about the element load...

[volvo]

While processing problems about the "element load",
we usually use the fixed end force (FEF) method of a element.
That is
Step 1: applying FEF to keep the element in zero deformation.
Step 2: using -FEF as the external nodal load tho solve the internal force/deformation of the element.
Thus the total force of the element is (FEF + force of Step 2),
the total deformation is deformation of Step 2.

In OpenSEES, it abstracts the element and material classes.
There would be two levels (force/deformtion of element; stress/strain of material).

So in the 1st step, how does material class consider the stress/strain from FEF?
(Does just stress exist and no strain exists in material?
Or how does OpenSEES process it?)

Thank you!

[Gang Wang]

Of course some materials have stress-strain information. The material
just takes trial strain from the element.
Why we have to use FEF to apply an element load?