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Complexity of Engineering
19

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

A few years back while working the Turbine Generator side of a power plant outage, one of the Westinghouse Tubine experts/consultants told about a 100 ton turbine moved over a bridge in Spain built by the Romans.  I wonder how many of structures built today will be functional in 2000+ years.  My guess is not many.  Everything today is about being economical which requires more exacting engineering methods, which has its' advantages and disadvantages.  Our codes today are good a requiring for various types of loads but don't seem to consider durability over time.  

RE: Complexity of Engineering

Are we to the point of "measuring with a micrometer, marking with a crayon, and cutting with a chainsaw?"

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

Vmirat:

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

Every pages added in newer editions make efforts to justify by rigorous analysis that less material can resist demand.  I don't agree with blind conservatism but calculating to anything more than 3 sig-figs is a wasted effort.  Surely, optimized member may perform to minimum code standards but one size larger member performs better with less "engineering" effort.

RE: Complexity of Engineering

I think the "publish or perish" mentality gets mixed into the codes and standards.  Unfortunately, academic engineers do not always make for good practicing engineers.  Working through the various codes (and constant tinkering) for a living is tough!

RE: Complexity of Engineering

3
It's amusing to me how some of that stuff works.  On the seismic, you pull a factor off a map, but eventually have to multiply by 2/3 to get the factor you need.  Why didn't they just multiply the map factors by 2/3 in the first place?  In certain areas, no seismic design is required.  Why don't they just mark that part of the map "no seismic required" instead of making you pull numbers off two different maps and compare to a particular requirement in the text?

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

I give a star to Vmirat,

"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

RE: Complexity of Engineering

Although I generally agree with what's been said (compare the thickness of an ASCE 7-88 with a 7-05), I have to say that the code committees have put an honest effort to make some of the codes more readable and useable.  Part of the reason the American steel manual has gotten so much thicker is because of the ASD/LRFD debate - they had to include both.  Also, they added many tables and User Notes to try and help out the practicing engineer.  Comparing the seismic sections of ASCE 7-02 to 7-05, you can see that the effort was to provide separate chapters for separate subjects so that you could just read the one small chapter dealing with your specific area.  This replaces reading a large chapter dealing with all seismic issues and trying to pick out what's applicable in your case.

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

Clearly the worst thing to happen to structural engineering was ultimate strength design...

RE: Complexity of Engineering

Thread reminds me of an engineer at United Steel Products over ten years ago.  At that time the engineer had submitted a report to ICBO to obtain a NER on a beam hanger.  The report contained both testing data and design calculations for the hanger.

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

DaveVikingPE - don't be so quick to condemn ultimate strength design.  I seem to have read somewhere that "ultimate strength" was actually the "first" method used back in the 1700's or 1800's or some such time.  It was only after further research helped engineers understand the concept of stress that the use of an "allowable" stress was developed and the ultimate concept was discarded.  After statisticians got involved with research, the idea of a uniform probability of failure then reared its ugly head and ultimate strength design came back to the front and center.



RE: Complexity of Engineering

If society was willing to pay $2 for something they could get built for $1, then we wouldn't need engineers and their complexity.  Going a little further, why continue to build for $1 when we could build for 90¢?  Why continue to use stone-age technology if we have the knowledge and tools to do a better job?  We have the processing power to actually do things right, to actually have a grasp of what is really going on with material behavior without spendign weeks working out matrices by hand.  I see no reason to rely only on equations that can be worked out in your head or on your fingers and toes.  Yes, we should be aware, blah blah, I know all that stuff about rough checking, error checking, hand checking, garbage in = garbage out ad nauseam.  The key word being check, not use.  My point is only if we can do a better job or a more true-to-reality job, I say we should do so.  When we stop advancing, we start stagnating.

RE: Complexity of Engineering

Codes are only minimum requirements. The EOR is still responsible for his design and plans, regardless whether the code was applied accurately or not, and whether economic objectives were achieved or not.

RE: Complexity of Engineering

related to this thread, airplanes have long since lost the capability of lifting their own paperwork.

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

and I hear "they don't build em like they used to"...

RE: Complexity of Engineering

Also, we'd be better off without calculus.

RE: Complexity of Engineering

When I was introduced to limit state structural design in college, one thing that was hammered home repeatedly, was that there had to be a comensurate improvement in QC/QA in the construction phase. This begs the question: are construction QA/QC methodlogies being enhanced to match the increasing level of sophistication in structural analysis/design?

RE: Complexity of Engineering

henri2 - absolutely not.  

RE: Complexity of Engineering

"airplanes have long since lost the capability of lifting their own paperwork"

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.

RE: Complexity of Engineering

FAR out!

If you want to make money, be an 8-A contractor!

RE: Complexity of Engineering

I think it is important to understand that structural engineering has not changed, only how we attempt to model and predict beam response to load. The actyual response of the beam is ignorant and uncaring of our predictions.
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.

RE: Complexity of Engineering

DRC1 - as Hardy Cross once said "strength is essential but otherwise unimportant."

RE: Complexity of Engineering

A college professor of mine had it right: "The only design code engineers need to follow is Mr. Newton's. His code is quite simple, there are only 3 rules".


RE: Complexity of Engineering

And which one of those nice three rules deals with the pages and pages of code language addressing serviceability?  F=ma is great, but F=ma with 7 feet of deflection does a structural engineer no good...

RE: Complexity of Engineering

More and more often, at seminars explaining code provisions, the first questions always seem to be "what software is available to do all these calculations?"  This phenomenon is especially prevalent at LRFD seminars.  It seems as though the attendees (myself included) are so overwhelmed by the code provisions that they intend to rely on software to "meet the code", and have no intention (or hope) of digesting the material just presented.  A dangerous situation, if you ask me.  If the purpose of the progressively complicated code provisions is to increase safety, it is having the opposite effect.

RE: Complexity of Engineering

DaveVikingPE... I've been using limit states and plastic design for nearly 30 years... Other than simple spans (which I avoid if I can make them continuous) nearly all steel design is Plastic... good economy and fewer pieces to handle... Our's was the first class at university to use Ultimate Strength Design for Concrete... and we haven't looked back...

Dik

RE: Complexity of Engineering

Maybe we should look at it from the other direction. Codes have always simplified a lot of design aspects because the calculation methods were too complex to do on a slide rule or abacus. Now we have computers which can do the calculations maybe we should use them and the simplifications can be removed.

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.    

RE: Complexity of Engineering

Many interesting points and counter-points.  Bottom line is I think some of us are too smart for our own good.

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

I worked am a former mechanical engineer (machine design).  I changed to structural engineering because I wanted to be involved in something more creative.  sorta "the grass is greener over there" concept.  It amazes me that structural engineers spend a great deal of time analyzing buildings using rather exact dimensions for joint locations, member lengths and spans, member sizes, rebar locations, connection designs.  However, the construction process is not nearly as exact.  Appears to me the construction industry uses the "close enough for the girls I go out with" concept.  In the machine design industry, if an engineer says something is not fabricated properly, things are done about it:  whatever it takes to get the final result to match specs.  The engineer is always right.  In the construction industry, if a contractor builds something not exactly to specs, he does everything he can to get it approved and accepted.  The engineer is not always right because "we all know engineers over-design everything", "that's the way I've always done it", or "I've never had to do that before".  The contractor's opinion means more to owners than does the architect or engineer.

RE: Complexity of Engineering

rapt-

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

ArchEng- you remind me of the quote I read a while back (possibly on this website) about how the engineers could show the elevations to 8 decimal places "but we still have to build it with the big yellow bulldozers".

RE: Complexity of Engineering

The adage that "If it looks right, it is right" nowadays probably means that it has not been designed and/or comply with some (if not all) clauses of the new codes.
Trac

RE: Complexity of Engineering

You know, if Hardy Cross were still around, there'd be no need for them fancy computer programs.

RE: Complexity of Engineering

JStephen, do you agree with that statement to a certain extent?  the methods we use to analyze and design are much more exact that the methods used to construct the building.  The interns who work for me want to calculate loads to the nearest 1/2 pound, for a tributary width to the nearest 1/8" and size a beam using a span measured to the nearest 1/8".  They do not believe me when I say you can have the load determined to the nearest kip and the span to the nearest 1/2 foot for most designs.  Mostly because their professors demanded that level of exactness and because they can calculate to the 10th decimal place using calculators or computers.  is engineering too complex?  I agree with vmirat's statment that we are at the point of "measuring with a micrometer, marking with a crayon, and cutting with a chainsaw."

RE: Complexity of Engineering

You simply think you're accurate, but that's a fiction based on the fact that you can carry 10 decimal places.  You and the industry make gross assumptions about the statistical distribution of the performances of the materials you use, you make assumptions about the ability to ignore the equivalent details like the strength and location of each and every fastener and joint.  

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



RE: Complexity of Engineering

Codes/research/technical comittees its an industry like any other at the end of the day I guess.
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.

RE: Complexity of Engineering

I tend to be an 8-digit person myself, just because so often, the work is done on computer anyway, and it's actually extra work to round it off, there.

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.

RE: Complexity of Engineering

jmiec,

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.

RE: Complexity of Engineering

7
(OP)
Well.  I never guessed this comment would garner such attention!  It warms my heart to know that I'm not alone in my frustration.  Now the hard question.  What can we do about it?  We have self-appointed committees (ACI, AISC, ASCE, etc.) that are telling us how to do engineering.  Is it time to "rage against the Machine" or do we continue to sit back and let them dictate our profession?  At this point, the model building codes like IBC have pretty much adopted what these institutes and societies say, and the building departments adopt the model building codes, with which we must comply in order to build.  Who's applying the common sense test to all this codes stuff?  Maybe we should form our own national organization called the National Organization for Practical Engineering (NOPE)?  We could charge membership fees and have conferences in Vegas!

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

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.

RE: Complexity of Engineering

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.  

RE: Complexity of Engineering

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 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

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.

RE: Complexity of Engineering

"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

RE: Complexity of Engineering

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.

RE: Complexity of Engineering

(OP)
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! smile

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