Abaqus Kinematic Coupling

[aliasgere]

I have a 30 m long cylinder made of 3-D shell elements. I have constructed a reference point at the centre of the cylinder at the top and kinematically constrained the surface nodes to it. I have left all degrees of freedom unchecked. Have applied a displacement boundary condition at the reference point of 1.2 m in U1 with U2, U3, UR1, UR2 and UR3 being zero. On processing the static analysis results I find that the shear force generated does not correlate to the bending moment at the base of the cylinder, that is the bending moment is not 30 times the shear force. The bending moment is higher by a magnitude of 5.3 MNm (Shear of 2.04 MN and Bending Moment of 66.5 MNm instead of the expected value of 61.2 MNm). I tried to restrict the degree of freedom in the U1 direction but it results in warnings of zero pivot point and negative eigenvalues. Can someone please advise me on what I am doing incorrectly at the moment?