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/306906
20 | ASPIRE , Fall 2007 A E S T H E T I C S C O M M E N T A R Y by Frederick Gottemoeller The design of the High-Main Street Bridge started with the agreement between the Federal Highway Administration, Ohio Department of Transportation, City of Hamilton, and the Ohio State Historic Preservation Offce that established fundamental aesthetic guidelines and mandated consultation with local historic groups. The resulting working group indicated a strong preference for a design that would emulate the best features of the existing bridge, citing as a model the Discovery Bridge in Columbus, Ohio, a fat plate arch of similar size built in the 1990s. Normally in a situation like this, it is preferable to develop a contemporary bridge design ftting the historical and monumental context of the site. However, it is not uncommon for communities to insist, as in this case, on a more traditional structure. So, the design team resolved to use the best of modern technology to create a bridge that recalled the best features of the aging bridge. The most positive aspects of the existing bridge were the graceful elliptical shape of the arches and the extreme thinness of the deck at midspan. Through the inspiration of Franklin County Engineer Mark Sherman and others, Ohio's precast concrete industry has built a number of similarly sized monumental bridges using custom precast con- crete girders. The team decided to use this technology, but to splice the girders to make them continuous. This allowed the transfer of moment to the pier sections, so that the midspans could be kept very thin. The end spans were designed as half-arches to allow for river walks on both banks. For economy, the more complicated pier segments of the girders were made identical, and all dimensional variations were taken up in the simpler center drop-in sections. The details of the fascia girders, overlooks, and railings were all derived from the architecture of the Soldiers, Sailors and Pioneers Monument, symbolically extending its infuence from the east to the west bank. The sidewalk paving patterns are the same as those used for the existing High Street sidewalks east of the bridge. The railing includes a series of bronze medallions depicting momentous events in Hamilton's history. One of the least attractive aspects of the old bridge was the pronounced hump in its profle. By lengthening the vertical curve to about the length of the bridge the team gave the bridge a more graceful curve and improved drivers' sight distance. However, this placed additional emphasis on keeping the girders thin in order to maintain the hydraulic opening. To extend the monumental district's presence to the west bank, a pair of raised plazas was developed with seating, fagpoles, and lighting. These replaced features that had been there before but at a grander scale. The west bank itself was regraded to create a pair of small amphitheatres fanking the plazas that provide visual and handi- capped access to the river. They will also be a good location for civic celebrations, such as the annual art festival and the 4th of July freworks. All of these features are aimed at integrating the new structure into not only the physical fabric of the monumental district but also into its daily life. The use of precast girders also eliminated falsework and shoring supports that would otherwise have restricted the hydraulic opening of the bridge during construction, which was critical for this project. As high strength concrete and other i n n o v a t i o n s c o n t i n u e t o e x p a n d concrete's design potential, designers can look to spliced girders for more opportunities to create a structure that meets a wide range of goals. Their use can help provide more solutions that are aesthetically pleasing, quickly constructed, and cost effective. ___________________________ John C. Shanks Jr. is Senior Bridge Engineer with Burgess & Niple, Inc., Columbus, Ohio. Dramatic lighting was provided at the fascia to illuminate the arch design at night and call attention to details in the design. For more information on this or other projects, visit www.aspirebridge.org. advertisers index ARCADIS 37 BASF 53 Deal 26 DSI 15 Eriksson Technologies Back Cover FIGG 3 Finley 5 Hatch Mott MacDonald 47 Hamilton Form 14 Grace 56 IBT 49 Larsa 7 LEAP Inside Front Cover Lehigh Cement 4 PCAP—CABA 33 PCI 64 Scott System 27 Sika 21 Splice Sleeve Inside Back Cover Stalite 63 Sumiden Wire 41 Tricon Precast 65 VSL 61 10802_Aspire_Fall07.indb 20 8/30/07 3:00:10 PM