LoadPath PDH — PE/NICET supplemental PDH (not FHWA/NBIS refresher training).

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SeismicOnline self-study

Seismic Bridge Design Basics

1 PDH · about 60 minutes · Course no. BR-E01 · Instructor: Michael Craig, PE

About the instructor

Michael Craig, PE is Senior Vice President and Southeast Director at Strinteg Corporation, leading bridge inspection and structural engineering across eight states and Puerto Rico. In 27+ years he has inspected over 4,000 structures and completed 3,000+ load ratings and 160+ load tests. He has managed repair and preservation design for complex bridges, including cable-stayed bridges. He holds PE licenses in twelve states, DC and Puerto Rico, SPRAT Level 1, and FAA Part 107 credentials.

Earthquakes load a bridge in a way no other design case does: the demand is a displacement imposed through the ground, the design event is rare, and the economical answer is almost never to resist it elastically. This course walks through the basics of seismic bridge design as taught in FHWA's reference manual for the NHI course on LRFD seismic analysis and design (FHWA-NHI-15-004). It covers how U.S. practice evolved after the 1971 San Fernando earthquake, the 1,000-year design hazard and NEHRP site classes, how seismic zones and seismic design categories scale the design effort, the force-based approach of the AASHTO LRFD Bridge Design Specifications and the displacement-based approach of the AASHTO Guide Specifications for LRFD Seismic Bridge Design, earthquake resisting systems and global design strategies, capacity design and overstrength, minimum support lengths, and the detailing that turns a column into a ductile fuse.

⬇ Download study guide (PDF)

Learning objectives

  • Explain seismic design philosophy
  • Describe seismic design categories
  • Apply capacity design concepts
  • Detail for ductility

Outline

  1. Why seismic design is different
  2. How U.S. practice evolved
  3. Seismic input: hazard, site class and the design spectrum
  4. Seismic zones and seismic design categories
  5. Two design methods: force-based and displacement-based
  6. Earthquake resisting systems and global design strategies
  7. Demand analysis
  8. Capacity design and overstrength
  9. Support length and connections
  10. Detailing for ductility
  11. Isolation, protective systems and putting it together
  12. Open the course (17 screens, 2 knowledge checks)
  13. Final quiz — 10 questions, 70% to pass

References

  1. FHWA-NHI-15-004, LRFD Seismic Analysis and Design of Bridges Reference Manual (Marsh, Buckle and Kavazanjian, October 2014)