I have a square concrete slab supporting a concentrated load at the center of the square. I am assuming that the slab is simply supported along four sides. I have choosen "Terms in x direction (m) = 2" and "Terms in y direction (n) = 2" which are the default values. However, if I change the number of terms in the x and y direction the stress in the slab increases. Is there a formula for determing the number of x and y terms to select? To be honest I am not sure how many terms I should select. Right now I am using the default value of 2 terms for the x and y direction. Also, I have noticed that no matter how big I make the square the stress remains the same as long as the load remains the same and the location is located at the center of the simply supported square slab section. I would think that the stress would increase with an increase in the size of the simply supported square slab plate. Why is the stress in the slab independent of the size of the square slab section choosen?