Magazine Article: "Braces buildings against Earthquakes"

Researchers at the University of Michigan in Ann Arbor, Michigan have developed a new method for bracing high rise concrete buildings. By reinforcing the concrete with steel fibers, they were able to design coupling beams (beams used to connect walls around openings like windows and door frames) that are both easier to construct and more effective than traditional coupling beams. A test structure using these new beams was shown to be able to withstand a fake earthquake stronger than any real earthquake ever recorded.

Openings like windows, door frames, and elevator shafts tend to weaken a structure. Coupling beams try to mitigate this weakness by providing extra reinforcement in the vulnerable areas. Using a test structure of a 40 percent replica of a four story wall, the beams withstood a peak load of 300,000 pounds with a three degree drift (a measurement of the movement of the top of the building versus the bottom of the building).

Even in large earthquakes, buildings rarely experience more than a one or two degree drift.In addition to being stronger, easier, and more effective, the steel fiber reinforced beams are also expected to be less expensive than the traditional coupling beams in widespread use today.

The success of the initial test, conducted at the University of Michigan’s Structural Engineering Laboratory facility, which was designed and specially reinforced for earthquake testing, prompted researchers to plan to install the beams in several high rise buildings scheduled for construction on the west coast of the United States, where earthquakes are most prevalent.