FEM Out-of-plane shear results

[ChiEngr]

Hello,

For a plate analysis, is there ever a scenario where you would sum the out-of-plane transverse shears Qx and Qy? I believe the answer to this question is "no", but I am confused at what occurs at the corner of the plate where the shear forces "intersect".

 

[SWComposites]

Yes. In many cases you should use the vector sum of the shear forces. Except if the thru thickness shear strength are different in the two directions, then it gets more complicated.

 

[ChiEngr]

Thank you; I have seen other threads on here where people have advocated for treating Qx and Qy independently and I have been getting confused accordingly. My out-of-plane shear capacity is the same for both bending directions so I believe the sum of Qx and Qy is certainly appropriate.

 

[SWComposites]

Its a vector sum, so sqrt(sum of squares)

 

[KootK]

What material are your designing your plate with and what software are you using?

 

[ChiEngr]

Im using RISA-3D, concrete is the material. Its a large box type structure I am analyzing (bio-retention structure).

SWComposites: I'm sorry, that is what I meant by summing the Qx and Qy (vectorially).

 

[KootK]

In concrete, one usually designs for each, orthogonal out of plane shear separately. That, in homage to the conventional practice of designing using orthogonal design strips. You could do some kind of vector combination but, then, you'd need to also develop a rigorous method for ensuring that equilibrium is satisfied everywhere as the orthogonal strip method does.

 

[rb1957]

that's what I'd've thought ... that the two out-of-plane forces are reacted by different faces within the slab. That said, the bending stresses created could (should?) be vector summed), or possibly principal stresses.

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.