The DEVELOPMENT of a NEW LANGUAGE OF STRUCTURES in ARCHITECTURE during the second half of the 20th century (with student case studies)
For SAP2000 problem solutions refer to “Wolfgang Schueller: Building Support Structures – examples model files”: https://wiki.csiamerica.com/display/sap2000/Wolfgang+Schueller%3A+Building+Su pport+Structures+-
If you do not have the SAP2000 program get it from CSI. Students should request technical support from their professors, who can contact CSI if necessary, to obtain the latest limited capacity (100 nodes) student version demo for SAP2000; CSI does not provide technical support directly to students. The reader may also be interested in the Eval uation version of SAP2000; there is no capacity limitation, but one cannot print or export/import from it and it cannot be read in the commercial version. (http://www.csiamerica.com/support/downloads) See also, (1) The Design of Building Structures (Vol.1, Vol. 2), rev. ed., PDF eBook by Wolfgang Schueller, 2016, published originally by Prentice Hall, 1996, (2) Building Support Structures, Analysis and Design with SAP2000 Software, 2nd ed., eBook by Wolfgang Schueller, 2015. The SAP2000V15 Examples and Problems SDB files are available on the Computers & Structures, Inc. (CSI) website: http://www.csiamerica.com/go/schueller
This presentation will introduce the new generation of structures that has developed primarily during the 1950s to about 1990. It is emphasized that structure is architecture and not just plugged into architectural space.
I will concentrate on the experience of building structures from a visual point of view primarily, as seen through the eyes of a design engineer and architect, rather than a detailed discussion of structural behavior, refinement of structural performance, or efficient construction methods. In other words, this lecture will celebrate the joy of structures as architecture and engineering art. The cases are shown in the context of education as unique solutions, which demonstrate the complexity and creative mind of designers and express the infinite richness of architectural form.
I like to briefly remind you of the basic position of the structural engineer which often is perceived by architects as a very narrow one. The structural engineer is responsible for safety, to him the building is a body that is alive, its bones and muscles are activated by external and internal forces. As it reacts, it deforms and suggests the pain it must endure at points of stress concentration. The arrangement of space, which defines members and their spans, becomes most important in controlling the force flow to the foundations and reducing stress concentrations to a minimum. In other words, engineers visualize buildings in an animated state moving back and forth as can be convincingly expressed by computers through virtual modeling. In contrast architects must respond in the design of buildings to the broader issues of the environmental context, be it cultural or physical. I like to emphasize that the theme of my presentation is not addressing the difference between structural engineers and architects is, but that STRUCTURE DOES NOT ONLY PROVIDE
BE ARCHITECTURE.
SUPPORT BUT ALSO CAN
A.
Introduction:
STRUCTURE IS ARCHITECTURE
First I like to remind you that the development of modern building support structures has its origin in the inventive spirit of structural engineering and the rapid progress in the engineering sciences during the 19th century, as reflected by:
•
• •
The enormous volume of the iron-glass structure system of the Crystal Palace in London (1851, Joseph Paxton), constructed in the short period of only six months. The longest span of 480 m (almost 1600 ft) of the Brooklyn Bridge in New York (1883, John and Washington Roebling), The unbelievable height of the 300 m Eifel Tower (nearly 1000 ft) in Paris (1889, Gustave Eifel)
The longest span of 480 m (almost 1600 ft) of the Brooklyn Bridge in New York (1883, John and Washington Roebling),
The unbelievable height of the 300 m Eifel Tower (nearly 1000 ft) in Paris (1889, Gustave Eifel)
The enormous volume of the iron-glass structure system of the Crystal Palace in London (1851, Joseph Paxton), constructed in the short period of only six months.
This world of engineering was absorbed into architecture by the early modernists at the beginning of the 20th century. They were concerned with the articulation of the functional spirit: FORM FOLLOWS FUNCTION, and the honest expression of building construction by freeing the hidden structure from its imprisonment of the wall, by exposing it. A celebrated example of this new philosophy of architecture is the Villa Savoye by Le Corbusier.
Villa Savoye, 1929, Poissy-sur-Seine, France, Le Corbusier; the new aesthetics of modernism is expressed by: (1) the pilotis or ground-level supporting columns, (2) the flat roof used as living space, (3) the free plan made possible by elimination of bearing walls, (4) the freely designed facade unrestrained by load-bearing considerations consisting of thin skin and windows
Maison Domino 1914 “domus” (house) and “domino” (suggesting serial production). Maison Domino’s serially reproducible units introduce greater horizontal spatial freedom (the free plan) achieved via pilotis (thin structural columns) and non-load-bearing walls freely arranged as spatial dividers
Bauhaus 2, Dessau, Germany, 1925, Walter Gropius
The full integration of the spirit of structural engineering into architecture happened during the 1950s and early 1960s or so, i.e. STRUCTURE IS ARCHITECTURE. One group of architects even went so far to claim, ARCHITECTURE IS STRUCTURE. It was the work of the pioneer design engineers Robert Maillart, Eduardo Torroja and Pier Luigi Nervi that had a strong impact on the new generation of architectural designers of the 1950s such as Eero Saarinen, Kenzo Tange, Marcel Breuer, and many others. The expression of structures during this era of the 1960s took many directions ranging from the minimal and functional forms of Mies van der Rohe, Philip Johnson, SOM (e.g. Bruce Graham/ Fazlur Khan, Myron Goldsmith), and I.M. Pei, to the more sculptural forms of Paul Rudolph, Marcel Breuer, Kisho Kurokawa, and Bertrand Goldberg. During this period, the experimentation with structures, as started by the design engineers of the 19th century, continued by adding the integration of complex geometry and bionics (i.e. natural systems), especially as related to minimum weight and surface structures which was brought to a high level of sophistication by Frei Otto, Robert LeRicolais, Buckminster Fuller, Felix Candela, Heinz Isler, and many others. This world of structural experimentation was convincingly represented by the space frames, cable structures, prestressed membranes, and
pneumatics skins of the Expos in Montreal (1967) and Osaka (1970).
The experimentation with structures is also reflected by the constructivist art of modernism and was first articulated particularly by the dreams of designers such as the pioneers Antoine Pevsner and Naum Gabo at the early part of the 20th century in Russia, and later by Alexander Calder's kinetic art and Kenneth Snelson's tensegrity sculptures.
The early position of architecture as structure is very much reflected by the drawing of Mies van der Rohe's 52-story, 212-m IBM Tower in Chicago (1973) celebrates the frame and the geometrical order of the grid – the building organization is controlled by the geometry of the 9 x 12 m bays (30 x 40 ft); the mathematical regularity of the frame layout almost subdues the expression of its structural action. This regular frame layout is typical for many buildings today because of its simplicity of construction
Lake Shore Drive Apts, Chicago, Ludwig Mies van der Rohe, at Chicago, 1948 to 1951
This expression of minimal geometry, however, is surely not dated as expressed by the rational, neo-classicistic Fuji Television Headquarters in Tokyo (1996) , designed by Kenzo Tange more recently. Here office and media towers are connected by 100 m long sky corridors providing urban spaces and elements such as small plazas, promenades, stair cases, bridges, and terraces at various levels. The mega-framework consists of Vierendeel steel columns and beams with reinforced concrete that support a 32-m titan covered globe containing a restaurant.
B.
THE
BIRTH OF UNIQUE STRUCTURES: a period of transition
During the late 1960s and early 1970s or so, architects understood the spirit of the engineering discipline and began to separate themselves from the predominance of structural engineering thinking. They had matured and developed the necessary courage to invent their own structures by superimposing upon them other ideas and meanings such as the effect of context, symbolism, possibly fragmentation in geometry and material. In other words, during this period, also sophisticated individual structures occurred in response to particular situations quite in contrast to the catalogued structure systems as identified by numerous types of line diagrams and rules of thumb.
The 22-story, 100-m high, BMW Building in Munich, Germany (1972, Karl Schwanzer) consists of four suspended cylinders. Here, four central prestressed suspended huge concrete hangers are supported by a post - tensioned bracket cross at the top that cantilevers from the concrete core. Secondary perimeter columns are carried in tension or compression by story-high radial cantilevers at the mechanical floor level. Cast aluminum cladding is used as skin.
BMW Building consists of four suspended cylinders. Here, four central prestressed suspended huge concrete hangers are supported by a post - tensioned bracket cross at the top that cantilevers from the concrete core. Secondary perimeter columns are carried in tension or compression by story-high radial cantilevers at the mechanical floor level. Cast aluminum cladding is used as skin.
C.
A NEW GENERATION OF STRUCTURES: the beginning
It was during the time of post-modernism of the late 1970s and early 1980s when the progress of new structural thinking went unnoticed by most architects in the USA and particularly in architectural education where architectural theory began to flourish. The potential of those new structures as space makers was not studied; the structures remained hidden and solely used to do their job as support. In contrast, in Europe the experimentation with structures continued by often brutally exposing structures and expressing them in a rather animated fashion.
Citicorp Center (59 stories), New York,1977, Stubbins + William LeMessurier
An early example of this new type of structure in the USA is the 59story, 279-m, 46 m square (152 ft) Citicorp Building, New York (1977, Stubbins), where the powerful expression of structure unfortunately is hidden behind the post-modern skin. The renowned structural engineer William J. LeMessurier introduced a new way of thinking about the building body and structures with his spatial 8story series of chevron braced stacks which act as 3-dimensional units. This new breed of megastructure looks so simple but is so complex in behavior. Here, the core acts as an interior vertical beam with respect to wind within the stacks.
In contrast in Europe, Richard Rogers, in his love for technology exposes in the Lloyd's of London (1978 - 86) the functioning of the building body by introducing a much freer and exuberantly decorative treatment of the structure recalling the 1960s plug-in cities of Archigram. In the typical Rogers kit-ofparts fashion, he broke the monotony of the classic frame and expressed, a piece of machinery with flexible kits, moving parts, a network of ductwork and a mechanically ventilated cavity façade (i.e. 3 layers of glass). He freely manipulated the form of the concrete skeleton structure by stepping it at various floor levels and surrounding the braced perimeter concrete frame by six structurally independent satellite service towers with permanent maintenance cranes located on top of them, while the internal perimeter columns carry the elaborate 240-ft (about 73 m) high central atrium structure crowned by a barrel vault.
Pompidou Center, Paris, 1977, Piano and Rogers
Naturally, it all started with the 6-story Pompidou Center in Paris (1977) by Piano and Rogers, which introduces a new generation of structures by exposing its functional layers of structure assembly, stairs, corridors, escalators and air ducts. Its tension-braced hinged assembly structure is quite opposite in spirit to the conventional rigid monolithic construction. The basic structure consists of parallel 2.4 m (8-ft) deep Warren truss beams that span c. 45 m (147 ft) across the building to rest on small cantilever beams called gerberettes, which are caststeel beams pin connected to interior water-filled cast steel tubular columns and tied down by exterior vertical tension rods. For the first time cast steel was used to articulate the joints
University Clinc (Klinikum), Aachen, Germany, 1981, Weber + Brand
University Clinc (Klinikum), Aachen, Germany, 1981, Weber + Brand
D.
THE
NEW LANGUAGE
Of
STRUCTURES A new language of structures may be characterized by the breakdown of the building into smaller assemblies, by complex shapes and geometry, by fractured forms as represented by fractal mathematics, by hinged assemblies, multi-layered construction, forms in tension and compression (i.e. buildings have muscles), mixed and hybrid structures, cast metals, lightweight composite materials, complex spatial geometry, and so on.
There is even an indication that certain passive structures may be replaced eventually by active structures with their own intelligence. We are already quite familiar with smart materials and energy dissipation systems. Computers and advanced technology give us answers that we will have to face, if we like it or not.
In the following discussion of cases, structures may take more or less three positions: •
The complex hidden structure derived from intricate geometry and not from the nature of the support structure; a convincing example is the Guggenheim Museum in Bilbao, Spain, by Frank Gehry (1997). In other situations computers find the optimum layout of structures within given boundaries
•
The structure as the primary idea of architecture, but not necessarily derived from traditional engineering thinking of optimization or tectonic expression, but other intentions: architects invent structures - subjectivity and creativity are introduced in spite of the limits imposed by the rules and physical laws of engineering.
•
The dialogue (or play) of architecture with structure, or symbolism with tectonics, on a more local scale, possibly as a leitmotif: architecture as structure detail.
I will present some of those characteristics by addressing the following six topics:
•
the large scale of the high-rise building
•
the smaller and more human scale of lower buildings
•
the effect of the building section, or columns as space makers
•
achieving the long span through arches and the corresponding effect on space
•
the transparency of the glass-skin structures
•
the conclusion, a new dimension of structure
THE LARGE SCALE: high-rise buildings
First I will be showing several high-rise buildings of this new generation that are broken up, hollowed out, lifted up, subdivided into smaller buildings, placed on top of each other, or by using mega-structures. An early example of this free manipulation of material space is,
the 21-story bridge-like concrete structure of the Hypobank in Munich, Germany (1981, Walter and Bea Betz), where the structural concept demonstrates another kind of a new generation of structures. Its shape reminds one of the metabolist architecture of the 1960s in Japan although somewhat softened by less articulation of tectonics and through the use of the skin and the lightness of the triangular prisms. Here, four cylindrical towers with a story high platform at the 11th service level (that consists of three rigidly connected prestressed box-like girders) form an irregular spatial rigid megaframe. This structure supports 15 stories above and the hanging 6 stories below.
The 43-story, c. 200-m high, Hongkong Bank in Hong Kong (1985, Foster/Arup) is an ikon of the 1980s - it is a celebration of technology and architecture of science as well of function as art. It expresses the performance of the building and the movement of people. The stacked bridge-like structure allows opening up of the central space with vertically stacked atria and diagonal escalator bridges by placing structural towers with elevators and mechanical modules along the sides of the building. This approach is quite opposite to the central core idea of conventional high-rise buildings. The support structure is clearly expressed by the clusters of eight towers forming four parallel megaframes. A megaframe consists of two towers connected by cantilever suspension trusses supporting the vertical hangers which, in turn, carry the floor beams. Obviously, it was not the intention for the structure to articulate structural efficiency.
Hiroshi Hara, the architect of the Umeda Sky City, Osaka (1993) called the building with the urban roof and floating gardens, city in the air. The building expresses postmodern sensibilities, challenging the unity of form by articulating diversity. The 40-story, 173 m high double-tower (54 m apart) is connected by a huge 2-story 54-m span roof bridge structure with a large circular sky window. This square platform- bridge (150 m above the ground) provides urban space and gardens in the air. The human scale is reinforced by a pair of almost floating escalators, free-standing transparent elevator shafts and staircases, as well as a 6-m wide steel sky bridge that links the buildings at the 22 level. Although the building required advanced structural engineering especially in earthquake country, Hara did not express the effort of the support structure; he softened structural engineering by the finish of reflective glass, polished aluminum plates, undulating surfaces, etc.
The 19-story City Gate in Duesseldorf , Germany (1998, H. Petzinka + Fink Arch./Ove Arup preliminary design of structure) consists of 80 m towers with the top three floors connected. The space between forms a 58 m (184 ft) tall atrium with suspended glass curtain facades enclosing the enormous volume. The twisted composition of the rhombuslike arched building adds a daring futuristic image to the city skyline. Exposed are the two triangular trussed framed core towers, which clearly give lateral support to the building. These megacolumns are connected to form three portal frames that is a Z-like bracing system in plan view; they seem to tie the vertical open atrium space visually together. The support of the mega columns is suggested to the outside through the transparent glass skin. The steel pipes of the trussed frames are filled with concrete. Not only the futuristic space atmosphere (which includes air bridges at various levels), but also the highly energy efficient design must be recognized.
The Commerzbank in Frankfurt, Germany, (1997, Norman Foster/Arup) is with nearly 300 m height the tallest office building in Europe. It is the world's first ecological (green) high-rise tower , energy efficient and user friendly. In other words, the goal was an environmentally friendly architecture that is living in harmony with nature and the integration of innovative concepts of energy conservation. Four-story gardens spiral around the gently curved triangular plan with a central atrium serving as a natural ventilation chimney. In other words, fresh air penetrates the central vertical atrium through the winter gardens to provide natural ventilation. The building structure consists of the vertical cores at each of the corners of the triangular plan linked and braced along the perimeter by staggered 8-story Vierendeel frames, which in turn, bridge the 4-story open garden spaces at various levels that are connected to the central atrium shaft. The steel /concrete structure acts as a perforated tube providing the necessary lateral and torsional stability.
In contrast, the monumental Tokyo City Hall (1991) by Kenzo Tange is designed in the postmodern style reminding us of French cathedrals composed with computer chips. The double-tower structure, a 48-story, 243-m high building consists of 6.4-m supercolumns (i.e. shafts) forming a megaframe. The supercolumn is made up of four 1.02-m steel box columns linked by K-braces. The megacolumns are interconnected by 1-story deep belt trusses at the 9th, 33rd, and 44th floors. Column-free space is allowed between the super- columns using twoway beam grids
In contrast, the 18-story, 87-m high N.V. Nederlandse Gasunie in Groningen, 1994, Alberts and Van Huut bv, is more organically shaped. It seems to be the skin, which is constantly in movement under the change of sun and weather. The slender tall building (1:6.69) consists of load bearing concrete walls anchored front to back by two nearly 0.5 m thick (20-in.) diaphragm cross walls. The central foyer is spanned by a 3-story, 2-legged A-frame which carries the central column around which the concrete stair case seems to be suspended and spirals upward thereby articulating the dynamics of space. This complicated, 3-dimensional structure forms the central vertical backbone of the building body. The 60-m glass wall in front appears almost like a waterfall; it is carried by an enormous steel space frame.
THE HUMAN SCALE: low-rise buildings
The next group of buildings represents smaller scale structures articulating similar concepts as before, such as: expressing the assembly character together with lateral bracing, or freedom of form giving from traditional construction, possibly resulting in irrational organization of materials and spaces
The Kandel apartment building, Heidenheim, Germany, 1997, Hoefler Arch., appears like several buildings on top of each other, each one with its own support structure. In other words, the building mass is broken up into different structures. Notice the red column running diagonally all the way up to the roof relaxing the hierarchy of the support structure.
The Information Box is a temporary structure at the Potsdamer Platz in Berlin, Germany, 1995 - 2001, (Schneider + Schumacher), it looks like a container sitting on a forest of columns. The container floats high above the ground and sits on the inclined exposed steel columns suggesting the building support. The window areas indicate large open inside spaces.
The dramatic building massing of the Hamburg Ferry and Cruise Ship Terminal (1994, William Alsop/ Ove Arup) reminds one of shipbuilding construction. The upper building portion and the balcony at the building end are supported by inclined pylons and tie rods reminiscent of the cranes and derricks along the quay side.
Frank O. Gehry's, three building complex (one is clad in metal, one in plaster, one in brick), Neuer Zollhof (1998) in Duesseldorf, Germany, looks like an unstable collage. The walls of the center building have a surface whose shape is much like that of folds of hanging fabric, where the undulating wall is clad in polished stainless steel. It is an example of how computers are required to deal with the complexity of form in designing and building a structure. The architect used the design software Catia to model the distorted and twisted façade walls with window boxes sticking out, which are identical for all three buildings. In contrast to Gehry's Guggenheim Museum in Bilbao where the complex surfaces were formed by skeletons, which were skinned, in the Neuer Zollhof they were solid concrete walls for the middle portion of the building group (but for the 13-story tower concrete frame construction with fill-in masonry walls was used). The walls were constructed from prefab panels (i.e. first Styroform molds, then steel reinforcing and finally concrete) all different from each other using Computer Aided Manufacturing (CAM). In other words, the construction of the houses was approached similar to the production of car bodies or airplane wings.
In the Saibu Gas Museum (1989) in Fukuoka, Japan, by Shoei Yoh, 4 floors are suspended from column shafts from within the building to liberate the ground floor from columns. The design with its central trees articulates an almost poetic expression of industrial technology
The School of Architecture at Lyons, France (1989, Jourda and Perraudin) incorporates a variety of structural forms and materials including arches, trabeation, cross-vaulting bearing walls, glass skins, and fabric membranes. The idea of the architecture is derived from the education of architects. It introduces a vocabulary of materials, details, and construction systems. The building consists of a massive concrete base, an open 2nd floor studio space covered with a timber framed vaulted structure (i.e. inclined radiating glulam timber struts rising to the roof), a central spine covered with a lightweight glass structure and cable trusses, and along the outside a fabric membrane to provide shade. At the junction of the glulam wood members castings are used to articulate the joining between beams and columns.
Nick Grimshaw clearly expresses the structure of the Sainsbury Supermarket Camden Town, London (1988). The main parallel 40-m span frames consist of slightly arched roof trusses suspended from tapered cantilever steel girders, where the flat profiles preclude the benefit from arch action. These girders form the long interior arms of asymmetrical double cantilever beams supported on concrete-filled stunchions, while the short arms project outside beyond the wall cladding where the arches are tied down by back-stays that consist of four 50 mm vertical tension rods.
In contrast, the main structure for the Wilkhahn Factory, Bad Muender, Germany, 1992, by Thomas Herzog Arch., is parallel to the façade (i.e. longitudinal); the building integrates function, construction, ecological concern and architecture. The 5.4 m wide (18 ft) tower structures that contain the offices and service zones, are centered at 30 m (98 ft) and give support to the long spans of the cable-supported beams (24.6 m/81 ft). The formal configuration of the cables (1.5 m deep) convincingly reflects the moment flow of continuous beams under gravity load action. The diagonal bracing of the towers gives lateral support to the post-beam timber structure to resist wind with a minimum effort.
Of exact opposite character is the Vitra Museum, Weil am Rhein, Germany, 1989, Frank O. Gehry: complex building bodies and irrational arrangement of shapes together with distorted geometry and construction cause an exciting space interaction.
In the Palais du Cinema (former American Center in Paris, 1994) Frank Gehry expresses the explosive nature of form and complex geometry, he articulates volumes that seem to tumble out. The inside of the building is as resolved and eroded as the outside (inverse of the outside) almost like medieval urban spaces. The intersection of stairs, corridors, openings, intersecting planes, cause a very dynamic explosive inside space. The complex geometry requires complex hidden structures.
The Hysolar Institute at the University of Stuttgart, Germany (1988, G. Behnish and Frank Stepper) reflects the spirit of deconstruction, it looks like a picture puzzle of a building - it is a playful open style of building with modern light materials. It reflects a play of irregular spaces like a collage using oblique angles causing the structure to look for order. The building consists of two rows of prefabricated stacked metal containers arranged in some haphazard twisted fashion, together with a structural framework enclosed with sun collectors. The interior space is open at the ends and covered by a sloped roof structure. The bent linear element gives the illusion of an arch with unimportant almost ugly anchorage to the ground.
THE COLUMN AS SPACE MAKER
The next group of slides addresses the COLUMN as space makers, or demonstrates the effect of the building SECTION as a controlling design determinant rather than solely considering the DOGMA OF THE PLAN. Column types include slender and stocky ones, compression and tensile columns, straight and inclined or branched columns, but they all are space makers.
The Netherlands Architectural Institute in Rotterdam (1993, Jo Coenen) is clearly divided into several sections. The concrete skeleton dominates the image supplemented by steel and glass. The main glazed structure appears to be suspended, and allows the concrete load-bearing structure behind to be seen. The high, free-standing support pillars and the wide-cantilevered roof appear more in a symbolic manner rather as support systems.
Art Museum, Wolfsburg, Germany, 1993, Peter Schweger Arch.: the building floats intospace. The building is laid out on an approximately 8.10 x 8.10 m (27 x 27 ft) grid and is further subdivided into 1.35 m (4'5" ) square bays. The plaza seems to reach/move into the building - the building is naturally grown allowing the interaction of building and urban space, where the diagonal access ramps/stairs forming the connecting element (i.e. entrance at building corner). The interaction of the building is especially articulated by the thin cantilevering roof at 19 m (62 ft) height carried by the slender columns. The building gives a feeling of openness and and permeability. The logic of construction, transparency, lightness, quality of detail all transmit a sense of clarity (i.e. no deliberate confusion as in some of the other cases).
Axel Schultes, the architect for the City Museum, Bonn, Germany (1992) calls the building the house of light. The curved flat roof sits on a forest of irregularly arranged columns. The grouped columns seem almost to generate a human quality in articulating space rather than supporting the roof, the columns seem to penetrate through the roof.
The 300-m long oval-shaped Grand Palais, Lille (1995, Rem Koolhaas/ Ove Arup for structures), is divided into concert hall, conference center, and exhibition halls. Koolhaas uses exposed concrete surfaces and a great deal of plywood and plastic to reduce the costs. The combination of unusual materials and unexpected angles seem to reflect an anti-poetic mood (a punk-like aesthetics) and redundancy of structure. The structure takes the place of language and reflects only the illusion of support (e.g. arch vs. columns, and hanging columns or tension ties to reduce bending moment at center span). Notice the stairs as an important architectural element.
For the multi-bay structure of the shopping center near Nantes, France (1988, Rogers/Rice) 94-ft (29 m) high tubular masts, spaced at 47 ft (14 m), support the roof framework in a spatial fashion from above without penetration of the roof. Only certain combinations of the 3-dimensional network of rods and struts are activated under various load actions. Under wind uplift, the tensile rod-strut system forms an inverted Vshaped truss.
An example of Rogers’ first stayed structures is the Patscenter in Princeton, USA (1984, Rogers/Rice). The building consists of parallel planar guyed structures along the central spine consisting of c.9 m wide portal frames set 11 m on center that support on top c.15-m high A-frames which consist of inclined pipe columns connected to a large ring plate from which are suspended steel rods to other ring plates on each side of the spine. Inverted truss action is required for wind uplift where the central hangers act in compression, hence had to be tubes.
The immense, c.153-m span roof of the beautiful Lufthansa Hangar at the Munich Airport, Guenter Buechl + Fred Angerer Arch., 1992, is supported by the diagonal cables suspended from the c.56-m tall concrete pylons
The Renault Center, Swindon, U.K. (1983) by Norman Foster and Ove Arup is a spatially guyed structure. Truss-like portal frames are placed along the 24 x 24m (79-x79-ft) square bays, but also along the diagonal directions. Rods are suspended from the top of the 16-m (53-ft) high tubular steel masts in the orthogonal and diagonal directions to support the tapered portal beams at their quarter points. In the center portion the sloped beams are cable-supported from below. The cable configuration follows the moment diagram of a multibay portal frame with hinged basis under uniform gravity loading by efficiently resolving the moment into compressive and tensile forces. The slender tubular columns are laterally braced with four prestressed rods that are connected to their sloped beams thereby providing a moment connection.
Whereas before, the cables supported a rigid cylindrical roof structure, in the Schlumberger Research Center, Cambridge, UK (1985, Hopkins/Hunt) it is a spatial domelike undulating tensile fabric membrane. The ship like masts and rigging as well as its high level technology and detailing reminds one of Roger's earlier work. The central portion of the building is subdivided by four parallel exposed portal steel frames into three bays, each 24 x 18 m (79 x 59 ft) in size. It consists of horizontal 24-m (79ft) open triangulated truss girders and nearly 8-ft (c.2.5 m) wide vertical trusses which support two pairs of upper and lower booms. The two inclined upper tubular masts are supported by tie rods, which are braced by lower masts (struts). Cables are suspended from the masts to give support to two parallel ridge cables at certain pick-up points. The translucent Teflon coated fiberglass membrane is clamped and stretched between ridge cables and steel work.
Quite different in spirit are the slender and minimal abstract planar, tree-like c.30-m (100-ft) high masts for the Horst Korber Sports Center in Berlin, Germany (1990, Christoph Langhof) with their five branches linked by cables from which the light cable roof trusses are hung but only on one side (i.e. asymmetry). The symmetrical abstract forms of the masts are completely opposite in expression from the tectonic shapes of most of the other examples which have been shown, they don't seem to give support.
The huge steel trees of the Stuttgart Airport Terminal, Stuttgart, Germany (1991, von Gerkan & Marg, Schlaich) with their spatial strut work of slender branches give a continuous arched support to the roof structure thereby eliminating the separation between column and slab. The tree columns put tension on the roof plate and compression in the branches; they are spaced on a grid of about 21 x 32 m (70 x 106 ft).
a.
b.
c.
THE
TECTONICS OF CONSTRUCTION
The tectonic organic world of structural resistance has become quite fashionable especially with the architect/engineer Santiago Calatrava. He is fascinated with how the structure works and how the loads are carried to the ground, which he demonstrates by articulating its tactile quality and the organic nature of the skeleton comprised of sculptural, bony-shaped elements asymmetrically arranged. He is concerned with the logic of material and the beauty of the section, he emphasizes the dynamics of structure by making the potential movement of forces visible. He achieves that by expressing the unbalance of forces.
The supporting cantilever frames of the glazed canopy structure of the Stadelhofen Station, Zurich, Switzerland (1990, Santiago Calatrava) capture movement. The columns seem to be just caught in time by the vertical struts. In other words, it seems as if the cantilevers are on the verge of rotating by articulating the hinge like tubular beam and by letting the slanted columns be just caught on time by the vertical struts. They are surely influenced by biological forms where the steel profile of the tapering members suggests a tectonic presence, frozen suspension and almost organic joints. The sword-like steel plates of the cantilever beams carry the glass roof and are welded to a continuous 12 cm (5 in.) dia. steel tube that acts as a beam and torsion ring to transfer the loads to the inclined, branching Y-columns of triangular crosssection which, in turn, are stabilized by vertical hinged pendulum columns. The 2-legged composite columns are spaced at almost 6 m (20 ft).
The Public Library in Munster, Germany (1993, Bolles + Wilson) is divided into two sections connected by a bridge. The asymmetrical, inverse A-frame not only carries the sculptured roof structure but also provides a vigorous energy and dynamics to the urban space.
The grandstand of the Charlety Stadium at the Cite Universitaire in Paris (1994, Henri and Bruno Gaudin) is brought alive by its organic and tectonic presence. From the highly articulated slanted concrete buttress piers is cantilevered the stayed steel canopy on top and the upper seating below. The play between tension and compression, between force resolution at the joints and stress concentrations in the members is forcefully articulated. From the inclined, 50-m high corner light masts at the lower level a conical Teflon membrane is suspended to give lateral protection to the grandstand.
SPANNING
SPACES
WITH ARCHES
This collage type visual study introduces the next theme that of the structure as span, in this case achieved through the A R C H; it attempts to articulate the spirit of the support structure resisting lateral thrust, in other words the tectonics of construction.
This collage type visual study introduces the next theme that of the structure as span, in this case achieved through the arch; it attempts to articulate the spirit of the support structure resisting lateral thrust, in other words the tectonics of construction.
The lateral thrust
The curved roof of the Kansai Air Terminal (1994) by Renzo Piano (and Peter Rice for structures) spreads over an artificial island like a glider. The irregular roof curve consisting of arcs of different radii, is shaped by the aerodynamics of the largescale air jets ventilating the whole space, that is the regulation of air movement. The three-dimensional, triangular truss-arches span 83 m and have a total length of 150 m each is supported by inclining columns and by vertical columns at the curb; the arches seem barely connected the building.
The column supports at the Novotel Belfort, Belfort, France (1994, Bouchez), almost seem human and express how effortless the arch action is transferred down to the ground.
The visually dominant arches of the new Leipzig Fair, Leipzig, Germany, 1996, (van Gerkan+Marg Arch, Ian Ritchie Arch. for glazing, Polonyi Struct. Eng.), make a strong statement and remind one of the glass and iron architecture of the 19th century (e.g. Crystal Palace, Galerie des Machines in Paris, 1889). The hall is about 243 m long, has a clear span of 80 m (262 ft), and 30 m (98 ft) up to the vertex. The primary system consists of the trussed triangular arches that contain a service walkway, and where the top chords span across the adjacent service roads. The sole purpose of the arches is to give lateral support to the tubular steel grid vault through its steel outriggers. The depth of the arches varies from 4 m at the crown to 10 m at the ground. The steel grid vault is formed by 3.125 x 3.125 m (appr.10 x 10 ft) cells, from which is suspended by frog fingers the glass vault beneath. The glass panes are approximately 3.1 x 1.5 m and are joined with silicone. It is the largest suspended glass shell in existence today.
Oguni Glass Station, Kumamoto Pref., 1993, Shoi Yoh Arch., is a small gas and service station covered with a unique glass canopy suspended from arched concrete frames. The thin glass membrane of glass plates with an inlayed layer of perforated aluminum sheet comes alive with sparkling brilliance when the sun shines through it.
The 100-m span tied arch Japan Bridge in Paris (1993, Kisho Kurokawa) consists of the two main inward leaning tubular steel arches, the walkway of triangular precast concrete panels covered by a curved glass enclosure, and the support of the arched spatial cable-strut network. The walkway and glass enclosure are suspended from the arches. The lateral arch thrust is taken by the cable-strut network at the base. Torsion due to lateral loads is efficiently resisted by the triangular cross-section of the bridge (i.e. torsion box).
Kempinski Hotel, Munich, Germany, 1997, H. Jahn/Schlaich: the elegance and lightness of the the 40-m (135-ft) span glass and steel lattice roof is articulated through the transparency of roof skin and the almost non-existence of the diagonal arches which are cable- supported by a single post at their intersection at center span. This new technology features construction with its own aesthetics reflecting a play between artistic, architectural mathematical, and engineering worlds. The depth of the box arches is reduced by the central compression strut (flying column) carried by the suspended tension rods. The arches, in turn, are supported by tubular trusses on each side, which separate the roof from the buildings.
The Munich Airport Business Center, Munich, Germany, 1997, Helmut Jahn Arch. Ove Arup Eng.: also is an open public atrium as transition between building blocks or walled boundaries to form a square which is covered by 6 arch-supported membrane leaves. In other words, a transparent roof is carried by spatial triangular column frames. Here a minimum of structure gives a strong identity to space.
The Satolas Airport TGV Train Station, Lyons, France (1995, Santiago Calatrava) consists of the big entrance hall and the long naves. The 40 m high (131-ft), 100 m wide, 120 m long entrance hall appears like a huge sculpture reminding us of a bird or butterfly that has a triangular plan with asymmetrical cantilevers. Here, the central spine is a 90-m (295-ft) span 3-dimensional arched torsion ring steel truss with a variable triangular cross-section where the two tubular bottom chord arches are anchored in immense single-fluted concrete thrust blocks or buttresses (one in front and two at the buildings rear) that look like animated. Steel ribs laterally brace the huge curtain wall box columns, which also carry most of the cantilever wing weight. The columns, in turn, rest on massive concrete arches on each side, which carry most of the building weight. The bird consist of 1300 tons of steel resting on the two concrete arches. The heavy closely set black steel members seem over structured because of the density of the layout. The oversized members obscure the relationship between the structure of the roof and the support of the glazing.
The long naves over the 3-bay track level are covered by 53-m (174-ft) wide lamella vaults of slender ribs on a c. 9-m (30-ft) structural bay. Each of the three vault segments rests on the apex of two triangular concrete supports (i.e. the side walls are rows of multi-faceted V- shaped concrete columns). The middle tracks are for through trains that move over 300 km/h requiring careful calculations of shock waves. The thrust of the vault at the middle segment is released by the box at the core, i.e. the triangular supports at the middle part of the vault are tied together at lower level creating an enclosed box tunnel at the core of the station. The lattice like barrel vaults can also be visualized as diagonally intersecting two-way arches, or almost like a triangular folded plate membrane with a maximum of material removed, leaving only folds. The roof panels are either glazed (clear), opaque (concrete panels) or left open, creating defused light and mystical spatial qualities. The wings are clad in reflected aluminum. The long naves represent a spectacular vaulted space, airy, translucent, with an effortless organic fluidity and lightness.
How opposite in spirit is the delicate roof structure of the Lille Euro Station, Lille, France (1994, Jean-Marie Duthilleul/ Peter Rice) consists of two asymmetrical transverse slender tubular steel arches (27 cm or 10.75-in dia., set at about 12 m or 40 ft on center) braced against buckling by deceitfully disorganized ties and rods; this graceful and light structure, in harmony with the intimate space, was not supposed to look right. A series of slender tubes are supported on arches which, in turn, carry the approximately 1.8 m (6-ft) deep longitudinal cable trusses that support the undulating metal roof. The support structure allowed the gently curved roof almost to float or to free it from its support, emphasizing the quality of light.
GLASS STRUCTURES
The next topic addresses briefly glass-skin structures, or glass as a structural material, where many of them are tension supported. Here the tensile glazing support structure becomes part of the glass skin; the traditional nonstructural members of glass and sash become structural. Special, non-conventional details are used as based on forging, casting, and machining steel. The glass weight is transferred across star-shaped (e.g. H-, or X-shaped) castings to vertical tension rods or each panel is hung directly from the next panel above. Vertical or horizontal cable-truss systems give lateral support to the glass wall. The glass panels are glued together with silicone, which makes them quite rigid so that racking movement is allowed in the sliding of the bolt connections to the star-shaped castings. Some typical examples are:
Shopping Center, Dalian, China
Xinghai Square shopping mall, Dalian
Museum of Science and Technology, Parc de la Villette, Paris (1986), Fainsilber/Rice).
three monumental greenhouses equivalent to a 10-story building that are attached to the south side of the museum
The development of suspended glass skins has been significantly influenced by the glass walls for the three monumental greenhouses equivalent to a 10-story building that are attached to the south side of the Museum of Science and Technology, Parc de la Villette, Paris (1986, Fainsilber/Rice). The tower like structures are about 32 m wide by 32 m high and 15 m deep. They capture and store heat for the museum. The glass wall is subdivided into 16 approximately 8-m square (27-ft) modules, which form the basis for the primary stainless steel tubular frame which is laterally supported against wind by cable trusses. Each of the 8-m (27-ft) square modules consists of sixteen 2-m square glass sheets laterally supported by a secondary system of horizontal cable beams (tension mullions), which are stabilized by the glass. The glass panels are suspended from the main frame. They are attached to each other with clear silicone sealant and are joined at the corners by a molded steel fixing that allows movement and reduces stress concentrations. The glass weight is transferred in tension from the lower to the upper panels and is hung from the main frame beam by prestressed spring devices that act as shock absorbers and allow readjustment in case of unusual loading.
The composition and materials of the massive skeletal support structure for the glass houses in the Parc AndreCitroen, Paris (1992, Patrick Berger/ Peter Rice) remind one of the past in contrast to the language of the minimal glass walls. The 15-m high portal frames are cladded in wood and stone (spaced at 15 m) and are connected by edge beams at the roof level. The glass walls seem to be independent of the internal support structure and are suspended from the top edge beam by spring connections as in the Museum of Science, La Villette. The connections act as solid support under normal loads but as shock absorbers under shock (over) loads to prevent accidental damage to the glass. The glass walls are laterally supported by the primary vertical cable trusses adjacent to the steel columns (which also provide the connection to the building skeleton) and the secondary horizontal lens-shaped cable beams with a central spine compression member that resists the tension in the cables. Vertical cables resist the buckling of the horizontal trusses vertically..
An extraordinary complex spatial steel framework supports the glass skin of the 22-m (71-ft) high, 35 x 35 m (115 x 115 ft) Pyramid at the Louvre in Paris (1989, I.M. Pei/ Roger Nicolet). Here, stainless steel bowstring trusses form a two-way diagrid structure on each plane of the structure. In other words, sixteen crossed beams of different lengths are placed parallel to the diagonal edges. By extending the truss struts, the aluminum mullion frame is supported. To prevent the outward thrust of the pyramid and to stabilize and stiffen the shape, the four faces are tied together by 16 horizontal counter cables (i.e. belts) in a third layer thereby bracing and stressing the diamond-shape network. In their search for visual lightness the designers developed a difficult layout of structure, which reflects a celebration of structural complexity and still achieving the goal of transparency and an almost immaterial lightness with its thin member fabric.
NEW DIMENSIONS OF
STRUCTURES
As conclusion I like to present three cases that represent truly the new dimension of structures. With the elliptical glass atrium hall of the Tokyo International Forum, (1997), Rafael Vinoly together with the structural engineer Kunio Watanabe express true structural originality. The unique 208-m long roof structure that is about 31.7 m wide, resembles an exposed ship hall or prehistoric structure which floats 60 m above the ground and together with the suspended lightweight ramps and bridges reflects an almost medieval cathedral like impression.
The main span of the roof structure which is about of 12-m depth at mid-span, consists of a pair of 1.2- m φ tubular inclined steel arches that span 124 m between the columns and curve up in half-arches in the cantilever portion. A series of 16 tension rods inversely curved to the compression arches complete the beam action. The layout of the compression arches and tension rods that follow directly the bending moment diagram under gravity load action of a beam with double cantilevers, are separated by 56 curved steel arch-ribs which also support the roof beams. The glass walls are supported laterally by 2.6-m deep free-standing vertical cable trusses which also act as tie-downs for the spatial roof truss.
The parabolic spatial roof arch structure with its 42-m cantilevers is supported on only two monumental conical concrete-filled steel pipe columns spaced at 124 m. The columns taper from a maximum width of 4.5 m at roughly 2/3 of their height to 1.3 m at their bases and capitals, and they are tied at the 4th and 7th floors into the structure for reasons of lateral stability.
As impressive, possibly more heroic is the TGV Station, Paris-Roissy (1994, Paul Andreu/ Peter Rice). Here, the roof is freed (separated) from the structural support, it seems to float above the walls - they never touch. It consists of parallel crescent-shaped transverse trusses (48 m or 156ft span, 4 to 7 m or 13 to 23 ft deep) of triangular crosssection. The two 36 cm or 14-in. dia. bottom chords form an arched ladder where the members merge at the ends (i.e. lens-shape) and are connected by the diagonal ties and slender vertical tubular web members to the horizontal solid rods of the top chord which are prestressed to keep them in tension. The trusses are hanging at the top chords near the center-span from asymmetrical tree columns on concrete pylons in the longitudinal direction. The truss ends are pulled down by prestressed vertical tension rods to control truss movement. The concrete pylons are located between the trusses so that the bottom chords seem unsupported. A further confusion is caused by the heavy suspended arch and the thin horizontal tie, which should be the other way around according to conventional thinking, but the truss is not simply supported at the ends as the form suggests. The main trusses support longitudinal triangular steel trusses which, in turn, carry the orthogonal steel grillage with glass panels.
The glass wall is laterally supported by vertical tubular cantilever masts with cantilever arms and are spaced at 4.75 m; the glass panels are hung from the cantilever arms. The masts are as much as 17 m high and are braced by pretensioned cables against twisting. The building column grid is offset from the trusses and vertical tension rods to avoid the impression that the roof is hanging or the masts carry the roof.
I like to conclude my presentation with La Grande Arche, Paris (1989, Johan Otto von Sprechelsen/ Peter Rice for the canopy) where the architecture masterfully interweaves the spontaneity of the moment and technology as reflected by the tensile roof and elevator tower, with the symbolism of the giant arch, a modern version of the Arc de Triomph. La Grande Arche is a giant nearly 110 m hollow cube. The 35-story side buildings are bridged by 3story frame beams at the top. The primary structure of each of the about 18-m wide side buildings consists of four post-tensioned concrete megaframes tied together every seven floors and stabilized by diagonal walls at the corners thereby forming nearly 21 meter squares in elevation. The frames and walls rest on neoprene cushions, the only movement joints, on top of huge caissons.
The floating, tensile textile membrane over the base reflects the lightness and spontaneity of the cloud and contrasts the perfect geometry of the giant cube thereby introducing a human scale besides providing shelter and improving wind conditions. The complex cloud structure consists of diagonally cross-braced parallel lensshaped cable beams prestressed against free-form edge cables. The translucent fabric membrane is stressed against the underside of the cable beams and also supported by small flying struts at the center of the meshes. The composite prestressed structure is suspended from the walls of the cube. The free-standing nearly 92-m (300-ft) high cable-braced steel lattice elevator tower is anchored laterally to the building with horizontal guyed columns.
The architecture clearly demonstrates that there can be harmony between the preservation of the past and the inventions of the present, and that they do not necessarily represent opposite positions.
