Modelling trilinear stiffness for discrete fasteners in Abaqus

[Tinni1]

Hi,

I am modeling a screw connection between the cold-formed steel beam and column flanges using discrete fasteners in Abaqus.

I am using a planner connection section. I am able to define a linear stiffness for the connector.

Now I want to improve the stiffness behavior and model a trilinear stiffness as depicted in the attached figure.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1643033259/tips/Trilinear_stiffness_qtv2qf.docx[/url]

Could anyone advise, if this is possible in Abaqus and if yes, how to do that?

Many thanks!

 

[Tinni1]

I forgot to mention in my earlier post that for a trilinear stiffness the coordinates of points 1,2 and 3 ( as shown in the attachment) are known to me.

 

[FEA way]

When you add elasticity as a behavior for the connector section, you can switch from the default linear to nonlinear. Then you will be able to specify force-displacement (or moment-rotation) data points to define the whole curve.

 

[Tinni1]

Thanks for your response.
Just one question, when I switch nonlinear, and F2, F3 ( Available DOF in my case: I have attached a screenshot below), I get one Force/Moment Vs displacement/rotation response. Does that mean when I input values in the table the same stiffness will be applied for both F2 and F3?

Many thanks in advance!

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1643035267/tips/Trilinear_stiffness1_zrejpo.docx[/url]

 

[FEA way]

If you want to define separate elastic characteristics for each direction, you can repeat the Elasticity behavior (add it more than once) and choose a different component for each definition.

 

[Tinni1]

That's great!... Thank you so much!