The big idea for this episode is to discuss the FIU Bridge Collapse with Gary Klein of Wiss, Janney, Elstner Associates (WJE). Mr. Klein takes exception to the NTSB/FHWA findings.

This episode is technical, detailed, and assumes the listener has a general knowledge of the FIU bridge and collapse investigation. For a more general introduction to the FIU Bridge, please see Collapse of the FIU Pedestrian Bridge, Episode 1.

Much of this conversation follows along with a presentation that Mr. Klein delivered to the AASHTO Committee on Construction 2020 annual meeting.

For full show notes, see Build Big Ideas - Gary Klein of WJE: FIU Bridge Collapse and Exceptions to the NTSB Findings, Ep. 11.

Outline and Notes of the Podcast Discussion

Brief intro to Gary Klein career and qualifications - National Academy of Engineering member - WJE has a massive structural laboratory, not just computers and pencils - Expert witness experience: Hyatt Regency, Boston Central Artery, and more

WJE exceptions to NTSB/FHWA findings - What is the role and incentives for an expert witness? - Obviously, you are committed to facts. Do you strive for impartiality? - Are NTSB, FHWA, and AASHTO aware of the WJE exceptions? Have they provided specific responses?

Redundancy: internal, structural, load path - Was the designer responsible for checking the construction sequences?

Interface shear transfer testing - Why not conservatively design the connection with enough shear reinforcement steel instead of relying on cohesion at a cold joint? - Is any structure ever constructed perfectly to spec? - Was the cold joint always intended during design, or added later during construction?

Load factors and safety factors under dead load during construction - Was the AASHTO code really relevant to a concrete truss member?

Lessons learned: EOR onsite, joint inspection, traffic closures for safety

References

Wiss, Janney, Elstner Associates (WJE) materials:

Presentation Slides

Party Submission Report

National Transportation Safety Board (NTSB) materials:

Video Summary (5 min)

Final Report (154 pages)

Threads to pull for future episodes

What are the human stories that preceded the collapse?

What thoughts do other knowledgeable people have about the collapse?