Simply Supported Plate - Bending in transverse direction 1

[SlenderBeam]

I have noticed when modelling a simply supported plate in an FE package, I am getting moment actions transverse to the main span. (I am just testing the software).

When the deformed shape is checked, the free edges deflect slightly more than at the midspan, which is consistent with some form of transverse action occurring.

Why is this occurring, considering the plate is spanning one-way?

I am using a finely meshed quad element mesh.

 

[hokie66]

If your plate is wider than the supports, then there would be transverse bending. I take it you have a plate of some width supported on a column at each end. If you make these columns knife edge supports all across the width, the deflection should be the same across the width.

 

[prex]

Look in the first site below, under Plates -> Simple bending -> Rectangular -> 2 supp.,2 free -> Unif.load, and you'll have the confirmation that there is indeed transverse bending with higher deflection at edge.
This is due to the Poisson ratio and the lateral contraction connected to it.

prex

http://www.xcalcs.com

: Online engineering calculations

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads

 

[SlenderBeam]

I was referring to a plate which is fully and continuously supported along the supports - no discrete supports such as columns. Essentially, a slab spanning between continuous walls.

I didn't factor in poisson's effect.

How relevant is this effect? I guarantee 90% of design engineers would never factor this in ("a slab spanning one way spans one way!!").

 

[prex]

If you play with that calculation sheet, you'll find that the maximum deflection for a beam is a few percent lower than the maximum at edges for the plate (and a few percent higher than the center one), and that the percentage difference in maximum stress is even lower.
I guess that anyone would consider these differences as negligible; more importantly the beam behavior gives a higher stress and is therefore on safe side.
But you raised a question and got the answer...

prex

http://www.xcalcs.com

: Online engineering calculations

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads