Dear All,

I am trying to simulate mechanical behaviour of a concrete unit cell for uniaxial compression laoding. I have apllied periodic bounadary conditions on both lateral edges using linear equation option available in ABAQUS where as on top and bottom edges load is apllied. Deformed structure shows there is no lateral deformation and unit cell behaves as if it is confined laterally on both sides. I am confused about my boundary conditions whether they are correct or not. 

 Equation used to aplly periodic bounadary condition are