Engineers are set to recreate the tremors of powerful earthquakes to test the durability of a two-story wooden structure, in hopes of one day creating buildings as tall as 20 stories that can withstand a major seismic event. The tests will use UC San Diego's massive shake table, which can simulate forces like the 6.7 magnitude Northridge earthquake that struck Los Angeles in 1994, killing 60 people and causing billions in damage.
The researchers are testing buildings that incorporate 'rocking walls' and cross-laminated timber (CLT), a high-performance material. Rocking walls move during an earthquake but then reset to their correct position, using vertical mass timber walls connected to the foundation by post-tensioned rods. 'Designing buildings that are safe even during large earthquakes is hugely important,' said Professor Shiling Pei of the Colorado School of Mines. 'We are working to minimise the time buildings are out of service after large earthquakes and cut repair costs.'
The two-story structure will be subjected to the world's largest shake table, with over 300 sensor channels gathering data in three phases. Engineers will measure how CLT panels bend and move, revealing how walls and floors interact during an earthquake. 'With the arrival of cross-laminated timber, we can start thinking about timber skyscrapers,' said Pei.
The 1994 Northridge earthquake, with its epicentre in Reseda, shook the ground for 10-20 seconds and was felt as far as Las Vegas. It caused damage across an 85-mile-wide region, destroying thousands of buildings and injuring over 8,700 people. The ground acceleration recorded was the highest ever in an urban area in North America.
After analysing the data, researchers plan to return to the shake table in 2020 with a 10-story timber building for further testing, including simulated earthquakes and fire. 'CLT and mass timber are part of a massive trend in architecture, but the seismic performance of tall wooden buildings is uncharted waters,' Pei added.
