Question about metric 6

[murdof]

Hi guys,

we are a company (ACE-Hellas SA) that has a software for static and dynamic analysis plus design of structures.

The question though is the following:

Currently we are looking for partners to promote our software all over the world.
Our software supports only metric and not imperial units.
I see that in US there are a lot of talks about adopting officially the metric system.
For us to support imperial units is not so easy - as we have to recreate all forms and calculations, so it will take a lot of time.

Do engineers in US work with metric or imperial units for the static and dynamic analysis?

We want to see if we should try to promote the software in the US as well.

Thanks!

 

[IRstuff]

"For us to support imperial units is not so easy - as we have to recreate all forms and calculations, so it will take a lot of time."

Seriously? Almost any program that supports units defaults all calculations to one consistent system. They convert any other unit inputs into their internal representation and present results converted back to the user input unit convention. Mathcad is a good example of that. It supports arbitrary dimensional units for input, but internal representation is always SI. In fact Mathcad supports mixed units as well.

"Do engineers in US work with metric or imperial units for the static and dynamic analysis?"

Yes, but, if anything, they probably do most things in imperial units.


TTFN
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[murdof]

Thanks for your reply and your feedback IRstuff.

For us accuracy is everything.
We have done some tests internally with converting but you get to loose always with decimals conversions.

For example 2.5 meters = 98.4251969 inches, so you see it is a matter of precision mostly for us and you know that there are a lot of mathematical calculations going on till the end result.

Our software is used to calculate skyscrapers and bridges. All numbers matters when we are talking about human lives.

I perfectly understand your point but we have chosen for the above reasons not to go down this road.
We prefer to not have it, than to have wrong results, or results that won't make sense and discredit the software.

 

[Archie264]

If you are considering making a business decision based on this topic you would do well to understand that the US will NOT likely switch to the metric system anytime soon. Be very skeptical of any reports that it will; the debate over whether or not to so has been going on since the country's founding, literally.

Whether or not that's a good thing is a different question. I happen to be among the minority of my associates in my belief that the Imperial system is superior for engineering applications. That might earn me a heap of scorn but that's ok. But if this thread turn into a metric vs. imperial debate don't let it detract from the answer to the question you originally asked: the US will NOT likely switch to the metric system anytime soon so make your business decisions accordingly.

 

[murdof]

Thank you Archie.

No need for this to be a debate.

I hear you guys loud and clear

 

[PicoStruc]

so you see it is a matter of precision mostly for us and you know that there are a lot of mathematical calculations going on till the end result.

Scary to read. Using Double Precision (double) should not be a problem.
Fire your programmer. Serious FEA Software should be able to use consistant unit. Your client should be able to switch Length or/and Force unit as they wish ! Ex : (kN / m or kN/mm or kip / in or kip / ft, etc...)

 

[murdof]

Hey Pico,

it is not only the calculation part - let's say we use double and let's assume that all goes well.

Still we have to recreate all the forms to be feet/inches, so two boxes - one for feet and one for inches.
Currently there is only one for cm for example.
Except if you tell me that using only inches (so only one box) is acceptable.
Then things are easy, I agree. We just change everything from cm to inches and do internal conversion.

Truly we never looked at imperial implementations as our target market was always EU.

 

[EngineeringEric]

Wouldn't the bigger issue than units be code equations used... lets say all your steel is designed with EuroCode, But i want AISC in the states. Now steel may be small difference but i bet Concrete would a different beast.
-
Or am i showing my ignorance of other country's engineering?
-
As for the two inputs, many programs only accept feet, ie 4.58' is about 4'-7"

 

[PicoStruc]

Impose a format, use a single textbox and parse the string.

Convert internally
8'-5" -> 8.416667 ft
8'-5 3/32" -> 8.424479 ft

 

[murdof]

EngineeringEric - yes we currently use EuroCode but every country in Europe has their own "extensions" which in some cases they might be required by local country laws.
So yes AISC would still be something we would need to do after we offer imperial.

Pico - thanks for your feedback. I will forward it to the development team.

 

[dik]

For my calculations... I normally only use about 6 significant digits <G>... for programming, or even Excel, I usually use double precision even for conversion since many programming languages execute double precision faster than single precision... I generally tone down the output to maybe 'sliderule' accuracy...

Dik

 

[IRstuff]

The conversion accuracy question is a bit of a red herring. Once you get past the initial input parameters, your calculations should be double precision, so it's mostly irrelevant what the inputs are, and given double precision, the accuracy loss is minor, at best.

Moreover, the imperial to metric conversion factor is EXACTLY 1 inch = 2.54 cm, so there is no precision or accuracy loss going in. The only loss would be on the other end of the calculation, and with double precision math, it's completely negligible.

TTFN
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[JStephen]

The problems would not be in unit conversion so much, but in using different codes, different methods mandated by different codes, different standard member sizes, etc.

 

[BAretired]

Canada converted to SI in the early 1970's but we do not use the same units as some metric countries. In engineering drawings and calculations we use metres with prefixes representing 10 raised to a power that is a multiple of 3. Thus we do not use centimetres but we do use millimetres (the editor is indicating a spelling error in all the above words containing "metres"...the editor thinks it should be meters, but that is not the case in Canada).

There are still a large number of engineers in Canada who refuse to use the SI system, instead clinging rigorously to the Imperial system. I became intimately familiar with both systems over the years and feel comfortable working in either system but I do not like mixing the two. Better to work in one system, then convert at the end if required.

BA

 

[JAE]

Well BA - you can call it bere but we here in the States prefer beer.

 

[racookpe1978]

Doesn't matter as much in the US that the design might be in metric.
But the parts and pieces will be bought in ANSI units, and built all-to-often by newly-arrived-unskilled poor-language labor using inches and (maybe) fractions correctly. Tools and jigs and steel and pipe and xonrete and boards are NOT metric. But they are NOT "pure ANSI" feet-inch-fraction-decimal either!

You will need specific and different pipe tables, steel tables, nut-and-bolt tables, wood size tables, and stair heights and sheet rock wall thickness and plywood sizes and rebar sizes. Plate dimensions, rail sizes, tube sizes, weld spec's, etc. Nails? Screws? Rill bit Diamters? Wheels? Bearings?

Today is NOT an easy world in construction.

 

[hokie66]

Whether or not your program handles different units, I won't use it if it mentions centimetres in any way.

 

[Tomfh]

I won't use it if it mentions centimetres in any way.

ooo I hate those things.

Then again, at least they're not as bad as "hectopascals".

 

[XR250]

Sounds like your programmers need to investigate "significant figures"

 

[Archie264]

Hokie66, you've piqued my interest. What's wrong with centimetres, specifically? Just curious.