Navigation:  ENERCALC SEL > Calculation Modules > Beams > Concrete Beam > Deflection Calculation Methods

What happened to the option to specify the "Deflection Calculation Method"?

 

As of Build 20.25.01.16, the user-specified option for the "Deflection Calculation Method" in the Concrete Beam module has been removed. This change was made to ensure compliance with ACI 318 standards and to eliminate potential errors that could arise from users selecting methods not supported under their chosen ACI governing code.

 

The deflection method is now automatically aligned with the governing code selected in the module to ensure that all calculations adhere strictly to the corresponding ACI 318 requirements.

 

 

What does this mean for my existing concrete beam calculations?

 

For projects created in versions prior to Build 20.25.01.16, you may notice some adjustments in the calculated effective moment of inertia, Ie, due to the standardized deflection calculation methods now employed. Specifically:

 

For governing codes adopting ACI 318-14: The module calculates Ie using Branson's formula as outlined in ACI 318-14 Equation 24.2.3.5(a), but with powers of 4 instead of 3. The "fourth-power" version of Branson's formula, as recommended by ACI 435R-20, provides a more accurate representation of stiffness variations along the member for section-based analyses. In contrast, the "third-power" version in Equation 24.2.3.5(a) represents an averaged Ie over the full member length, which is not suitable for the section-based analysis performed by the Concrete Beam module.

 

 

 

For governing codes adopting ACI 318-19: The effective moment of inertia, Ie, is calculated based on the provisions in ACI 318-19.

 

 

 

These changes ensure that all deflection calculations are compliant with the selected ACI code and remove any risk of non-code-compliant designs resulting from unsupported deflection methods.