Friday, July 24, 2009

Earthquake-Proof Wood House Survives 7.5 Magnitude Quake

On July 6, 2009, in Miki City, Japan, we tested the NEESWood Capstone building to the Canoga Park recording of the Northridge earthquake. The steel frame was locked down providing a a rigid base for the six-story wood building. It was scaled to the Design Basis Earthquake for Los Angeles, which is 120% of the original record. This short video of the shake is provided by Dr N. Kawai, BRI.

The building performed very well with minimal damage propagation. After 4 shakes the building is still within the range of continued occupancy.
If you’re in search of a home that can withstand even the most powerful natural disasters, the solution might reside in the nearest tree. A team of researchers from five universities are currently working on ways to make wood earthquake-proof. If they succeed, the world may soon see cheap, sustainable wooden homes that can hold up even when earthquakes shake them to their cores.
So far, researchers have seen promising results: During a July 14th test at Japan’s Hyogo Earthquake Engineering Research Center, researchers used an E-Defense shake table, the largest shake table in the world, to simulate an earthquake measuring 7.5 on the Richter scale. The seven-story, million-pound wood condominium that was placed on the table remained standing, only suffering some minor cosmetic damage.

Researchers say that to get the building to withstand a whole lotta shaking, they changed the condo’s nail distribution to better distribute stiffness among the different floors, taking into account changes in structural pressure that occur during an earthquake. Designers also used 63 anchor tie-down systems from Simpson Strong Tie, steel rods that run from the foundation to the roof and prevent the building from rocking.

While many designers have looked at expensive, complicated building materials like flexible concrete and metal alloys to create quake-proof structures, this is the only experiment to use buildings crafted from wood. It’s important to optimize this particular building material because wood is both inexpensive and sustainable, meaning it can be used in all parts of the world, even in impoverished nations.

While researchers are quick to label quake-proof wood as sustainable, the extent of the wooden buildings’ eco features are unclear (for example, if they aim to use reclaimed or FSC-certified wood, or if they incorporate other eco-friendly building materials). But based on these early rounds of testing, one thing is certainly clear: earthquake-proof wooden structures are bound to really shake up the design world.

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