Modulus of elasticty for concrete with tempreature change

[ahmedhegazi]

Hi all,

I have a building with a floor slab of considerably big length around 120 Meters, we decided that thermal analysis is required to study the effect of increase and decrease of temperature between winter and summer with respect to construction temperature.

After analysis we found that steel reinforcement required for this temperature loading it is very huge!!

I think that the reason is because of using same modulus of elasticity and considering the concrete to be untracked which is not actual!

According to the famous equation F=EA/L

So force is affected by modulus of elasticity and area of my slab plate.

What values I should use for modulus of elasticity to allow for creep and shrinkage as well as cracking which will happened over a period of time expected to be minimum of 2 months.

Regards

 

[dik]

How large are the panels you are cutting the slab into?

Dik

 

[ahmedhegazi]

Dik,

My slab is not pannels(i.e. there is not expansion joints throught it) it is dimension is 120mX30m

 

[Dinosaur]

You will get cracks in this slab. Your analysis probably assumed the slab would not move while it was subject to temperature variations. This is unrealistic. But the whole thing is moot. A concrete slab is going to crack.

 

[civilperson]

For increase in temperature and compression in concrete because of thermal expansion, use 57000 x SQ Root of F'c.