Modélisaiton d'une dalle appuyée sur 4 bords

[Anonymous]

Bonjour,

Etant un utilisateur débutant, j'ai une question concernant la modélisaiton d'une dalle appuyée sur 4 bords dans Robot Structural Analysis 2012. Dans la pièce jointe, ce sont les données et les résultats obtenus. Je n'ai pas très bien compris le message d'erreur affiché juste après le calcul du ferraillage théorique, ainsi que la section d'acier obtenue. Merci d'avance pour vos commentaires.

Cordialement.

[Artur.Kosakowski]

Is your load really 10T/m2 ?

For SLS combinations check http://forums.autodesk.com/t5/Robot-Structural-Analysis/SLS-combination/m-p/3316923 please.

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.

[Anonymous]

Yes, it is the earth pressure varying from 5 T/m2 to 10 T/m2 which acts on the wall which is considered as slab here.

If i used the obtained moment to calculate the steel section, I do not obtained that much (i.e. 42 cm2).

I do not know what's wrong witht model.

Sorry for my English if I do not correctly use the key words.

[Artur.Kosakowski]

Mind that for reinforcement calculations Robot uses Mxx/Myy + Mxy (I assume you selected bending only). In addition the result of reinforcement may be influenced by deflection if you marked this option on.

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.

[Anonymous]

It seems that the reinforcement founds is not changed although the deflection is not taken into account in the calculation. Would you mind to have a look at the model in the attached file? Thanks in advance.

[Artur.Kosakowski]

Have you included in your hand calculations the the limit imposed on stress level in rebars for SLS combinations (point 7.2 of EC2 if I remember correctly)?

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.

[Anonymous]

No.

Using French code, with crack condition "préjudiciable", we obtain only 19cm2 as the steel section (shown in the attached file).

The condition of concrete configured in the model is more favourable, but the obtained steel section is much. It is not logic.

[Artur.Kosakowski]

As the only available version of EC2 code in the RC Calculator was its draft version it cannot be compared with the current one you selected in Robot.

For the current one when you enter a load case in the SLS field of the slab reinforcement calculation dialog the check is done for 3 limits:

7.1 - stress limit

7.2 - crack limit

7.3 - deflection limit

As the last two are switched off in the set of parameters you decided on the stress limit (7.2) is the factor. You can see that comparing the results for ULS and ULS + SLS calculation modes.

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.