- Associated Press - Saturday, February 6, 2016

CHAMPAIGN, Ill. (AP) - In a very loud building north of Champaign, a powerful earthquake simulator causes a scaled-down concrete bridge column to wobble.

You have to be ready to rumble when the enormous shake table takes out earthquake-strength forces on the bridge columns.

It’s so loud at the Army Construction Engineering Research Laboratory that the table needs a room of its own, and the shake, rattle and roll is enough to make concrete look woozy.

The University of Illinois and CERL have a history of working together, and in this case, the accent is on demolition - or its prevention.

The Army placed a top civil-engineering lab here because the UI is considered the No. 1 civil-engineering school.

The forces here are mimicking one of America’s worst earthquakes - 1989’s World Series-interrupting Loma Prieta quake that occurred in northern California - said UI Professor Bassem Andrawes, whose experiments showed a method to both prevent and repair earthquake damage.

Earthquakes can and will happen in the Midwest, Andrawes said. We are near the New Madrid, Mo., seismic zone; an earthquake there in 1812 caused church bells to ring in Boston.

Andrawes tested his metal spirals to both prevent and repair earthquake damage, working with James Wilcoski, the CERL engineer who runs the simulator.

Wilcoski set up the table with a 1/6th-scale model of a typical bridge column, allowing the experimenters to put it through its paces on a unique piece of equipment.

The shake table has been in Champaign since 1971; Wilcoski said it was improved in 1995 to better simulate earthquakes.

“Our table is smaller than some in California, but has a greater force component. It’s the best in the Midwest and in some ways the best in the nation,” Wilcoski said.

America has aging basic structures, with many of its bridges built before the 1971 San Fernando earthquake north of Los Angeles - including many existing interstate bridges.

The 1971 quake caused engineers to come up with new measures to reinforce structures that face high levels of energy.

For Andrawes, the work to repair earthquake damage has a personal side.

“The largest and most devastating earthquake I encountered was in Egypt back in 1992,” Andrawes said. “Although it was relatively moderate, it caused great damage. Back then, I was still in my second year of college. This earthquake triggered my interest in studying earthquake engineering.”

Andrawes’ alloys “remember” their original shape and can return a bridge column to its original shape when heated, even after a catastrophe.

Working with graduate research assistant Donghyuk Jung, Andrawes was testing an idea he has been working on for about seven years: using spirals made of the memory alloy on existing columns, and to do emergency repairs to bridge columns after they have been grouted.

Andrawes said that a spiral is the best way to work with a circular column.

“It takes the shape of the column cross-section. One advantage of the spiral is that it is continuous - that helps tremendously in increasing its integrity and strength,” he said.

Part of the experiment was to see if the technique could prevent damage. It did. But the same technique also allows for rapid repairs.

“In one hour and 15 minutes, we were able to completely repair the column, wrap it with these alloys, heat them, and then test them again,” said Andrawes, who lived in quake-prone California before he came to the UI.

Time is everything in an emergency.

“We want the bridge to still be open, to be used by emergency personnel or vehicles without disrupting its functionality,” Andrawes added.

He said a key advantage of the technique is that it can be employed by workers in hurried situations.

“It doesn’t need much training. I don’t see any problem doing this on a bigger scale if there is enough manpower,” he said.

Wilcoski said the table allowed the experimenters to see the full effect of an earthquake - or beyond.

“We went up substantially further than the point where the (bridge) system was designed to fail,” he said.

“This was done to mimic an earthquake followed by a very strong aftershock,” Andrawes said.

___

Source: The (Champaign) News-Gazette, https://bit.ly/1SycVGn

___

Information from: The News-Gazette, https://www.news-gazette.com

LOAD COMMENTS ()

 

Click to Read More

Click to Hide