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Groundbreaking Tests for 5-Story Building on Shake Table

Building

Structural engineers at the Jacobs School have just completed an unprecedented series of major earthquake simulation tests to gauge the performance of nonstructural components in a building, such as working elevators, piping, air conditioning and fire barriers.

Researchers built a five-story building equipped with all these features, plus a surgery suite, an intensive care unit, computer servers and more. Then they put the structure through a series of high-intensity earthquake simulations on the world's largest outdoor shake table at the Englekirk Structural Engineering Center.

During the first phase of testing, the building was placed on a base isolation system – large cylindrical rubber bearings that isolate structures from most of the lateral motion they would normally experience during a temblor. This was the first time such a system was tested under a full-scale building outfitted with nonstructural components on a shake table in the United States. For the second phase of testing, the building's foundation was anchored directly on the shake table.

Graduate Students
Structural engineering graduate students Michelle Chen, (left), and Elide Pantoli, inspect one floor set up as an operating room. Pantoli checks the surgery lights. The building's top two floors were set up as a mock hospital.

With base isolation, critical systems, such as the elevator, stairs, hospital equipment and fire sprinklers, remained operational, even after putting the building through simulated motions from the 6.9-magnitude 1994 Northridge earthquake to the 8.8-magnitude 2010 Chile earthquake.

GPS
GPS units tracked the building's motions.

“It was very much like putting the building on roller skates,” said Tara Hutchinson, the lead researcher on the project and a professor of structural engineering at the Jacobs School. “The base isolation system uncoupled the building from the motions of the ground during the earthquakes we simulated,” said Hutchinson, who is working with a multi-disciplinary team of academics and industry representatives, including structural engineering professors Jose Restrepo and Joel Conte.

With the base fixed onto the shake table, the building suffered extensive damage to its contents and interior, while the structural skeleton remained in good condition following motions the building and its contents were designed to withstand. But under extreme motions, a number of beam reinforcing bars fractured and punching shear mechanisms developed at the interface of column and slab. Hospitals beds overturned and stairs suffered repairable failures. During all fixed base tests, equipment powered by electricity remained functional.

Water Tower
Water splashes from a water tower on the roof during a test.

The overarching goal of the $5 million project, supported by a coalition of government agencies, foundations and industry partners, is to understand what can be done to keep high-value buildings, such as hospitals and data centers, operational after going through an earthquake. Researchers also assessed whether the building's fire barriers have been affected by the shakes. Engineers from the Worcester Polytechnic Institute ignited live fires in selected areas of the structure to see how fire suppression systems would function in an earthquake-damaged building – another first.

Engineers monitored the structure's performance with more than 500 high-fidelity sensors and over 70 cameras that recorded the movement of key elements and components inside. Researchers will spend the coming year analyzing data from the project before publishing their complete findings.

“What we are doing is the equivalent of giving a building an EKG to see how it performs after an earthquake and a post-earthquake fire,” said Hutchinson.

Design

The tests made the national evening news on NBC, ABC and CBS, as well as CNN and other major media outlets, including The New York Times, USA Today and BBC News.

Academic Partners

San Diego State University: Professor Ken Walsh; Worcester Polytechnic Institute: Professor Brian Meacham; and Howard University: Professor Claudia Marin

Major Funders

National Science Foundation, Network for Earthquake Engineering Simulation, California Seismic Safety Commission, Charles Pankow Foundation and Englekirk Advisory Board

Links

Watch and read the media coverage: http://bit.ly/INwXU7

Watch a video of the tests: http://bit.ly/KttS1W

Find out more about the project: http://bncs.ucsd.edu/

Industry Partners http://bit.ly/L0Rs3D