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How long did it take you to be confident about your calculations?

How long did it take you to be confident about your calculations?

(OP)
Hello,

I am an EIT with a few months of SE experience. My concern is that for some reason, I sometimes don't feel confident about my calculations or numbers even though I do recheck my numbers. Obviously, my seniors look over the results which really helps with the confidence. So, how long did it take you to be confident of your calculations and/or design? and how long did it take you to finish up work with no questions asked to your seniors?

Kind regards,

RE: How long did it take you to be confident about your calculations?

It comes with experience, and, most EIT's don't get the supervision they should. After a while you will be able to look at something and visually 'see' that it looks appropriate or that it looks 'out of whack'. A large part of design is just simply putting things together so they fit/work. Have fun...

Dik

RE: How long did it take you to be confident about your calculations?

2
I am retired now but at the end of 53 years of structural engineering, there were times I did not feel confident in my calculations. Admittedly, the confidence grew with time but you will never be one hundred percent confident in every calculation, particularly if you are designing something with which you are not familiar.

It is always useful to look at the results and give them a sanity check. If it doesn't seem right, it probably isn't. When in doubt, discuss it with an associate.

BA

RE: How long did it take you to be confident about your calculations?

A bit of advice from this OG. I'd be more on the unsure side than the for sure side for a long time. I have had to fire two employees who were over confident and nearly cost the employer a serious problem and expense by not checking back with superiors and then giving orders or approvals that were very risky. The story still is "better safe than sorry".

RE: How long did it take you to be confident about your calculations?

50+ yrs.....

RE: How long did it take you to be confident about your calculations?

sorry, that should be 40+ yrs....

RE: How long did it take you to be confident about your calculations?

EngineeringIsLife :
‘Discuss with, or Check with an associate....’ If we were all so lucky as to have an associate like BA or the Oldestguy, we would be very luck indeed, there is a real wealth of knowledge and experience there for the sharing, and young people need this advice and guidance. If you can find a superior or mentor with that knowledge and willingness to teach and help you are mighty lucky. With experience, you will develop and learn rules of thumb, like depth to span ratios for slabs, steel, concrete, and wooden beams, etc. You never quit checking your own calcs., assumptions, and results. Does it look right, are its proportions about right, how does it relate to what you know has worked int the past? You will (at least old guys like BA, Oldesrguy and I developed) a few dozen good ref. books which we could usually go to for some guidance.

RE: How long did it take you to be confident about your calculations?

for me, until the 1st mistake (approx 2 years). After that I check twice with different procedures (i.e. by hand and by software).
In my PC I collected all the doc and procedure of calculation I am sure of : so I don't need to invent anything every time.
I had an associate (very old at that time) who was used to ask me : "Ok. You did your calculation. What about the opposite ?" (Frankly speaking, often He was right)

RE: How long did it take you to be confident about your calculations?

dhengr... I recall when I did the stair at the Cornwall Centre in Regina (about 30 years back), I asked the partner in charge if he wanted to review the design and he stated that he probably wouldn't understand it anyway, and he was happy to leave it at that. I was both pleased and concerned...

The contractor didn't want to remove the shoring because he didn't think it would stand up... The deformation was less than 1/16" from what I'd calculated.

Dik

RE: How long did it take you to be confident about your calculations?

Quote (SAIL3)

sorry, that should be 40+ yrs....

Not confident in that calculation...smile

RE: How long did it take you to be confident about your calculations?

yes, that is a prime example..although, I was only off by 20%.....

RE: How long did it take you to be confident about your calculations?

I'm not structural engineer, but my confidence is inversely proportional to the consequences of a failure.

RE: How long did it take you to be confident about your calculations?

Quote (OP)

So, how long did it take you to be confident of your calculations and/or design?

Almost two decades in, I'm still not confident in my calculations without some kind of verification. I'll take one of two paths to get there:

1) If it's something that's been done before, I'll check that my solution looks substantially like prior solutions. This covers 90% of things.

2) If I'm blazing new ground, I'll solicit opinions from two or three independent, rockstar engineers. I'll usually also post something here at Eng-Tips. Can't beat this place for diversity.

Quote (OP)

and how long did it take you to finish up work with no questions asked to your seniors?

I imagine this as an inverse logarithmic curve. Question asking drops off pretty quickly. For a particular type of work, you really only need to see a couple of projects through to completion before you'll probably drop from a few questions a day to a few questions a week. So, if you're doing houses, you may be good to go in six months. Skyscrapers or power plants, maybe two to five years.

In a way, you never want to stop asking questions of your senior. Ideally, you'd have a suitable mentor at all stages of your career and the only thing changing would be the nature of the questions. Now it might be top flange bracing schemes; tomorrow it night be contract negotiation or leadership.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: How long did it take you to be confident about your calculations?

As everyone said, I'm never hundred percent sure of anything. But after a while, I've learned to eyeball things pretty well. i.e. This wall is going to be 12 inches thick; this beam will be a W8 x 33; etc. If my eyeballing is close, I'm pretty confident in the calculation.
Another thing that provides confidence is if your calculations yield the same result as an another engineers' design. I figure we both can't be wrong.

RE: How long did it take you to be confident about your calculations?

I find that if I lean towards the "KISS" rule of thumb most of the time, I feel a lot more confident that I am capturing/enveloping the behavior and preventing "paralysis of analysis", which tends to lead to mistakes by complication or results in what I call "calculation fatigue"! Often, we engineers get too bogged down in trying to optimize for contractors and satisfying our desire to drill down to the 'truth' of the behavior. There is a time and a place for really sharpening the pencils - when you are juggling many projects, that is not usually the time to do it. Honestly, I have to remind myself of that regularly. Also, I find that I am less stressed out the more I try not to simplify.

-Mac

RE: How long did it take you to be confident about your calculations?

Quote (MacGruber)

Also, I find that I am less stressed out the more I try not to simplify.
Shouldn't that be "the more I try to simplify"?

BA

RE: How long did it take you to be confident about your calculations?

Maybe... ;)

-Mac

RE: How long did it take you to be confident about your calculations?

3
SAIL3: 25%?

OP: I'm still concerned after decades & so are other people. I'm going to a meeting tomorrow where the building department won't accept my design for changes to an existing building; they asked for a peer review & the owner got one that was positive, but there are still questions. Trouble is, I've still got questions myself because we're adding storeys to an existing heritage building. I was pleased at the peer review, yet I'm still leery to tell the plans examiner to go fly a kite. If you never wonder if you've missed something, you're too cocky. If you always wonder, maybe it's time to try something else. You have to have a healthy respect for what you're doing and your own abilities without letting it blind you. You'll get there.

RE: How long did it take you to be confident about your calculations?

Quote (OldBldgGuy)

If you never wonder if you've missed something, you're too cocky. If you always wonder, maybe it's time to try something else.

Great quote. May I use it for my tag line?

-Mac

RE: How long did it take you to be confident about your calculations?

The problem is rarely the calculation itself. Usually doubt arises from the assumptions and load conditions made in the calculations, that is where the real art of engineering comes in.

RE: How long did it take you to be confident about your calculations?

OldBldgGuy...no, I am absolutely confident that it is approx 20%......

RE: How long did it take you to be confident about your calculations?

Mac: Be my guest, sans royalties.

Sail3: So you're a retailer marking down not a wholesaler marking up :)

RE: How long did it take you to be confident about your calculations?

By the way, after my meeting today, the building department wants a 4th opinion (we have mine, his, and the peer review) and I guess that's going to settle it.
Or not.

RE: How long did it take you to be confident about your calculations?

Quote (JedClampett)

As everyone said, I'm never hundred percent sure of anything. But after a while, I've learned to eyeball things pretty well. i.e. This wall is going to be 12 inches thick; this beam will be a W8 x 33; etc. If my eyeballing is close, I'm pretty confident in the calculation.

I think you might need to re-think things if your beam is going to be a W8x33! bigsmile

RE: How long did it take you to be confident about your calculations?

Relax and give yourself a little time (year/years). The worrying early on is quite possibly a necessary evil/rite of passage if you will. Took me around 2-3 years to 'calm down'. My wife would say it took me 5+.

When you get a chance, try to peruse the calculations of more senior engineers doing the same tasks you are doing. Or look at old job files and see how the calcs were done 'back then'.

Good luck. What you are feeling is natural at this stage.

RE: How long did it take you to be confident about your calculations?

I think it depends on your style. I went to school with a lot of people less "smart" than I was, but they memorized what to do very well. Regardless, I think we were all just as likely to make a random error, but I had more confidence in my methods if they weren't "by the book". So... we all make mistakes in calculations, but can you catch them? I was accidentally catching errors from professors and students alike. That's how my mind works. But I'm not necessarily seeing the calculation mistakes, I'm seeing errors in approach or "this doesn't look right" kind of stuff. If you are confident in your theoretical ability and estimation/sanity checks, you probably won't make those big mistakes.

Still, and importantly, the main kind of mistake i make is missing things. I have only a few years of design experience, am comfortable with all different systems etc. but I don't have those years of experience that remind me of the little things. My supervisor (owner of the company) pretty much lets me design what I want and go with it, but I think hard and search hard, and ask for a look over if I'm unsure if I missed any kickers, or out of plane wall anchors, etc. Stuff that I might not think of from a formal education alone. And yeah, just out of grad school I was getting pretty mad at the 95% of stuff I see on the job that no one ever mentioned in grad school!

RE: How long did it take you to be confident about your calculations?

I've been working for nearly 20 years and am not very confident. I've seen too many things go bad - often designed by very experienced engineers - to ever be truly confident.

A very experienced engineer was joking the other day that you have to get the young guys to design anything of any difficulty, because they're the only ones silly enough to do it. The rest of us are too petrified to design anything knowing all the traps that await...

RE: How long did it take you to be confident about your calculations?

...how long did it take you to be confident of your calculations and/or design?

- one added safety factor of 2
- 3 beers
- 1 week into construction without "that phone call"
- just a little more arrogance


RE: How long did it take you to be confident about your calculations?

I've been in the profession for 40 years and I often joke that I long for the days when I was young and knew everything. I have confidence in my calculations - however there is always the possibility of making a mistake or missing something. I never lose sight of that.

RE: How long did it take you to be confident about your calculations?

I can attest to the sentiment of others above that even the most seasoned professionals can (and do) screw up. On my very first day on the job at an engineering firm, right out of school, I began working on a DOT bridge project. Needless to say, I knew little to nothing about bridges at the time. I was working with a senior engineer who had recently retired from spending his entire career at the DOT. He came out of retirement to work on bridge projects at this firm. Just to ease into things, he handed me a binder of the standard DOT bridge details and asked that I look them over. After several hours of comparing those details to the details on our bridge plans, I observed one particular detail that was noticeably different. The DOT detail showed the minimum negative reinforcement required in the top of a flexural member. When I looked at the detail on our drawings, there was no negative reinforcement shown at all. I brought this discrepancy to the engineer's attention, expecting to have my concern dismissed since it was probably something I overlooked. The engineer looked at the two details and immediately recognized that there should have been negative reinforcing shown on our drawings. He turned to me and said "You saved the day Charlie Brown!". While we can speculate whether the error would have gone unnoticed, the point is this: whether you have 1 day or 40 years of experience, we all lack confidence at some point in our career. The fact that you question your calculations and design is part of being a diligent engineer.

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