Slab supported by 4 simple supports

[Ezine]

Hi,
I have to modelize simple support in slab supported by 4 simple supports. But I need to modelize with square dimension (500 x 500 mm). Only the head of column. I did it but I find negative moemnt, How to vanish this moment. Because I did n't have fixed only simple support.
Thanks

 

[JoshPlumSE]

Is is simply supported continuously on all four edges? If so, then there will be some "curling" that happens towards the corners that causes negative moments in those regions. But, along the mid span of the edge you should not be seeing any negative bending.