Two-way slab - reactions and shear results not equal

[Anonymous]

Hello!

I am having some trouble with two-way slab design. When I compare shear value at support and the reaction value at the same place then there is a significant difference.

I created a simple example of a two way slab and found that the outcome is the same - reaction value does not equal the shear value.

In my original and more complex design the vales differ even more (reaction value is 49 kN/m and shear value at the same place is about 30 kN/m).

Can someone please explain this difference?

Your help is very much appreciated,

Siim Toots

[Artur.Kosakowski]

Could you attach the rtd file?

[Anonymous]

I´ve shared a dropbox link of the file:

https://www.dropbox.com/sh/ryonf0nktwy07lv/wEbR7zdXUh

Siim Toots

[Artur.Kosakowski · Accepted solution]

The reason for the difference is the shape function of surface elements used in Robot which is not accurate for out of the plane shear. If you make denser mesh (smaller elements) then both values come closer but the one displayed for reactions is the accurate one.

If you find your post answered press the Accept as Solution button please. This will help other users to find solutions much faster. Thank you.

[Anonymous]

Thank you for the quick responce!

I´ll keep in mind that the reaction value is the more accurate one.