Engineers “Shake” a 40,000-Pound Concrete Dome
Degenkolb Engineers Perform Seismic Testing on Yerba Buena Center Art Installation
SAN FRANCISCO, CA (July 2, 2010)—A team of San Francisco structural engineers and project volunteers today conducted full-scale, human-powered seismic testing on a new 20-ton performance arena at the Yerba Buena Center for the Arts (YBCA), called the Bowls Project. The project—a 24-foot-diameter main dome interconnected with a smaller 18-foot-diameter dome—is constructed from three layers of 8,000 concrete tiles.
“We are very excited to be volunteering our time on this one-of-a-kind addition to San Francisco’s art scene,” said Mark Sinclair, Degenkolb Engineers New Technologies Group Principal. “We credit the San Francisco Department of Building Inspection with their willingness to consider this alternative means of getting the project up to code.”
Although the structure is reinforced with geotextiles (fabrics that are usually used in roadway construction), the building code considered the conjoining domes to be an unreinforced masonry structure, and unsuited for a seismically active region like the Bay Area—until it could be demonstrated to be safe. To meet this requirement, the project team asked Degenkolb to step in.
Working with architects Michael Ramage and Michael McCall, and Matarozzi /Pelsinger Builders, Sinclair and his team designed a base-isolated platform that reduces the seismic forces on the dome by a factor of six. Similar systems are used in less than a dozen buildings in San Francisco, such as San Francisco City Hall, the Asian Art Museum, and the de Young. The system will project the domes from significant damage in even the largest earthquake expected to occur at the site.
Seismic isolation projects usually require special design review and isolator testing due to their perceived complexity. The Department of Building Inspection agreed to this test in lieu of a traditional plan review process in advance of project’s July 6 opening, leading to today’s unique demonstration.
During the test, 25 engineers and volunteers cycled the platform back and forth up to its displacement limit, simulating a major earthquake. As the platform shook, the engineers collected data from the simulated “quake” to measure the two domes’ structural integrity, and verify that the system performed as assumed in design.
The Bowls Project will house music, ritual and workshops July 6-August 22. Performances will feature project artist Jewlia Eisenberg’s band, Charming Hostess. Eisenberg says, “The Bowls Project is based on Babylonian Jewish women’s amulets known as ‘demon bowls.’. The shape of the domes evokes the shape of the demon bowls, and the interior echoes the intimate preoccupations of the ancient bowls texts. “Performances will continue through the end of August.
The dome structure itself is the creation of award-winning architect and Cambridge University lecturer, Michael Ramage. Inspired by ancient Babylonian amulets known as “demon bowls,” the Bowls Project construction is an architectural extension of the 14th century practice of tile vaulting—layering light-weight masonry tiles (made of autoclaved aerated concrete) with fast-hardening cement instead of traditional mortar to create soaring arches with no steel beams or rods for either temporary or permanent support.
“I am proud to offer this unique multi-sensory architectural exhibit and performance space to a city like San Francisco where it will be truly enjoyed,” said Ramage. “I am impressed that YBCA, the City of San Francisco and Degenkolb Engineers were able to bring construction of the project from conception to completion in less than two and a half months.”
The isolation platform is modular and completely reusable, and the project team is also hoping to reuse the domes. By slicing them into pieces and lifting them out with a crane they could be reassembled on the platform at another location.
Degenkolb Engineers has an established history of offering structural engineering support and consultation for large-scale art installations in San Francisco and other Bay Area cities. Most recently, Mark Sinclair worked with the San Francisco Arts Commission and the Recreation and Parks Department on the installation of the 26-foot-tall “Three Hands Six Arms” Buddha statue (made of four tons of copper and six tons of steel). The installation currently stands at the entrance to San Francisco’s City Hall.
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About Degenkolb
Established in 1940, Degenkolb Engineers is one of the nation’s leading structural engineering firms in the design and seismic strengthening of buildings. Degenkolb offers comprehensive design, rehabilitation, and consulting services to architects, building owners, hospitals, educational institutions, corporations and government agencies. The firm has offices in San Francisco, Los Angeles, Oakland, San Diego, Portland and Seattle. Degenkolb routinely leverages firm-wide experience, calling on support from any of its six U.S. offices to ensure technical excellence on all projects.
About the Artist
Jewlia Eisenberg is a composer, extended-technique vocalist, lay cantor, and the founder of Charming Hostess. Her work explores the intersection of text and the sounding body, pushing for translation strategies between verbal and non-verbal languages. Jewlia’s work has been curated into the Prague Bienalle and the Contemporary Jewish Museum of San Francisco, she has taught classes on the boundary lands holding music, poetics and critical theory at CalArts, MIT, and the University of Denver. Commissioned work includes Harmonices Mundi (Sloan/EST), an opera about Kepler’s mother, and Red Rosa (Puffin/SF Goethe Institut), a song cycle based on the letters of Rosa Luxemburg.
About the Architects
Michael Ramage has a degree in architecture from The Massachusetts Institute of Technology and currently teaches at Cambridge University in England. He designed the masonry vaulting for a museum in South Africa, the Mapungubwe Interpretation Center, winning the World Architecture of the Year award in 2009. He also designed the domes for the Pines Calyx, the first Guastavino-style vault to rise in the United Kingdom.
McCall Design Group views architecture as the context for everyday life. The firm views design as an unfolding of visual, technical, and programmatic concerns that evolve over time and through adaptation to place. Working individually with each client, Mr. McCall oversees the creation of unique spaces that speak to and enlighten the locations they occupy.
About the Builder
Matarozzi/Pelsinger has earned a reputation as a leader in San Francisco’s construction industry. We specialize in residential, commercial and sustainable design projects and take pride in providing superior craftsmanship and exceptional service. We distinguish ourselves in a highly competitive market, by focusing our attention on the needs of our clients, and the architects and consultants with whom we work. We have significant experience building and renovating historic and modern homes.
