Shear/Axial Springs in Columns

[evgin]

Hi

I have a 3D reinforced concrete model . I wanna add Shear/Axial springs on top of each column (with fiber section) to model shear/axial degradation.

Should I just define ONE additional node besides the join node and connect those 2 nodes using a zerolength element? Then I can add 3 different materials in 3 different directions to simulate shear in both directions (3D model) and axial responses. I also constrain the rotational DOF's.

In Elwood's work I saw he attached a spring to the end of the column and then define a rigid element connecting the other end of the spring and the joint node. If I am to do so can I just use another zerolegnth element with rigid material properties to connect the end of the shear/axial spring to the join node?

As per recording the response , can I use an element recorder to record the force and deformation response of the shear/axial spring (response of the entire column) instead of using node/reaction recorder?

Thanks
Reza.

[fmk]

if that is the way you want to model it then use one additional node .. if you have a rigid material just use a constraint, too high a stifness to give a rigid member can lead to numerical issues.

you can use an element recorder to monitor the foces and deformations in the zero length element