Wood or would not? Earthquake test to study how 10-story timber building stands up to Seattle shake – GeekWire

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Kurt Schlosser
2023-05-08 16:15:00

A 10-story building constructed from mass timber stands on a shake table in San Diego where it will be tested to see if it can withstand significant seismic activity. (University of California San Diego Photo)

If the idea of a Seattle earthquake gives you the shakes, this test might be right up your alley.

Researchers from the University of Washington are taking part in a project to determine how a 10-story building made entirely out of timber will perform during an earthquake simulation.

The building, to be tested on Tuesday on a large shake table at the University of California San Diego, is the tallest to ever be tested in such a way. Back-to-back shake tests will be streamed online starting at 10:30 a.m. PT.

The tests are meant to simulate earthquakes equivalent to two previous seismic events: the magnitude 6.7 Northridge earthquake in California in 1994, and the magnitude 7.7 Chi Chi earthquake in Taiwan in 1999.

But the location this time, theoretically, is Seattle’s Capitol Hill neighborhood.

“We picked the location in Capitol Hill and did exactly what you need to do if designing a 10-story mass timber building in the city,” Professor Jeffrey Berman, with the UW’s Civil and Environmental Engineering department, told UW News.

The researchers worked closely with both an architecture firm and structural engineers. A site-specific hazard assessment — from soil types to fault lines — informed the building design.

Standing on top of the 10-story building, Jeffrey Berman, left, UW professor of civil and environmental engineering, and Sarah Wichman, UW doctoral student in civil and environmental engineering, oversee the construction of the rocking walls and connections. (UW Photo)

The Natural Hazards Engineering Research Infrastructure (NHERI) Tall Wood project is being funded by the National Science Foundation and is collaborative effort between university researchers and engineering firms. The UW joins lead institution Colorado School of Mines, University of Nevada, Reno, Colorado State University, Washington State University, University of California San Diego, Oregon State University and Lehigh University. Local industry partners include KPFF Consulting Engineers and LEVER Architecture.

The aim is to pave the way for more widespread use of mass timber — layers of wood bonded together — in taller structures, particularly in earthquake-prone regions. Timber is a more sustainable resource than concrete, for instance, a widely used construction material that generates about 8% of global carbon dioxide emissions through its production.

The building includes a unique rocking wall system, also made of timber, designed by the UW team. The lateral stability system, typically constructed from more traditional materials such as concrete or steel, stabilizes the structure in the event of an earthquake.

Rather than prevent the building from moving, the rocking wall system is specially designed to rock back and forth during a seismic event. This enables the structure to snap back into its original position with minimal damage.

A rocking wall is prepared to be lowered into the structure. (Timberlab / FLOR Projects Photo)

The monthlong testing process will simulate earthquakes with increasing intensity. Seattle has two primary faults: The Seattle Fault that runs east-west through the middle of the city, capable of earthquakes up to 7.4 magnitude; and the Cascadia Subduction Zone along the coast, capable of a magnitude 9 earthquake. 

More than 800 sensors were installed throughout the structure. UW researchers plan to use data to refine their computer models, which they hope will be utilized by industry to predict the performance of similar buildings. The researchers also hope their findings will inform building code requirements for timber structures.

The researchers are evaluating the performance of two primary types of mass timber, Cross Laminated Timber and Mass Plywood Panels.

When the cracked and closed West Seattle Bridge was out of commission a couple years ago, one Seattle architect proposed rebuilding the bridge using a mass timber-and-steel hybrid construction approach. Plans for a high-rise timber building in Portland were previously put on hold, but there are others around the world.

“We want people to be using mass timber everywhere,” Berman said. “This is providing a demonstration and validation of this particular system and is aimed at higher seismic zones, largely along the West Coast, but many of the principles from the building itself can apply anywhere.”

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