Auburn Foresthill Bridge Seismic Retrofit

Seismic retrofit of historic long span steel truss bridge in Placer County, California


Seismic Retrofit


Auburn, CA


Placer County

The Auburn Foresthill Bridge is a long span steel truss bridge that crosses the north fork of the American River and connects the cities of Auburn and Foresthill, CA.  At approx. 730 ft. above the riverbed, the bridge has the highest deck in California and fourth highest in the country.  The bridge is over 2,400 feet long and consists of two tall concrete piers, a steel truss superstructure (with perforated and non-perforated members), and a steel-concrete composite deck.  Other key components include the truss suspension system at center span, abutment and pier to truss connections, and deck expansion joints.
SC Solutions was commissioned to support the seismic vulnerability, strategy, and final design phases.  The objectives of the project were to evaluate the seismic performance of the bridge, identify potential vulnerabilities, and develop and validate a seismic retrofit strategy.  SC Solutions’ scope included the following key tasks:

  • Developed a database of superstructure elements with all section parameters for generating member properties
  • Developed a detailed 3D nonlinear finite element model
  • Performed time history analysis with three governing moments
  • Generated superstructure member and pier demand/capacity ratios using a performance-based strain capacity criteria
  • Performed retrofit design optimization analyses

Project Awards

2014 Seismic Retrofit Project of the Year
California Transportation Foundation (CTF)

2014 Engineering Excellence Award – Honor Award
American Council of Engineering Companies (ACEC, California)

The nonlinear FE model was developed consistent with the project performance design criteria.  The model nonlinearities include: material and geometric nonlinearities, moment-curvature steel superstructure members and concrete piers, and nonlinear springs for the expansion joints and the Buckling Restrained Brace (BRB) retrofit.  Detailed local models of the built up members were also constructed and exercised to validate the performance of the moment-curvature beam elements in the global bridge model.

SC Solutions collaborated closely with the design team to optimize the design, to minimize construction schedule impacts,  and to fast track approvals by the peer review panel.