## Robot Structural Analysis

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# minimum reinforcement of foundation

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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

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Solved! Go to Solution.

# Re: minimum reinforcement of foundation

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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.

# Re: minimum reinforcement of foundation

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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.

**Jakub Brożonowicz**

# Re: minimum reinforcement of foundation

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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

# Re: minimum reinforcement of foundation

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This condition is SLS oriented one.

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

**Jakub Brożonowicz**

# Re: minimum reinforcement of foundation

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"

* 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?