Load transfer from concrete surface to downstand steel beams

[Artsiom]

I have a little difficulty in rfem.
I am trying to apply a load from the self-weight of a concrete slab (surface) to steel beams [primary and secondary].
I set the surface, edit it material and thickness. But after calculating from self-weight, I can see that the weight of the concrete surface is not taken into account correctly.
Found out that it is possible to impose load through the "From area loads to member loads via planes", but its not what I need. Also try to use different Member Type such as "Beam", "Rigid", "Rib...", "Compression" and "Result Beam" - so it doesnt help. Try to support surfece and enter eccentricity - doesnt help me too. How to transfer self-weight of a concrete slab to steel beams correctly. Thank you.

[Frank Faulstich]

Hello Artsiom. Did you check that check box?



Frank Faulstich

[Artsiom]

Yes sure.
I check it only in self-weight load. And I dont make any Load Combinations or Result Combinatiobs.

[Artsiom]

Seems to me like I tried everything.
I check all nodes, try all variation of eccentricity between beam and surface - - doesnt help.
in the pictures I sent the surface self-weight load and area load to member via planes are the same.
But I still dont have correct members internal forces in both of my constructions...

According to internal forces it looks like surface ''can see'' only columns and doesnt see downstand beams.

I cant find out my fault.

[Frank Faulstich]

I see, now I understand the problem.

Let me try to explain the difference between the right and left systems.

In the right-hand system, the load is transferred only through the beams to the columns.

In the left system it is different. There, both the beams and the slab transfer the load to the columns.

How much load the slab and how much load the beams take depends on the ratio of the stiffnesses. If you make the slab less stiff (e.g. thinner) and the beams more stiff, then the moment diagram will come closer and closer to the right system.

Frank Faulstich