This Berkeley building can snap back into place after a major earthquake

Zig-zagging around the glass-and-steel perimeter of the UC Berkeley Grimes Engineering Center, 36 thin metal rods could be what it takes to prevent the building’s total destruction.

The rods are the central element of a novel seismic-responsive structural system that is designed to help the building snap back to its original shape in the event of a major earthquake. Their trick is an embedded cluster of taut cables made from a highly flexible compound called a shape-memory alloy that’s capable of bending under tension—like the lateral shaking in a California earthquake—and then straightening out.

Developed by the architecture firm Skidmore, Owings and Merrill (SOM), which also designed the building, the shape-memory alloy tension rod system is making it possible for architects and engineers to create truly earthquake-resilient buildings.

David Shook, a senior associate principal based in SOM’s San Francisco office, helped develop the shape-memory alloy system for the building. He says testing showed it to be able to bend more than 25 times as much as typical structural steel, which he compares to a coat hanger. “When you bend it, it stays,” Shook says, while the shape-memory alloy tension rod system “can behave more like a rubber band.”

A building that can snap back into place after an earthquake is important not only for life safety but also for the ongoing use of a building in a post-disaster scenario, says structural engineer Mark Sarkisian, a partner at SOM who’s also based in San Francisco. The current building code “allows for your building to be damaged structurally in a way that still protects life and stays stable during an earthquake. But after the earthquake, there are big questions around whether that building can go back into service or not,” Sarkisian says. “What SOM has really pushed hard on for many years is can we come up with seismic systems that are essentially elastic?”

What is a shape memory alloy?

Shape-memory alloys make that possible. Commonly used by NASA and the aerospace industry and also to make heart stents, shape-memory alloys are new to architecture. This system is being used for what SOM says is the first time at the Grimes Engineering Center, a student center and educational space in the middle of several engineering-focused buildings on UC Berkeley’s campus. “The medical industry has been using a lot of super elastic shape-memory alloys. So as the production of that material has gone up, the price has been going down and we kind of hit a point here where it made sense to start using it in a building,” Shook says.

This particular building was an ideal opportunity. It’s located about a quarter of a mile from the Hayward Fault, considered one of the most dangerous fault lines in the seismically active San Francisco Bay Area. It’s also a part of UC Berkeley’s vaunted engineering school, known for its work on earthquake-resilient buildings and structural engineering.

“This is a place where they test, understand, and deploy new technologies in seismic zones year after year after year,” Sarkisian says. “It’s remarkable what the professors here have done. And it’s really fun to be able to work with them to bring this forward in a very visual way.”

Like an engineering student doing an assignment in one of its classrooms, the building not only offers a solution to the problem, it shows its work. The shape-memory alloy tension rod system, made from a nickel-titanium alloy, is intentionally left out in the open on the perimeter of the building, demonstrating its functionality as part of the building’s minimal glass-and-steel architectural expression.

A teaching tool

Technically this is also an adaptive reuse project, with a new three-story, 36,000-square-foot pavilion added atop the base of the former Bechtel Engineering Center, built in 1980. The original building was a mostly subterranean Brutalist structure made of reinforced concrete, with a library and an auditorium sitting below a landscaped roof deck. The new design replaced the landscaping with the pavilion, trading the weight of the soil and planting for the mass of the new pavilion.

Because it utilizes so much of the original building’s foundation and structure, the project’s embodied carbon was measured to be 42% lower than industry baselines. In many ways, the building is meant to be a teaching tool as well as an example for other projects to follow.

The real test of its worth will come with the next major earthquake to hit the region. Shook says SOM ran extensive physical tests and computer simulations that show the shape-memory alloy tension rod system performing as planned, even during the biggest possible earthquake expected to strike. Unlike buildings that might have a cracked wall or an off-kilter lean after a big earthquake, the Grimes Engineering Center likely won’t offer any hint that it’s even experienced a tremor. “The building’s going to come back to plumb,” Shook says.

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