Autodesk Robot Structural Analysis

[#1]

Morning All,

I'm trying to allocate 150mm deep RC slabs for very small cantilever spans. Whenever I go 150mm or  below I get the warning / error (not sure which as it doesn't say) of:

"Too small distance between reinforcement layers, for panel ** it is 14.7% of it's section. The incoherence error may occur".

The slabs are 150mm thick with 30mm cover. 150mm thick is overkill for such a low loaded and low span panel. Screenshot of the panel (highlighted red) attached. On analysis the "required reinforcement" comes out as 2 layers of A252 mesh T&B for this 150mm slab (screenshot for this also attached), therefore distance between T&B reinforcement is much > 14.7% of the section... Is the message a false warning?

Thanks,

Scott

[#2]

Could you make the screen capture of the last tab (reinforcement) of the reinforcement parameters assigned to the discussed panel please?

[#3]

Hi Artur,

See attached.

Thanks

[#4]

Actually I need this one

[#5]

oops sorry, see attached

[#6]

Apparently you created the label for a different reinforcement database than you have currently declared in the job preferences which results in values of selected bar diameters not being visible. In general the discussed value is calculated as:

( panel thickness - d1 - d1' - d2 - d2' - c1 - c2) / panel thickness

[#7]

Hi Artur,

I've checked job preferences but can't see anywhere where a custom reinforcement allocation has been selected. Materials are still general concrete there. The purpose of the "30mmcover28day" reinforcement property was to control cover and also the shuttering time in case the contractor wanted to remove shuttering at say 7 days later on.

Is there a way to switch off this warning / error message that keeps popping up then if it's a false positive?

Many Thanks,

Scott

[#8]

Scott,

The message is more informative as the calculations are performed in the same way as if the clear distance was larger. You may try to define a new reinforcement label selecting 8 mm bar diameter as used for the wire fabric type you mentioned and run reinforcement calculations again. My assumption is that the diameter you selected for the label you defined was bigger.

[#9]

Hi Artur,

I've swapped the floor slab back to the default "RC Shell" reinforcement property which stops the false warning from popping up.

Regarding the "28day30mmcover" reinforcement property, I left the reinforcement section in that property blank as the property is being used for slabs of widely ranging thickness, span and reinforcement density in the building. It was mostly to control the shutter removal / loading time.

Thanks for the speedy responses Good to know it's not an issue.

Scott