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Transfer of Unbalanced Moment in two way flat slabs according to ACI318-08 CODE 1

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ayelamayem77

Structural
Oct 2, 2012
47
Dear all,

as we all know that sap2000 gives the moment (m11 , m22 using finite element design method in unit width).

ACI318-08 STATE THE FOLLOWING:

13.5.3.2 — A fraction of the unbalanced moment
given by γfMu shall be considered to be transferred by
flexure within an effective slab width between lines that
are one and one-half slab or drop panel thickness
(1.5h) outside opposite faces of the column or capital,
where Mu is the factored moment to be transferred.



My specific question:

does the previous requirement applies only if the analysis is carried out using the code methods ( Direct Design Method or Equivalent Frame Method) ??
and if not , how can we calculate the flexure unbalanced moment required by aci318-08 code specially that the moments (m11&m22) by sap2000 are given in unit width???


thanks in advance
 
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I think that this requirement applies only to these methods, as you say.
Regarding the calculation of the unbalanced moment, it is very difficult to calculate that in SAP, as you will have to integrate the reported moments per length on a squre area 3h*3h around a column. Maybe you could assign very small bending modifiers to the slab areas OUTSIDE that region, and then get a mean value of the reported moments m11 and m22 inside this region and integrate them to have the unbalanced moment calculated.

Analysis and Design of arbitrary cross sections
Reinforcement design to all major codes
Moment Curvature analysis

 
That refers to punching shear checks, right? SAP2000 doesn't automatically perform punching shear checks for slab design. The SAFE program does do punching shear checks.
 
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