Earthquake Simulator Tests Four-span Bridge

RENO, Nev. - Students and researchers from across the country and beyond crammed into the University of Nevada, Reno engineering lab to see how a 110-foot long, four-span bridge would stand up to the destructive power of the 1906 San Francisco earthquake.

Project leaders said Thursday's simulation was the largest of its kind, and will help determine whether a new design code under review is adequate and should be adopted nationwide.

It was the first time anyone in the world has conducted such an earthquake simulation of this scale on a four-span bridge, said project director M. Saiid Saiidi.

"In terms of what it does to the structure, it is comparable to a 7.5 to 8.0 magnitude," he said of the simulation.

"If there were a large earthquake in a city like Los Angeles or San Francisco, many bridges could not be used, and imagine the impact on traffic and on emergency vehicles trying to deal with fires or getting people to the hospital," said Saiidi, a civil and environmental engineering professor.

A study released last year calculated that a repeat of the 1906, 7.9 earthquake would cause 1,800 to 3,400 deaths, damage more than 90,000 buildings, displace as many as 250,000 households and result in $150 billion in damage.

The model bridge used in Thursday's simulation was made of steel and concrete, materials commonly used in bridges.

Two more simulations using different innovative materials will be conducted during the next two years to see if the models can withstand greater earthquake damage, researchers said.

Nevada is the third most earthquake-prone state in the nation, behind California and Alaska. Chances of an earthquake with a magnitude of 6 or greater striking somewhere in the region of Reno-Sparks, Carson City and Douglas or Storey counties within the next 50 years is 34 to 98 percent, according to a study released last year by the Nevada Bureau of Mines and Geology.

The UNR laboratory where the test was conducted was packed with students and researchers from other universities, including Georgia Tech, Stanford and Kansas. Some of them came to see the simulation because they are working with UNR on certain aspects of its project, or as part of their own efforts to build bridges and other structures to withstand quakes.