UNR Tests Bridge in Earthquake Simulation

Engineering students at the University of Nevada are continuing their earthquake research. This time, they are finding out how well a specific type of bridge construction can handle a powerful quake. Accelerated Bridge Construction (ABC) allows a bridge to be prefabricated, then moved to the site where it will be constructed. Officials say it can cut construction time by 60-70 percent.

"The traveling public will have access to the bridge a lot sooner than they normally would," Saiid Saiidi, Professor of Civil and Environmental Engineering at UNR said.

Saiidi says the bridges cost less to build and they can result in fewer workplace accidents but the question is how well they can handle a powerful earthquake.

"I'm trying to make the safest bridges possible," Jared Jones, Graduate Researcher at UNR said.

Eight students put a 70-foot bridge through two earthquake tests. The first simulated an earthquake that was 75 percent more than the bridge was designed for and the second was double the amount. Saiidi says the tests were estimated between a magnitude 7.2 and 7.5 earthquake. The goal is to prevent the bridge from collapsing.

"Of course, with collapse you have loss of life and so as a structural engineer, when we do these kinds of tests, we are trying to make sure we have bridges that will withstand these events," Jones said.

The California Department of Transportation funded the $500,000 project, designed for the Los Angeles area. After the two tests, the bridge remained intact.

"Damage at the top of the column, at the base of the column, but the rest of the bridge is in perfect condition," Jones said.

Since most of the bridge was unharmed, Jones says it would be easier to repair in a real-life situation.

"If it's large enough that it causes significant damage to the columns then you will just temporarily support the bridge, replace the columns and your bridge is good to go," Jones said.

Along with Caltrans, the Nevada Department of Transportation is observing the experiments. Nevada is the third most seismically active state in the country, behind Alaska and California, so these bridges could be used here. California is already utilizing UNR's research.

"They have taken the results of our previous research and they have implemented it in two bridges already," Saiidi said.

Saiidi says one of the bridges is under construction in Bakersfield. 

The students get hands-on experience in the laboratory, along with their classroom education. They have learned what works well, and what does not during their experiments.

"We are finding that some of the materials and solid connections are not always appropriate for high seismic areas, so we have eliminated those," Saiidi said.

Students from the Oregon Institute of Technology also made the trip to Reno to see the experiment. 

"We have very small shake tables, bench-scale tables at our university and there's nothing like coming to a big structures lab like this and seeing tests like this, so I brought 10 students," CJ Riley, Professor of Civil Engineering at Oregon Institute of Technology said.

Friday's simulation represented six ABC connection types and resulted in 300 channels of data. Riley says this type of bridge construction is the future. Especially because it disrupts traffic much less.

"Things need to happen more quickly and more reliably, so this is absolutely coming and it's important that we have this kind of data to ensure it's done safely," Riley said.