Rohith Patchigolla
Ansys Employee

Hello Maurya, 

Beam elements have 6 degrees of freedom (three translations, three rotations). 

Since you have not constrained the rotation, especially, rotation about beam axis, you get this rotation pivot error. 

Please also add the boundary condition, "fixed rotation" on one of the vertices in order to constrain this rotation (about beam axis). 

Have a look at documentation here for further reference.

Best regards,