Orange County Branch Newsletter

September 2020


Seismic Retrofit of Bridges in Southern California

By Lynn Odgiiv, PE, SE | SEI Co-Chair

ASCE Orange County Structural Engineering Institute (SEI) held its August 2020 technical presentation on “Seismic Retrofit of Bridges in Southern California” on Thursday, August 27th. The presenter, Amit Joshi, is a Bridge Engineer at Caltrans, Division of Engineering Services, Office of Bridge Design South. Mr. Joshi has 10 years of experience in structural design and construction of bridges in California. He serves as a Project Engineer on various seismic retrofit, bridge widening, and replacement projects in the Los Angeles Region. He is part of the Post-Earthquake investigation team at Caltrans. Mr. Joshi has recently founded the ASCE Los Angeles Chapter SEI.

The presentation covered the primary performance standard for retrofitting bridges in California, which is to prevent the structure from reaching its collapse limit state for the Design Earthquake, i.e. “No Collapse” performance is the goal to protect human life. Mr. Joshi covered unique methodologies used for structural analysis and innovative technologies used for determining the seismic retrofit strategy of the bridge in Southern California and described Caltrans Seismic Retrofit program and its evolution over time in detail. He also went into details of seismic retrofit concepts including mass reduction, mass separation, column casing, and hinge modifications. Mr. Joshi described the seismic retrofit projects he worked on in the Southern California region:

  • S55-S73 Connector OC
  • Gaffey Street Bridge
  • Harbor Scenic Drive Bridge


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