Internal Forces along the elements

[imurdereri]

Hi all!

I am new in this program. I am trying to get the internal forces along the element. For example, for a "element elasticBeamColumn"

The next command:

"recorder Element -file Element1.out -time -ele 1 force"

just five me the nodal forces in the element and i need, for example, the moment o shear along the element

Thanks for your help!

[fmk]

simple undergraduate statics will give you want you want!
http://en.wikipedia.org/wiki/Shear_and_moment_diagram

[imurdereri]

Hi, that was not the answer i was looking for.

You cant apply simple statics if you have a dynamic analysis with no linear elements, for example.
So, in that case, if i want to obtain the moment and shear diagram, there is a recorder to do that? or element?

Thanks!

[m12s12sa]

If you are using a nonlinear elements (such as http://opensees.berkeley.edu/wiki/index ... mn_Element, or others NL elements) you can ask for internal forces along the element, at integration points locations. Read the NOTES on the page I linked.

[imurdereri]

OK thanks!, that's very useful

However, for the most basic element such as elasticBeamColumn you can't do the same? or something similar? for example, define more nodes in the element?

[m12s12sa]

ElasticBeamColumn doesn't have that option because... well it is elastic!, hence the distribution of internal forces can be calculated with common shear and moment diagram rules.
You can of course always define more nodes and hence elements along a structural member...At that point you also have to define more elements!

[fmk]

you cannot obtain the moment and shear force diagram from a recorder .. AND YOU CAN APPLY SIMPLE STATICS

the forces returned from an element are all you need .. simple statics applies for both static and dynamic case and for elastic or nonlinear case .. equilibrium is equilibrium .. even for dynamic case these forces returned do not include any inertia forces or damping forces , they only return the fs(t) forces as defined in Prof. Chopra's book Dynamics of Structures. There are no inertia or damping forces that need to be considered acting along the length of the beam column elements.

the forces returned from the displacement beam column at the sections should NOT be used to figure out moment and shear forces along an element; equilibrium for these elements is satisfied in the average sense (review your theory on finite element method and concept of "weak equilibrium" in the elements) due to the approximate displacement field chosen for numerical integration.