Q-Bridge Reconstruction: Learning Experience
On September 26th, Dr. Arash E. Zaghi and nearly 30 students enrolled in his graduate-level Bridge Structures class traveled to New Haven for a presentation and tour of the Pearl Harbor Memorial Bridge, commonly called the “Q-Bridge,” which is undergoing a complete replacement under the I-95 New Harbor Crossing Corridor Improvement Program.
The project, begun in 2000 and slated for completion in 2018, includes improvements to the I-95/I-91/Route 34 Interchange as well as the reconstruction of the Q-Bridge, so nicknamed for its span over the Quinnipiac River. The Q-Bridge is among the most heavily traveled in the Northeast, serving more than 120,000 cars per day.
Opened in 1958, the existing bridge is being replaced by a $554 million 10-lane bridge. The northbound span was completed in 2012, and the southbound lane is currently being constructed, with an expected completion date of 2015. Currently, north and south-bound traffic shares the renovated northbound span.
When the project is completed, the new bridge will be among the first extradosed cable-stayed bridges constructed in the United States, making the tour especially exciting for the students. An extradosed bridge combines structural aspects of both girder and cable-stayed bridge designs.
The Q-Bridge is providing a second “teachable moment” for faculty and students in the form of some 50-year old steel beams culled from the old Q-Bridge and recently donated to Dr. Zaghi by construction management giant Parsons Brinckerhoff. Dr. Zaghi will use the beams in conjunction with a recent Connecticut Department of Transportation-funded project, with Dr. Kay Wille, aimed at developing advanced retrofit repair methods for existing steel bridges that suffer from corrosion after years of service.
In receiving the beam donation, Dr. Zaghi said “This will add a significant value to the experimental portion of our project and will make our results unique in many aspects.”
He explains that a common problem with old bridges is the tendency for the beams to corrode at the ends. “The water penetrating into the bridge deck transports corrosive chemicals used for deicing to the beams, where the chemicals concentrate near the ends. The current repair procedures are complex and cost prohibitive,” he notes.
The team will explore a number of repair options including the application of ultra-high performance concrete (UHPC) as a less-costly, more time-efficient repair strategy that restores the structural integrity of the corroded beams, according to Dr. Zaghi. To test the performance of their alternative strategy, the team will test both retrofitted and unretrofitted beams to failure on the four-foot thick floor of UConn’s Structures Laboratory.
Read a related news story here.