Fiber vs WWF

[manofstl]

So, without telling anyone, Contractor decided to substitute fiber reinforced concrete instead of the Vulcraft metal deck with concrete/6x6WWF I spec'd for a second floor. Now he calls, wanting approval from yours truly so the job can proceed. I checked with Vulcraft to see if the FRC is an acceptable substitute, and they (understandably) have no position either way.

Anyone run into this scenario before?

 

[JAE]

haynewp -

The Vulcraft catalog, for example, has three tables, not two.

One table is titled, "Max. Construction Clear Spans"
The second is, "Reinforced Concrete Slab Allowable Loads"
The third is, "Allowable Uniform Load"

I'm talking about the third table.

The first is a construction span table, providing a maximum allowable span for specific thicknesses of normal and lightweight concrete.

The second works with the first table, and provides the max. loads for various spans of reinforced concrete slabs. This table requires reinforcing as the deck here is simply a temporary form.

The third table is a generic tabulation of various deck gages, spans and limit states (strength and deflection). The formdeck can be designed from this table directly (without the first two) simply by ensuring the strength (Fb = 36,000) is OK, and then selecting one of two deflection criteria (L/2400 or L/180). The W1 value in this table corresponds to the first table.

You can see that the W1 value is the same as the constr. clear span table by comparing 1.5C24 / 1 span / 4'-6" span - gives 60 psf as the max. The first table, for the same parameters shows that a 61 psf weight (5 1/2" total thickness) is the limit.

 

[haynewp]

Sorry for the stupid oversight.

 

[JedClampett]

LPPE, you're probably right. But watch out for anything with a 4 x 4 spacing. That's where I ran into availability issues.