Virginia Tech engineering professor conducts research to build better bridges

BLACKSBURG, Va.—Carin Roberts-Wollmann, an associate professor in the Via Department of Civil and Environmental Engineering (CEE) in the College of Engineering at Virginia Tech, has been responsible for $1.15 million in research while at Virginia Tech. She’s also one of the researchers in Virginia Tech’s Cooperative Center for Bridge Engineering. All of her research has examined and analyzed new materials and/or new construction techniques that will create better bridges with improved durability and less maintenance, which translates into long-term savings for bridge builders.

This includes her latest research, looking into the behavior of a new full-depth, precast, concrete, bridge deck panel system. If the new construction method proves strong and durable, bridges could be built quicker and last longer than bridges built with conventional methods.

The bridge system Roberts-Wollmann is testing consists of two 36-inch-deep prestressed concrete beams and five 8-foot-long precast concrete bridge deck panels. The concrete panels were delivered to the lab with ducts within the slabs. The slabs are connected, and high-strength steel strands are run through the ducts and then tensioned onsite.

To test the bridge, Roberts-Wollmann is using two 200-ton rams. She’s pushed the bridge to 360,000 pounds, and so far, the bridge is behaving as expected with all connection details performing well. Although her current research is not yet complete, it looks promising. She hasn’t pushed the bridge to its breaking limit yet, but she anticipates doing that soon.

In addition to the deck panel project, Roberts-Wollmann is also assisting on a $248,000 Federal Highway Administration grant investigating Grade 300 prestressing strands versus Grade 270 girder strands. She’s evaluating stress-strain behavior, yield strength, ultimate strength, ultimate strain, modulus of elasticity, and relaxation of the Grade 300 strands in hopes of identifying any issues in this higher-strength strand.