Taking Lessons From What Went Wrong ~ NYT 3

[paddingtongreen]

An article from the New York Times:

http://www.nytimes.com/2010/07/20/science/20lesson.html?pagewanted=1&_r=1&partner=rss&emc=rss

I particularly like the following extract:

"Eric H. Brown, a British engineer who developed aircraft during World War II and afterward taught at Imperial College London, candidly described the predicament. In a 1967 book, he called structural engineering “the art of molding materials we do not really understand into shapes we cannot really analyze, so as to withstand forces we cannot really assess, in such a way that the public does not really suspect.” "

He's clearly speaking of aircraft but, at rock bottom, we do the same, we just have rules that generally avoid catastrophe.

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[strucguy]

Interesting article, paddingtongreen. Thanks for sharing it.

 

[dhengr]

Paddington:
A really good read. Henry Petroski has several books and they are all very interesting.

The next catastrophe isn’t going to come from lack of rules, and I know you didn’t suggest that. It is going to come from today’s thinking that if you set up enough rules, however poorly understood the origin of those rules, their interconnectedness, or the history and limitations of what we really know and have done; then any damn fool can design anything just by following the rule book (cookbook). Once you have CAD and FEA you can draw and analyze almost anything and barley have the vaguest idea of what you are really doing or how it really works. There is no need to teach and learn the basics anymore, we can just make the codes and computer programs more complicated to negate the need to even understand the fundamental concepts.

Some of the disasters we’ve learned from were designed by some pretty smart engineers who should have known the basics and had some understanding of the limits of what they were doing. Sometimes arrogance or pushing the limits way to far got in their way. Sometimes complexity of the problem caused them to reach to far. Sometimes the client or company said we want this crazy design, but we can’t afford to do what you want to make it work. It still takes someone who really understands the basic concepts and asks the question does this seem like a reasonable solution, do these details look reasonable, where and how could it fail. Then we are right back to Eric Brown’s definition of structural engineering, and we are only fooling ourselves if we think more complicated rules, codes, and FEA programs will change his definition, they just make some of us more cocksure of ourselves and our approach.

 

[ToadJones]

dhengr-
A good rant....seriously.

One thing that has always bothered me was the super complicated code prescribed methods for determining loads (seismic, wind) and the super complicated methods often required for analyzing structures for these loads. It almost leads you to believe that these things are an exact science and they clearly are not.
My point being, we determine these types of loads by some prescribed method that is probably not exact and then design structures to 90% of this capacity.
But, I guess we have to start somewhere.

 

[ash060]

I remember one of my college professor saying that engineer's would use the stock market for design if it provided answers that worked.

He was saying this in the context that analysis is just a guess at how we think the building should behave, but in the end how a building really works in anybody's guess

 

[RockEngineer]

That's the difference between a WAG and a SWAG.

Anyone can make a WAG (Wild Ass Guess)
It takes understanding and use of the best information possible to make a SWAG (Scientific Wild Ass Guess)
Engineers make SWAGs.

 

[hokie66]

Good start to my day, guys. We design structures to perform in a certain way, but often a structure is smarter than we are. Thankfully, that usually works in our favor.

 

[slickdeals]

I am sure you guys know of Wooten's laws.

http://www.aisc.org/WorkArea/showcontent.aspx?id=18544

We are Virginia Tech
Go HOKIES

 

[IDS]

I always thought the quote was much older than that, but an interesting article here:

http://www.structuremag.org/article.aspx?articleID=829

agrees with Dr Brown in 1967.

Doug Jenkins
Interactive Design Services

http://newtonexcelbach.wordpress.com/

 

[jenofstructures]

this is a very interesting thread

thank you paddingtongreen for the link

Poems are made by fools like me, but only God can make a tree. engineers creates wonderful buildings, but only God can creates wonderful minds

 

[paddingtongreen]

Welcome.

The problem with Wooten's law is the idea that common sense rules, educated common sense rules. Uneducated common sense says that the Earth is flat. Otherwise, it is a great article.

I have a different gripe than Wooten, I thought when I first learned of it, and I still think, that it is a bad practice to state the reduced column capacity due to buckling in terms of stress. It is not a stress problem, it is a column geometry problem. I don't know how many times people have been worried because a column was damaged and they have compared the local stress to the buckling load allowable stress instead of the material allowable stress.

Michael.
Timing has a lot to do with the outcome of a rain dance.