Researchers tested a two-story wooden structure this week at the UC San Diego shake table in Scripps Ranch.Â (by UC San Diego Jacobs School of Engineering)
UCSD holds quake test at local facility
No one felt any shaking, but a small earthquake was orchestrated in Scripps Ranch Friday morning as an experiment by the University of California, San Diego (UCSD) Jacobs School of Engineering. The event was carried out in a nearly hidden location at 10201 Pomerado Road near Camp Elliott, off the eastern end of Pomerado Road.
The off-campus facility is the Englekirk Structural Engineering Center and the equipment used to simulate an earthquake is called a shake table. A two-story wooden structure was built and went through a series of earthquake simulations this week. Friday, the building was put through a simulated temblor of 6.7 magnitude, the same magnitude of the 1994 Northridge earthquake. Data was gathered to help engineers design wood buildings as tall as 20 stories that do not suffer significant damage during large earthquakes.
“Designing buildings that are safe even during large earthquakes is hugely important. We are doing that – and we are going further. We are working to minimize the amount of time buildings are out of service after large earthquakes. We are also focused on cutting the costs required to repair them,” said professor Shiling Pei, an assistant professor at Colorado School of Mines who is leading the tests funded by the National Science Foundation (NSF) and a variety of industry sponsors.
Using information gathered from these recent tests, the team will return to San Diego in 2020 to build, shake and eventually burn an earthquake-resilient 10 story timber building on the UCSD shake table.
This week, the researchers studied the behavior of full-scale seismic safety systems made from advanced wood materials – including rocking walls, which can rock during a temblor and then re-center back by itself, and a mass timber floor designed to withstand strong earthquakes. The wood is primarily cross-laminated timber (CLT), which is a relatively new, high-performance material made from layers of wood laminate.
“With the arrival of cross-laminated timber, we can start thinking about timber skyscrapers,” Pei said. “CLT and mass timber more generally are part of a massive trend in architecture and construction, but the seismic performance of tall buildings made from these kinds of wood is uncharted waters.”
The 22-foot structure tested this week is a minimalist system aimed at collecting the information required to design tall timber buildings that have this kind of earthquake resilience. One of the key goals is to study how the different seismic safety systems interact with each other during realistic earthquake simulations.
The researchers working on the two-story building collected data through more than 300 sensor channels in three phases of testing. Data was generated at pre-selected points to measure how the CLT panels bend and how the panels move relative to each other. Researchers are particularly interested in a system that allows the building to rock in response to an earthquake and on how the walls and floors interact during shaking.
In rocking wall systems, vertical, mass timber walls are connected to the foundation by post-tensioned rods that run up through the floor and special U-shaped steel energy dissipaters. The rods allow the wall to rock during an earthquake and snap back into its original upright position, minimizing the deformation and the resulting structural damage.
The tests are being conducted at NHERI@UCSD, the shake table experimental facility at UC San Diego funded by the National Science Foundation as part of its Natural Hazard Engineering Research Infrastructure (NHERI) program.
The researchers from a consortium of U.S. universities, with collaborators from industry and the public sector, performed the testing at the UC San Diego shake table. It is part of the Englekirk Structural Engineering Center at the UC San Diego Jacobs School of Engineering.
The consortium of universities includes Colorado School of Mines, Colorado State University, University of Washington, Washington State University, Oregon State University, Lehigh University, University of Nevada Reno, and University of California San Diego.
—Provided by UC San Diego Jacobs School of Engineering; modified by Scripps Ranch News.