epoxybot said:
During an interview with FIGG, OSHA quizzed FIGG about the lack of Redundancy. FIGGS reply was that the numerous PT bars were a form of Redundancy. Let’s hope that was Linda Figg & not Denny Pate.
What a deflection - Yes, the PT system has redundancy - if one strand fails there is only a small reduction in the prestress force and a small increase in loads to the remaining strands at near ultimate moments. But the PT system is not the only thing important in this structure.
I saw somewhere in the past a factor to be used if there is no redundancy, and as I recall the example, they were using maybe +3%, like divide phi by 1.03. I don't think that would have saved this structure.
What would be an appropriate redundancy factor for a bad idea? A factor of 2? So lets use two bad ideas?
A V-8 engine has 8 connecting rods - but not a redundancy of 8, because if one rod fails you walk.
Redundancy in a structure seems to mean alternate load paths. Or joints and members so well designed that they just don't fail. One intended redundancy in this case was the peer review. An alternate path to a safe design. Which, by the way, did not help much.
Redundancy in the construction phase is provided by the Project Inspectors - a redundant set of eyes.
If a redundancy factor of +10% had been used in this case, the thing might not have failed when it did. And with full consideration for loss, and very real sadness in my heart for those lost and injured in this collapse, this might have been a better time than sometime in the future when even more lives could have been lost. A better time would have been 2:00 AM with no traffic. But my point is, and I am not good at making it, no formula can compensate for a simple oversight. Engineers simply must pay attention.
To see two prominent companies go bankrupt over a small project like this does not seem right. The risk/reward ratio seems badly skewed. Sure, this project in this form should have been load tested - in fact, I submit that it should have been a research and development project with a budget of maybe $50 million. How do we get that funded? Sounds cheap, now.
So after the dust and the lawsuits have settled, what will we have learned?
Probably that the Architect was right when he told me "Never be the first to try something, and never be the last to use something."
