I just don’t believe this conclusion. It is too convenient. It lets everyone alive off the hook. I have gone through a number of AISC code revisions. EVERY one of them increased the thicknesses (and/or lowered the allowable stress) when compared to the previous one at least somewhere in the code. Over 40 years, they add up to quite a difference.
So if they were comparing the as-built sizes with the current code, they are guaranteed to find a “flaw” in the design. In addition, the number of lanes was increased at sometime between the original building and the collapse. That was bound to increase loads. Who approved that decision? Again, checking calculations with the current number of lanes is guaranteed to find a flaw.
In addition, the inspection report showed that there were NUMEROUS cracks in those very gusset plates and many of them were only half the original thickness because of serious corrosion. That was all noted in the reports — and ignored. If they intend to ignore reports, why bother even having them.
This is a whitewash. A coverup.
From the article above:
The bridge, built in 1967, was designed by Sverdrup & Parcel, a prominent firm that also designed Busch Stadium in St. Louis, the Superdome in New Orleans and the Chesapeake Bay Bridge-Tunnel.
The founder of the firm, Leif Sverdrup, is dead. The company is part of Jacobs Engineering Group in Pasadena, Calif., which did not return calls.
And from wikipedia:
Sverdrup & Parcel was an American civil engineering company formed in 1928 by Leif J. Sverdrup and his college engineering professor John I. Parcel. The company worked primarily in a specialty field of bridges. Many of the company’s projects were located in the St. Louis, Missouri area near the company’s headquarters.
So one of the founders is dead, but that doesn’t mean that the particular engineer who designed the bridge is not still with us.
I completely agree.
This report is about like saying the bridge failed, because it fell down. It explains nothing, and it conceals much.
The gussets, as designed, held fast for decades. They held four extra lanes of additional traffic, after the expansion project. They held concentrated point loads of construction traffic, a hopper truck and apparantly a concrete applicator truck, just north of the failure point.
The gussets, as originally designed, were re-analyzed by the U of M study, and the original design criteria were used in comparison with the actual strain measurements gathered under that study, and the traffic loads DID NOT APPROACH DESIGN LIMITS.
Like you, I am appalled at the visual condition of that bridge, from end to end, as shown in the inspection report photos.
That bridge was neglected, for decades. serious problems were neglected, for decades. In spite of that, the bridge held four additional lanes of extra traffic, and held additional construction loads too. The I-35 bridge did not fail Minnesota. MnDOT and Minnesot politicians abdicated their responsibility, and failed the bridge, along with the people who died using it.
What we see here, in my opinion, is a perfect example of the wolf guarding the sheep. I smell a fix, I do not trust or believe this report’s conclusions, I believe it is an attempt to sweep the true failings under the rug, to avoid responsibility for professional and political neglect, and believe further, that many, and quite possibly, ALL OTHER BRIDGES IN MINNESOTA ARE SUSPECT.
Minnesota has a HUGE problem right now. The people paid to watch and take care of your bridges, are not.
Instead of fixing problems, they pretend there are no problems, even now, today, after the collapse.
Minnesotans, you need to speak up, and don’t stop until you get action.
Your lives are at risk.