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Reaction Forces

I like to check that my reaction forces for any of my structural analyses. This is for my benefit because I may've applied the loads incorrectly and the reactions quickly show any mistakes.

 

Is there such a feature in SnS? If not, can it be added.

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Permalink Reply by Vadim Shapiro on July 14, 2011 at 11:06pm

Thanks for the suggestion.   Reaction forces are not currently computed,  but  we added them to the list of the requested features.

Permalink Reply by Bob Johansson on January 29, 2012 at 12:24pm

I asked about requiring reaction forces also.

 

Bob

Permalink Reply by Olivier Suire on February 21, 2013 at 6:58am

Reactions would also be very useful to me.

It could allow me to know the traction in the anchor bolts of a steel structure baseplate, along with the check of the baseplate itself.

Olivier

Permalink Reply by CCL_NavArcht on February 27, 2013 at 8:12am

Hi,

First of all. Hello everybody, since this is my first message in the forum.
FYI - I use Scan&Solve to check my hand calculations on structures used for marine transportation.

Reaction forces would be really interesting for me since they are the actual loads that I'm introducing in my ship's structure from the supports that I'm checking using SnS.

Can I ask in which position of the "wish list" is this point? ;)

Regards!

Permalink Reply by Michael Freytag on February 27, 2013 at 6:19pm

We are not working on reaction forces yet,  but you could compute the resultant forces on any restraint surface by integrating the component stresses over them, using SnSScript. These resultant forces approximate the reaction forces, but are not quite the same.    If you give me couple of days, I'll add to the documentation a script that does this.

~Michael

Permalink Reply by Michael Freytag on May 2, 2013 at 5:49pm

I've added an example script to the documentation for SnSScript that computes (approximately) internal forces by integrating component stresses in the model.  The script and documentation can be found at this link.

This script could be adapted to approximate your reaction forces by extracting the surfaces where you have your restraints applied and choosing the correct stress components to integrate.  Let us know if you would like help doing this.

~Michael

Permalink Reply by Bob Johansson on May 2, 2013 at 6:07pm

I missed you guys. Im back.


Bob

Permalink Reply by Olivier Suire on May 16, 2013 at 3:23am

Michael,

Now it's time to hard-code this in Scan and Solve :)

I notice a discrepancy of 111 N (5%) between the 2000 N and the internal shear forces in your example.

What do you think accounts for this ?

Cheers,

--

Olivier

Permalink Reply by Bob Johansson on May 16, 2013 at 10:57am

Reaction forces are a really important feature.

Bob

Permalink Reply by Michael Freytag on May 16, 2013 at 12:33pm

In finite element analysis, stresses are computed from displacement/deflections and are not in strict equilibrium with the applied loads.  Internal forces are computed (integrated) from stresses and are not equal to reaction forces, but they can provide a decent approximation of them.  The accuracy of the approximation improves with increased resolution.
If you want a more rigorous explanation, you may want to look at this presentation from this page.

~Michael

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