Composite beam with concentrated plasticity

[sahinburak]

Hi everyone,

I need to model a composite beam (steel beam with concrete slab) with concentrated plasticity by assigning uniaxial bilin material to the springs and elastic beam column element to the beam part. So, can anyone explain briefly how I can do it?

Thanks
Burak Sahin

[fmk]

assuming you have nodes at the column line floor intersections.
1) add 2 duplicate nodes for the ele ends.
2) use equalDOF to connect nodes to existing nodes for the translational dof
3) add elastic beam between these 2 new nodes
4) add a bilin material for moment-rotation of the spring
5) add 2 spring elements connecting the original nodes with 2 new nodes

[sahinburak]

Thank you so much for the answer.
Due to concrete floor, the behaviour of composite beam will differ from bare steel one. Therefore, to represent this difference, should I use bare steel beam properties for the elastic beam element and concentrate all composite effect to the springs by using calibration parameters suggested by Elkady and Lignos (2014). Or should I use composite beam properties for elastic beam element as well?

Regards,
Burak

[fmk]

that is a modelling choice i leave to you .. if you are a student you might want to find some expeimental data and try to see what best fits .. you might do both and see how the differences effect the results .. larger displacements, smaller forces if pure steel! .. in actuality probably between the 2 as the connection not perfect .. i encourage you to play with it.