minimum reinforcement of foundation

[ricardo_moreira]

Hi everyone,

I would like to Know how what is the expression of Eurocode, that the Robot use to calculate the minimum reinforcement of the foundation.

Thank you, best regards:

Ricardo Moreira (Portugal)

Edited by
Discussion_Admin

[GabrieleNovembri1027]

Hi,

I don't know what  kind of criterion Robot uses but Eurocode 8 prescribes minimum reinforcement only for beams and not for the footings for which local ductility is not required. See attached Page.

[Jakub.Brozonowicz]

If the results from the minimum value that the answer is as follows:
We accept that the elements are reinforced ones.

Due to the limitation of damage to fragile bent elements the condition (9.2.1.1-beams, 9.3.1.1 - boards) is always used:

AsMin = 0.26 * (fctm / fyk) * b * d

When grown fck then fctm grows too.

Also the minimum reinforcement grows with it.

[ricardo_moreira]

Thank you,

 When we define a load in "RC_Foundation design" with nature of design the programm don't use this expression "AsMin = 0.26 * (fctm / fyk) * b * d" to calculate the minimum reinforcement. It´s possible to change it ?

Best Regards:

Ricardo Moreira

[Jakub.Brozonowicz · Accepted solution]

This condition is SLS oriented one.

In case of Design load only ULS state check is done and other formulas taken as reference.

[Mirko.Jurcevic]

"

  This condition is SLS oriented one.

  In case of Design load only ULS state check is done and other formulas taken as reference.

"

I don't understand this answer, and I have similar problem.

For my spread footing, Robot calculates minimum reinforcement as 4,17cm2/m' for bottom zone, and 3,14cm'/m' for top.

According to EN 1992-1-1, this values should be calculated as:

As,min = 0.0013⋅bt⋅d = 0.0013⋅100⋅44 = 5.72 cm2

or 

As,min = 0.26⋅(fctm/fyk)⋅bt⋅d = 0.26⋅0.22/50.00⋅100⋅44 = 5.03 cm2

whichever is greater.

??

Question is simple: Which expression Robot uses to calculate minimum reinforcement of the spread footing?