Shell and solid

davefo

can anyone shed some light on the correct way to model a reinforced concrete slab with holes in it.
attached are two models one using shells, the other using solids. The Z direction deflections are completely different as are the stress and moments.
Am I right in thinking that for comparison of the moments for the solid model moment are calculate by using the stress value * (the thickness of the slab)²/6

Thanks

barmin

https://i.imgur.com/7mzb1pU.png Solid model has 150mm thickness while shell has 300mm https://i.imgur.com/gxOxA3l.png

davefo

thanks it was supposed to be two part of 150mm

Victor

As well as the thickness difference:

A ) Y and X BCs one two edges are missing in the shell model.

B ) All BCs on the solid model are on the edge of the plate's face, not the midplane like in the shell model.

Correcting those brings both models' displacements into agreement.