[New Material]- ElasticPlastic Slip-lock material.

[Nero]

I have created a new material that I though some of you may find useful. It is what I call a "slip-lock" material. It behaves just like a typical elastic-plastic material (you specify E, fy, and a hardening ratio), but you also specify the number of analysis steps you want to perform until the material becomes active. For the first x steps of the analysis, the material has zero stiffness, then on the x+1 step, whatever the strain the material has, it is assumed to have zero stress. This is very useful for making connections to a post-tensioned member, if you want that connection to take place after the post-tensioning has happened (ex- you want the connected member to have zero stress after the member deformation due to the post-tensioning). This material can also be used to create a post-tensioned member. Simply apply an axial force to the member you want to post tension, put a truss member with a slip-lock material in parallel with it, then in the second analysis step, release the axial force.

I will be happy to post it when it is all done (in a few days) if there is any interest in this material.

[silvia]

Sure thing,
if you send me your e-mail, I can send you a template for the documentation.
Please make sure you test it well and give examples.
Please get in touch with Frank to check the requirements for incorporating it.

silvia

[Nero]

Sure thing,
if you send me your e-mail, I can send you a template for the documentation.
Please make sure you test it well and give examples.
Please get in touch with Frank to check the requirements for incorporating it.

silvia

Will do- it will be tested prettey heavily on a project I am currently working on.

I should also mention- there is also a "partner" material called "Elastic Lock-slip" which does just the opposite- it is active from analysis step 0 to the specified step. This is good for creating supports for slip-lock elements until they are active. For example- if you are connecting a leaning column to a 2D post-tensioned frame, and the connection between the column and frame is a zero length spring to simulate diaghram stiffness. You would make the zero-length springs a slip-lock material (so that they aren't stressed by nodal displacements during post-tensioning that occurs in the first step) and for this step have the leaning column supported by a lock-slip material, that shuts off after the first step. This way, your leaning column is supported while the slip-lock material is inactive, but once the slip-lock material becomes active, the supports "go away".

[JCEE]

Hi,
where would we obtain this new material if possible? thanks

[Nero]

JCEE-

I never ended up submitting the slip-lock material to FMK. I'll drop him an email, and see if he wants to add it. Otherwise, feel free to drop me a PM here with your email address, and I can email you the source code.

[sriram]

Hi Nero,

I want to try your material model for modeling post-tensioing. so where can get the model ? is it going to be released soon??

-sriram