High-tech and structural expression

Dr. Arslan meets the class in the middle of the Esplanade Riel, the pedestrian bridge across the Red River between downtown Winnipeg and Saint-Boniface, completed in 2004 to a design by Étienne Gaboury. A single tall pylon rises from the middle of the river, and a fan of steel cables runs from its top to the deck, holding it up. 'Look at the cables,' she says. 'You can see exactly how this bridge works. The deck wants to fall; the cables pull it up; the pylon is pushed down into the riverbed; the back-stays balance the pull. Nothing is hidden. For some architects, that is not just engineering. It is the most honest kind of beauty.' Callum, who has been drawing the cables, says it looks like a harp.

High-tech architecture, sometimes called structural expressionism, is the name for buildings that display their structure, services and technology as the main source of their architectural character. It emerged in Britain in the late 1960s and 1970s, and its leading figures, Norman Foster, Richard Rogers, Renzo Piano, Nicholas Grimshaw and Michael Hopkins, built some of the most famous buildings of the late twentieth century. It continued a long tradition of structural thinking that runs from Gothic cathedrals through the iron and glass of the nineteenth century, and it shaped the work of engineers who became celebrated in their own right.

Sources: the machine aesthetic and Banham

The idea that architecture should express the technology of its time goes back at least to the nineteenth century. Viollet-le-Duc, the French architect and theorist whose writings you met in ARCH-121, argued that Gothic architecture was a rational system of structure and that new materials such as iron demanded new forms. The Crystal Palace of 1851, the great railway sheds and the Eiffel Tower were admired by early modernists as engineering without architectural pretence. Le Corbusier's Towards an Architecture of 1923 praised ships, airplanes and grain elevators as models of form shaped by purpose.

In the 1960s, the critic Reyner Banham revived and redirected this tradition. In Theory and Design in the First Machine Age (1960), he argued that early modernism had betrayed its own enthusiasm for technology by freezing it into a white, static style. In The Architecture of the Well-Tempered Environment (1969), he argued that environmental services, heating, ventilation, lighting and air conditioning, had become as important to architecture as structure, and that architects should design with them openly rather than hide them in ceilings. The drawings of Archigram, which you met in Lesson 2, and the work of the American engineer and inventor Buckminster Fuller, gave younger architects images of a lightweight, adaptable architecture of frames and plug-in parts.

Kahn: served and servant spaces

An important idea came from an architect who was not high-tech at all. Louis Kahn, designing the Richards Medical Research Laboratories at the University of Pennsylvania (1957 to 1965), separated what he called served spaces, the laboratories where people work, from servant spaces, the towers that held stairs, exhaust ducts and supply ducts. The servant towers stand outside the laboratory blocks, in brick, and give the building its silhouette. Kahn's distinction became a basic tool of architectural thinking: identify what serves and what is served, and give each its proper place and expression.

The Pompidou: a building turned inside out

The first great high-tech building was the arts complex in Paris named after President Georges Pompidou, designed by Renzo Piano and Richard Rogers with the engineering firm Ove Arup and Partners, especially the engineer Peter Rice. Piano and Rogers, then young and little known, won an international competition in 1971 against nearly seven hundred entries, and the building opened in 1977. Its idea was radical: to provide huge, completely open floors for a library, a museum of modern art and an industrial design centre, by moving everything else outside.

The structure is a steel frame of columns and long trusses spanning about 48 m (157 ft), connected to the columns by cast steel brackets called gerberettes, which project beyond the columns and carry tension rods at their outer ends. The services, air ducts, water pipes and electrical conduits, run up and across the back façade, painted in a code that identifies each system. On the front, escalators in glass tubes climb diagonally across the façade, carrying visitors to the top with views over the city. Parisians were shocked; critics called it an oil refinery. It became one of the most visited buildings in France, and the sloping square in front of it became one of the liveliest public spaces in Paris.

Foster and Rogers in the 1980s

In the 1980s high-tech became the architecture of finance. Richard Rogers's Lloyd's building in London (1978 to 1986), for the insurance market, has a central atrium surrounded by trading floors, with six service towers of stainless steel outside, containing stairs, lifts and toilets, and with cranes left permanently on top for maintenance. Its outside is a forest of pipes, ducts and gleaming steel, and inside it is a calm, top-lit hall.

Norman Foster's headquarters for the Hongkong and Shanghai Bank in Hong Kong (1979 to 1986) was at the time one of the most expensive buildings ever built. Instead of a central core, it has eight groups of steel masts at the sides of the building, from which floors are hung on giant trusses at five levels, so that the banking hall can rise as a tall atrium through the middle. A sunscoop of mirrors reflects daylight down into the atrium. Many components were prefabricated in different countries and shipped to Hong Kong. Foster's earlier Willis Faber and Dumas building in Ipswich, England (1975), with a black glass wall that follows the curve of the medieval street pattern, a swimming pool and a roof garden for the staff, showed that high-tech could also be humane.

Lightweight structures: Fuller and Otto

A parallel line of thought aimed at doing more with less material. Buckminster Fuller's geodesic domes, built from short struts arranged on the surface of a sphere, could enclose enormous volumes with very little material. His United States pavilion at Expo 67 in Montreal, a dome about 76 m (250 ft) in diameter originally covered in acrylic panels, still stands on Île Sainte-Hélène as the Biosphère, though its skin burned in 1976. The German architect and engineer Frei Otto developed tents and cable nets, finding their shapes by experiments with soap films, chains and fabric models. With Rolf Gutbrod he designed the West German pavilion at Expo 67, and with Günter Behnisch the roofs over the Olympic stadium and arenas in Munich (1972), a vast cable net covered in transparent acrylic panels. Otto was named the Pritzker laureate in March 2015, an announcement brought forward because he had died the day before.

Lightweight structures are an argument as well as a technique. They suggest that architecture should use resources sparingly and that structural efficiency is a form of beauty. The same argument runs through the work of the Spanish engineer and architect Santiago Calatrava, whose bridges and stations of white steel and concrete are shaped like skeletons and wings, and through the work of engineers such as Cecil Balmond and Jörg Schlaich, whose collaborations with architects made new forms possible.

# A cable carrying a uniform load hangs in a parabola.
# Horizontal pull H = w * L**2 / (8 * f): less sag means far more pull.
w = 2.0       # load along the span, kN per m (illustrative)
L = 60.0      # span, m

for f in (12.0, 6.0, 3.0, 1.5):    # sag at mid-span, m
    H = w * L**2 / (8 * f)
    V = w * L / 2                    # vertical reaction at each support
    T = (H**2 + V**2) ** 0.5         # tension at the supports
    print(f"sag {f:4.1f} m: span/sag {L / f:4.0f}, horizontal pull {H:6.0f} kN, support tension {T:6.0f} kN")

sag 12.0 m: span/sag    5, horizontal pull     75 kN, support tension     96 kN
sag  6.0 m: span/sag   10, horizontal pull    150 kN, support tension    162 kN
sag  3.0 m: span/sag   20, horizontal pull    300 kN, support tension    306 kN
sag  1.5 m: span/sag   40, horizontal pull    600 kN, support tension    603 kN

The script shows why cable structures look the way they do. Halving the sag doubles the horizontal pull, so a very flat cable needs enormous anchors or masts to hold it. Designers of cable roofs and bridges choose a sag that balances appearance, height and the size of the supports. When a building expresses its structure, it also expresses choices like this, and a trained eye can read them.

From high-tech to eco-tech

From the 1990s, many high-tech architects turned their skills toward environmental performance, sometimes called eco-tech. Foster's Commerzbank tower in Frankfurt (1997) has sky gardens spiralling around a triangular atrium that ventilates the offices naturally. His dome over the restored Reichstag in Berlin (1999) has a mirrored cone that reflects daylight into the parliament chamber and draws stale air out. Renzo Piano's Jean-Marie Tjibaou Cultural complex in Nouméa, New Caledonia (1998), uses tall timber shells inspired by Kanak huts to catch the trade winds. The technology is still expressed, but now it serves climate as well as flexibility. You will study this shift in Lesson 9.

Criticisms of high-tech

High-tech has been criticized on several grounds. Its buildings were often very expensive, and exposed services are costly to maintain, clean and replace; the Pompidou needed a major renovation within twenty years, and another long closure for renovation was planned from 2025. Steel and glass buildings with large exposed frames can lose heat and gain sun, which had to be countered with energy-hungry plant. Critics have also argued that high-tech often expressed technology as an image rather than a necessity: a tube or truss placed outside because it looks technical, not because it works better there. Defenders reply that the best high-tech buildings delivered real flexibility, light and public space, and that their honesty about how buildings work is an educational value in itself.

Exercise 6: structure you can read

This exercise takes about three hours.

• Find a building, bridge or canopy in your city whose structure is visible.
• Draw it in elevation and section, and draw arrows showing how loads travel to the ground.
• Identify each part as working in tension, compression or bending.
• Deliverable: one page with drawings, load arrows and a paragraph judging whether the structure is expressed honestly or only as an image.

Self-critique checklist

• Have I traced every load from the roof or deck to the ground?
• Have I identified which members are in tension and which in compression?
• Have I noticed what is hidden as well as what is shown?
• Have I considered how the exposed elements are protected from weather and fire?