Man-induced quakes to help in building safer, sturdier buildings

caused engineers to be very conservative in their design methods. The tests being conducted atop two “shake tables” at the University at Buffalo should help close those information gaps and lead to better constructed buildings, says lead researcher Benjamin Schafer, of the Whiting School of Engineering at Johns Hopkins.

“This is the first time a full building of cold-formed steel framing has ever been tested in this way, so even the small things we’re learning could have a huge impact,” said Schafer, the Swirnow Family Scholar, professor and chair of the Department of Civil Engineering. “We’ll see code changes and building design changes. We think this will ultimately lead to more economic, more efficient and more sustainable buildings.”

The release notes that in May, Schafer’s team began supervising a construction crew in assembling a first version of the test building. This structure, about the size of a small real estate or medical office building, was mainly composed of the cold-formed steel skeleton and oriented strand board (OSB) sheathing. When those first tests were completed, that structure was torn down and replaced by an identical building that also included non-structural components such as stairs and interior walls. The researchers are trying to determine whether these additions, which do not support the frame of the building, can still help reduce damage during a quake. It is the second version of the test building that in August will face the strongest seismic forces, as recorded during the Northridge earthquake.

At the test site, the construction of the buildings, the shake trials and the collection of data have been overseen by Kara Peterman of Fairfax, Virginia, a Johns Hopkins civil engineering doctoral student being supervised by Schafer. She has been gathering data from more than 150 sensors and eight video cameras installed in and around the test buildings. During a simulated quake, these instruments are designed to track the three-dimensional movement of the structure and to record any piece in the building that has “failed,” such as beams that have bent or screws that have come loose.

Peterman said tests on the first version of the building yielded surprisingly good results.

“It moved a lot less than we were predicting,” she said. “We did find one small portion of the steel that failed, but that was because of a conflict in the design plans, not because of the way it was constructed. And that small failure was purely local — it didn’t affect the structure as a whole.”

She said she is anxious to see how much the addition of interior walls and other non-structural components will add to the building’s stability during the more powerful tests ahead. Peterman predicted that the final high-intensity test is likely to damage the building, but not enough to cause a catastrophic collapse.

When the testing is completed and the results are analyzed, Schafer’s team plans to incorporate the findings into computer models that will be shared freely with engineers who want to see on their desktop how their designs are likely to respond in an earthquake. “The modeling,” Schafer said, “will create cost efficiencies and potentially save lives.”

In addition to the Johns Hopkins participants, academic researchers from the following schools have taken part in the project: Bucknell University, McGill University, University of North Texas, and Virginia Tech. Steel industry partners who have provided technical expertise, materials and additional funding include Bentley Systems, Incorporated; ClarkDietrich Building Systems; Devco Engineering, Inc.; DSi Engineering; Mader Construction Company, Inc.; Simpson Strong-Tie Company, Inc.; the Steel Framing Industry Association; the Steel Stud Manufacturers Association; and the American Iron and Steel Institute.

The research has been funded by National Science Foundation grant number 1041578.

— Read more in Cold-Formed Steel Earthquake Testing Web site; and Kara Peterman’s Earthquake Testing Blog