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

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Bearings & JointsOnline self-study

Bridge Bearings: Types, Inspection and Replacement

1 PDH · about 60 minutes · Course no. BR-B01 · 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.

Bearings are small, cheap compared with the girders they carry, and easy to ignore until one stops working. A frozen rocker, a pad that has walked off its seat or a pot bearing leaking elastomer can push forces into a substructure that was never designed for them. This course covers the three families of steel bridge bearings, how the AASHTO LRFD design requirements shape them, how to detail bearings so they can be replaced, how to inspect and code them using the AASHTO element definitions, and how to plan jacking and replacement. It draws mainly on the Steel Bridge Design Handbook, Chapter 15, Bearing Design (NSBA/AISC B915-22, February 2022, updated to the AASHTO LRFD 9th Edition from FHWA-HIF-16-002 Vol. 15), and on the AASHTO element definitions as reproduced in the Alabama DOT Bridge Element Inspection handbook (rev. 08/2014). Section numbers are given so you can check each point. Numbers in worked examples that do not come from these documents are labeled illustrative.

⬇ Download study guide (PDF)

Learning objectives

  • Identify bearing types
  • Recognize bearing problems
  • Understand elastomeric bearing design concepts
  • Plan jacking and replacement

Outline

  1. What a bearing has to do
  2. Elastomeric bearings
  3. Designing elastomeric bearings: Methods A and B
  4. High-load multi-rotational bearings
  5. Mechanical bearings and why they freeze
  6. Choosing a bearing type
  7. Detailing bearings so they can be replaced
  8. PTFE sliding surfaces and field welding near elastomer
  9. Inspecting bearings: what to look for
  10. Coding bearings with AASHTO elements
  11. Worked example: is this pad over-translated? (illustrative)
  12. Planning jacking and bearing replacement
  13. Summary checklist for owners and engineers
  14. Open the course (19 screens, 2 knowledge checks)
  15. Final quiz — 10 questions, 70% to pass

References

  1. AASHTO, LRFD Bridge Design Specifications, 9th Edition, 2020
  2. NCHRP Report 432, High-Load Multi-Rotational Bridge Bearings, 1999
  3. FHWA, Bridge Inspector's Reference Manual (BIRM), FHWA-NHI-12-049, 2012 (as revised)
  4. NSBA/AISC, Steel Bridge Design Handbook, Chapter 15: Bearing Design, Publication B915-22, February 2022 (update of FHWA-HIF-16-002 Vol. 15)
  5. Alabama DOT Maintenance Bureau, Bridge Element Inspection (element and condition state definitions following the AASHTO Manual for Bridge Element Inspection), revised 08/2014