OPAC Consulting Engineers

San Diego - Coronado Bay Bridge

San Diego, California


California Department of Transportation


Evaluation completed 1995

Scope of work:

Seismic Evaluation

Construction cost:


Services Performed:

  • Developed global computer model
  • Performed dynamic response analyses
  • Developed evaluation criteria


  • State-of-the-art seismic evaluation
  • Soil-structure interaction analysis
  • Propagating seismic wave analysis
  • Distributed seismic source analysis
  • Capacity evaluation for repairable damage

The San Diego - Coronado Bay Bridge carries California Highway 75 across San Diego Harbor between downtown San Diego and Coronado Island. Originally completed in 1969, it consists of a three-span channel crossing with orthotropic steel box girder spans of 660 ft and 550 ft, and 26 curved approach spans with steel plate girders and lightweight concrete deck spanning up to 280 ft. All spans are supported on reinforced concrete frame piers and prestressed concrete pipe piles.

The California Department of Transportation contracted a seismic evaluation of the bridge as part of the state-wide toll bridge retrofit program. OPAC participated in the contract as subconsultant to Anatech for global modeling and response analysis, and also contributed to scope, criteria, capacity evaluation, and retrofit strategy tasks. The initial vulnerability assessment was based upon OPAC's global multi-support excitation dynamic response analyses of seismic demands.

This evaluation was one stage of a multiple-consultant effort to evaluate seismic vulnerability, develop and design retrofit measures, and strengthen the bridge. Seismic retrofit design and construction were programmed by Caltrans based upon this initial seismic evaluation.