Get Help

Turn on suggestions

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

- Community
- :
- PTC Mathcad
- :
- PTC Mathcad
- :
- Crane formulas

Options

- Subscribe to RSS Feed
- Mark Topic as New
- Mark Topic as Read
- Float this Topic for Current User
- Bookmark
- Subscribe
- Mute
- Printer Friendly Page

Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.

Showing results for

Highlighted

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

09-12-2019
09:52 AM

09-12-2019
09:52 AM

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

Solved! Go to Solution.

Labels:

1 ACCEPTED SOLUTION

Accepted Solutions

Highlighted

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

09-13-2019
02:09 AM

09-13-2019
02:09 AM

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

7 REPLIES 7

Highlighted
##

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

09-12-2019
12:34 PM

09-12-2019
12:34 PM

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

Highlighted
##

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

09-12-2019
01:31 PM

09-12-2019
01:31 PM

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

Highlighted
##

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

09-12-2019
02:48 PM

09-12-2019
02:48 PM

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

Highlighted
##

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

09-12-2019
11:31 PM

09-12-2019
11:31 PM

Re: Crane formulas

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

Highlighted

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

09-13-2019
02:09 AM

09-13-2019
02:09 AM

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

Highlighted
##

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

09-13-2019
06:31 AM

09-13-2019
06:31 AM

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

Highlighted

- Mark as New
- Bookmark
- Subscribe
- Mute
- Subscribe to RSS Feed
- Permalink
- Email to a Friend
- Notify Moderator

09-13-2019
11:17 AM