Engineers subject new bridge design to earthquake test

WHAT: A 30-foot, scale-model steel bridge will be rocked and shaken on an earthquake simulator at the University of California, Berkeley. Engineers will demonstrate a new bridge design that they say can better resist significant damage and improve transportation safety in the event of large earthquakes. They will subject the bridge to ground motions equivalent to large quakes that have hit California, Chile, Japan and other parts of the world.

"What most people expect and hope from a bridge's performance in an earthquake is that it doesn't collapse," said lead investigator Stephen Mahin, director of the Pacific Earthquake Engineering Research Center (PEER), a consortium of nine universities on the West Coast and headquartered at UC Berkeley. "We want to do better. We are developing bridges so that they not only stay up, they'll stay open."

The bridge will be equipped with a set of rail tracks and a model rail car to illustrate the applicability of the concept to high-speed rail systems. Dozens of domestic and international engineers from industry and state bridge departments are expected to be on hand to observe the demonstration.

Research in the new bridge design is supported by PEER, the National Science Foundation and Earthquake Protection Systems, a Vallejo-based seismic isolation bearing manufacturer.

WHEN: Wednesday, May 26. The agenda will include:
10:30 a.m. — Presentation of the bridge system, Building 445
11:30 a.m. — Live shake table demonstration, Building 420 (cameras can set up at 11 a.m.)
12:15 p.m. — Media interviews and lab tour

WHERE: UC Berkeley's Richmond Field Station, 1301 S. 46th St., Richmond. Maps and directions are online.

WHO: Stephen Mahin, PEER director and UC Berkeley professor of civil and environmental engineering
Kenneth Ogorzalek, UC Berkeley graduate student in civil and environmental engineering

DETAILS: UC Berkeley engineers have constructed a scaled, three-span steel bridge on the 400-square-foot platform of the earthquake simulator, or shake table. The table's computer-controlled hydraulic actuators can reproduce 3-D acceleration comparable to the largest quakes recorded in California.

The bridge segments are supported by seismic isolators and utilize a new Segmental Displacement Control Isolation System. The system is designed with lockup guides between bridge segments to constrain movement during a quake, allowing the roadway's center line to remain continuous. The strategy is meant to improve driver safety while minimizing damage to the bridge and the joints between the bridge segments.

Provided by UC Berkeley