EFEECT OF USING 36 ksi Steel and 60 ksi steel on a Slab thickness

[wzaka]

Respected Sir,
Only considering the deflection what is the effect of using 36 ksi steel in a slab and 60 ksi steel or lets put it this way that if we have 2 slabs one has 36 ksi steel and the other has 60 ksi steel which one will require more thickness and why ?
According to ACI code then higher the strength then more will be the depth required for slab means that the slab used with 60 ksi will have more thickness than 36 ksi steel what is the reason behind this ?

 

[lolo]

The yield stress of the reinforcing will not affect deflections much. This is because all bars have modulus of elasticity of about 29,000 ksi. Lower strength bars tend to be more ductile while stronger bars strain harden more, but for deflection there isn't much difference. This is because deflection is a service-level criteria and we don't consider extensive post-yield behavior.

By the way, I believe rebar is available in grades 40, 50, 60, and 75. Grade 60 is by far the most common in my experience.