Dear Sir or Madam,
I would like to calculate a restrained concrete slab. The slab is subject to uplift, which is why the relevant tensile reinforcement is located at the top. When adjusting the concrete cover of the top layer, I noticed that the required tensile reinforcement in the top layer does not or hardly change. However, when adjusting the concrete cover of the bottom layer, the required amount of reinforcement changes both in the top and bottom layers. This should hardly have any influence on the reinforcement of the top layer. Attached is the calculation file with 3 variants. The screenshots show the results in the mid-span of the slab section with a thickness of 1.0 m.
Concrete cover-100-100 (top 100 mm bottom 200 mm) --> a_s,req(top) = 11.38 cm²/m
Concrete cover-200-100 (top 200 mm bottom 100 mm) --> a_s,req(top) = 11.38 cm²/m
Concrete cover-100-200 (top 100 mm bottom 200 mm) --> a_s,req(top) = 12.88 cm²/m
In summary, the following can be observed:
Adjustment of the top concrete cover --> No influence on required reinforcement
Adjustment of the bottom concrete cover --> Higher reinforcement top and bottom
Can you tell me how this discrepancy comes about?
P.S. I actually wanted to submit a support request and send the associated model files. However, the form cannot be submitted. There seems to be a problem with the Captcha.
Thank you very much in advance for your help!
