Difference between abt and abr - Robot 2018

[Anonymous]

Hi, I am studying a beam that results in minimum area reinforcement. My final hand calculation does not match with the Robot final reinforcement, although my minimum and theoretical reinforcement area match. I used the same diameter as the Robot (12mm), mine is resulting in 2Ø12 and the robot is resulting in 3Ø12.
Someone has a clue why is that happening?
I am using Eurocode 2 in both methods.

[Artur.Kosakowski]

Hi @Anonymous

Maximal allowed bar spacing?

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[Anonymous]

30cm

[Artur.Kosakowski]

Hi @Anonymous

Could you attach the file and indicate the beam to look at?

[Anonymous]

I have attached the file and a photo that shows the location of the beam. Thanks for helping me.

[Artur.Kosakowski]

Hi,

 

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[Anonymous]

Okay, but I use another setting. I use EST1 for reinforcement pattern and EST for calculation options, not the standard. I dont know if those configuration are save at the model. I attached a photo from the general configuration to this answer.
Maybe it is another configuration setting making this mistake.

[Artur.Kosakowski]

Hi @Anonymous

They are not saved as labels but they are stored in the file if you saved the rtd file with the designed beam which wasn't the case for the file you attached. You can compare what is different in the reinforcement pattern you created and the standard one. 

If one or more of these posts answered your question, please click Accept as Solution on the posts that helped you so others in the community can find them easily.

[Anonymous]

I tried again with the default setting, but Robot is answering me with 2ø16 and not 2ø12. I just calculated without ø = 16 and the answer was 3ø12 again. I can’t understand why abt is so difference from abr. My abmin is 2.24 cm², I could use 2ø12 which result in 2.26 cm².

This picture above are 2ø12 or 2ø16?

[Artur.Kosakowski · Accepted solution]

Hi @Anonymous

When the reinforcement segment is set as the whole beam then the bottom rears are 2 fi14 as required for the last span but you can manually change the bar diameter for the three first one and run reinforcement verification after freezing it. If you set it as the single span it is 2 fi12 for the 3 first spans and 2 fi14 for the last one.

Both examples attached.