Researcher says technology exists to minimize effects vessel collisions have on bridges

A West Virginia University civil engineer sees extensive recovery and rebuilding ahead following the Tuesday (March 26) collapse of the Francis Scott Key Bridge in Baltimore due to a barge collision.

Hota GangaRao, Wadsworth Professor and director of the Constructed Facilities Center in the WVU Benjamin M. Statler College of Engineering and Mineral Resources Wadsworth Department of Civil and Environmental Engineering, is available to explain the extent of the structural damage to the bridge and to discuss available options for minimizing the shock of vessel impacts on bridges.

Quotes:

“To rebuild the bridge to the point where they can restore traffic is going to take a couple of years, at least, and will cost hundreds of millions of dollars, in part because there are several additional problems associated with the failure of the main spans that collapsed.

“No. 1, the pier that got hit has to be examined, and perhaps has to be rebuilt, depending on the extent of the damage. Secondly, there are approach spans that need to be carefully examined before they can open the bridge to traffic. And thirdly, are they going to take precautions to prevent this type of incident from repeating?

“There are donut-shaped objects known as bridge pier bumpers that can minimize the shock when you have this kind of a hit. They’re not common in the United States, but they’re quite common in China, and my lab has helped designed a composite bumper, which has a better shock-absorbing capability.

“In February, there was a similar incident in China when a bridge collapsed near Guangzhou due to a barge hit. However, that bridge collapsed even though it had bumpers, because the barge hit the bridge above the level of the bumpers.

“In addition to bridge pier bumpers, there are a couple other preventive measures one can take with regard to bridge pier design. Both are very expensive.

“One option is having a much stronger tie-down of the superstructure — that is, the deck where we travel — to the piers. The second possibility involves designing the bridge in a way that accounts for the fact that when a barge hits the bridge, the impact could create a torsional instability at the top that leads the superstructure to collapse, depending on the barge’s speed and tonnage and its angle to the pier.

“The forces generated by a barge hit could potentially be, under specific circumstances, much higher than those generated by an earthquake or explosion. Current standards for bridge design do include the brief recognition that engineers need to account for situations like barge hits — but the question is, is this a one in 100 years event? That is where the economics come into play.

“There may have to be somewhat more stringent specifications to account for these kinds of incidents. It could be time to accept that more regulation is going to cost more money. While we cannot totally prevent accidents like these, at least we can minimize the damage, not only from the bridge design point of view, but also by developing novel bumpers for surrounding bridge piers.” — Hota GangaRao, Wadsworth Professor and director of the Constructed Facilities Center, Wadsworth Department of Civil and Environmental Engineering, WVU Benjamin M. Statler College of Engineering and Mineral Resources