reinforced concret beam deflection

[civil1980]

My question is about reinforced concrte beam deflection.Deflection due to gravity loads are calculated for service load and flexural behaviour of concrete under service laod is variable which means the strain diagram differs as load increases.concrete cracks under under service load.
In chapter 9 of Aci there is a formula for calculating immediate deflection.In that formula Icr is defined as moment of inertia in the cracking level that deflection is calculated.Shall I assume that reinforced conctrte is cracked or not?

 

[JedClampett]

That's accounted for in the deflection formula. You calculate Mcr and by a ratio of you actual moment to Mcr, you adjust the moment of inertia for the portion that is cracked.
It's a real mess. You're better off either using the beam depths where you're not required to calculate deflection or seeing if you can get someone else to do it.