One Way Diaphragm Slab

andrew_cross2 — Mon, 24 Oct 2022 10:32:21 GMT

Hi,

I have a steel frame building supporting Comflor slabs. When I model the Comflor as panels on contours that are one way spanning some of the load is still going to edge beams spanning in the same direction as the Comflor thus giving a lower load on the main support beam. As an alternative I looked at a one way cladding instead of a panel; this distributes the load correctly but the cladding wont behave as a diaphragm to distribute the lateral load to the braced end bays.

I have attached a simple model with three frames supporting one-way slabs. The slabs on the left are panels while the slabs on the right are cladding. All beams are pinned. Under a 10kN/m2 UDL (Load Case DL2) the internal beam should have a moment of 1250 kNm which is correct on the cladding option but the moments on the panel option are incorrect as some of the moment appears to be taken by the edge beams spanning in the same direction as the one way panel.

The cladding it therefore a better option, the issue arises when I apply a lateral load to the frames as the cladding does not appear to behave as a diaphragm and does not distribute the load back to the bracing. As you can see the middle frame of the cladding option on the right is deflecting excessively due to the middle frame being pinned and not getting lateral support from the diaphragm.

Have you any thoughts for the most appropriate slab type for a Comflor slab that will be used to distribute load one direction and also behave as a diaphragm to bring the lateral loads back to the cores.

Thanks,

Andrew

Re: One Way Diaphragm Slab

Krzysztof_Wasik — Mon, 24 Oct 2022 11:23:22 GMT

Hi @andrew_cross2

In model with meshed slab, loads forces to side beams due to model deformation and not heglected finite elements stiffness.

Use the following calculation model. Block RZ in supports to obtain expected results.

Re: One Way Diaphragm Slab

andrew_cross2 — Mon, 24 Oct 2022 13:38:37 GMT

Thanks for your help Krzysztof

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One Way Diaphragm Slab

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Re: One Way Diaphragm Slab