Lowry Avenue Bridge, USA – an exceptional project awarded twice
The Lowry Avenue Bridge crosses the Mississippi River in Minneapolis, Minnesota, USA and is an important transportation corridor in Hennepin County. The old steel truss bridge that was built in 1905 and remodelled in 1958 was officially closed in 2008 and imploded in 2009 after an in depth inspection questioned the stability of the bridge foundation. Construction of the new bridge began in early 2010, and the new structure was opened to traffic on October 27th, 2012.
The steel through arch bridge spans the Mississippi with a 137.1 m (450 ft) long main span. The Lowry Avenue Bridge deck is designed as a post-tensioned hollow box girder bridge with stay cable suspenders and, unlike the old bridge, features only two instead of five piers.
The two large arch ribs, topping out approx. 39.6 m (130 ft) above the mean water elevation, are tilted towards one another and meet in the middle of the main span, thus creating a kind of "basket handle". The arch ribs rise up from two delta shaped piers. Vehicular traffic passes between the arch ribs while the sidewalk for pedestrian traffic curves out around the pillars. In summary, the bridge deck carries four lanes of traffic at a varying width of 27.7 to 32.6 m (91 to 107 ft).
DSI USA supplied all post-tensioning systems that were needed for the bridge girders and the bridge deck and provided the necessary equipment for the tensioning and grouting works. 100 pieces of Type 4-0.6" DYWIDAG Strand Tendons with FA Anchorages were used as transverse tendons in the deck slab.
For the transverse tensioning of the deck slab at the edge girders, DSI supplied 100 pieces of 4-0.6" DYWIDAG Strand Tendons with FA Anchorages that were pre-assembled at DSI's facility in Bolingbrook. 100 pieces of 19-0.6" DYWIDAG Strand Tendons were used as curved tendons at the curved sidewalk lookouts. In addition, 100 pieces of 27-0.6" DYWIDAG Strand Tendons were installed for all web tendons in the box girders. 100 pieces of 27-0.6" DYWIDAG Loop Tendons were used in the delta pier/thrust blocks supporting the steel arch ribs. Furthermore, Type 37-0.6" DYWIDAG Strand Tendons were installed in the edge girders.
36 Type DG-P 19 DYNA Grip® Stay Cables were used as suspenders. DSI also provided four DYWIDAG jacks with capacities of 300 t each. The hydraulic jacks were used for lifting the 453 t edge girders from barges on the river into their final position. Afterwards, the steel arches were assembled directly above the river. Per arch, nine segments and four connecting elements were placed and then bolted together.
In 2013, the exceptional project received the Engineering Excellence Grand Award of the American Council of Engineering Companies (ACEC) as well as an award by the American Public Works Association.
Minneapolis, Hennepin County, Minnesota, USA (2012)
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