Holding their ground
A unique structural system that helps multistory buildings withstand powerful earthquakes—an idea so promising it received a 2010 Popular Mechanics Breakthrough Award—has been codeveloped by civil engineering professor and chair Jerome Hajjar.
The revolutionary system uses steel frames that move up and down during an earthquake, elastic steel cables that can right a tilting building, and replaceable steel “fuses” that absorb much of an earthquake’s destructive energy.
Hajjar devised the system along with Stanford University civil and environmental engineering professor Gregory Deierlein as a research project
for the National Science Foundation’s Network for Earthquake Engineering Simulation. Their design places steel frames around a building’s core or
along exterior walls. During an earthquake, the frames rock up and down within steel “shoes” secured in the ground. Steel tendons control the
rocking and return the frames to a vertical position. And a series of energy-dissipating steel fuses, located at the base of the building’s frame, twist and contort during an earthquake; if they’re damaged, they’re easily replaced.
“Buildings are currently designed not to collapse during large earthquakes,” explains Hajjar. “But they are not designed to withstand damage.”
The new structural system remedies that, thereby reducing costs. “Many structures, even if relatively new, have to be condemned after earthquakes,” Hajjar says. “Our design focuses all the damage into replaceable fuses.”
Hajjar and Deierlein’s innovations have already been incorporated into several new buildings, including the Orinda, California, City Hall.
Child’s play
For months, Bouvé researchers have been watching intently as young children stack blocks, roll toy trucks, and place puzzle pieces.
It’s not just fun and games. Working under a four-year $1.6 million grant from the U.S. Department of Education’s Institute of Education Sciences, the researchers are studying what play reveals about the development of children, particularly those with delays or disabilities.
“We’re examining natural play to see what children know and what they’re thinking about,” says Karin Lifter, professor of counseling and applied educational psychology and the project’s principal investigator (Northeastern professor Emanuel Mason and Takuya Minami of the University of Wisconsin at Madison are also working on the project).
Over the course of the study, Lifter and her team will analyze the play of 820 children, age eight months to sixty months. The researchers tape the activity of the children—who play with groups of toys during thirtyminute sessions—then analyze the kids’ play behaviors, considering both quantity and quality.
“You have to know what you’re looking for,” says Lifter. “If you put a truck and blocks in front of kids, the youngest will just suck on the blocks. The toddler will load blocks into the truck. The preschooler will pretend that a driver is loading the blocks. These are qualitatively different activities.”
Eventually, Lifter hopes to produce a new version of the Development Play Assessment she created in 2000, one that will help clinicians devise interventions for young children with delays and disabilities.
In concert with Lifter’s work, Northeastern’s EdTech Center is creating a website and an online training package for clinicians, which will include videotaped examples of play gathered at the university’s Russell J. Call Children’s Center.