Unique bridge superstructure geotechnical recommendations..
Location: Tucson, AZ Client: University of Arizona Status: Design Complete
Update 10/5/06: The new President of the University of Arizona, Robert Shelton, has decided as of 8/29/06 to abandon the rainbow bridge concept, citing a lack of consensus among community stakeholders and a lack of funds. Read more about his message to the U of A Campus community. The project has nevertheless been a very interesting and challenging project to work on and we are grateful to have had the opportunity. The U of A is currently determining what the new location and configuration of the Science Center will be, and we anticipate being involved in the geotechnical aspects of that facility when the time comes.
The University of Arizona (UA) has contracted with NCS to provide geotechnical recommendations for one of the most unique structures to be found in Tucson or the Southwest. As a centerpiece of Tucson’s extensive Rio Nuevo downtown redevelopment plan, the UA is designing a Science Center facility that will be integrated with an arch bridge structure.
Coined as “The Rainbow Bridge,” the proposed bridge structure is a bold and innovative sweeping arch that is cable-suspended and blurs the line between a facility and an arch bridge. Suspended from the arch will be a deck with several levels, including a pedestrian level, and a level containing portions of the Science Center exhibits. There will be additional facilities associated with the Science Center at both bridge abutments. Components of the Science Center include a butterfly vivarium, 24-hr observatory, unispherium, mineral museum, giant screen theater, cafe and gift shop, and more.
The span of the arch is approximately 1,200-ft with a maximum height of 350-ft which, would make it one of the tallest structures in Tucson. The arch bridge will span both the Santa Cruz River and Interstate 10 (I-10) and connect two major components of the City of Tucson’s Rio Nuevo Project, the Civic Plaza on the east, and the Cultural Plaza on the west. The arch consists of a triangular truss constructed of tubes.
NCS performed a field investigation consisting of 18 borings, with some borings up to 150-ft deep at the locations of the arch tube landing points. The foundations for the arch must be designed for loads of up to 60,000 kN (13,500 kips) vertical and 70,000 kN (15,700 kips) horizontal for each tube. Our geotechnical report provided recommendations for the massive foundations that will be required to support the structure, and included some very detailed analysis. We are proud to be working on this project and partnering closely with the architects at Rafael Viñoly (New York based firm), the structural engineers at Schlaich Bergermann and Partner (Germany based firm), and of course with the UA. Specialty laboratory testing was performed by GeoTesting Express.