When to use the FLOOR DIAPHRAGM Command?
please see technical reference 5.28.2 Floor Diaphragm
The rigid diaphragm is a structural system which has infinite in-plane stiffness used to transfer lateral loads to shear walls or frames primarily through infinite in-plane stiffness.
Usually, the floor system or roof system in a RCC building, or the deck of a bridge follows the diaphragm action in a structure .
Answer Verified By: SSV Consulting Engineers
Infill plates provides very large stiffness against the lateral loads.
A floor with shear walls or large columns exhibits Rigid Diaphragm action as shown below.
As per IS:1893(Part-I)-2002 code (Clause-7.7.2.2 Note: 2 ), Reinforced Concrete monolithic slab-beam floors or those consisting of prefabricated/precast elements with topping reinforced screed can be taken a rigid diaphragm. In STAAD.Pro, you can provide Rigid Diaphram specification.
Dear sir dsanju,
do you any illustration about how can affect the opening slab in floor diaphragm. thus the stiffness reduces in how many percent, how can i apply this reduced percentage to staad model?
thank you sir!
rekcah
As far as the modelling of rigid diaphragm in STAAD.Pro is concerned, you can model the whole floor as a rigid diaphragm. The effect of cut out has to be judged before modelling a rigid diaphragm. In a floor, if there are very large cut outs, you cannot use rigid diaphragm commands for a floor. The program cannot compute the effect of openings in diaphragm. But, in the model, you can exclude the nodes which does not come under in-plane rigidity action just like the nodes where there is openings.