minimum reinforcement in slabs again
EC 1992-1-1 p7.3.2. (7.1) As, min=kc*k*fct,eff*Act/fyk=0,4*1*3,2*200*1000/500=51
assuming bending only. For bending + tension/compression kc may increase up to 1.0. Is this the answer to your question?
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Artur Kosakowski
The 'additional' area is due to
Personally I would consider upgrade to the latest version of Robot so that you have the options to switch use of some code provisions off when you decide to disregard them 
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Artur Kosakowski
My hand calculation:
EC 1992-1-1 p.9.2.1.1 (1) As,min=0,0013*bt*d=0,0013*1000*339=441mm2 or 4,4cm2.
EC 1992-1-1 p.9.2.1.1 (1) As,min=0,26*fctm/fyk*bt*d=0,26*3,2/500*1000*339=56
EC 1992-1-1 p7.3.2. (7.1) As, min=kc*k*fct,eff*Act/fyk=0,4*1*3,2*200*1000/500=51
Firstly, it looks that Robot doesnt take As,min=0,26*fctm/fyk*bt*d, but only takes As,min=0,0013*bt*d (if reinforcement adjust is unchecked), but is first expression gives bigger value it should go in.
Secondly, As, min=kc*k*fct,eff*Act/fyk doesnt go with hand calculation.
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Artur Kosakowski
But my second question is still unanswered, my hand calculation of As,min by 7.3.2 (2) dont go with Robot ones.
Agree with Robot upgrading, we will take it in near future 🙂
Set the concrete grade from as in the model to C35/40. As far as I can see the change of some parameters in the label reset it from as in the model to C20/25 which then changes fctm in the formulas you referred to. We will investigate why this happens.
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Artur Kosakowski
EC 1992-1-1 p7.3.2. (7.1) As, min=kc*k*fct,eff*Act/fyk=0,4*1*3,2*200*1000/500=51
σs is the absolute value of the maximum stress permitted in the reinforcement
immediately after formation of the crack. This may be taken as the yield strength
of the reinforcement, fyk. A lower value may, however, be needed to satisfy the
crack width limits according to the maximum bar size or spacing (see 7.3.3 (2))
According to the table from this point Robot assumes 280 instead of 500.
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Artur Kosakowski
But my second question is still unanswered, my hand calculation of As,min by 7.3.2 (2) dont go with Robot ones.
Agree with Robot upgrading, we will take it in near future
Set the concrete grade from as in the model to C35/40. As far as I can see the change of some parameters in the label reset it from as in the model to C20/25 which then changes fctm in the formulas you referred to. We will investigate why this happens.
Corrected in SP1 for Robot 2016.
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Artur Kosakowski
For simple bending Robot uses the envelopes of each of combination types separately. For axial force plus bending each combination is checked separately.
Design is based on all SLS combinations unless the minimal reinforcement for 7.3.2 has been switched off. Calculations are not done for X0 and XC classes.
Kc is calculated exactly as in the code for each of SLS combinations separately (or envelopes when applicable).
There is no change in concrete resistance or other parameters to set the time below 28 days.
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Artur Kosakowski
My assumption is that you have materials in the model defined according to one code and your reinforcement design code is different. Try to set materials as Eurocode for a model and EC2 (BS EN) for reinforcement of British for model and BS for the design code. Mind to make sure the panel thickness definition and the reinforcement type assigned to the panel are with these sets of materials before running calculations.
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Artur Kosakowski
The tables under 7.3.3(2) is based on a few conditions according to note a).
Question 1: If there is some other cover or fcteff for instance does Robot concider that in anyway?
I'm not sure if i understand you correctly but fct,eff is used for calculations of minimal reinforcement according to formula (7.1)
As I understand it Robot also does the crackcontrol according to 7.3.4.
As Robot follows 7.3.4 the paragraph 7.3.3 is not 'used'.
Question 2: If I choose to do the cracking Control under "SLS parameters" should I check the "Disable the SLS conditions 7.3.2(2)" under "Reinforcement" then?
I don't think so. If you do the formula (7.1) will not be applied. This is to be used only when for some reason you don't want to include the minimal reinforcement provisions at all.
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.
Best regards
Henrik C
Artur Kosakowski
Clarification of Question1: Look at note 1 in the picture below which specifies the assumptions, for the table that Robot uses, is based upon.
Let's say I choose concrete with some other value for fcteff or some other value for cover than 25 mm. Does this affect Robot's results or is the results only valid if my slab fits with these assumptions ?
