Autodesk Robot Structural Analysis

[#1]

Hi,

    I am currently designing a steel structure with deck slabs. pinned - pinned releases have been applied to the joists but they seem to be carrying negative moment. In addition, the moment diagram looks irregular and I was thinking maybe it is because the stiffness of the girder is much greater than that of the joist. Why is this happening. Please refer to the attached image.

[#2]

If you do not mind please attach view of whole structure indicating the element of your interest or send us model.

PLates, Diaphragms there?

[#3]

The attached image shows the joists supported on the girder which is supported on two columns at its ends. The panel on top of them is a shell element of 10 cm thickness. I usually study the joists using a shell element and use cladding to study the main girders. Anywyas, I still don't understand the reason for the negative moments in the joists.

[#4]

So ...

Sharp diagram - it depends on mesh - then more refined mesh the smoother diagrams

Negative moments - I guess joists without releases or... check Private Message

[#5]

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AJA14 wrote:

. Anywyas, I still don't understand the reason for the negative moments in the joists.

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I assume the beams are released but the slab is bi-directional and not released along the edges. See the difference.