High-tech survey points to buildings' storm weaknesses

Some of us Nebraskans like to tease our California relatives every time we hear of an earthquake in their region.

That usually brings a retort: "Well, at least we don't have tornadoes."

Actually, they can have tornados, but say twister, and Kansas is more likely to come to mind than Cupertino.

Some of the expertise that helps Golden State architects deal with earthquakes is now being used to help Nebraskans deal with our tornadoes.

University of Nebraska-Lincoln civil engineering assistant professor Richard Wood and a couple of graduate students made three trips to Pilger, Neb., last year to survey damage from the tornado that ripped through the town, killing two people and injuring 20.

Using a LiDAR 3D scanner and a tethered drone -- presumably tethered to avoid running afoul of federal regulations -- they scanned damage to dozens of homes and buildings such as a church and a middle school building that was damaged beyond repair.

While Wood studied earthquake damage in California before joining UNL in 2013, his trip to Pilger was his first time studying tornado damage.

He and his students created a 3D model of the school building that can be rotated to study fine details of how the structure was damaged by the storm.

"It is data mining," Wood said. "We assemble millions of data points to look for changes in the surface geometry to detect damage. We're statistically determining the potential quantity of damage and the whole point is to do it in terms of minutes, not hours."

They're creating a report that will go to the school and posted to UNL's Digital Commons, an open-access online repository of academic papers and similar materials.

What did they find?

* Brick buildings like the school, a bank and funeral home in Pilger looked strong, but they were easily damaged by the storm.

* Storms will always break windows, but treating them with a shatter-reducing film will prevent shards of glass from injuring people during the storm and after.

* Steel anchors connecting buildings to their foundations often failed. Anchors and rivets also failed on steel grain bins, turning them into missiles, like the one that caused a corner of the school to collapse.

There's no way to make a building completely tornado-proof. We remember surveying damage from the June 15, 1990, F4 tornado that roared through our area, and comparing it to what we imagined a nuclear bomb would cause.

But there almost certainly are economically feasible construction changes that could be made to reduce damage from the storms that are all too common in our region.