nathan7
Structural
- May 24, 2011
- 36
Hi,
I'm building an ETABS model which will have PT slabs. The PT slabs will be design in SAFE. I've done the preliminary design of the slabs and i know that 200mm works. My maximum long term deflection will be no more than 25mm. If i don't have the PT the deflection can be up to 60-70mm long term.
When i'm building the etabs model there is obviously no post tensioning in the model hence the linear deflection is very high (50-60mm). The slab supports are very irregular hence parts of the slabs deflect 60mm and other parts 10mmm.
My question is: if the slab is floppy does this mean that the load is attracted by stiffer parts of the slab hence the load distribution in the columns is incorrect? In reality the slab will be stiffer and able to carry the loads but etabs doens't know this.
I'm puzzled by this question. The slab stiffness is a function of E ad I. I is improved by the PT but i guess is it's the same value everywhere it should't make any difference.
Anyway, let see if someone had similar thoughts and look forward to hearing some opinions.
Cheers
Nathan
I'm building an ETABS model which will have PT slabs. The PT slabs will be design in SAFE. I've done the preliminary design of the slabs and i know that 200mm works. My maximum long term deflection will be no more than 25mm. If i don't have the PT the deflection can be up to 60-70mm long term.
When i'm building the etabs model there is obviously no post tensioning in the model hence the linear deflection is very high (50-60mm). The slab supports are very irregular hence parts of the slabs deflect 60mm and other parts 10mmm.
My question is: if the slab is floppy does this mean that the load is attracted by stiffer parts of the slab hence the load distribution in the columns is incorrect? In reality the slab will be stiffer and able to carry the loads but etabs doens't know this.
I'm puzzled by this question. The slab stiffness is a function of E ad I. I is improved by the PT but i guess is it's the same value everywhere it should't make any difference.
Anyway, let see if someone had similar thoughts and look forward to hearing some opinions.
Cheers
Nathan
