Report on Minnesota I-35 Bridge Collapse

Two links to news stories about the pending NTSB report on the collapse of the I-35 bridge in Minneapolis, MN. Check back; I plan to update this article with additional links as they become available.

News articles from 12 and 13 November:

• AP: Safety Board to release report
• Duluth: State of Minnesota improves bridge inspection process
• AP: Extra load of construction material contribute to collapse
• AP: Design errors led to collapse

NTSB Presentation and related articles:

• NTSB Official Press Release
• Synopsis of NTSB conclusions
• Presentation by Jim Wildey on conclusions of investigation (11 Mb pdf)
• Links to other presentations and flash or wmv animations

Anyone who has seen my class lecture on the static equilibrium calculation for the gusset plate (based on the January 2008 NTSB Interim report (400 kb pdf) about gusset plate design flaw) will recognize many of the details in this presentation.

• WP: article on the report
• ASCE article about the report
• and collection of ASCE info on the investigation
• CNN: Design flaw led to collapse
• AP: Design errors led to collapse (includes photo of deformed gusset plate)

The final NTSB report does not seem to be in their publication archives yet. Based on the publication dates, it might not appear there for some time.

Fourier Analysis of the Beatles

I mentioned this in class late last week:

The mathematical technique of a Fourier Transform (see pg 230 of the Wolfson physics textbook we use, but also any number of math or physics textbooks) has been used to solve the mystery of the unique opening chord of the Beatles' "Hard Days Night". The mathematical software used to do this is capable of isolating the fundamental and all harmonics of a note played by a particular instrument, which made it possible to find the missing fourth instrument (George Martin on piano) responsible for the sound.

The article in Wired includes a sample of this chord, and a link to the pdf version of the report.

Computer aided bridge inspection

News story forwarded to me by my dad:

German scientists say they have developed an image-processing software program that automatically detects irregularities in bridge materials. (United Press International)

Quite interesting. This program would probably have warned of the defect in the Minnesota I-35 bridge that was in photographs taken several years before it collapsed, but not noticed at the time.