ASPIRE is a quarterly magazine published by PCI in cooperation with the associations of the National Concrete Bridge Council. The editorial content focuses on the latest technology and key issues in the Concrete Bridge Industry.

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Bridge No., Trunk Highway No., Bridge Name, and Location 04002, T.H. 72 over the Tamarac River, Waskish 13004, T.H. 8 over Center Lake Channel, Center City 33008, T.H. 65 over the Groundhouse River, Kanabec Co. 33005, T.H. 65 over the Ann River, Kanabec Co. Year Built 2005 2005 2007 2007 Total Length 143'-11" 72'-5" 90'-8" 112'-5" Width 50'-4" 76'-2" 66'-0" 47'-4" Span Lengths 44'-11", 54'-1", 44'-11" 22'-0", 27'-0", 22'-0" 29'-7", 30'-4", 29'-7" 36'-5", 36'-10", 36'-5" f' c Precast and CIP, psi 6500, 4000 6500, 4000 6500, 4000 6000, 4000 Fabricator (PCI-certified producer) County Materials, Roberts, Wis. County Materials, Roberts, Wis. County Materials, Roberts, Wis. County Materials, Roberts, Wis. Contractor Robert R. Schroeder Construction Co., Glenwood, Minn. Lunda Construction Co., Black River Falls, Wis. Redstone Construction Co., Mora, Minn. Redstone Construction Co., Mora, Minn. by Moises C. Dimaculangan and Tony Lesch, Minnesota Department of Transportation This is Bridge 66004, TH 60 over the Cannon River in southern Minnesota after completion. Photos: Minnesota DOT. With aging bridge infrastructure and higher levels of traffic on roadways, the demand for bridge replacement and rehabilitation is very high. For this reason, there is a need to look for innovative w a y s t o r a p i d l y c o n s t r u c t l o n g e r lasting bridges while reducing traffic disruption. One solution is prefabricated bridges. The Minnesota Department of Transportation (MnDOT) has embarked on the development of such a system. The system can provide an effective and economical design concept that can be implemented for new bridges and the rehabilitation of existing bridges. In 2004, MnDOT state bridge engineer, D a n D o r g a n , p a r t i c i p a t e d i n a n International Scan Tour sponsored by the Federal Highway Administration, the American Association of State Highway and Transportation Officials, and the National Cooperative Highway Research Program. The Prefabricated Bridge Elements and Systems scan team visited Japan, the Netherlands, Belgium, and France. The objective was to look for innovative ways for rapid construction of bridges while minimizing the impacts on the traveling public. The focus areas of the scan were prefabricated bridge elements and systems that minimize traffic disruption, improve work zone safety, minimize environmental impact, improve constructability, increase quality, and reduce life-cycle costs. The Scan Team identified 10 technologies for implementation in the United States. Poutre Dalle System One practice in particular that showed p r o m i s e i n i n n o v a t i o n o f r a p i d construction was the Poutre Dalle System from France. This system consists of shallow, precast, prestressed concrete inverted-tee beams that are placed directly adjacent to each other. The beams are connected across a longitudinal joint that is established through the use of 180-degree reinforcement hooks that protrude from the sides of the webs. Cast-in-place (CIP) concrete is placed between the beam webs and over the top of the beams to form a solid composite cross section. In Minnesota, CIP concrete slab span construction has a long history and a useful place in the bridge inventory where shallow depth structures are desired. But construction of the traditional slab span bridge can require large amounts of time and labor due to curing periods and formwork construction and removal. Impressed with the Poutre Dalle System, MnDOT began developing a similar system for use on Minnesota highways as a potential alternative to CIP slab span structures. Minnesota's System Bridge engineers in the MnDOT Bridge Office started the design process by first roughing out some initial design concepts that were discussed with several local precast beam fabricators. The team then created a partnership with researchers from the University of Minnesota. In a series of design workshop forums, the designers and researchers worked together to develop design details and an outline for a parallel Minnesota bridge research project. The research project was multifaceted research intended to instrument a pilot bridge to verify the design assumptions and to conduct additional research on beams in the university's laboratory. MInnesota's Precast coMPosIte slab sPan systeM 40 | ASPIRE , Summer 2010 ASP10-1625.indb 40 6/21/10 12:20 PM

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