Temperature Effect on Slab

[ahmedhegazi]

Hell All,

i have got basement RC slab with plan dimensions 60X60 ms slab where it is serving as car parking with grid of columns and flat slab ,outer perimeter of the slab is supported by Basement RC wall on two sides (L shape) while the other 2 sides are supported by columns (as there is ramp along the basement wall of these 2 sides).

Checking engineering has requested Temperature study using finite element analysis ,after checking ACI 224 ,design gudies for spacing between expansion joint ,it was found that building dimension qualify to be built without expansion joint.
however checking engineer insisting on the study using finite element.
After Carrying out material linear analysis, i got nearly double the steel required to resist vertical load ,which does not sound reasonable!!
My personal believe is linear analysis under temperature is decisive as slab will form crack when stress exceeds the modulus of rupture.
Would highly appreciate input from anyone who has faced this situation before.

 

[slickdeals]

What temperature gradient are you using?

 

[ahmedhegazi]

Uniform Temperature +10C or -10C

 

[slickdeals]

How have you modeled the walls? Since you don't have walls on all four sides, the 2 sides walls (unless they have significant returns) should be rather flexible to allow the slab to breathe.

Your temperature gradients are not large enough to double the steel.