Stiffness factor - deflection

[mathias_peron]

Hi everyone,

I'd like to use the stiffness factor to calculate the real deflection of a reinforced slab.

I'm not sure if what I think is correct but my idea would be:

- provide reinforcement in the slab with the 'provided reinforcement' module

- go in the 'required reinforcement' module and read what is the stiffness factor of the slab in a particular direction (which takes into account the reinforcement provided previously)

- go back in the model space and multiply the inertia of the slab with the stiffness factor previously got

- get the real deflection of the reinforced slab

If someone could tell me if what I'm explaining here is possible (a little tutorial about that would be welcome 🙂 ), that would be nice.

If what I say is completely incorrect, I'd like to be explained what the stiffness factor is for.

Have a nice day,

Mathias.

[Artur.Kosakowski]

You can check the values of the reduced stiffness for each surface element of the slab 

and then either apply the global reduction of inertia to the entire panel or divide it into smaller parts and assign different reduction to each of it but you may calculate the deflection using the stiffness update method which means that you calculate the slab with such reduction applied to each of the surface elements (applicable to one SLS combination at at time only):

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[mathias_peron]

Thanks Artur, I have tried to do it but I still have problem to get the results that I want. Could you help me find my mistake?

1 - modelling:

SLS combination: self-weight + live load (5kN/m2)

2 - Required reinforcement module:

(Results displayed before providing reinforcement)

First of all, why can I see a stiffness factor if I haven't provided any reinforcement yet?

3 - Provided reinforcement module

(32 @ 300 all directions / all faces)

4 - Required reinforcement module

As you can see, the exact same results are displayed as before? The reinforcement provided wasn't taken into account...

I am wondering what I'm not doing right here.

Thanks in advance,

Mathias.

[Artur.Kosakowski · Accepted solution]

First of all, why can I see a stiffness factor if I haven't provided any reinforcement yet?

As it is calculated at the stage of the required reinforcement calculations.

As you can see, the exact same results are displayed as before? The reinforcement provided wasn't taken into account...

The verification for the provided reinforcement should be launched from this module rather than from the required one.

For the requiredreinforcement:

For the provided reinforcement:

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[mathias_peron]

Thank you Artur.