Quake simulation tests strength of precast concrete
Groaning and trembling slightly, a three-floor, 400-ton concrete structure was playing its part Wednesday in an earthquake simulation project meant to help prepare California for the Big One.
In an obscure area east of Interstate 15, investigators at the UC San Diego Camp Elliott Structural Research Center are testing the strength and flexibility of precast concrete. The goal of the $2.3-million project, funded by government and industry, is to provide better designs to keep buildings from coming apart during large quakes.
Nine parking structures, for example, collapsed during the Northridge quake in 1994.
But industry officials believe that advances in the composition and assembly of precast concrete should minimize the possibility of a repeat of the Northridge experience. Precast concrete is put together in a factory and then shipped to a site, not poured wet into forms at the assembly site.
To test the latest in precast concrete technology, researchers put the parking structure-like building under the same strain as the 8.0 earthquake that struck Peru in 2007.
Data recorded by monitors will be compared with data collected from a computer model. If it matches, future tests can be done using computer models, a quicker and cheaper process, said Robert Fleischman, a professor of civil engineering at the University of Arizona. Is precast concrete the answer to survival in shake-prone California?
“It’s going to be part of the answer,” said James Toscas, president of the Precast/Prestressed Concrete Institute, based in Chicago. “Twenty years ago that would not have been the case. That’s how far we’ve come.”
As several dozen engineers, researchers and industry representatives watched, the three-level structure was put through a series of simulated quakes with the help of powerful pistons beneath the foundation. The structure shook but did not appear to be damaged.
Tests will continue through next month.
“This is how to find out if these things really work,” said Gilbert Hegemier, director of the UC San Diego Jacobs School of Engineering’s Charles Lee Powell Structural Research Laboratories.