## Calculations, Calculation and More Calculations!!

## Calculations, Calculation and More Calculations!!

(OP)

Why is it that I feel, we as engineers sometimes get a little too overboard in doing or asking for calculations for each and every simple aspect of design. I am an licensed engineer myself. And, I am in no way undermining the importance of design calculations in ensuring we deliver a safe and sound structure to our clients. But, when calculations in whatever form they are, overtake our engineering commonsense and judgement, I think it's time to step aside and take a serious look at ourselves and the not so sensible approaches we sometimes take. There has to be a limit to the level of documentation that has to be maintained for any specific design job, so that our efforts can be channeled towards aspects that have a bigger impact on the project. Also, unless we start thinking in terms of systems and not worry about every nut and bolt, we are definitely headed towards a road to nowhere. What are your thoughts on this?

## RE: Calculations, Calculation and More Calculations!!

Engineering

ISthe details.Take a look at the Hyatt Regency for a good example of what can happen when

every nut and boltis passed on for the next guy to deal with.On the subject of calculations:

Intuition is very often wrong. Even the intuition of the experienced can fail. The experience is required to understand what the calculations are saying. It is not a free pass to skip them.

## RE: Calculations, Calculation and More Calculations!!

Tell your argument to a lawyer and see how far you get. He will love your philosophy, but for the wrong reasons.

Mike McCann

MMC Engineering

http://mmcengineering.tripod.com

## RE: Calculations, Calculation and More Calculations!!

## RE: Calculations, Calculation and More Calculations!!

My original post was in regards to many trivial redesign issues that we come accross during the course of a project. Say...the client wants to make a 1 ft square hole in 30 ft wide masonry wall, drill a 6" hole through the slab at the middle of 30ft x 30 ft bay. If you can't take an engineer's word for issues like these...and expect to see a piece of paper with fancy stress strain analysis, I am forced to think that either my license has no value or the reviewer has some issues with his intellect. Mistakes do happen in the kind of profession we are in...but that should by no means cipple us from using our intuition that we as engineers have gained from years of experience.

## RE: Calculations, Calculation and More Calculations!!

Maybe these other folks don't understand what you are saying, but I do. Engineering still must involve judgment, not just slavery to indecipherable code provisions. Having a detailed calculation for every conceivable thing in a structure does not insure safe designs unless accompanied by a good dose of common sense, which unfortunately is too uncommon these days.

## RE: Calculations, Calculation and More Calculations!!

The issue I think is that there tends to be an air of unwarranted awe in formulas. But a formula is subject to the same principle as a computer - GIGO. Even applying the formula again, and again and again doesn't fix issues of misapplication or misinterpretation. I'm a particular fan of applying judgement that represents an alternative approach to the standard applicable calculation. Too many times I've seen someone establish an hypothesis (that forms a prejudice) and then construct a calculation that simply confirms that based on their invalid assumptions their conclusion is correct.

This of course, is a common criticism in Safety Engineering - that so much time and effort is spent on working through mechanistic calculations, that the task of stepping back, considering and applying sound engineering judgement is overlooked.

## RE: Calculations, Calculation and More Calculations!!

A few times a year I get sent a page questionare, front and back, asking for specific data. I know they don't need it all, and the engineer that sent it is looking to take one number and put it into a formula somewhere. But he sent me the whole questionare.

The worst thing is on a big project, I will see the same questionare from different engineers at the same company. And my answer to them, when I call them, is always "it depends on what you need it for". If an consultant can't tell me why he needs a piece of data, then he dosen't get an answer.

And they never seem to understand what difference it makes. It's simple, it changes my assumptions.

Bottom line, don't send me a one page questionare if you only need one answer. Don't waste my time.

So I do understand about over the top calculations, because other people don't want to communicate.

Put an end to useless, and unused data.

## RE: Calculations, Calculation and More Calculations!!

If you get requests like this and you are not asking the right questions in return, small request like these are the ones that bite you in the a$$ at the end. The only way to be diligent in your designs especially if there are loads and moments is to go thru the analysis. I think of it as a check list to make sure it is ok because you never know it may turn up something the requester did not realize or did not tell you. You may get down to loads and the requester will come back and say “oh, so we can add a 10 ton thing a ma jig thru it…will this break something?”. So the hole may be innocent, but the application may be over the top.

Tobalcane

"If you avoid failure, you also avoid success."

“Luck is where preparation meets opportunity”

## RE: Calculations, Calculation and More Calculations!!

Here is the thread: thread507-89434: Calculations: Personal Tool or Public Record

## RE: Calculations, Calculation and More Calculations!!

I got paid a lot (from your tax money) as a contractor several times to "analyze to death" several circuits for spacecraft. The original design was very sloppy; high voltage spikes causing noise on the mixed-signal boards, transistors running very hot, and all sorts of other problems. I wasn't allowed to change the circuit, only to perform analysis showing how reliable it was....but is wasn't reliable. You'd go down to the lab to run a test and half the time something would break. The good news for taxpayers though: it had lots of paperwork with the word "Quality" stamped on every sheet and lots n lots of calculations.

Oh, and the first two comments were from people who thought your question was, "Can you please write a worthless, sarcastic comment?" I re-read your post....um...nope. Didn't see that question in there.

## RE: Calculations, Calculation and More Calculations!!

## RE: Calculations, Calculation and More Calculations!!

Cheers

Greg Locock

New here? Try reading these, they might help FAQ731-376: Eng-Tips.com Forum Policies http://eng-tips.com/market.cfm?

## RE: Calculations, Calculation and More Calculations!!

VoD

## RE: Calculations, Calculation and More Calculations!!

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com

## RE: Calculations, Calculation and More Calculations!!

I'll try harder next time.