Earthquake Resilience at 10 Stories
NHERI 10-Story Shake Table Test | San Diego, California
Timberlab is collaborating on an industry-wide research project to test mass timber’s seismic resiliency. The Natural Hazards Engineering Research Infrastructure (NHERI) project will examine the viability of a 10-story tall wood building by subjecting it to earthquake simulations on the world’s largest shake table. The research project represents a huge step toward advancing the mainstream adoption of mass timber construction. If successful, the NHERI shake table will reshape the possibilities for tall timber buildings in high seismic areas.
The NHERI shake table project speaks to the collaborative spirit of the mass timber community. The building is comprised of largely donated CLT, GLT, DLT, NLT, VLT, and MPP from industry stakeholders who are all equally invested in the seismic potential of wood construction. The design of the building's structural elements was influenced by the comprehensive testing requirements backed by multiple researchers. The NHERI shake table project is unique in that the floor panels and components alternate every other floor. The structure has five-panel types supplied by three different vendors. Each floor is equipped with sensors to measure the simulation’s impact on the structure.
The NHERI project also offers research opportunities for mass timber deconstruction. After the initial seismic testing, researchers will disassemble the top four floors and send the deconstructed wood back to Oregon State University for additional testing and research. The remaining structure will undergo the same seismic simulations as a six-story building. It is a unique opportunity to gather data on wood’s seismic potential while simultaneously providing data for end-of-life reuse.
WORLD'S LARGEST SHAKE TABLE
The University of California and UC San Diego received National Science Foundation grant money in 2015 to run the world's largest shake table and has been instrumental in seismic research initiatives globally. The table itself can withstand structures that weigh 2,000 tons. The table has the capacity to simulate the ground motions of some of the world's largest earthquakes. For the NHERI 10-story tests, the structure will shake using data to replicate magnitudes up to the infamous 1906 San Francisco earthquake.
MASS TIMBER ROCKING WALLS
The star of the show on the NHERI 10-story structure is the innovative rocking wall system. The mass timber rocking walls are designed to shift seismic loads back and forth during an earthquake, dissipating energy and reducing the impact on the overall structure. By allowing controlled rocking motion, this system effectively mitigates seismic forces and enhances the building's ability to withstand earthquakes. "The building should go back to plumb. We designed everything to be elastic, like a spring or a rubber band. You can stretch it, but it will come back." says Shiling Pei, the project's co-director.
EPOXIED ROD CONNECTIONS
One component of this complex structure was the wood-to-wood epoxy connection utilized for the mass timber rocking wall. This type of connection has never been done before and was developed by Simpson Strong-Tie. Although challenging, the calculations that guided the epoxy connection details have promising results for the industry.
Timberlab fabricated all the columns and beams at our Portland, OR fabrication facility and partnered with Swinerton to erect the 10-story structure on the shake table in San Diego. The structure topped out in early 2023. When research completes in the summer of 2023, the fabricated materials will be deconstructed and studied at Oregon State University. Our team's specialty fabrication services were instrumental in the projects construction process, featuring many different types of engineered wood products.
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