Property Modifiers

[Ahmad Alhamad]

Hello,
I have an issue about Etabs property modifiers
when I used the modifiers for all members, how these modifications will reflect on ETABS
(what are the results will be changed exactly)
if the design will change so when i export the slab to SAFE, the program made cracking analysis for deflection, but what about the design?
thanks

 

[cyrosmith85]

Hi,

How does modifiers affect the analysis results?
The modifiers "modify" the element's stiffness → displacements are directly related to stiffness → design forces are dependent of displacements. So there you go, by changing the modifiers you are affecting the design forces.

Now, if you are designing a floor slab and are going to use the cracking analysis option from SAFE to calculate deflections, you don't have to use modifiers once your model is a SAFE model. SAFE does not read the property modifiers from an ETABS model, so if you want SAFE to consider those modifiers you have to re-input them in your SAFE model, but as said above, if checking long term and immediate deflections (considering cracked section) is what you are using SAFE for, then you don't need to input any modifiers since this is precisely what SAFE is great at.

Hope it helps.

 

[Enrique2015]

Modifiers will affect stiffness, hence everything in the model will be affected, by some degree. In most cases Modifiers in ETABS are used to try to somehow capture the effect of cracking in concrete structures. In SAFE you can do an explicit nonlinear cracking analysis so you don't need modifiers at all, otherwise you will get wrong results.