Historical Progression of Los Angeles Metro Seismic Design Criteria: Fid-Bau Portal

Historical Progression of Los Angeles Metro Seismic Design Criteria

Hudson, Martin B. / Martin, Geoffrey R. / Danielians, Androush

The Los Angeles Metro transit system has been undergoing a rapid expansion since the 1980s. The expansion includes complex structures comprising elevated structures with major bridges, circular tunnels, oval caverns, rectangular tunnels, and underground stations. In addition, the Metro transit system overlaps with the lifelines of other jurisdictions, including the California Department of Transportation, Los Angeles Bureau of Engineering, and many others. The Los Angeles area is also subject to a significant seismic hazard. The seismic hazard creates risks of damage due to fault rupture, ground shaking, liquefaction, landslides, and seismic settlement. Accordingly, Metro provides the Supplemental Seismic Design Criteria as part of its overall Design Criteria to provide a comprehensive basis for design of new structures for seismic hazards. Metro’s design criteria have progressed over time based on capabilities in the engineering community, new research, and changes in parallel standards such as Caltrans standards and ASCE 7. Metro’s criteria have served as models for other lifeline system design criteria, and are anticipated to continue to change over time based on additional capabilities and knowledge in the engineering community. This work reviews the history of changes of the Metro Supplemental Seismic Design Criteria. Metro’s criteria anticipate changes to computational methodologies used for design of Metro structures, including three-dimensional seismic response analysis and structure-soil-underground structure interaction with Metro facilities. The Metro criteria could be applicable to other codes and standards of practice utilized by the profession for transportation and other lifelines structures in seismic regions.