Simplicity Approaching Functional Perfection 19

[jheidt2543]

“The highest attainment in design is a simplicity approaching functional perfection.”
- Linton E. Grinter, Ph.D., C.E.

“Nothing discredits the usefulness of theory as a practical design tool so much as the use of theoretical toys. It is often true that theory tends to become an end in itself instead of a tool for practical use. The literature is full of formulas, graphs, and mathematical studies that are of interest mainly because of their intricacy. This criticism is in no way intended to discredit sound analytical studies, however complex. Mathematics should neither be avoided nor displayed.”
- Linton E. Grinter, Ph.D., C.E.
Vice President and Dean of the Graduate School,
Illinois Institute of Technology in
Design of Modern Steel Structures
The MacMillan Company, 1941, p. 3

I wonder what Professor Grinter would say about structural design today, some 70 years after making the above statement? He saw the future and didn’t know it! The problem today, as I see it, is the compounding of the “theoretical toys” mixing with the evolution of extremely complex building codes that change every 3 to 5 years.

I'm just wondering what others have to say about Professor Grinter’s comment and what, if anything we can do about it?

 

[Ron]

His book (I have a later edition) shows that he practiced his preachings. A very concise book.

Yes, current analysis is getting more complicated, not simpler. Is that because we need further understanding? Is it because we need greater accuracy? Is is because we need rationalization and justification for our existence? Are we as a public and a profession better for it?

 

[Qshake]

Great Topic jheidt, and, as always, interesting musings, Ron.

I'd like to note that some of our structures are getting more complex as the industry continues to push the envelop. On the other hand, I do see a lot of young engineers with too much dependency on the computer to solve problems that can be, and often were, rationalized by simplifying assumptions and solved with hand calculations. Having said that I believe some of the complexity is industry driven and the rest is on the engineering community for replacing solid understanding of structural theory with emphasis on computer analysis.

As to whether we're better for it, I beleive we'll ultimately have a better understanding of some things but this will come at the expense of others and may take more time. It's as though we came to where we were by the methodology of Grinter only to be taken back several years with the re-invention of structural analysis on the computer.

Rather than replacing the old methods with the new emphasis on computers, the computer methods should have remained a natural extention of the methods and understanding we once had. That would place computer methods in grad school in academia and under well experienced engineers in practice. Not with newbies.

Happy 4th.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[Ron]

Good comments as always, Q. jheidt2543....nice topic!

I look at computers and computer analysis much in the same way that I look at a camera to a photographer. A good photographer can take a good photograph with a cheap camera. A bad photo is not made better by an expensive camera...only clearer. Composition is in the eye of the photographer, not the "eye" of the camera.

As with a camera, the computer and computer analysis are just tools. If we don't know how to use them, they do nothing to enhance our "product"...in fact they can give a detrimental false sense of accuracy and correctness. When the perceived correctness of sterile computation replaces a logical problem-solving thought process, we have problems.

Q, I share your concern about some of the younger set. It can be seen clearly in some of the posts.

 

[JAE]

I think the best things that ever happened to me in terms of my engneering education were the classes I took that introduced me to the matrix solutions that current computers use to solve redundant structures. These types of classes help me to perceive what general structural analysis programs actually do.

I like the current crop of programs that allow me to minimize time doing tedious hand calculations and maximize time solving framing, detailing and general design challenges.

However, It is SO important for any engineer to have a good understanding of what the dang program is doing with your input. The disconnect is always between the engineer and the programming company providing the software.

I was reminded of this recently with a program that does 3D and finite element solutions. I (wrongly) assumed that the program did second order PDelta solutions with not only beams, but finite elements. I found out that it DIDN'T do so with finite elements. I also discovered that it didn't use a routine that iteratively re-set nodal coordinates but rather added member shears to mimic the second order effects. I was therefore uncomfortably surprised to realize a disconnect between me and the program.

Software companies, and we engineers, perhaps need to spend more time in educating each other in the use of these software monsters.

There are many younger engineers that know what they are doing, and are careful to test their program outputs, etc. There are, I'm sure, other younger engineers that respond to Obe-Wan-Kenobee's voice: "Luke....let go.....feel the program...use the program....don't trust yourself....let go".

 

[Qshake]

JAE - I agree and echo the sentiments on my having taken matrix structural analysis and FEA as coursework. But that was after I learned structural behavior as 5 hour course and had advanced methods, 3 hour, and many other material structural courses.

By then I learned to estimate behavior and to really understand what i was after and what the program can do for me.

Like you, with today's computer programs, I am also at a distinct disadvantage in not having time to understand the nuances of each and every new program on the market. I work hard to understand better the ones I do know.

And believe me it's not that I'm down on the younger generation. I don't think they can help it as the focus is now on universities providing hiring firms what they want. And a good many, unfortunately, want engineers that can make the model sing. I think they are the same lot that are surprised when that young engineer regrettably notes he doesn't really know if the mode shape, or reactions really make sense.

IMHO, I beleive we should go back to structural analysis by hand and encourage those given to structural interest to go to grad school and learn advanced techniques.

Of course, there's no easy answer.

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[dhengr]

Wow! What a good topic. This thread should be must reading for all engineers, and everyone on this forum. If I didn’t know better I’d think Jheidt and the rest of you stole a bunch of my std. rants.

It seems that every time there is a two bit advancement in methods or knowledge, the people who are driving our train these days, think this advancement must be codified, instead of just showing up in the tech. lit. for our edification and testing over an extended period of time. That’s how you sell new code books and that’s what is most important to those drivers. At some much longer rewrite interval, these advancements could be melded into a new edition of the codes. And, just like Grinter’s comments about good design and analysis being all the better when it is also clean and simple and functional without a lot of appended crap, a good code change would simplify the process rather than add layers of complexity when it doesn’t really improve the final product.

As for today’s computer software, we are in the same pickle, what do they have to sell you next year if it isn’t more complex, never mind that the newer version doesn’t really do anything more for you, those bells and whistles are appealing to some. You still will have spent much money and then the time needed to learn the new tricks and idiosyncracies of the new version for no real gain in the finished product or your productivity. They’re fatter and happier for the transaction and you’re poorer and no smarter for it. The only way we’ll tame these beasts, be they codes or software, is to let them sit with the next couple editions, and force them to spend the money to recycle the paper or plastic they were printed on. This may involve our explaining to our legislators or building officials/depts. that there is little evidence that they will get better end products by adopting that latest version of the codes being pushed by those publishers. Furthermore, structures or products are not going to start failing or falling down around us if they give us enough time to learn to use the current editions. In fact, for the confusion of each change or new edition, the opposite might be true. Witness the number of discussions about the interpretation of many new details of the latest code, when in the same OP there appears to be some lack of basic understanding of the problem. Interpreting the code or software output has become an end in itself, never mind understanding the fundamentals well enough to know that the output reaction is in the wrong direction.

As for the educational system, young engineers shouldn’t be allowed to use computer programs for their work until they prove to their superiors that they understand structural concepts. And, if the Uni’s don’t want to teach these basics we are going to be in one hell of a mess, but we are now for lack of these basics in the hands of many younger practitioners. I agree with JAE that my matrix analysis and FEA courses were absolutely essential to where I’m at today; but I like much better the way Qshake said it, and that is that these became essential tools and analysis aids once he had the fundamentals down pat, and understood structures well enough so he understood what the program was doing and spitting out. And, all of Ron’s questions in his first post should be answered before we buy another code or software package.

One of my std. preachings to young engineers has been that sometimes good clean design may actually take a little longer, and invariably it doesn’t have the same ‘wow factor’ as the more complex (Rube Goldberg) design or analysis, but it is almost always a better solution; as long as you haven’t neglected something in your simplification. In fact, many times, the simpler design looks so clean that others can’t imagine why it might take a bit longer. And, I doubt that Grinter would disagree with that. What he said in my 1949 ed. of his books is “Of all things, but proverbially so in mechanics, the supreme excellence is simplicity.”

 

[Ron]

dhengr....well stated!! Speaks for many of us.

 

[msquared48]

I agree..

Mike McCann
MMC Engineering

 

[hokie66]

I would just agree, but should point out that all the participants in this thread are old guys, or at least mature, if you prefer. What I think is missing from many young engineers is the ability to know/estimate the answers before they start. With that ability, computers are very useful in verification, adjustment, and manipulation of designs. My first mentor could walk by my board, say "that's not the right size", and keep on walking. Took me about 5 years to approach that degree of confidence. Some of the difficulty young engineers face is that so much of what they do is trying to learn and interpret overly complex code provisions, rather than developing the ability to think like the structure.

Perhaps we will get some input from the younger set after the July 4th revels are finished.

 

[kieran1]

Excellent post dhengr

Kieran

 

[JStephen]

I think to realize what Dr. Grinter was getting at, you have to peruse some of the older books. One that illustrates this well is Timoshenko's "Theory of Plates and Shells" which was written in that era. In that work, it is not uncommon to make some simplifying assumptions, then "solve" the problem theoretically. Only the solution turns out to be a double series which pretty much takes a computer to get any actual numbers out of it.

What I see today is not so much an expansion of theory but an expansion of detail.

 

[jheidt2543]

Great comments all!

My thought in starting this tread was not so much to bash computers, I think we all agree they are a necessary part of the engineering landscape. I still remember the hours upon hours of number crunching that we don’t have to do anymore. BUT, one of the problems is the “black box mentality” that destroys the thought process in design. Back in the slide ruler day, those long hours of calculation allowed a design to “gestate”, the engineer developed a “feel” for the structure. Now, because of time constraints, the tendency is to take the black box output and plug it in, we get a solution but something doesn’t “feel” just right.

I liken it to the push for the conversion to metric units. Yes, it is just a ratio between SI units and metric and should be autmatic, but I know what 100 psf “feels” like, I have no “feel” for 488.2 kilogram/meter^2 assuming that’s the correct conversion.

The big knock on computers is the false sense of precision it gives. What good is a solution to three decimal points, when we don’t know the loads within 10%? So, now we have statistically generated loads and safety factors!

 

[jheidt2543]

As hokie notes, we are all older (mature, seasoned, experienced, scarred) engineers and as such we have a responsibility to transmit an “engineering philosophy” to the next generation. Our predecessors did that through their writings as JStephen noted, engineers like Grinter, Timoshenko, Hool & Kinne, Hardy Cross; Johnson, Bryan & Turneaure; Robling, and many others. These guys not only wrote the books, but practiced engineering in a time when there were not many references or codes to look too. They had to think the problems through on their own from basic principals. Reading those older engineering books gives some real texture to our profession.

 

[Qshake]

I agree that we're not out to bash the computer. I just favor more intelligent use of it. It's much needed to solve large problems....though it is ironic that much of the bridges I retrofit are of an age that their analysis was done by hand and purely as 2D structures. And as a side note, many of those structures were detailed on cloth with as few as 13 sheets for bridges reaching up to 1500'. Try to do that today!

Regards,
Qshake

Eng-Tips Forums:Real Solutions for Real Problems Really Quick.

 

[ash060]

I don't understand what is coming from the older generation of structural engineers. Many seem to question the younger generation's ability to "feel" structures and interpret computer output, well my response to that is where are the mentors?

In most of my experience older engineer's gave vague responses to any difficult question and very little direction except do this faster and cheaper. The idea of learning structures and increasing output seem to be at odds with one another. How can I learn to do elegant and simple design if more experienced engineers decline to teach it.

Maybe I am an isolated case, but I have encounted others that are in similar situations. If posts from younger engineers make it appear that there is a disconnect between new and the experienced, than there must be an issue in those offices with the older not mentoring the younger. If some questions appear to be so basic to base engineering knowledge that it is surprising that they would be posted. Should it not be considered even more surprising that no experienced engineer was available to answer the question in house.

Be satisfied you had a mentor, and show some understanding to those of us who didn't.

 

[a2mfk]

Well I just finished modeling this one story steel-framed building in RAM 3-D using FEA and LRFD and the latest ASCE 7-XX wind pressures, the latter of which took me 15 hours to figure out the MWFRS and C and C cladding pressures, but no matter, the way I figure it- wait, let me crunch the numbers, I reduced the steel by a whopping 4% and got my safety margins down to nothing! It took me more time than doing it by hand but you should see my pretty colored 3-D model. And I have no idea what any of the numbers in the calcs mean but they are neatly printed out in this 1000 page stack if anyone wants to check my work. And it meets next years code and the one from two years ago and the one from 4 years ago, and its OK with the green book AISC but not the silver, but definitely the black. Let me go to Appendix D now in ACI for some connection design, wait, once you go there you NEVER LEAVE!!!!!!!!

Shoot, I am out of time from all my efficient modeling. Better delegate connection design to some other schlub who will have to guess at my intent and reactions, and some field coordinate notes, and a few typical details I have no time to check and then BAM, out the door the drawings fly!

And it never would get built unless it is in BIM so better do that too, even though I'm not getting any more fee to do that, and probably have craploads more liability, but again, the pretty colors in the picture are mesmerizing so it must be better. And you can spin the model in any direction, which is just TOO COOL!

Throw in some scrap steel and some fly ash, get that LEED rating, oops, almost forgot about that. Saving the planet one building at a time, feeling good.


YEAH PROGRESS! WHOOOOOOOOOO HOOOOOOOO!!!!!

 

[Bobber1]

An older engineer in our office asked me last week to check his hand prepared moment distribution analysis of a frame. I used the computer and his values were accurate to one decimal.

 

[hokie66]

ash060,
Sadly, you are not an isolated case. The mentors are not there...they quit in disgust because practical engineering has been overtaken by agenda driven academic code writers and clueless management types. I don't know the answer, but your post will discourage me from being dismissive of basic questions.

a2mfk,
Watch it, your post sounds like dhengr. Only better.

 

[jheidt2543]

ash060 I feel your pain! I started my career as the only engineer in a small general construction company doing a wide variety of small projects about 25% of which were design-build. I had no engineer mentor and I didn't have Eng-Tips to ask either. If you don't have an in-house mentor, find one somewhere else - the phone rings both ways!

My intent was not to pick on old engineers or young ones either, but the state of the profession. Our profession is being driven by the code writers, both computer code and building code; along with the legislators. Where are our engineering associations? They are planning and producing continuing education programs, at $1,000/ea, so we can keep up the code changes!

a2mfk is not exagerating much in his rant! In an economy that produces little work at even smaller margins, where do we get the time and money to sit on the engineering association committees and government advisory boards? Some how we have to get more practicing engineers to do it if we are ever going to get more workable codes.