Temp and shrinkage reinforcing.

[shin25]

I have a 10" thick precast concrete plank. I like the reinforcing for temp and shrinkage to be .002*Ag. How many layers of reinforcing should I provide? Both top and bottom surfaces will be exposed.

 

[COEngineeer]

I thought concrete planks were flexural members? Youll need at least .0033 . Am I right?

Never, but never question engineer's judgement

 

[Lion06]

I haven't seen pre-cast plank with mild steel for T&S (I should clarify I am talking about hollow-core).
Are they hollow-core? What kind of conditions will they be in (inside or outside)?
Have you discussed this with the pre-caster?
Are they pre-stressed?

 

[shin25]

Yes, they are prestressed. After they are produced at the precast facility, the planks will be left stored in the open air for a while. In the main direction the planks will be pre compressed, so I am not worried about temp and shrinkage this direction. My concern is in transverse direction only.

 

[Lion06]

I would check with the pre-caster, I don't think they typically provide reinforcement in the transverse direction.
It may not even be possible to provide a continuous mild steel bar transverse without going into the cavities (or having very minimal cover at the bottom.

 

[shin25]

Few more things I missed-

These are solid slabs, about 18' long and 8' wide.

 

[hokie66]

Why would you need t&s reinforcement for a concrete element that is not restrained? No restraint, no cracking.

 

[shin25]

These planks are infact for a pier. When erected they will be side by side making a complete span. I shall need these transverse reinforcing for two reasons-
1. Help to transfer the load transversely.
2. after erected the slabs will be restrained transversely. Depending on how soon after casting they are erected, the concrete will continue to shrink. So these reinforcing will act as T&S reinforcing.

 

[apsix]

I would use T&S reinforcement top & bottom, with cover approaching 3" for a marine environment.

 

[Lion06]

Shin-
I really don't think you need T&S steel for these. They may shrink, but they will shrink into themselves. I would talk to the pre-caster, they will tell you this is not necessary.
The only place you might see shrinkage cracks is at the slab joints, but steel in the slab will not do anything for that.