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Crane formulas

SOLVED
Alexandrite

Crane formulas

Hello,
In the attached example I cannot execute the formula described in the spreadsheet in Table 5.1.
Maybe I'm the one who misplaced the formula or there's a printing error.
Sincerely.
Denis

1 ACCEPTED SOLUTION

Accepted Solutions

Re: Crane formulas

That makes sense!

It also explains why I could not find what unit should be used for 'A'. But then the 'e' symbols in the formulae should be upright instead of italic.

Comparing with the English version of EN 1993-6:

- There the mu's are italic and e is upright.

whereas in the french (picture in the prime file) the e's are italic and the mu's are upright.

Is this (yet) another thing the French do opposite?

 

Luc

View solution in original post

7 REPLIES 7

Re: Crane formulas

You're trying to add apples to pears. Mathcad will (fully rightly and fortunately) not allow that.

You're raising A to a power 3.015*mu.A and adding the result to 0.05 and subtracting 0.58*mu.A.

The unit of A  is mm, the unit of mu.A is 1 (unitless). This makes the first two terms of the expression to calculate c.xA unitless, the third is in mm. Apples and pears...

 

Most probably these are empirical formulae. Often they are NOT unit-balanced.... as in this case.

One way to use them is to work without units with these formulae. You also have to be aware that the various factors (such as 0.580, 0.148 etc.) may contain unit conversions, so you MUST supply the variables with values corresponding to the units that these formulae are devised/designed with. As there is no information on that in ENV 1993-6 (that is, I couln't find it), you'll probably have to look in ENV 1991...

 

Success!
Luc

 

Re: Crane formulas

Thank you for your very complete answer.
That's exactly what I noticed about the units.
I tried to multiply each factor by a 1 mm unit, but it doesn't work either.
One surprising thing if we just look at the result of the last line, is this power after the units?

Denis

Re: Crane formulas

You raise A to a power other than 1, this means that the unit of A (mm in this case) is raised to that same power.

What's surprising, is that this power (2.388)  is presented as 683/268 by the numeric processor. I could expect this from the symbolic process...

 

Luc

Re: Crane formulas

Your expression should not have the length "A", it should have "e"

Capture.JPG

Re: Crane formulas

That makes sense!

It also explains why I could not find what unit should be used for 'A'. But then the 'e' symbols in the formulae should be upright instead of italic.

Comparing with the English version of EN 1993-6:

- There the mu's are italic and e is upright.

whereas in the french (picture in the prime file) the e's are italic and the mu's are upright.

Is this (yet) another thing the French do opposite?

 

Luc

View solution in original post

Re: Crane formulas

Hello FredKohlhepp, LucMeekes,
Thank you very much for your explanations.
I looked at the English version and it changes completely.
What a shame for this transcription of a mathematical formula.
With my thanks.
Denis

Re: Crane formulas

Attached is the amended version:

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