Structural dynamic using the beam-spring model and non-linear time history analysis is currently recognized as one of the most accurate tools for seismic design and analysis of bridge structures.
Selection of ground motion intensity with regard to its frequency content relative to the natural frequency content of the bridge structure is essential to estimate its seismic response. Typically, geologic conditions of high seismic zones are extremely variable which includes a large incidence of fault crossings with high slip rates and potentially large rupture displacements. Bridges that cross hazardous faults or are located in close proximity to active faults are subject to both transient ground motions as well as static fault offset displacements. The transient motions can cause large deformation demands, due to near-fault (e.g., rupture directivity and fling) effects. Larger displacements due to permanent fault offsets can also cause severe damages to bridge structures crossing the faults or in close proximity to active faults with the threat of total collapse which must be considered in design. These hazards bear significant risks to public life safety, as well as service interruptions and consequent losses in revenue.
This presentation discusses ground motion selections for bridges crossing active faults or are located in close proximity to active faults with regard to their frequency content for seismic design and analysis of bridge structures. Results of a three-dimensional nonlinear time history analysis of instrumented bridges subjected to ground motions with various frequency contents and static fault offsets will be presented.
The content of this presentation:
Bridge Abutment and Transition Zones
Implementation of Fault Rupture
Frequency Impact of Earthquake Motions
Anoosh Shamsabadi - Senior Bridge Engineer
Dr. Shamsabadi has over 33 years of experience in earthquake engineering. For 29 years, he served as a Senior Bridge Engineer for the Office of Earthquake Engineering at Caltrans and over 3 and half years as a Supervising Transportation Engineer for the California High-Speed Rail Authority. He also served as a member technical advisory panel for different projects including BART and High-Speed Rail. He also taught number national and international short seismic courses.
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