How we can design continuous slab w 4

[Myo Maung]

How we can design continuous slab with single layer bottom reinforcement only and also not to have cracks at hogging moment location?

 

[hokie66]

You would have to keep the spans very short, probably unusably so, and/or the slab too thick for your liking. Why would you want to do such an illogical thing?

 

[Myo Maung]

Hokie
How is your thought for this slab which is going to cast? See photo Rebar is bot layer only

 

[Myo Maung]

To all my engineering friend , how is your thought for the photo of slab rebar arrangement ?

 

[centondollar]

You put the rebar where it is needed, i.e., where there is tension. Obviously, a single layer is not enough if you have both hogging and sagging.

 

[Lomarandil]

I'll contest that -- a slab with a single layer of reinforcement is viable for the thinner slabs and shorter spans that are typical of slab-on-beam construction as shown..

This is common for low- and mid-rise structures in SE Asia. I designed a number of these in Cambodia and Myanmar. Although most commonly the slabs and beams are placed monolithically.

----
just call me Lo.

 

[phamENG]

Do those bars even have chairs under them?

 

[hokie66]

Not acceptable to me. But you could improve the situation by using different height chairs, longer ones near the supports.

 

[Enhineyero]

How we can design continuous slab with single layer bottom reinforcement only and also not to have cracks at hogging moment location?

Easy, columns every 2nd step in both directions.

 

[MotorCity]

Not my preference, but if I HAD to....place the single layer of bars in middle of the slab to achieve equal positive and negative moment capacity. Or you could create mother nature's cracks yourself and sawcut joints at the negative moment locations to make it look a little nicer than the inevitable jagged cracking that will occur (essentially making it a series of simply supported slabs)

 

[BridgeSmith]

Without rebar in the top over the inside supports, it's not a continuous span - it's 2 simple spans that, if the concrete is not cut over the interior supports, will develop cracks there, most likely big ugly ones.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[Lomarandil]

I appreciate what you guys are saying, but remember that in a two-way beam supported slab, the beam stiffness is going to draw a bunch of bending out of the slab regions.

They perform way better in reality than a first glance would indicate. And with shallow elements and small steel at tight spacing (driven by economics), cracks stay tight.