Systematic Centre Pompidou
The team's architectural intention was to provide a large degree of flexibility, an open plaza area as a vital extension of the interior functions, and long building facades that would be "information surfaces." The street side would display traffic-related data, and the plaza side would present entertainment and information to pedestrians.
The building would be turned inside out, thus liberating the interior spaces from the permanent accommodation of circulation and servicing. And it would estrange itself from the historic character of its urban context in every way imaginable: scale, height, form, and expression. Reintegration with the cityscape would rely on attractive differences rather than soft-edged harmony.
The building portrays its own datum — spreading vertical circulation components across the length of a pedestrian plaza on the west side and its mechanical workings across the long east street side elevation. This public display of components is framed by an exposed steel skeleton and diagonal bracing.
The external display of structure and services is actually generated by programmatic requirements for flexibility of the interior spaces. These machine infrastructures were moved outside the glass skin to leave unobstructed and adaptable interior volumes. The exterior zone of the structural frame is there to provide tension forces outside the main volume's external columns, pulling the cantilevered horizontal members downward to reduce the bending forces on the floor span.
This complementary structural strategy eliminates the need for supporting columns across the unencumbered interior span of 157 feet (53.3 meters). The mechanical and air-conditioning services are then placed in the exoskeletal frame, leaving the interior open and adaptable.
Public access to the museum areas is not from the escalator tubes, as the building exterior seems to suggest, but from doors located centrally at the lower edge of the plaza. A double-height interior forum connects the street level with the plaza level in a single volume. This room contains the general reception area, retail facilities, and temporary exhibits on the plaza level.
The street-level mezzanine of the forum holds an exhibit area with a cafe to the south of the double-height entry reception, plus a large theater to the north. The plaza-level reception area also looks down into a performance-level basement where a theater and meeting rooms are situated.
From ticketing booths on the plaza level, an interior escalator takes visitors to the street level on the northwest corner of the building. Here, a small lobby connects to elevators and the exterior escalator. At this point in the journey, visitors can already look down 46 feet (14 meters) onto the plaza. Four elevators are located at this corner.
In reality, the escalator serves only the mezzanine, level four, and level six. Horizontal circulation platforms occur inside the frame — most of them restricted to staff access and emergency exits.
Critical Structural Issues
Above grade are six floors of 23-foot (7-meter) floor-to-floor height spanned by 9.3-foot- (2.8-meter-) deep lattice trusses. In plan, the superstructure of the building consists of three zones. The middle zone contains the 157-foot (48-meter) clear span across the building interior between the main columns.
The outside two zones make up structural wall frames to support and cantilever the main span lattice girders. These outer frames visually resemble oversized scaffolding. The inside wall frame support consists of 34-inch- (850-millimeter-) diameter steel tube columns.
Outer tension-rod members of 7.9-inch (200-millimeter) solid steel in the wall frame act to reduce the bending moments on the center of the span by producing a 19.7-foot (6-meter) cantilever outside the main columns. This cantilever force acts through horizontal 9.6-ton (8700-kilogram) cast steel gerberette beams that are threaded around the main columns.
Compression forces in the top chord of the long-span lattice trusses are thus transferred through the main columns without acting on them laterally or torsionally. Instead, the compressive shortening forces in the trusses move through the gerberettes and are transferred in tension down the outer frame wall rods to the foundation. Consequently, rotational forces on the columns are greatly reduced, and they are required to act only in pure compression.
The frame is stiffened laterally by cross bracing in the vertical plane across the long facades attached to the ends of the gerberette beams. Stiffening in the other vertical plane is added by diagonal braces between the lattice girders on both gable walls.
Envelope and Mechanical
Walls on all the elevations are held back 5.3 feet (1.6 meters) from the columns and gable trusses to distance the structure from potential fires. In addition, glass wall frames are fitted with metal roll-down shutters, which are activated by fire to protect the external structure from heat coming from an inside fire. The shutters can also be operated manually for solar control.
Heavy equipment — boilers and chillers of the building's central plant — is located in the basement of the building. The services are distributed vertically within the east wall frame to equipment on the lower levels and finally to the roof-level air-conditioning plants and cooling towers. Some horizontal distribution occurs across the east facade, where trumpeted air vents are clearly visible.
There are no permanent partitions on any of the floors, but a relocatable, bolted-together two-hour firewall divides each typical level into two zones of less than the allowable 106,000 cubic feet (3000 cubic meters) compartment size. The trusses were all designed to carry a bolt-on system of demountable mezzanines, but because of client disinterest, few of them were ever deployed.
Turning the building inside out was the most successfully realized architectural intention. The wall frames, with their captured servicing and movement systems, are unavoidably read as the corpus of the building. Static monumentalism is out; dynamic servicing and flexible floor space is in. The envelope hardly exists as a statement of this high-tech architecture, except in its transparency.
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Leonard R. Bachman teaches at the University of Houston's Gerald D. Hines College of Architecture. He is director of the college's simulation and modeling lab and a registered architect and technical consultant.
This article is excerpted from Integrated Buildings: The Systems Basis of Architecture, copyright © 2002, available from John Wiley& Sons and at Amazon.com.