Complexity of Engineering 19

[vmirat]

Recently, I received the latest edition of the Steel Design Manual from AISC. While purusing through the pages of this weighty tome, I reflected on how complex the field of engineering, specifically structural engineering, has become over the years. The respective institutes, societies, and such have spent lots of time and money developing more and more exacting methods for determining forces on structures. I'm wondering if we are getting to a point of diminishing returns? The more complex we make the process, the greater the chance for error. We develop computer programs to help us solve these complex problems but at the same time don't trust them. Are we to the point of "measuring with a micrometer, marking with a crayon, and cutting with a chainsaw?" And then I thought about the entire construction process, of which we are only a part. What about the builder? There was recently a very long post concerning additional certification for Structural Engineers (SE) based on the premise that the structural world is so complex that addition qualifications are required to insure quality. But what about the builder? Should there be additional qualifications for those involved with the building of these structures that we spend so much time and mental energy designing?

 

[JStephen]

Perhaps we could draft a 600-page IRS-type document detailing the requirements for simplicity in other design documents, and then get it forced onto the other specification writers.

 

[WillisV]

It is a little disconcerting to me to see the overwhelmingly negative attitude displayed towards the standards committees. Though I agree that the codes have gotten more complex and are at times difficult to understand and/ or apply to real world situations, I believe it is truly the committees' intent to forward the profession and not, as some people seem to think, to write confusing codes just for the sake of selling more codes and holding seminars and wringing out every iota of strength from each member. That is utter rubbish.

Though I cannot speak for every standards committee, I know that AISC at least has a significant portion of practicing engineers mixed in to each of their internal committees as well as some fabricators and detailers. Most of these people are strictly doing this on a volunteer basis and spend large amounts of time and effort to make the codes better instead of sitting around bitching about them on some internet forum.

Keep in mind that the codes need to be written to be all encompassing because they need to cover almost every possible scenario thrown at them. If it seems unnecessarily complex in typical situations, it is because somewhere, somebody has come up with a situation that needed that level of complexity to solve the problem. It is up to the practicing engineer to determine how to best apply the portions of the code applicable to their specific problem. If Wl^2/8 works for everything you do then that's great, but there are many situations where more rigirous analysis and complexity are warranted. Some of the code changes might appear to be made in an effort to confuse, but very rarely is this the case. Take for instance the new "Direct Analysis Method" in Appendix 7 of the 13th edition AISC manual. Though it still does have some bugs to be worked out before it can be universaly applied, it is an honest attempt to erradicate the use of widely misapplied effective length ("K" factors) and simplify design by using the analysis of the structure itself to account for effective lengths and out of straightness type criteria.

"Raging Against the Machine" is not going to solve anything. Contacting these organizations and getting involved just might.

 

[JAE]

WillisV - nice post and I agree with your views.

One other view on this, though, is that I don't believe the committees are malicious and intentional in writing difficult codes. But I do think there are some cases where the code committees are somewhat ignorant of the true effect of their new code on the practicing engineer.

One example:

Back in my pre-computer days, the ACI code came out with new provisions for moment magnification factors (the [δ]b and [δ]s terms in Chapter 10). After studying this for a while, I then had the opportunity to visit with one of the committee members, a professor from a major university. I asked him if my interpretation was true, that to properly design a concrete column with these [δ] factors, one would have to calculate a different [δ] for each and every column, and for each column...a separate [δ] for each and every load combination (as these factors change with load).

He blinked at me and initially said no, but after pressing him on the details, he agreed that for a multi-story concrete framed building, there would be hundreds of these factors necessary to technically meet the intent of the code. I asked him if the committee foresaw this requirement and it was obvious that this was the first he'd ever considered it.

 

[JStephen]

Willis, take a look at the recent post about wind torsion loads from ASCE 7. It seems that it is marginal whether the structure even needs to be engineered or not, yet if it is, the only solutions seem to be wind tunnel testing, or a cobbled-together solution that doesn't technically meet the standard. At least that's what I get out of that thread.

 

[HgTX]

"We have self-appointed committees (ACI, AISC, ASCE, etc.) that are telling us how to do engineering. "

Nothing stops you from joining those committees, or at least attending their meetings. You don't like their output? Become a volunteer yourself and volunteer some of your own time and effort into it instead of whining about it.

Hg

Eng-Tips policies: faq731-376

 

[jen4950]

Well- I can't speak for everyone (obviously)- but especially in my Master's program, I was taught and understood the theory behind the software. I know the linear algebra, stiffness derivations, dynamic and optimization algorithms well enough to feel comfortable using commercial software. For instance, I have written my own FEA software (and optimization algorithms)- so I know what to expect. And hey- I've even designed a beam by hand that meets strength AND servicability requirements using LRFD!!! OMG!!

Of course, I don't expect an old salt to go down my road at this stage in their career- but those of us who have been exposed to state of the art and are willing to embrace it will be carrying the future of the business.

LRFD is here to stay-
FEA is here to stay.

In regards to this business- computers are the key to risk mitigation and bottom-line inflation if you ask me. Learn your tool.

 

[vmirat]

I think we've heard from all sides of this issue by now. I suggest we end this thread on a good note, and since I started this thing, I would like to end it. My original post was intended to provoke thought about how complex engineering has become and whether more complexity is better. Some have stated that we should always strive for improvement, and I think we all agree to that. Others have echoed the concern for applying practicallity to the engineering processes we develop, with which I think everyone would also agree. In the end, I think it's just a matter of continuing to ask "why". If we don't question why things are the way they are, then we become complacent and that can be dangerous. I enjoyed everyone's comments and thanks for playing!