Why is effective depth "d" calculated different for flexure and shear in s-concrete?

Saif Mohammed

Hi. 

I have a question on calculation of effective depth (d) by s-concrete. Why is s-concrete calculating different d for shear and flexure capacities? also why is s-concrete considering d as 0.8*h for shear where as this should only apply to prestressed beams and not regular beams as per ACI code.

 

Can you please shed some light onto the logic behind "d" calculation by s-concrete?

Matthew_Sauer1

Hello Saif,

Thank you for reaching out.  This is a topic that our team has been investigating, and we are looking to make improvements to ensure consistency in the effective depth calculations used for shear and flexure in ACI 318.

Currently S-CONCRETE uses a strain compatibility approach that is influenced by the number of bars in tension.   If you have high bending moments in a beam, for example, this could lead to a lot of the reinforcement being in tension, and the effective depth, and thus the effective shear depth.  It is possible that different loading conditions may govern for shear, than flexure, thus the amount of area of steel in tension may also vary between those cases.  As mentioned, this is something our team is taking a closer look at for future releases.

More details on this topic can be found under the help system topic 'Shear Resistance' if you are curious.

Regards,
Matthew Sauer

Altair Support