Difference between shell and deck slab (two ways)

[tommasovidali94]

Hi everyone, 

I have a model composed by an aluminum plate, aluminum frame and aluminum stiffener. I have to questions: 

-QUESTION A

As you can see from the two image I have attached to the post (deck and shell), the model gives me different results in case I cosinder a deck slab (two ways) and a shell. Why do you think the deflected form is that different in the two cases? What is the correct model to consider? Shell or deck slab (two ways)?

-QUESTION B

The frame and the stiffener are localed in reality behinde the plate, is there a way to do it as well in the model? How the relationship between the frame-stiffener-plate can be defined properly? 

[Krzysztof_Wasik · Accepted solution]

Hi @tommasovidali94 

In deck slab calculation model planar load is not applied to FE of panel loads are transferred to bar elements using tributary method and applied as linear load to beams on panel edge. Panel deformation are enforced by bar elements deformation

In shell model loads are applied to panel FE. Panel is directly loaded. This is a reason why deformation is different fro both models.

For your panel with beam frame, when you are interested in panel deflection shell model is correct..

If neutral axis of your frame structure are placed behind neutral panel plane you can simulate that using offsets

Geometry >additional attributes >Offsets. Offset option will move bar neutral axis in respect to panel neutral plane. Connection between bar and  plate will be simulated by fictitious rigid members.