Rotations of FBE

[IsmBaha]

Hello Frank,

I am a bit puzzled about the plastic deformation recorder of FB elements.

As you mentioned before,
V = Ve + Vp
Vp = V - Finitial * S (Finitial flexibility matrix in local system at initial state, S current forces in local system)

Let's say this structure goes through an EQ time-history loading and the element material has damage properties.
At an arbitrary point in time after some damage (strength, stiffness) occurred in the elements in previous cycles, is the elastic portion of the deformation/rotation still: Finitial * S ? Shouldn't the elastic flexibility matrix be updated due to the damage in previous cycles? This might be a totally stupid question and I might be thinking wrong... I appreciate if you can explain this.

Regards,
Baha

[fmk]

this is a real simple hack to get a rough estimate, basically unloading elastically and difference from 0 is the plastic strain .. if mhs wanted to be more accutae he would have kept history variables around for the plastic strain and updated them each step.