Complexity of Engineering
Complexity of Engineering
(OP)
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?






RE: Complexity of Engineering
RE: Complexity of Engineering
perhaps. we design building structures using the some of the latest technology available. yet, the contractor employs the same kind of people to build with basically the same technology that was used by our great-grandparents.
RE: Complexity of Engineering
I don't think I could agree with you more!!
Unfortunately, IMHO, I think the practicing engineers have let the academic folks take over the code writing committees, and they have gone off and made things more and more complicated in some eternal quest for 'economy'.
Designing to the last bit of capacity is fine as long as your not the person who has to stamp and sign the drawings and say that no matter what happens over the next 50 or 75 years, the building isn't going to fall down. I think when you are that person, all of a sudden your not so ready to go right to the edge.
RE: Complexity of Engineering
RE: Complexity of Engineering
RE: Complexity of Engineering
When you start reading about where these maps come from, it sure sounds like some voodoo engineering going on. That 2/3 factor, as best I can tell, came from a "That's too high so let's multiply by 2/3" logic. The R and I factors look like they came from a committee process, and could just as easily have been 50% less or more, and no one would know the difference. But hey, we've got maps accurate to two decimal places, so lets calculate all those forces to 8 decimal places and feel good about it.
I find the newer codes read suspiciously like the tax code, and can't help but wonder if there's not some connection. "Design of this widget shall be per some other paragraph as modifed by this paragraph but not less than this other section or greater than this equation", etc.
RE: Complexity of Engineering
"measuring with a micrometer, marking with a crayon, and cutting with a chainsaw" is definitely quotable.
I also give a star to JStephen for his insight. I heartily agree with his assessment of the current seismic requirements in ASCE 7-05. And your thoughts on the similarities between engineering codes and the tax code is food for thought.
regards,
chichuck
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From what I've heard and read, the code committees have listened to these arguments and have put much effort into making the codes as practical as possible while still being state-of-the-art.
RE: Complexity of Engineering
RE: Complexity of Engineering
The evaluation person wanted USP to run a finte element analysis on the hanger. The USP engineer response was that finite element was just another approximation of an approximation.
I am in agreement with the comments above, and feel that the codes have gotten so complex to make them practically useless for the design of the vast majority of structures that most engineers deal with.
RE: Complexity of Engineering
RE: Complexity of Engineering
RE: Complexity of Engineering
RE: Complexity of Engineering
in a place where i worked for many years, there was a microfiche filing cabinet ... a model airplane from the late 40s to up part of one drawer; in the 50s a design required 1 whole drawer, in the 60s several drawers, 70s a whole side of the cabinet (1/2 the cabinet), in the 80s they had to but a neew (much bigger cabinet (and this didn't include the computer models which would have been on a bushel of tapes), and so it goes ... today (well some time ago) they gave up on microfiche and now everything is on-line, thankfully disc memory is very cheap.
RE: Complexity of Engineering
RE: Complexity of Engineering
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RE: Complexity of Engineering
I like that one rb1957! Funny part is in the end it really comes down to those folks signing/stamping the paperwork and how conservative they really want to be, like lkjh345 says.
Are the codes too complex? Try reading a FAR or similar regulation and tell me how many times through it takes to get the gist of it. Then see if how you interpreted it matches the next guy's interpretation. Seems even the FAA doesn't have much luck even getting internal agreement.
I've always watched in amazement as legislators continue to pass law after law, lengthening the legal codes ad infinitum - and to what end? I guess its just dawning on me that the same goes for professional codes and standards. At some point, you've just got to start over; pick through the rubble for the real substance and make new. Perhaps all this bureaucracy has something to do with the life span of the "great" (read large/dominant) organizations and societies? Stagnation indeed.
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If you want to make money, be an 8-A contractor!
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I think in college we are taught to design to the absolute least weight for a set of given conditions. This is fine for mastering the concepts of analysis and design. Unfortuantely, nobody ever tells us at our last class that you never really know floor loads, joint releases, construction quality and a host of other alues that effect the data we have been "Given". The other great seceret that no one shares at graduation, is that the steel costs are the least expensive part of the structure and increase the size of the member is the most cost effective insurance you can buy.
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Dik
RE: Complexity of Engineering
unfortunately we then get the situation that jmiec points out where a lot of engineers use software because they do not want to learn the theory and assume the computer will do it all for them. Computers are calculators and the software available today and for the forseable future are and will be calculation algorithms, not engineers. The engineer still must understand the background, the logic and the expected results and use the computer to his advantage, not to replace him. And far too many do not. They see design as producing a drawing as quickly as possible. Doesn't matter what is on it as the computer produced it so it must be correct!
Engineers must accept that there is a need for continuing education and that does not mean how to push a go button on a computer program. Would you go to a doctor who was still practicing the 2000 year old Roman operation or health care methods.
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An earlier comment sugested ultimate strength was first before working stress. In my opinion, that was before there was anything like structural engineering. In those days, designers were architects of buildings who relied on empirical evidence learned on the construction site. They didn't do anything like what we consider engineering calculations today.
The advent of the railroad industry was the impitus <sp?> for modern structural engineering because you couldn't just throw a bunch of material at the problem anymore. That caused us to learn about structural mechanics, stress and strain, etc.
Regarding the durability of Roman structures, it is all very quaint. Kill a few thousand slaves and let the world admire your engineering prowess! Please, give me a break. With their budget, I could build a few things that'll last.
Codes are necessary for defining the loadings otherwise we'll never get off square one. After that, it all comes down to capacity on one side of the equals symbol and demand on the other. I agree with the concept of applying a smaller amount of the factor of safety to dead load than live load. This is the single best element of LFD in my opinion. It could have been accomplished in WSD but would have left folks scratching their heads.
Likewise, plastic hinges, yeild line theory and all that is interesting, but becomes terribly cumbersome on multi-DOF systems.
In the end I have two substantial complaints about the current trends; we are getting less and less savy about actual construction and we are not getting paid more to go through the more complicated processes of LRFD but we have the same expectations and liability. I have reviewed other engineers work too many times only to discoved they didn't "know their sphincter from an excavation." Lets get back to basics and forget all this fancy stuff that inflates our egos.
RE: Complexity of Engineering
RE: Complexity of Engineering
Ironically, most engineers collect thier CEU certificates right after the questions about software are answered. (Notice that there are seldom many other questions.)
I'm afraid that Continuing Education may, if fact, be exacerbating the problem. Code commitees can make the codes as convoluted as they wish, and then use the complexity to justify a code seminar. The CEUs are offered as carrots to entice addendees, as we all need to show our licensing boards those CEUs. Because of time and budget restraints, the seminars are squeezed into an intensive session. The result, a complex code, a confused engineering community, and a call for more software.
Dinosaur-
Very insightful and well said.
RE: Complexity of Engineering
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Trac
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RE: Complexity of Engineering
RE: Complexity of Engineering
In the end, you have to throw in a factor of 2, 3, or 4 to ensure that want you've ignored or simplified won't come back and bite you.
The reason that you can then allow the cuts to have such wide apparent uncertainties is that you've sufficiently overdesigned the system to tolerate these uncertainties, AS IT SHOULD BE.
You're the guy with the 4-yr degree, training, and license. Would you really want a 100-story building's fate to depend on the accuracy and discipline of a guy who might not have even finished high school? The design complexity is incumbent on you because you're trained for it.
TTFN
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I don't mind the codes, it the continual changes that are time consuming. We deal with six different materials. Its a full time job keeping up, never mind the demand side of the equation and all those related changes.
Limit States Design, Allowable Stress Design the mechanics are still the same. Elastic or Plastic analysis not much has changed. 1st. order vs. 2nd order elsatic/plastic analysis Hardy Cross vs. a computer matrix program. I'll take the computer any time.
Recently the phi factor (material reduction factor) for reinforced concrete increased from 0.60 to 0.65. Recently we were at a job inspecting reinforcing, dowels and vertical reinforcing, contact lap splices in a shear wall, it would make your head spin.
Its amazing how many of the references still in the new codes refer to guys coming out of the 40's, 50's and 60's for the fundamental mechanics.
I don't think nearly enough time is spent on mechanics and basic structural analysis.
I have a problem with proprietory products and code compliance based on third party testing and approval based on some governmental authority checking of the appropriate boxes. This is a whole different level of acceptance and required understanding removed from codes and calculations.
Lots of good points in this thread.
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On the overall complexity question, it seems to me like when a structure is actually built, stands a 100 years, and is then demolished, that there is nobody in the world that can say within a factor of 2 what the seismic loads are that the building will actually see during that time. That being the case, I can't see much reason to get beyond the 4-zone type of earthquake design.
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I do not regard a seminar of any sort as contributing to continuing education. Just shows what a joke the whole system and the people who have risen to a psoition to run it are.
A good engineer will question what he does not understand and research it and improve himself. That is continuing education but we do not get many points for that. That is supposed to be the whole aim of our university education. Not to put out technicians who know which buttons to push. Unfortunately now a lot of universities are now putting out button pushers.
Anyone who does that research will understand the reasons why codes are becoming more complex (in many cases) and will learn the theory behind what we do and be better engineers for it.
The rest will just figure out which new buttons to push.
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Although I'm being a little silly here, I suggest we all think about who it is that's telling us how to do engineering.
RE: Complexity of Engineering
RE: Complexity of Engineering
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.
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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 δb and δs 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.
RE: Complexity of Engineering
RE: Complexity of 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
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RE: Complexity of Engineering
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.
RE: Complexity of Engineering