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This wooden high rise wiggled its way through two devastating earthquakes

It’s a big step forward in proving that wood buildings can go tall in seismic zones.

[Image: Timberlab/FLOR Projects]

BY Nate Berg5 minute read

In a single day in early May, one 10-story building survived the brunt of some of the biggest earthquakes in recent history.

Standing in a clearing next to a warehouse outside San Diego on what’s known as a shake table, this building was put through a battery of tests to analyze its seismic resilience, shaking side to side and up and down with forces at the upper end of the Richter scale. But unlike most tall buildings around the world that have been hit by big earthquakes, this 10-story building’s structure is made out of wood. Also unlike many of the rigid but brittle concrete and steel mid- and high-rises that stand in cities around the world, this wooden building came out of these full-force earthquake simulations intact.

[Photo:  Timberlab/FLOR Projects]

The building is part of the Natural Hazards Engineering Research Infrastructure (NHERI) TallWood project, an eight-year, multi-institution research project focused on developing designs and standards for tall wood buildings that are resilient to seismic activity. Participants include the Colorado School of Mines, the University of Nevada, the University of Washington, and the USDA Forest Products Laboratory.

With funding from the National Science Foundation, NHERI is testing ways to use engineered mass timber products like cross laminated timber beams to build structures that wiggle their way through seismic activity without suffering major damage. The tests are also looking at specific types of joints, fittings, floor slabs, windows, doors, and facade treatments to test their seismic performance. The idea is to put them all together in a tall wood building, shake it, and see what happens.

Lever Architecture, the sole architecture firm involved in the testing, has spent the past decade designing mass timber buildings of increasing height. Mass timber has grown in popularity in recent years, with many designers opting for it as a robust and carbon-light alternative to concrete and steel, and some, especially in Europe, using it to build buildings more than a dozen stories tall. The trend is fully underway in the U.S., with mass timber being used for everything from apartments to office buildings to airports. The world’s tallest mass timber building, the 25-story Ascent MKE Building, opened in Milwaukee last summer. The NHERI project is a way to show that these structures can work even in active seismic zones like the Pacific Coast.

The NHERI project’s primary focus is testing the seismic stability of what’s known as a post-tensioned rocking wall, a kind of structural system that can self-center after an earthquake. The NHERI test building has a wooden version of this kind of wall, which has a steel cable running up through its center, like a stabilizing spine.

[Photo:  Timberlab/FLOR Projects]

Most timber buildings use massive engineered beams to form their structure. While these are capable of flexing under the stress of an earthquake, the NHERI test building’s structure is designed to bend, wiggle and re-center after an earthquake, making it much more nimble than a typical high rise made of concrete and steel.

“In an earthquake, most buildings are designed to be super stiff. They don’t fall over, but they may be crushed in the process of resisting that force,” says Thomas Robinson, founder of Lever. Many buildings survive earthquakes by simply not falling but are so internally damaged that they are unsafe to occupy and often have to be torn down. “What this system does is it takes the force and allows it to be distributed as the building moves, and then brings it back to center.”

That system was run through a quaking gamut earlier this month. On a single day, the building stood on the shake table as it replicated the 6.7 magnitude earthquake that struck Northridge, California, in 1994, causing tens of billions of dollars in damages to Southern California, as well as a 7.6 magnitude earthquake that crumbled buildings across Taiwan in 1999.

“In the back of your mind you’re thinking something might fail, what could it be. We didn’t really know,” says Jonathan Heppner, a principal at Lever Architecture. “Walking through the test afterward, both the non-structural and the primary structure had no visible damage, which was really great. It performed as well as anybody could have expected it to.”

[Photo:  Timberlab/FLOR Projects]

About 800 sensors have been embedded in the building in order to gather precise data on movement and potential damage. During the quakes, walls remained intact, windows were crack-free, and the joints between thick wooden beams held true. There was even an empty water bottle placed on a table in one of the upper floors. It toppled over, but didn’t fall off.

The 10-story structure was specifically designed to reflect the kind of building mass timber might be realistically considered for in the current market. It was modeled after a mixed use building, with open and tall-ceilinged retail space on the ground floor and smaller floors above that would be more suitable for apartments or offices.

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“This type of system is a way to create more resilient structures,” says Robinson.

It’s also a way to help convince city officials to approve tall mass timber projects when they’re proposed. “There will probably will be code changes that occur as a result of the testing that incorporate or allow mass timber and remove some of the mysteries around it,” Heppner says.

The successful test results may also give developers confidence that if they can get one of these buildings built it won’t be a disaster zone when a big one hits.

[Photo:  Timberlab/FLOR Projects]

Anyeley Hallová is a Portland-based developer who has worked with Lever Architecture on two timber-based buildings, both a few stories in height. Since launching her own firm, Adre, she’s partnered again with Lever on a project now in the design phase using the same mass timber rocking wall technique used in the NHERI project. She says that project is bolstered by the results from the NHERI test. The structural approach, she says “is demonstrating its commercial viability as a cost effective solution and providing a code pathway for other developers to incorporate this form of seismic resilience into their buildings.”

Tests are ongoing. “They’re running as many different earthquake profiles as they can,” says Heppner, including what’s known as a maximum considered earthquake, or a really, really big one. “These are like 500-year earthquakes. Statistically they’re rare, but [the researchers] are just trying to make sure the building can perform under basically the worst condition that is known currently,” Heppner says.

Asked if the researchers will just push the building all the way past its limits, shaking it until it falls apart, Heppner answers flatly: “It won’t fall apart.”

“Knock on wood,” he adds.

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ABOUT THE AUTHOR

Nate Berg is a staff writer at Fast Company, where he writes about design, architecture, urban development, and industrial design. He has written for publications including the New York Times, the Los Angeles Times, the Atlantic, Wired, the Guardian, Dwell, Wallpaper, and Curbed More


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