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.
Issue link: http://www.aspiremagazinebyengineers.com/i/297006
40 | ASPIRE , Summer 2013 CBP Concrete Bridge Preservation Twyckenham Drive over St. Joseph River, South Bend, Ind. by Leslie Benson, American Structurepoint When the Twyckenham Drive Bridge was constructed over the St. Joseph River in 1929, it was conceived as more than part of the transportation system. The beautiful concrete open spandrel arch was also intended to honor those who gave their lives in World War I, represented by decorative pylons along the bridge. The bridge originally had 16 deck expansion joints and inadequate drainage that caused signifcant damage as water leaked through to the substructure. When it came time for repairs, the St. Joseph County Board of Commissioners turned to the project team to re- store the structure to its original condition. By analyzing the bridge using fnite element analysis, the number of expansion joints was reduced to one joint at each end of the bridge. The reduced number of joints and improved drainage sys- tems are intended to keep roadway salts away from the concrete, increasing the bridge's service life. To protect the bridge from fu- ture deterioration, zinc galvanic protection was placed at the inter- face of the new and original concrete throughout the bridge. Additional structural improvements for the deteriorating bridge included repair of concrete elements and replacement of non-orig- inal aluminum railings with concrete ones that closely resemble the original. While some key portions of the bridge had to be re- placed, one of the project's goals was retaining as much of the existing structure as possible in order to retain the aesthetically pleasing look of the historic bridge. This also resulted in a savings of time and money for the county. Unique features of the bridge are its plaza areas. These were con- structed to allow pedestrians a place to rest and enjoy the view of the river from the bridge. The historic plazas at the four corners of the bridge were restored by placing new sidewalk and concrete railing and lighting for night-time safety. A newspaper photograph from the opening of the original bridge was used to match the standards and lanterns along the roadway. Eight ornamental street- lights and 36 ornamental lanterns were installed across the bridge and plazas. The design scope also addressed removing and replacing all trans- verse beams and spandrel columns under the existing expansion joints, as roadway salts had saturated these. In addition, the exist- ing concrete deck and sidewalk were removed and replaced with concrete deck panels, a 6-in.-thick concrete sidewalk, and a 12-in.- thick concrete curb. A coating was applied to all concrete sections of the bridge. This project honored the structure's original engineers by restoring the monument to last well into its second century. American Struc- turepoint used the lessons learned and new materials developed over the last century to produce a tighter, more durable bridge. Since its completion, the Twyckenham Drive Bridge has been recognized with the 2011 Award for Outstanding Achievement in Concrete in the Special Structures–Concrete Restoration from the American Concrete Institute, Indiana Chapter, as well as the 2012 Concrete Bridge Award from the Portland Cement Association. _________ Leslie Benson is a public relations specialist with American Structurepoint, Indianapolis, Ind. CBP CONCRETE BRIDGE PRESERVATION The spandrel arch bridge was restored to its original appearance using modern materials. Photo: American Structurepoint. The concrete open spandrel arches of the Twyckenham Drive Bridge. Photo: Susan Fleck Photography. Book_Sum13.indb 40 7/1/13 7:01 AM