Cracks in adjacent elements

I am analysing a simply supported beam with a point load at mid span using non linear finite element method. The element is one dimensional having shear deformation. on applying monotonically increasing load not the middle element but the adjacent eleemnts are cracked as well. I am using a well documented beam  and using the same material properties for concrete, steel and bond as documented.

the material models for concrete is elastic, for steel is elato plastic and for bond is Trilinear. 

could anyone highlight the possible error?