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ETABS Modelling help

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eng.chix

Structural
Jun 22, 2022
9
I'm modelling a 6 Storey concrete structure in ETABS. Since the loading requirements are fairly unbalanced and variable, I've introduced numerous 'none' slab properties to apply these variable loads. It appears as though these none properties have caused issued with the model run as I get error messages each time stating that there are area load transfer warnings. These warning always coincide with these none slab properties.
1. Do I worry about these? Or is it just a warning saying that I have these none properties, but that it does actually take them into account when it runs the model?
2. Are there tricks to applying these types of non-uniform loads other than how I've been applying them?

I appreciate any feedback! Thank you!
 
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I would do the following:

1) Hand verification of the loads. Prove to yourself that 100% of the load is accounted for.

2) switch the null slabs to have the same properties as the base slab. Check if / how the loads changed.

3) just for good measure, Review the etabs docs on how they treat overlapping slabs for loads, stiffness. It changed a few major versions ago as well, to align with the behaviour of SAFE


-JA
try [link calcs.app]Calcs.app[/url] and let me know what you think
 
From what I've heard the issue might be from overlapping null shells with two shell types. Try splitting the null shells at the slab boundaries.
 
I sorted it!

The issue was openings within none slab properties. If I draw around the openings such that there is no opening within the slab property, the warning disappears. So my theory is that it tries to apply the area load to the opening surface as well, but doesn't have anything to apply it to, so it gives off a warning.

Previously, in older versions of ETABS, if you drew an opening, it didn't matter whether the opening was within a slab or none slab property, it still cut through any of the properties and actually acted as an opening. This version doesn't appear to do that anymore. It recognizes that it needs to cut the defined slab property, but not the none slab property.

Regardless, happy I solved this. Thank you for all your ideas!

 
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