combinationof galvanizing and hot-applied stainlesssteel spray, which was hand-buffed,creates a most attractive finish.

The merits of this finely crafted projecthave helped to enable visitor numbers to double.

Wellcome Collection Dynamic Stair,London

JUDGES’ COMMENT

The Dynamic Stair is a key feature of theWellcome Collection’s development projectand the concept was to create a free-flowing form, travelling from floor to floorwithout any visually intrusive supports.

Building the stair within the confines of anexisting building presented a series ofconstraints in terms of capacity andaccessibility.

To install the stair the team was requiredto make significant alterations to the firstand second floors, firstly introducing anopening to facilitate the stair’s insertionand then to provide the supportingsteelwork to carry the stair loading back tothe historic primary structure. Accessbelow ground floor was not possible andso the strengthening of this floor, or thevertical structure, would be impossible.Hence, it became clear that steel was theonly realistic option for the stair,exploiting the strength and stiffness of thismaterial and its readiness to be workedinto complex forms.

For the stair itself, the chosen solution usesthe inner balustrade and floor componentsas a structural monocoque that exploits

every part of the stair as part of thestructural system. This provides the verticaland torsional stiffness necessary to deliverthe desired vibrational characteristics andarchitectural aesthetic in an efficient andlightweight manner.

Each of the 18 sections was made up of8mm thick steel plates which were formedby a mixture of pressing or cold rolling andthen welded together. The heaviest of thesections weighed 3.5 tonnes and was liftedin to position via a bespoke temporarystructure and lifting strategy.

The aspiration for the finish of the stairwas to exploit the natural steelwork asmuch as possible. The final solution wasfor the outside face to be shot blasted andsealed with clear lacquer. The inside faceswere sprayed with a cold zinc and hotstainless steel solution. The inside surfaceswere then hand polished.

The Dynamic Stair now provides therenovated Wellcome Collection with astrong central visual statement. Thesimplicity and tactile nature of the polishedwhirling form allows the crafted steel of thestair to be displayed and celebrated. The

outer balustrade glass accentuates themovement of visitors around the staircaseand up through the building, allowingvisibility throughout the floors. Generousbreakout spaces surrounding the stair giveit room to breathe as a sculptural object inits own right.

© Wellcome Trust © Wellcome Trust

The historic ‘Market Place Shopping Centre’was originally constructed in 1851, utilisinga cast iron framework with feature fretworkpanels and dowel pinned lattice roof trusses.The redevelopment adds a nine-screencinema complex extension on the roof of theexisting building, and restructures the centralfeature atrium to provide further restaurants,bars and cafés in the underground‘Victorian’ arched vaults.

A steel-framed solution was selected tomaintain the slimline effect of the existingstructure and minimise the weight of thecinema extension. Steel also suited therestrictive nature of the site, where theshopping centre had to remain fullyoperational throughout, in terms of thespeed of erection and omission oftemporary works.

The 250 tonne 30,000ft2 steel-framedcinema extension adopted a beam andcolumn arrangement with long-spanrafters, internal clear heights of 10m andstructurally independent internal seatingsupport frames and maintenancewalkways. S355 grade steel sections wereused throughout and the new frame wasspliced onto the existing building columnsand floor structures.

Internal strengthening and remodelling ofthe existing four-storey steel frameworkwas needed to carry the additional loadingfrom the cinema extension and amendedescalator runs. This included theinstallation of underslung stiffening beamsto the existing floor members, and theincorporation of two new 16m long 762 x267 UB battening beams to the undersideof the existing floor at level 2, to facilitatethe removal of the central section of aprimary existing steel column in order toprovide clear unrestricted access to CinemaScreens 1 to 4.

The restructuring of the central Atriumarea included the provision of a fullywelded 21m high exposed ‘feature’ steel liftshaft, infill link bridges and the creation ofa new 14m x 10m opening in the groundfloor slab.

A feature ‘space-frame’ roof structure at thehead of the remodelled central Atrium,incorporating ‘T’ section top chords and asuspended circular tie rod bracing system,replicates the original roof detail on theadjacent cast iron framework.

Whilst a tower crane was available forapproximately 60% of the upper roof

extension with a working radius of 78m,the balance of the cinema above level 2 hadto be installed using a series of spidercranes and Roust-A-Bout lifting frames.

All of the internal steel members for thestrengthening and remodelling worksbetween basement and second floor levelhad to be hoisted through service holes inthe existing concrete slabs and ‘hand-balled’ into position.

MERIT

Market Place Shopping CentreRedevelopment, Bolton

The new steelwork provides for theaddition of a nine-screen cinema over aGrade II listed shopping centre.Construction was particularly demandingbecause the Centre was required tofunction throughout the contract period.The tower crane reached only 60% of theworks, so many components had to bemanhandled into position.

The tough logistical challenge was met ina meritorious way.

Architect: Wren Architecture and Design

Structural Engineer: Ramboll

Steelwork Contractor: Shipley Structures Ltd

Main Contractor: McLaren Construction Ltd

Client: Moorgarth Properties LtdPROJECT TEAM

JUDGES’ COMMENT

MERIT

Waterford Fire Station

Architect: McCullough Mulvin Architects

Structural Engineer: O’Connor Sutton Cronin

Steelwork Contractor: Steel & Roofing Systems

Main Contractor: Duggan Brothers Contractors Ltd

Client: Waterford City & County CouncilPROJECT TEAM

The scheme is characterised by thearchitectural concept of a ribbon ofaccommodation wrapping around acourtyard in which emergency vehiclescirculate and drills are carried out. Thedistinctive ‘origami-folded’ roof, formedfrom cranked steel beams, twists and risesover the different levels of accommodation.

A most interesting addition to the town.

JUDGES’ COMMENTShaped around active service wherefunction is paramount, the building formderives from tracking the movements of firetenders leaving the appliance bays at speedand returning after firefighting. A strongform wrapped in zinc is folded - origami-like - to enclose a drill yard with differenttraining zones.

Organised in a spiral, rising from singlestorey vehicle parking, workshops anddormitories to first floor offices, canteen,leisure and study facilities and terminatingat a second floor lecture theatre, the zincroof is angled and cut away to providesheltered inside-outside spaces overlookingthe yard, where the drill tower acts asurban beacon in a new public space.

The steel structure is supported on stripfoundations and supports precast concreteplanks which form the floor slab. Thebuilding is formed from inclined planes andfolded volumes and the flexibility in designof the steelwork facilitated the complexgeometries of the structure, whileexpediting following trades such as zinc,drywall, blockwork, mechanical andelectrical services. This allowed a shorter

and simpler build programme. Steel trussesare utilised to give long spans in theappliance bay to facilitate the appliancesdriving to and from the drill yard tooutside active duty.

The building brings together many differinguses, requiring a variety of structuralsolutions to achieve the desiredfunctionality for the client.

The large open-plan appliance bay, withsufficient space for 10 appliances, isachieved using long span steel trusses.Above this open space, a mixture ofblockwork and steel provides the structureto the office area. A second wing, consistingof load bearing blockwork and precasthollowcore slabs, provides training facilitiesand living quarters over two storeys.

Both wings of the building, together with acovered car parking area to the rear, serveto enclose the large central training yard.The roof to all covered areas consists of asteel frame sloped to suit the profile of theroof. This steel frame supports a timberbuild-up underlying the finished sheeting.

The Layered Gallery is an extension to aprivate residence, housing the owner’scollection of photographs, prints, pastelsand lithographs.

The design concept was based on a series ofsuperimposed screens, creating a layeredeffect against a blank brick wall. Theoutermost ‘layer’ is a structural griddedscreen made of weathering steel. Thesecond is a weathering steel-framed glazedfaçade of museum quality UV-treated glass,which opens to allow natural ventilation.Inside the extension, two additional layershang from each storey’s ceiling: red blinds,which protect the collection of artworks,and the weathering steel display screensthat showcase the collection.

The dendritic façade of the gallery issupported by the visible structuralweathering steel frame on the building’sexterior. Made from flat stiffened platesbranching out over the three-storeystructure, the entire frame is supported offjust two 120mm x 12mm steel posts with astiffening rib on the rear face, creating a T-shaped section. In a reversal of the usualstructural hierarchy, this façade is also themain structural frame of the gallery,

supporting all the floors and roof as well asproviding lateral stability. Around 25 steelmembers make up the façade, each fallinginto a family of just three sizes: 120mm,100mm and 70mm wide T-sections - allfabricated from flat weathering steel plate.At the upper storey, the steel members alsowrap over the top of the extension andsupport the glazed ceiling, ensuring acoherent structural system and aesthetic forthe entire extension.

Cranage at the site was impossible due tothe constricted space and protectedsurroundings, so all structural componentswere sized to be carried into the courtyardthrough the house. The components thatcomprise the structural frame wereprecision fabricated offsite and erectedwithin the courtyard as a kit-of-parts usingonly scaffolding.

Thoughtful connection design and carefuldetailing were key to the building’s success.As the façade is the structural frame and,therefore, outside the building envelope, thefloor beams, which connect to the façade,are detailed with a thermal break at theglazing line. Further, the numerousconnections (45+) were each carefully

coordinated to ensure ease of assemblybetween the members, and were detailed toconceal many of the bolts which arecountersunk into the plate.

The Layered Gallery exploits the aestheticand structural possibilities of weatheringsteel in nearly every detail, providing aspace that blends the interior and exteriorthrough its lightness of construction and itsinnovative structural solution.

MERIT

Layered Gallery, London

This delightful filigree extension hascompletely transformed this historic housefor its art-collector owner. Forming thebackdrop to a new oasis of calm in afrenetic area of London, the buildingdraws inspiration from organic forms ofcourtyard planting. Exposed weatheringsteel and external glazing systems arecleverly integrated.

This is a thoroughly contemporary takeon a historic gallery and courtyard.

Architect: Gianni Botsford Architects

Structural Engineer: Entuitive

Steelwork Contractor: Trescher Fabrications Ltd

Main Contractor: Verona Construction

PROJECT TEAM

JUDGES’ COMMENT

© Gianni Botsford Architects © Gianni Botsford Architects © Gianni Botsford Architects

MERIT

Maxwell Centre, Cambridge

Architect: BDP

Structural Engineer: Ramboll

Steelwork Contractor: The Wall Engineering Co Ltd

Main Contractor: SDC

Client: University of Cambridge Estate ManagementPROJECT TEAM

The BREEAM ‘Excellent’ rated MaxwellCentre forms the latest development forThe University of Cambridge. The newfour-storey building contains researchlaboratories and offices complemented byseminar rooms, interactive spaces anddedicated hubs.

During the early stages of the project thedesign team investigated a number ofdifferent structural schemes. However, asthe design developed, it became clear that asteel frame with precast planks was the onlysolution that could deliver the architecturalaspirations within typical structural zones ofjust 350mm on 13m spans.

Steelwork was also the obvious choice torealise the architectural intent whichfeatures a doubly curved roof.

The 1200m2 laboratories’ area at lowerground level has no movement joints in thefloor slab and just seven internal columns,allowing the laboratories to be easilychanged in the future to cater for differentconfigurations. The heavily servicedlaboratory area benefits from a largebulkhead at the external perimeterallowing future flexibility for serviceinstallations. In addition, a generous

allowance was included to suspend servicesfrom the precast plank soffit above.

The complex and challenging doublycurved roof was designed to reflect thecurved roof of the adjacent Physics ofMedicine Building. The roof was createdusing a series of curved steel beams, eachwith a slightly different radius.

The different uses of space between lowerground and the upper floors meant thatthere were many constraints on thestructural layout. For example, to avoidcolumns disrupting the seminar room, thebusiness lounge above is partly hung fromthe main roof beams. An 18m truss madeup of open sections was used, suspendedfrom three points in the roof. A trussconcealed in a wall was utilised as theincreased stiffness mobilised more massand improved the vibration performancewithin the business lounge.

The centre of the building also boasts athree-storey central courtyard covered withan ETFE roof. Within this courtyard twomeeting pods cantilever out within thespace, as well as an open balconysuspended from the frame.

The exposed precast plank soffits are animportant visual element and are alsoutilised for thermal mass in the naturallyventilated upper levels. The coordinationof the steelwork support details wastherefore of great importance, particularlyat the column to soffit junction whichincluded support plates for the planks,substantial torsional connections for thebeams, and a connection for an invertedtee beam which acts as a frame tie.

Flexibility and efficient distribution ofservices were critical to this project. Thesolution was to use long-span floorssupported on steel slimfloor beams, whichalso enabled natural ventilation. Four storeysare arranged under a doubly curved roof,reflecting the adjacent building to which itneatly links.

The result is an efficient and elegant building.

JUDGES’ COMMENT

The British Constructional Steelwork Association Ltd and Steel for Life have pleasure in inviting entries forthe 2018 Structural Steel Design Awards Scheme.

The objective is to celebrate the excellence of the United Kingdom and the Republic of Ireland in the fieldof steel construction, particularly demonstrating its potential in terms of efficiency, cost-effectiveness,aesthetics and innovation.

The Structural Steel Design Awards Scheme

2018 ENTRY FORM

OPERATION OF THE AWARDSThe Awards are open to steel-based structures situated in theUnited Kingdom or overseas that have been built by UK or Irishsteelwork contractors. They must have been completed and beready for occupation or use during the calendar years 2016-2017;previous entries are not eligible.

THE PANEL OF JUDGESA panel of independent judges who are leading representativesof Architecture, Structural Engineering and Civil Engineeringassess the entries.

The judging panel selects award winners after assessing allentries against the following key criteria:

Planning and Architecture

■ Satisfaction of client’s brief, particularly cost-effectiveness■ Environmental impact■ Architectural excellence■ Durability■ Adaptability for changing requirements through its life■ Efficiency of the use and provision of services■ Conservation of energy

Structural Engineering

■ Benefits achieved by using steel construction■ Efficiency of design, fabrication and erection■ Skill and workmanship■ Integration of structure and services to meet architecturalrequirements

■ Efficiency and effectiveness of fire and corrosion protection■ Innovation of design, build and manufacturing technique

SUBMISSION OF ENTRIESEntries, exhibiting a predominant use of steel and satisfying theconditions above, may be submitted by any member of thedesign team using the appropriate form. The declaration ofcompliance with the award requirements must be completed bythe entrant.

Entrants should ensure that all parties of the design teamhave been informed of the entry.

GENERALThe structures entered must be made available for inspection bythe judges if they so request. All entrants will be bound by thedecision of the judges, whose discretion to make or withhold anyaward or awards is absolute. No discussion or correspondenceregarding their decision will be entered into by the judges or bythe sponsors. The decision of the sponsors in all matters relatingto the Scheme is final.

A short list of projects will be announced and the project teamsnotified directly. The results of the Scheme will be announced inthe autumn – no advance notification will be given to the projectteams as to which structures will receive Awards.

Any party involved in a project that is no longer in business forwhatever reason will not receive any recognition in theStructural Steel Design Awards.

AWARDSEach firm of architects and structural engineers responsible forthe design receive an award as do the steelwork contractor, maincontractor and client.

PUBLICITYThe sponsors assume the right to publish the drawings,photographs, design information and descriptive mattersubmitted with the entry to publicise the award-winningstructures in relation to the Structural Steel Design AwardsScheme.

FURTHER DETAILSAll correspondence regarding the submission of entries should beaddressed to:

Gillian Mitchell MBE, BCSA, Unit 4 Hayfield Business Park,Field Lane, Auckley, Doncaster DN9 3FL

Tel: 020 7747 8121Email: gillian.mitchell@steelconstruction.org

CLOSING DATE FOR ENTRIES - Friday 23rd February 2018

Sponsored by The British Constructional Steelwork Association Ltd and Steel for Life.

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Total tonnage: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Approximate total cost (£): . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Cost of steelwork (£): . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PERSON SUBMITTING THIS ENTRY

Name: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Tel: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Email: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ARCHITECT

Company Name: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Address: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contact: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tel: . . . . . . . . . . . . . . . . . . . . . .

Email: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

STRUCTURAL ENGINEER RESPONSIBLE FOR DESIGN

Company Name: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Address: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contact: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tel: . . . . . . . . . . . . . . . . . . . . . .

Email: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

STEELWORK CONTRACTOR

Company Name: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Address: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contact: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tel: . . . . . . . . . . . . . . . . . . . . . .

Email: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

MAIN CONTRACTOR

Company Name: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Address: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contact: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tel: . . . . . . . . . . . . . . . . . . . . . .

Email: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CLIENT

Company Name: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Address: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Contact: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tel: . . . . . . . . . . . . . . . . . . . . . .

Email: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

SUBMISSION MATERIALThe submission material which should be hard copies, should include:

n Completed entry form

n Description of the outstanding features of the structure (c 1,000 words), addressing the key criteria listedoverleaf, together with the relevant cost data if available

n Architectural site plan

n Not more than six unmounted drawings (eg. plans,sections, elevations, isometrics) illustrating the essentialfeatures of significance in relation to the use of steel

n Six different unmounted colour photographs which shouldinclude both construction phase and finished images

n Memory stick containing the images submitted as digitalJPEG files at 300dpi A5 size minimum and an electroniccopy of description text in Word (not pdf format)

Entry material should be posted to:Gillian Mitchell MBE, BCSA, Unit 4 Hayfield Business Park, Field Lane, Auckley, Doncaster DN9 3FL to arrive by not later than 23rd Feb 2018

2018 ENTRY FORMPLEASE COMPLETE ALL SECTIONS BELOW IN FULL (including email addresses):

DECLARATION OF ELIGIBILITYAs the representative of the organisation entering this structure inthe Structural Steel Design Awards 2018, I declare that this steel-based structure has been fabricated by a UK or Irish steelworkcontractor. It was completed during the calendar years 2016-2017. It has not been previously entered for this Awards Scheme.

Signed: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Date: . . . . . . . . . . . . . . . .

On behalf of: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Designed and produced by Kovic Design Limited • www.kovicdesign.co.uk