How is the cooperation between a plate and beams?

There are two ways of cooperation to distinct.

Either the plate is loose on the beams, which also means that they can shift laterally along each other (model A).
Either the plate is connected to the beams, which also means that it can no longer slide laterally along each other (model B).

The import of both calculation models in SCIA Engineer is as follows:

Model A is obtained by not giving an eccentricity to the beams.
Model B is obtained by giving an eccentricity to the beams

The composite stiffness for both models will be as follows:
The composite stiffness for model A is (EI)plate +(EI)beam (so just a linear summation).
The composite stiffness for model B is (EI)whole (with plate and beam are considered as an cooperating entity)

This results in the following results in case of a loaded plate with beams in bending
Model A: the beams and the plate will only take a bending moment and on this dimensioned.
Model B: the beams will also (in addition to a bending moment) have a resultant tensile force and the plate may also take a resulting pressure force . They will be dimensioned on this.

Note: In model B can also be made use of the option 'rib' in which a part (defined by the effective width) of the forces in the plate are included in the rib.

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