floor slab panels with large openings

[Opel5]

Hi Artur,

Please refer to attached screenshot.This screenshot refers to "second case".

"first case" - The roof slab with a large slotted hole in was originally 1 panel with 1 panel "opening" specified. This seemed to deflect as expected but reinforcement seemed low at the front hinge area we were talking about even after reducing slab thickness to 300mm.

"second case" - I have now decided to model this panel as seperate panels instead with a gap between the panels to mimic the panel opening previously. I have re-allocated and checked loadings on this zone of panels and all loads appear to be applying. However the deflection and reinforcement levels have dropped off even more than the first case. It does not seem to be abnalysing correctly.

I'll email over link to zipped RTD file. Could you have a look what is going wrong? I have checked openings to make sure the previous "first case" opening or it's polyline isn't still lurking in some fashion and causing some form of hidden support.

Many Thanks,

Scott

[Artur.Kosakowski]

OK. Send me the model and indicate what case/combination you check deflection for.

[Opel5]

Thanks Artur, it shoudl be arriving with you any second 🙂 Deflection indicated in the screenshot was for SLS combination 3. Even when looking at required reinforcement map for ULS combination 4 of the area it seems to be much lower in reinforcement than before.

[Artur.Kosakowski · Accepted solution]

Scott,

I have checked the results for both models using W&A method for cases ULS:5 SLS:4. Despite the fact that the model with beams is calculated according to EC2 with UK NAD and the new one for BS8110 and the panels have got different thicknesses  the results are similar and are at the level of minimal reinforcement (you can switch on using minimal reinforcement for all the panels). I think that for 30 or 37.5 cm slabs this is reasonable.

I'm attaching the maps of elastic and cracked deflections which seem to be correct too.

[Opel5]

Thanks for checking that Artur. That's a bit bizarre, when I closed down the model to zip it, then re-meshed and re-analysed I got the same correct deflection profiles which match your attachments too. Not sure what was going on with the deflection screenshot earlier.