hi all how can you calculate the

[alshaiji]

hi all
how can you calculate the deflection in a waffle slab or the two way system? is there any ACI reference? i have the system shown in the link below and i want to establish the depth of the waffle or two way system based on deflection requirments

http://malshaiji.topcities.com/room/chemlab.htm

thank you in advance

 

[RobertoMiguel]

If you were hoping for a simple equation you can throw at this, forget it. It depends on your loadings a great deal and you should have a few load combinations thrown in there, for good measure. So, sharpen the pencil and model that slab. Your FEA software should be able to map the deflections for you.

Roberto Sanabria

 

[rapt]

Yes, your FE analysis will be able to give you reasonable estimates of elastic short term deflections.

Then you will have to add the effects of cracking, redistribution, shrinkage and creep. These effects could increase your deflections by a factor of 5 to 10 depending on mconditions so they are very important.

Do not believe the numbers from your FE software alone.

 

[BryanStein]

AHHH, finite element modeling of concrete. I like to see it because it eventually means more work for me.

Few people properly model the cracking effects of concrete they run a FEM of concrete. I've often found good old horse sense works best when analyzing concrete. Be careful with FEM of concrete. I've seen in done wrong more times that correctly.