The experiment took place atop an outdoor shake table at the Englekirk Structural Engineering Center on campus. The shaking rocked an unoccupied, fully furnished concrete hospital building that contained an elevator, partition walls, piping, HVAC system, sprinklers and passive and active fire systems.
The motions simulated the 1994 Northridge earthquake (magnitude 6.7), and a future experiment will simulate the 2010 San Pedro earthquake in Chile (magnitude 8.8).
The National Science Foundation (NSF) funded the project with a grant to investigate the performance of both structural and nonstructural components during a quake. The NSF’s collaborators included the Englekirk Advisory Board, the Network for Earthquake Engineering Simulation, the California Seismic Safety Commission and construction and engineering equipment company Hilti.
Photo courtesy of the UC San Diego Jacobs School of Engineering.
Data from the experiment can be used to improve building construction and assist in handling earthquake-related scenarios after the fact.
During a live Q&A session after the simulation, UC San Diego professor Tara Hutchinson, the principal investigator, deemed the experiment a success because the building’s base supports held throughout the shaking. “The base isolators below the building protected the nonstructural components from the damaging effects of the ground motions,” she said. “Had this building been occupied, it would remain operational after these earthquakes.”
Some minor interior damage did occur, however, like cracking in partition walls, but Hutchinson said those components would be easily repairable in a real-life situation.
The project was the first phase of an experiment. The next phase will shake the building with the isolators removed.
“We will lift the building slightly, remove the isolators, and re-anchor the building to the shake table, and then the building will be in a fixed configuration,” Hutchinson said. “The motions would now get transmitted directly to the building.”
Image credit: Detail illustrations and layout Zina Deretsky, National Science Foundation; Building illustrations UC San Diego Department of Structural Engineering. Click on the image for a full-size version.
UC San Diego’s shake table is part of the NSF’s 14-site earthquake simulation network, and each site enables researchers to test a large-scale or full-scale catastrophe.
Researchers will collect data from about 500 channels of sensor data and 75 camera channels, and digesting the information could take years. The results will be made available to the earthquake engineering community, and Hutchinson expects others to contribute to the results with their own opinions and data.
“We can anticipate quite a growth in the future of the availability of the information and its impact on design and construction practices,” she said.
