Post-Tensioning Systems Secure New Highlands-Sea Bright Bridge
New Jersey is currently working on a construction project that will be the state’s second precast segmental bridge. The structure crosses the Shrewsbury River and will ultimately replace the existing 75-year old functionally obsolete and structurally deficient double-leaf bascule bridge. After its completion, the bridge will serve as a central access route to the shore towns of Highland and Sea Bright in Monmouth County and to “Sandy Hook Unit”, a local recreation area.
The bridge structure has an overall length of 482m (1.582ft) and the main span over the navigation channel of the Shrewsbury River measures 71m (233ft). The bridge is being built as two separate, parallel structures with one driving direction each. The eastbound structure is being built first, while parts of the old bridge remain in use.
Unistress Corporation began casting the first segments, which were used for constructing the eastbound pier columns, at their Pittsfield, MA production facility in September 2008. A total of 98 precast segments were produced for the pier columns until September 2009.
The precast segments for the piers were post-tensioned using a total of 120t of epoxy coated DYWIDAG Strand Tendons and approximately 11.5t of 36mm (1-3/8") Ø, St 830/1035 (GR 150) THREADBAR®.
DSI USA supplied all post-tensioning systems for the precast segments and supported the general contractor with engineering services and technical know-how. All in all, DSI supplied more than 615t of 15mm (0.6") Ø DYWIDAG Strand Tendons and more than 81.5t of 36mm (1-3/8")Ø, St 830/1035 (GR 150) THREADBAR®.
According to project specifications, the post-tensioning systems were required to have a very high level of corrosion protection. In response to this requirement, DSI supplied their “System 100” post-tensioning system designed for structures with extended design life. Both type 4x0.6" flat anchorages and type 12x0.6", 15x0.6", 19x0.6" and 27x0.6" anchorages were successfully used for this project.