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A Fake Earthquake in San Diego Tests Vulnerable Buildings

By Roger Corral     Feb 16, 2009 in Technology
"Shake table" testing provided answers to building infrastructures problems that affect many architecture projects around the country.
A group of engineers have conducted a simulated earthquake test, the first in the world, to determine what building materials are vulnerable to causing the most structural damage in earthquake-prone areas.
In a matter of seconds, the amount of damage that an earthquake can cause was immediately seen as pieces of bricks, mortar, wood, drywall and cement tumbled to the floor from the single-story house.
The project consisted of two high-intensity jolts, matching and topping the intensity of the 1994 Northridge earthquake in Los Angeles,California, which is estimated to have caused over $20 billion in damages and at least 52 fatalities.
The goal of the test was to improve the seismic performance of certain structures, mainly the structure blueprints of many Southern California homes, and to provide new design suggestions for new masonry buildings.
The first test, executed at 80 percent of the Northridge earthquake’s 6.7 magnitude, caused the structure to almost collapse fully, with a few pieces in tact.
"I was not expecting to see this at this level," said Richard E. Klinger, a civil engineering professor at the University of Texas at Austin and the lead researcher on the project, after seeing the surprising effects of the sudden jolt.
The final test, which was executed at 120 percent of the intensity of the Northridge earthquake, provided a 7.2 magnitude-enough to bring the complete structure down.
“Based on the results, we see a clear relationship between the methods used to attach veneer connectors to the wood-stud frame, and subsequent seismic performance,” Klinger said. “Connectors attached by electro-galvanized box nails almost always failed by nail pullout, while connectors attached by screws rarely failed by screw pullout. We are evaluating the extraction capacities of different commercially available nails and screws, with the objective of refining our current design provisions for the types of fasteners used to attach veneer connectors to wood-stud frames.”
The $950,000 project included top engineering researchers from The University of California at San Diego, The University of Texas at Austin, North Carolina Agricultural and Technical State University and Washington State University.
The test was conducted on the world’s only outdoor “shake table,” at the Englekirk Structural Engineering Center of the UC San Diego Jacobs School of Engineering and was paid for by the masonry industry and the national government.
"This shows us there's a lot of room for improvement,” said Benson Shing, engineering professor at UC San Diego.
More about Engineering, Earthquake, California