Clear or Center-to-Center Span

[ChiEngr]

Hello,

I am checking a one-way slab for flexure, and I am hovering around capacity based on the loads applied. For the attached image, my question is, can I use the span length indicated as "l_e"? The slab is slightly overstressed when considering the center to center span, but it checks out considering the span from the centerline of the left wall to the face of the monolithically poured beam to the right.

 

[dik]

For simple bearing I'd often use a couple of inches, based on a rectangular stress bearing block. With the deflection of the slab, the reaction load will be closer to the edge, I suspect (my reasoning). Can you determine the moment capacity of the hooked bars at the other end, and/or the torsional resistance of the beam and use that if critical?

I normally don't sweat slight overloads. If it's an issue, there are likely other problems. My $.03CAN.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[WesternJeb]

See snip from a thread a while back. For the record, I take it face to face of supports for one-way slabs like this.

 

[CDLD]

A few snippets from ACI:

The key here, is determining whether your slab is built integrally with supports.
If your slab is slightly overstressed from c/c span, I wouldn't sweat it.

 

[HTURKAK]

My points ,
- Apparently the ht of the basement wall more than 12 ft and simply supported . Did you consider the lateral load due to soil thrust ?
- You may assume the span length is (le ) . But 10in depth for 24 ft span would be problem for deflection. Can you use joist slab etc.





Use it up, wear it out;
Make it do, or do without.

NEW ENGLAND MAXIM

 

[BridgeSmith]

I'm looking at a slab bridge on an interstate highway right now with a 25' center span, where the slab is 10". The amount of reinforcement can make a big difference.

 

[lexpatrie]

Guess this is existing?

but.... Depth to span for the slab? Meaning you also need to check deflections?

If the slab is overstressed for moment and it's older construction, moment redistribution was a fairly popular approach, in this case it turns into torsion in the beam, but it would still be able to add resistance to the slab moment. It's possible the torsion in the beam is low enough that it's below threshold torsion and no supplemental reinforcement was needed at the time.

If this is retrofit/renovation or new, the "foam glass insulation" is that going to be rigid enough to endure the loads from that topping/wearing surface slab and maintain slope to drain?