Cracked deflection at time infinity

To calculate the cracked deformation at time inifinity:

• Click or go to the menu ‘Analysis – Cracked deformation‘.
  The following dialogue appears:

• Reinforcement type
  This option allows you to choose with which reinforcement the stiffness of the cross-sections should be determined. You can choose between:
  
  • only the theoretical reinforcement (incl. minimum reinforcement)
  • only the practical defined reinforcement
    This option is often used to verify the cracked deformation in already existing plates because you can enter the applied reinforcement as practical reinforcement.
  • both the theoretical (incl. minimum reinforcement) and practical reinforcement
    This is the default setting.
• Factor β
  This parameter takes the nature of the load into account.
  • β = 1.0 for single short term load
  • β = 0.5 for long-term and/or repeated loads.
    

In practice, it is suggested to always use 0.5, because neither fixed loads, nor the service loads are single and short-term loads.

Note: In the former standard ENV 1992-1-1 the factor β was divided into two factors β₁ and β₂ where β₁ takes into account the adhesion between concrete and the bars. For bars with better adhesion, we take β₁ equal to 1.

• Compute deformation after creep
  This option allows you to take into account the effect of concrete creep. If you check this option, the elasticity modulus of concrete will be calculated as:
  

     

  
  is the creep factor defined in the material library. The default value is 2.
  In the cracked deformation at time infinity, it is assumed all loads cause creep for the full 100%. Even the non-quasi-permanent part of the live loads. Therefor this deformation is quite conservative.
  If you don’t check this option, Diamonds will calculate the instantaneous cracked deflection.
• Extend cracking theory to axial forces
  Flexural stress will cause tension. Tension will cause cracks. And the cracks will decrease the flexural stiffness of the element.
  But axial stresses can also cause tension and cracks. They will not affect the flexural stiffness, but the axial stiffness!
  If you check this option, both the flexural and axial stiffness will be reduced so the cracking in for example a wall loaded with axial tension, can also be evaluated.