bonsoir,

 

 

alors voila j'ai une petite question qui attend une grande réponse

 

dans un livre qui traite l' EC8 j'ai trouvé le paragraphe suivant:

a good criterion at the stage of conceptual design for providing a wall, a dual or a core system, with a hight degree of lateral stiffness so that at least second order effects are prevented, could be the use of the provisions of DIN 1045(1982) as they have been adopted by the revised greek code for reiforced concreate structures, that is

voila la formule dans le fichier word (j'ai pas pu l’écrire directement c'est compliqué)

 

 

ma question est comment appliquer cette formule comment trouver cette rigidité,

SVP aidez moi c'est vraiment très très intéressant pour moi

 

merci d'avance pour toute réponse

cordialement.

doc1.docx

Bonjour,

 

ce critère ne pose pas de gros problème de calcul, pour J, on prend en général les inerties des voiles.

à noter qu'il est très proche de celui de l'eurocode 2 avec k2=0.62:

 

• 1. As an alternative to 5.8.2 (6), global second order effects in buildings may be ignored if
  2. 
  3. where:
  4. F_V,Ed is the total vertical load (on braced and bracing members) n_s is the number of storeys L is the total height of building above level of moment restraint E_cd is the design value of the modulus of elasticity of concrete, see 5.8.6 (3) I_c is the second moment of area (uncracked concrete section) of bracing member(s)
  5. Note: The value of k₁ for use in a Country may be found in its National Annex. The recommended value is 0,31.
  6. Expression (5.18) is valid only if all the following conditions are met:
  7. - torsional instability is not governing, i.e. structure is reasonably symmetrical

• - global shear deformations are negligible (as in a bracing system mainly consisting of shear walls without large openings)
• - bracing members are rigidly fixed at the base, i.e. rotations are negligible 67
• - the stiffness of bracing members is reasonably constant along the height
• - the total vertical load increases by approximately the same amount per storey

1. k₁ in Expression (5.18) may be replaced by k₂ if it can be verified that bracing members are uncracked in ultimate limit state.

   Note 1: The value of k₂ for use in a Country may be found in its National Annex. The recommended value is 0,62.

Il y a beaucoup de conditions à respecter qui ne sont pas toutes présentes dans beaucoup de projets...

 

Salutations

bonjour

 

Bonjour,

 

ce critère ne pose pas de gros problème de calcul, pour J, on prend en général les inerties des voiles.

à noter qu'il est très proche de celui de l'eurocode 2 avec k2=0.62:

 

• 1. As an alternative to 5.8.2 (6), global second order effects in buildings may be ignored if
  2. 
  3. where:
  4. F_V,Ed is the total vertical load (on braced and bracing members) n_s is the number of storeys L is the total height of building above level of moment restraint E_cd is the design value of the modulus of elasticity of concrete, see 5.8.6 (3) I_c is the second moment of area (uncracked concrete section) of bracing member(s)
  5. Note: The value of k₁ for use in a Country may be found in its National Annex. The recommended value is 0,31.
  6. Expression (5.18) is valid only if all the following conditions are met:
  7. - torsional instability is not governing, i.e. structure is reasonably symmetrical

• - global shear deformations are negligible (as in a bracing system mainly consisting of shear walls without large openings)
• - bracing members are rigidly fixed at the base, i.e. rotations are negligible 67
• - the stiffness of bracing members is reasonably constant along the height
• - the total vertical load increases by approximately the same amount per storey

1. k₁ in Expression (5.18) may be replaced by k₂ if it can be verified that bracing members are uncracked in ultimate limit state.

   Note 1: The value of k₂ for use in a Country may be found in its National Annex. The recommended value is 0,62.

Il y a beaucoup de conditions à respecter qui ne sont pas toutes présentes dans beaucoup de projets...

 

Salutations

 

je viens de lire votre réponse

merci infiniment pour cette explication,

salutations.