Calculate stress induced in concrete slab 2

[saatsen]

Hello,
I have a 100m length of reinforced concrete slab and instead of traditionally putting an expansion joint at every 30m, I want to compute the stress in the 100m length caused by the change in length due to the annual temperature change of 10degrees Celsius in my country. I have my change in length but now my struggle is how to compute the stress induced by that change in length. Any assistance would be helpful please.

Beverly.

 

[Agent666]

The stress will be zero at all the cracks at 100m between free joints or points of no restraint? (I.E. 100m is about three times longer than what you would typically see in practice for a slab on grade.

But to figure out how long you can go without cracking you need to know the friction on the underside of the slab, then the max length you can achieve is based on the sum of the friction based on slab weight. Until such time that you exceed the cracking capacity of the concrete. If you have reinforcement you might limit the crack width and drive further cracking further along the slab from the free edge. The total shrinkage just gives an idea of the cracking potential and potential sum of the crack widths that might occur.

 

[jayrod12]

You may not want to provide joints in the slab. But please realize, the slab doesn't really care what you want to do. It will provide it's own joints if you don't.

 

[BAretired]

If you do not provide for expansion, you can expect the slab to buckle under extreme heat. This happens in midsummer, even in moderate climates. 100m is too long for a slab, especially in a hot climate. And the buckling can be sudden and dangerous, like an explosion, so please don't do it.

BA