The North Carolina Department of Transportation (NCDOT) is partnering with North Carolina State University (NCSU) on a research project related to the parts of the Herbert C. Bonner Bridge.

The beams of the now demolished Bonner Bridge were sent to NCSU in Raleigh for stress testing at the college’s built facility lab. The goal is to use lessons learned about how an aged bridge exposed to half a century of extreme weather conditions can inform better bridge designs in the future, according to a press release.

NCDOT is funding the project and facilitated work to salvage the beams and test them in Raleigh.

“This is a very unique opportunity,” said Neil Mastin, who heads the research and development unit of NCDOT, in a statement. “It’s not often that you get a bridge in this extreme environment for almost 60 years that was intact enough that we could actually use it for testing.”

According to the NCDOT, the test consisted of two parts. First, the beam has been subjected to a low level cyclic load in which the force is repeatedly applied, removed, and reapplied in a manner similar to the types of stresses a bridge experiences on passing vehicles. Then it was subjected to a monotonous load until it reached peak load levels, essentially pressing it continuously until it broke. NCDOT says it took over 200,000 lbs of force to break the beam of the bridge.

Sensors with cameras were used to observe how the beam reacts to loads, how it moves and where cracks form when pressure is added to the beam.

The Bonner Bridge once served as a lifeline for people heading to the Outer Banks until it was dismantled a few years ago to make way for a new bridge. It was replaced by the Marc Basnight Bridge, whose work was completed in February 2019 and was named the second bridge of the year in Roads & Bridges’ Top 10 Bridges 2019.

————

SOURCE: North Carolina DOT