Composite beam with quad elements


What would the best way to model a composite structure with quad elements? I was planning to use the same SLN for the concrete quad (BELO) ant the top flange (ABOV) of the steel beam, but I’m concerned about the connection…

Thanks and regards


Do I understand you correctly that you want to model a composite beam only with QUAD elements?
If so, you need to connect the top flange with the concrete deck.
This can be done with spring elements and/or with couplings.
If you use the same structural line in both constructional elements (deck and flange), you get a rigid connection.

Why don’t you use a combination of SLNs and SARs? You could model the concrete deck with QUAD-elements and the steal beams with beam elements.
For this case we have a new detailed tutorial on our website. > Infocenter - Overview > Documentation - Tutorials 2022 > bridge design > composite bridge

Best regards
Frederik Höller
Your SOFiSTiK Support Team

Thanks, Frederik. You understood my question right, so I can’t combine SLNs and SARs because I have to study a specific area of the beam with quad elements (stiffeners and so on).

Then I should use springs or couplings, but two SARs sharing a face is not a great idea, isn’t it?


Well basically this is up to you. It depends on your model and the results you want. But I think springs give you the best possibilities to model the shear connection between the two components (-> user defined (non-linear) work law).
If this is a student research project, you should debate the connection with your supervisor.

Don’t get me wrong a connection between two area elements is possible, as long as these areas have the same nodes. Keep in mind that elements are only connected if they have identical nodes. If you want to know how to link two SARs together, check out my colleague’s short video.

Cleared up!

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