Peter Zumthor’s David Geffen Galleries is a reinforced-concrete structure supported on seven 10m-high pavilions, spanning 50m across Wilshire Boulevard
Los Angeles, as Hal David and Burt Bacharach once pointed out, is a “great big freeway”, so it seems fitting that the city’s new $715m art gallery works both as statement building and highway infrastructure. Designed by Swiss Pritzker prize-winning architect Peter Zumthor, the David Geffen Galleries for the Los Angeles County Museum of Art is a reinforced-concrete structure supported on seven 10m-high pavilions.
Its main exhibition space is 300m long and spans 50m across the four-lane Wilshire Boulevard. Chris Bell, project executive at main contractor Clark Construction, describes the structural design as more akin to a box girder bridge system than a typical building.
The Geffen Galleries, which open in April, will house LACMA’s permanent collection of more than 150,000 objects, and contains 26 standalone gallery spaces, as well as a shop, restaurant and auditorium, all on a single level. “The horizontal single-level design eliminates traditional cultural hierarchies, placing all works of art on the same plane,” says LACMA. It also meant that the floorplan quickly burst out of its original site, requiring the bridge across Wilshire Boulevard to an additional plot on the other side.
The resulting structure covers more than 1.5ha. It curves and cantilevers up to 25m beyond its supporting pavilions, and has no internal columns. A continuous band of glazing wraps around the exhibition level between the solid bands of the floor and roof slabs. These are actually box girders, which conceal all of the services, allowing the concrete soffits and walls to be exposed and almost entirely uninterrupted.
Clark and Zumthor worked through more than 100 samples and two full-scale mock-ups to define the precise specification of the concrete. Different formwork finishes, including MDO and HDO plywood, phenolic plywood, high-density polyethylene (HDPE), and extruded plastic, were used to produce distinct surface characteristics. The board layouts follow a precise pattern throughout – notably, the soffit has an equilateral triangular joint pattern that fits together perfectly from the north to the south tip of the building, coordinating with all of the lighting, sprinklers and air ducts.
The structural design was hugely challenging, not least because of the seismic threat in LA and the underlying ground conditions, which contained high levels of tar. This meant that the soil characteristics could change metre by metre. As a result, 1,500 ground-stabilising vibro piers and 450 rotating helical piles were need to support the structure.
To make the building earthquake-resistant, each of the building’s 10 concrete cores rests on four 18-tonne isolators, which separate the structure from the foundations, allowing it to move laterally up to 1.5m in any direction. This also meant that the horizontal structure could be cast as a continuous slab with no movement joints – during the curing process, the isolators at either end of the building were unlocked to accommodate shrinking and alleviate stress.
The slabs, ribs and walls are all post-tensioned, in a structural system that contains some 360 miles of sheathed PT cables. The cables converge on the roof, where they were pulled tight by a hydraulic jack, lifting the cantilevers like a suspension bridge.
This vast building contains about 65,000m3 of concrete and 15,000 tonnes of rebar. Skidmore Owings & Merrill, the architect of record, has measured the building’s embodied carbon as 518.25kgCO2e/m2.
The structure also helps to reduce operational carbon in LA’s harsh desert climate. The exposed concrete surfaces provide thermal mass to moderate internal temperatures and the deep overhangs protect the glazed facades from direct sunlight. This contributed to a designed energy use 20% below the baseline for museums set out by the ASHRAE, the US society of building services professionals.