Project Overview
When the existing bridge was struck by a barge and temporarily shut down, bridge owners needed to rebuild the structure, but they also saw it as an opportunity. It was clear the community wanted accommodations for bicycle and pedestrian traffic as well and in response, a 4211-foot-long (1284 m) high-level bridge was created. The profile of the bridge is fairly symmetrical with the existing bridge, creating an appealing twin bridge appearance while also providing the team with a conventional and readily available construction method.
Because the project was funded through the Beaufort County Sales Tax Referendum, rather than state and federal funds, construction cost was a significant hurdle. Time, aesthetics, and durability were also top concerns. For all of these reasons, designers chose a high-performance precast concrete design.
Precast Solution
Prestressed concrete beams were chosen to accelerate construction time and reduce long-term life-cycle costs. The 96 in. (2400 mm) prestressed concrete bulb-tee girder section provided the span range and beam spacing needed to deliver an economical concrete solution. It also made the 170 ft (52 m) main span one of the longest conventional prestressed concrete bridges in South Carolina.
Safety and durability were also provided through the use of precast concrete. The site required a multihazard extreme event design methodology to account for possible storm surges, scour, seismic events, and vessel collisions. The prestressed concrete pile bents, isolated reinforced concrete drilled shaft bents, and shaft groups supporting waterline footings and hammerhead piers met all seismic design requirements. The combination delivered an aesthetically pleasing bridge that will withstand the worst that nature—or rogue river barges—might deliver. |