The centerpiece of the new Veterans’ Glass City Skyway Bridge is a pair of 612-foot long main spans supported by a single 400-foot-tall cast-in-place concrete pylon in the center of the bridge. The top 196 feet of the angular pylon is faced on four sides with specialty glass that will reflect the sky during the day and be backlit at night by LED fixtures that are capable of 16.7 million color combinations.
Owned by the Ohio Department of Transportation (ODOT) and designed by Figg Engineering Group, Tallahassee, Fla., it is the world’s first cable stayed bridge to showcase glass— a theme selected by the public in honorof the city’s industrial heritage in the glass industry.
Figg developed the unique cable stay cradle system used on this project. Each strand of the stay cable passes through its own individual sheathing tube in the cradle, eliminating the need for anchorages in the pylon and providing ODOT with the ability to replace an entire stay cable strand by strand. Four of the cable stays (each with 156 strands) are the largest in the world for a cable-stayed bridge. The first stay was stressed on July 20, 2006 and the last of the 20 stays was stressed in December. It’s also the largest single project ever undertaken by ODOT, being bid at $220 million in 2002.
The bridge, which will carry I-280 traffic over the Maumee River, includes a total of 1.2 million square feet of bridge deck in the main span, ramps, approaches, and variable-width gore areas where the ramps and approaches meet—all built with precast concrete segmental construction. Segments for the bridge’s southern main span were supported by temporary piers and lifted into place with erection trusses. The segments to the north of the main pylon were erected in cantilever out over the main shipping channel.
Mike Gramza, project manager forODOT, says the 90-ton segments weretransported by truck across the completed portion of the bridge deck out to the end of the cantilever where two 350-ton cranes lifted them into position. Threaded post-tensioning bars and strand tendons connected them to the previously-erected segments. When three segments were erected for each travel direction a 90-ton precast concrete “delta frame” was lifted by crane under the end segments and connected to the box girders with cast-in-place concrete closures and post-tensioned tendons. The delta frame then provided the anchorage for the stay cable. Upon completion of the stay installation the entire cycle would begin again.
The Veterans’ Glass City Skyway bridge used 185,000 cubic yards of concrete, 32.6 million pounds of rebar, and 1.6 million pounds of post-tensioning tendon.