BTE 2A - Structural Case Studies

-please note that the original essay was accompanied by detail drawings and photographs.

Selected Buildings -

Elbe Philharmonic Hall - Herzog & de Meuron - Concrete

Barajas Airport - Richard Rogers - Steel

Cologne Museum - Peter Zumthor - Masonry

Downland Gridshell - Edward Cullinan - Timber

British Museum Roof - Norman Foster - Glass

Allianz Arena, Munich - Herzog & de Meuron - Innovative Cladding



Project - Elbe Philharmonic Hall

The new Elbe Philharmonic Hall by architects Herzog & de Meuron will be situated directly on top of what used to be known as ‘Warehouse A’, a warehouse located in Hamburg harbour directly adjacent to the river Elbe. It was used to store cocoa, tobacco, tea and coffee. The original warehouse dates from 1966 and had a total floor area of around 4200 square metres over 7 floors. In 2001, having not been used for years, the warehouse started to develop into a cultural landmark of Hamburg, playing host to a nightclub, exhibition spaces, concerts and festivals.

In 2006, Herzog & de Meuron were granted planning permission to build a new philharmonic hall. Their proposal was a new ‘floating’ structure sitting on top of the old warehouse. The existing warehouse construction used a reinforced concrete frame sitting on more than 1000 piled foundations. Some areas of the building use steel to improve the performance of the structure in tension.

The main soil type in the area was silt, meaning the ground had a maximum bearing capacity of under 75kN per square metre. Like the builders of the original warehouse, the engineers behind the new building decided that any additional foundations which needed to be added would have to be piled. This is so as to avoid issues with bearing capacity and also variations in the volume of soil with moisture. Because of this, before the new hall could be constructed 600 additional piles were driven into the soil to support the loads of the new structure. Around 200,000 tonnes of new construction needed to be supported.

The existing warehouse had no windows and only 250mm thick concrete walls with no insulation, this made it unsuitable for a public building so it will be used mostly for parking and some basic public amenities. The new building sits directly on top of the old warehouse and follows the same footprint, adding 667,000 square feet and continuing it’s form 360ft upwards. The new structure will be supported by the warehouse using large, angled concrete columns.

Between the two buildings there is a public terrace where visitors can view the city and the harbour. This serves to separate the two buildings. The buildings are connected to each other by a 3-storey escalator. The building itself is reminiscent of middle eastern or European tent structures, with a number of peaks dominating its form. The tallest peak reaches around 100m sitting tall over the waters of the river, the lowest peak is around 80m at the other end of the building. The cladding of the building will consist of different styles of glass, varying with the use of spaces. Similar to Herzog & de Meuron’s BTU building, the glass will be imprinted with thousands of small white dots, controlling lighting, solar gain and levels of glare. A computer system will be used to calculate the density of dots on each pane of glass, this will be defined by the orientation of the glazing and the function of the internal space.

The building incorporates many spaces, the major on being a 2200 seat concert hall. There will also be a smaller, 550 seat hall for different styles of performance, a 220 room, five star hotel, restaurants, bars, a fitness suite and more than 30 apartments.


Project - Barajas Airport Terminal 4

The Barajas airport in Madrid is the largest project ever undertaken by Richard Rogers. More than 1,000,000 square metres of buildings and a budget of almost one billion Euros. The new terminal is designed to accommodate more than 35 million passengers per annum and is therefore 1.2km in length.

I am going to focus on the main terminal space and its large, distinctive roof structure. The building works on an 18m x 9m structural grid which was needed to give continuity and ease of production to such a massive design. It also allowed for flexibility and adaptation given that the number of passengers through the airport will increase over the lifespan of the building. The roof is held up by ‘tree’ structures every 9m and there are four supporting each main beam. These trees consist of a concrete base which holds two steel columns of elliptical cross-section. The columns are 16mm thick elliptical hollow pipes which are 800mm x 480mm at the base and 480mm x 200mm where they connect to the unique curved roof beams via a spherical joint and a steel pin.

In section, the main beams of the roof are 500mm by 30mm and the stem is made from 15mm steel plate. The depth of these beams varies, ranging from 1500mm in the centre to 750mm at the outer edges. They were designed to interrupt the ’flow’ of the roof as little as possible. The curves of the beams varies to create a sequence of repeated waves which. Running between the main beams are secondary beams at 3.5m centres, these were fabricated from rolled sections, upon these beams are the purlins which support the roof. The secondary beams are arched between the main beams to give the roof its distinctive wave form. The roof is punctured by large roof lights which allow natural light into the space. The ceiling is clad in Chinese bamboo, chosen for its ability to create smooth curves and because of its availability in such large quantities. What the architect describes as ‘light-filled canyons’ divide the floors of the buildings upper level. These floors are made from concrete planks sitting on post-tensioned beams cast 72m at one time.

The roof is the main focus of the design and as it also take structural priority. The exterior walls of the terminal are large expanses of glass. The roof overhangs the glazing to provide shade and reduce solar gain which is also achieved with an additional tubular steel shading system. Rogers claims that the building is the most environmentally efficient building which could have been build at this scale. The 3m x 2.3m glazing panels are fixed to steel rods and hung from the roof trusses every 9m. The need for any vertical support members has been eliminated which helps to emphasise the structure of the roof and make the building feel more open.


Project - Cologne Museum

Museum Kolumba in Cologne contains within it the ruins of the gothic church St. Kolumba, a chapel and an archaeological excavation. It is a unique project executed beautifully by the architect. The building is 4500sq metres and is divided into two wings, one for the church and another containing the chapel. The method of construction used relates to the church it houses, the thick masonry wall with high, large windows allowing light into the lower levels. The architect has used the language of construction to add a spirituality and contextuality to the design.

The 30m high façades are all finished in the same material, a light grey brick specially developed for the project by a Danish company, Peterson. The bricks were made to match the colour of mortar. Unusually each brick is only 36mm high and they vary in lengths, up to 520mm. Each course of mortar is also half the height of the brick. The walls are 600mm thick and uninsulated. The walls support the floors and roof, along with an internal concrete structure and provide the stability of the building. To avoid movement caused by temperature changes they are kept at a constant temperature by circulating water drawn by an aquifer from 70m below ground, keeping the temperature steady at all times of year. The cavity used to circulate the water also serves to reduce heat loss through the walls.

The room containing the ruins of the gothic church is 12m in height. Light enters the space through small perforations in the bricks which gives the room a similar climate to the outdoors, necessary to conserve the excavation site. The perforated bricks came to be referred to as “pullover brickwork” by Zumthor and his team. A timber walkway navigates you over the ruins towards and exterior courtyard created by the ruins of the church. Either side of the walkway are 250mm concrete columns which support the roof above, these are located carefully so as not to damage the ruins and thus, there is minimal structural order to their layout.

On the upper floors of the buildings, light is more prominent and large areas of glazing, supported by concrete, allow views over the city ensuring a connection between the city and the building. All the floors, ceilings and roof structures of the buildings are in-situ reinforced concrete. Internally the floors are finished in travertine. There are no joins or grooves visible in any of the internal brickwork, flooring or concrete.


Project - Downland Gridshell

The Downland gridshell is the first gridshell structure in Britain. The building is part of the Weald and Downland open air museum which dismantles old buildings and rebuilds them on their own grounds, where there are country walks, farm animals and a lake for visitors to enjoy. The gridshell itself is a conservation workshop for repairing large old timbers, the building also houses the museum’s collection of rural tools and artefacts as well as a classroom for visiting school children and for teaching workshops on timber construction methods, most of which are no longer taught in mainstream construction education.

The brief was to create a strong, well-lit building to be open to the public and used for repairing building components as well as storage of the museum collections and a small display area. The museum’s main concerns were materiality, contextuality, environmental issues and historical issues. Several architects were interviewed and asked to develop a design. Edward Cullinan Architects were chosen because the museum felt that the work of the practice displayed similar principles to that of the museum.

It was important to the museum that the new building was not an imitation of an old style, instead they wanted something modern and innovative, hence the use of the gridshell structure and not a more widely used building technique. The structural system used in the building was designed using a computer, the architects had to test the feasibility of using a grid structure and then build models to test its capacity for taking load, both in use and during construction. After constructing the concrete ground floor, the glu-lam beams for the first floor were installed and the spruce and ash flooring system was put in. After this the arches which act as the ends of the building, made using a glu-lam arch and a Siberian larch cross beam, were lifted into place.

To construct the gridshell, first the team had to construct 7.5m high scaffolding where the structure could be assembled. The gridshell is made from two layers of latticed laths, these were made from green oak, grown in France and chosen for it’s flexibility and strength, and were just 35mmx50mm in section. 600 laths in total were used in the final building. Each lath was 36m long and made from six 6m long lengths joined together by scarf joints. To construct the roof, the two layers of lattice were laid flat on top of the scaffolding, then the scaffolding was lowered at predetermined points by just a few centimetres each day. In order for the gridshell to move into it’s final curved shape, movement was needed between the two layers of timber lattice. For this to be achieved some innovation was needed which came in the form of the “Holloway-Happold Node Clamp” named after its inventor and the engineering firm who developed it. Basically it allows the outer laths to slip over the inner laths while still holding the joint in place. In total, 11,323 of these laths were used in the final structure and there were only 53 breakages which were soon fixed by carpenters. During the formation of the structure adjustments were made by eye while referring to a pre-produced computer model. It took 3 months for the roof to take its final shape and be attached to the first floor structure and a further 9 for the building to reach completion. Insulation of the structure was achieved using 25mm thick Foamglas panels covered by two layers of aluminium foil. The glazing on the building is polycarbonate, mainly for cost purposes. Sustainability was an important part of the design. Most of the building does not require heating because the people inside are working and therefore are unlikely to be cold, solar collectors heat water which is used in under-floor heading pipes when heat is required. The building is also uses very little electrical lighting because of the abundance of natural light.


Project - British Museum Roof

Foster’s roof over the Great Court at the British museum Joins the cylindrical reading room in the centre of the courtyard with the courtyard walls which define the rectangular space. Similar to other Foster designs, the roof is made up of a lattice of steel which supports triangular glass pieces. The difficulty in this project however was that the design team were not able to just design a shape and make it work structurally, they also had to think about the existing buildings and how the roof would integrate into these.

Several limitations on the design were imposed by the existing buildings and the demands of the client. The cylindrical reading room appears to be central within the Great Court, however it is in fact 5m closer to the North wall than to the South wall. This causes major problems because a symmetrical or regular geometry wouldn’t naturally work in these circumstances. Secondly, the roof had to be vaulted, further complicating the geometry, to clear the porticos at the centre of each surrounding façade but the roof structure also had to be as shallow as possible to reduce visibility from nearby streets, the client wanted the exterior of the museum to remain classical in character. These limitations, in my opinion make the design much more interesting than most Foster designs and understanding how the structure works around all of these issues is helpful when it comes to thinking about solving structural issues in my own designs.

Initially the design team intended to use inflated EFTE ‘pillows’ supported on a 4.3m grid. This technology has been used before by architects, notable examples being the Eden Project, the Allianz Arena in Munich by Herzog & de Meuron and the Beijing National Aquatics Centre. The problem with this design was that it would need a heavy steel structure to stop the roof being blown of by the wind, the system would have required fewer members but each one would have been a lot thicker than the chosen system. This was deemed unsuitable to the geometry an classical character of the courtyard.

The system used in the final design is a more conventional but complex system using glass panels and a steel supporting lattice. The roof itself covers the 110m x 70m courtyard with spans from the reading room in the middle to the outside walls varying between 14m and 40m. At one point in the design process there were more than 10,000 panels of glass, this was reduced to 3312 for the final design, this gives you an idea of the scale and complexity of the project. These 3000+ panels of glass are supported by a steel structure consisting of 5162 box beams which connect at 1826 points in a unique 6-way node, each of which was designed and located in 3 dimensions and was built to within +/- 3mm. In total there is 11km of steel members in the roof and including the glass, the roof weighs more than 800 tonnes. At the corners of the courtyard, where the largest forces are generated, tensioned cables help to strengthen and stiffen the roof.

The geometry of the roof consists of concentric circles from the reading room in the centre of the courtyard, these circles are then connected by two opposing spirals, creating the triangular openings. The dimensions of the steel box sections vary across the roof, starting thick at the reading room and becoming thinner as they reach the outer walls. The width of the members is always 80mm but the depth ranges from 80mm up to 200mm in the centre.

After construction, when the props supporting the roof were removed in Spring 2000 and the roof was supporting itself for the first time, the height of the structure dropped by 150mm and spread 90mm laterally on its sliding bearings, exactly as the engineers had predicted that it would.


Project - Allianz Arena

The Allianz Arena in Munich was designed by architects Herzog & de Meuron and constructed for the 2006 World Cup. The stadium can accommodate 70,000 spectators. The dimensions of the building are 258m x 227m x 50m, 205,000 cubic metres of concrete and 36,000 tonnes of steel were used in its construction. The 3 year construction cost more than €340 million. The most striking and innovative aspect of the building is its façade and cladding system.

The stadium is home to two club teams, FC Bayern Munich and TSV 1860 Munich, and also hosts national matches, such as during the World Cup. Because it is the home stadium of two teams the architects wanted the stadium to be able to change colour depending on which team was playing. The building glows red when Bayern Munich play, blue when TSV 1860 Munich play and white when the German national team is competing.

The façade of the arena is made using 2874 EFTE-foil (Ethylene Tetrafluoroethylene) air panels or cushions, the skin of which is only 0.2mm. Each cushion is unique and could only fit in its designated spot. The installation of the panels required 35 skilled climbers. These cushions are filled with air to a pressure of 0.038hPa. The EFTE, a kind of plastic, is strong and durable and performs well in a wide range of temperatures and weighs only one thirtieth of the weight of glass. The panels also require no cleaning due to a special surface coating. Each individual cushion can be lit either red, blue or white by a lighting system behind the panels. There are blinds within the building if it is necessary to reduce the amount of sunlight entering the internal spaces. Also, if the fans which keep air pressure in the panels fail and moisture builds up within them a valve is triggered which releases the excess moisture ensuring that a build up of water doesn’t put strain on the roof structure. Similarly, if snow collects on the roof, a number of sensors measure the increase in load and adjust the air pressure in the panels to compensate meaning the building is always in balance. Similar technology to this cladding was used in the Eden project in Cornwall.

The main structure of the building is a concrete frame consisting of 350 inclined pillars sitting on concrete foundations. Each pillar has a cross section of 650mm x 650mm and have a maximum bearing load of 10,000kN. The tiers for the seating in the stadium are made from 2446 pre-cast concrete sections and 3985 stair elements.

The roof of the stadium is made from 48 radial main beams connected by cross beams. The main beams are 65m long and weight up to 106t each. The cross beams, rectangular hollow sections measuring 180mm x 180mm, form a rhomboidal ‘steel net’ which holds the roof panels. In total the structural steel for the roof weighs around 8700t and can support 5000kN, its own weight plus a full load of snow at the centre. The roof has a maximum deflection of 550mm.

Overall, the building uses its innovative cladding system in an interesting and contextual way and achieves dramatic results.



Compare and contrast :

Each of these 6 buildings has a unique structural system with its own positives and negatives.

The Elbe Philharmonic Hall uses a large amount of concrete to ‘float’ above an existing building, something which would have been virtually impossible using any other material. It makes the building heavy and the structure bulky but frees up the façade allowing a very interesting appearance.

The Barajas airport uses a steel system which works perfectly with the design and the ease with which steel components can be mass produced was obviously an advantage on such a large project.

Zumthor’s museum in Cologne uses masonry in a very unique way which is not only interesting visually but connects to its context and purpose very well.

The timber system used for the Downland Gridshell is very lightweight and gives an organic form at a low cost both financially and environmentally, the craftsmanship and detailing in the project is astounding.

The glass roof at the British Museum is a very large and complex project which is solved very simply and elegantly and the finished product could have easily been a lot less interesting and a lot bulkier.

My favourite of the six buildings from a structural point of view is the Downland Gridshell. I think that the client and designer have worked very well together and developed a project that meets its brief but also pushes the limits of engineering. The quality of construction, scale and detailing all make it an elegantly complex structure which sets the standard for timber construction in Britain.