Surviving the Shake Test

Winter 2014


Many scientists consider their research earthshaking. But a project headed by the Whiting School’s chair of Civil Engineering actually did make the earth tremble.

Using massive moving platforms and an array of video cameras and tiny sensors, Benjamin W. Schafer, the Swirnow Family Faculty Scholar, along with a team of scientists from six universities, last summer replicated the devastating 1994 Northridge, California, earthquake in a hangar-like laboratory at the University at Buffalo. The so-called “shake table test” was the culmination of a three-year $1 million National Science Foundation research project also involving design consultants from the steel industry.

The mission: to find out whether a two-story, office-size building constructed of cold-formed steel would stand up to forces comparable to those of the infamous Los Angeles–area earthquake, which killed 60 people and caused about $13 billion in damage.

The answer: a resounding yes!

“This building would have been just fine in the Northridge earthquake,” said a clearly excited Schafer, still wearing his hardhat, moments after the mid-August shakedown of the 50-foot-by-23-foot model building. “Its performance was far better than we would have expected.”

Cold-formed steel is made of 100 percent recycled steel, fashioned by bending very thin sheets of structural steel (also called hot-rolled steel) into construction materials. Although many modern apartment buildings,

college dormitories, small hotels, and other low- and mid-rise buildings already are framed in cold-formed steel, until now experts have been conservative about how such edifices would stand up to earthquakes and other extreme conditions.

The results from Schafer’s study promise to be a game-changer in the world of earthquake engineering, leading to improvements in cold-formed steel seismic design codes and leading to safer, sturdier, and more environmentally sustainable buildings.

“What we’re after is a better picture of how these buildings react to an event like a large earthquake, so we can make more informed design decisions going forward,” said Kara Peterman, an engineering doctoral student at the Whiting School who worked on the project as part of her dissertation.

Several weeks post-shake, Schafer, Peterman, and their team had torn the building down piece by piece, collecting and interpreting data from the more than 150 sensors and eight video cameras installed in and around the building to track three-dimensional movement during the temblor. The building’s “autopsy” included intense scrutiny of every component—from nails to beams to the smallest screw—to note what had failed and what had not.

“We do not have an answer—yet—as to why the building did so well,” said Peterman. “One working theory is that the structural parts of the building that were not intended to resist earthquake forces actually significantly contributed to the performance. Another theory is that the nonstructural elements add more to the strength than what is assumed. Again, neither of these theories has been definitively proven. We are still playing with data, with much more ‘playing’—months and months—ahead of us.”