San Francisco-Oakland Bay Bridge

Temporary structure for world’s largest self-anchored suspension bridge

The San Francisco Oakland Bay Bridge East Span is the world’s largest self-anchored suspension bridge. This design required a temporary structure to support the entire bridge deck during construction. The Contractor, American Bridge Fluor Joint Venture, engaged KCB to provide the structural and geotechnical engineering for the temporary trusses and towers, and for the erection analysis. The temporary structures needed to provide all the support for the bridge, access for the construction activities, and safety in the event of an earthquake.

Challenges

  • Construction required twin temporary steel trusses to support box girders during deck erection until loads were transferred to suspension cables
  • Falsework needed to be in service for 3 to 4 years, a relatively long time for temporary structures
  • Fast track design and construction required to meet tight schedule
  • Deck assembly required precise positioning

Solutions

  • Temporary trusses supported by steel frame towers designed as state-of-the-art “tubular” eccentrically braced frames using steel box sections
  • Falsework designed for substantial earthquake and vessel impact loading
  • Bolted field connections used instead of welded connections, reducing waste and amount of exposure to fumes and other hazards
  • Unique cradles and sliding supports were designed for each deck segment and its planned assembly procedures using precise 3-D modelling

Successes

  • Amount of material waste kept to a minimum during construction of temporary works; material modified and reused as much as possible
  • Advanced design techniques used for temporary towers and trusses reduced steel used by over 2,000 tonnes
  • Deck assembly was carried out according to plan, without incident

Papers:

Dowdell, D.J., B.W. Hamersley, M. Bruneau and S. Tudor. 2015. “Tubular Eccentrically Braced Frames for the San Francisco Oakland Bay Bridge Temporary Works,” in Proceedings of the 11th Canadian Conference on Earthquake Engineering (11CCEE), Facing Seismic Risk, July 24-24, Victoria, BC.

Thavaraj, T., A. Sy. and D. Dowdell. 2017. “Micropile Solutions for Construction of SAS Span of the New San Francisco-Oakland Bay Bridge,” in Proceedings of the 13th International Workshop on Micropiles, March 29-April 1, 2017, Vancouver, BC.

Thavaraj, T., A. Sy and M. Reyes. 2013. “Driven Pipe Pile Solutions for the Temporary Foundations at the New San Francisco-Oakland Bay Bridge,” in 38th Annual Conference on Deep Foundations, September 25-28, 2013, Phoenix, Arizona.

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