Bending stiffness and parallel axis theorem

[rhig2000]

I've got VABS output "*.k" files that seems to defy parallel axis theorem. The Classical Stiffness Matrix and The Classical Stiffness Matrix at Shear Center are essentially the same out to 8 or 9 sigfigs, but The Shear Center of the Cross Section in the User Coordinate System is not zero. Applying parallel axis theorem by taking square of (The Shear Center of the Cross Section in the User Coordinate System) times the axial stiffness term in (The Classical Stiffness Matrix at Shear Center) gives a value that represents a much more significant change bending stiffness. How is this possible?

[wenbinyu-PU]

When there are couplings, you cannot simply use parallel axis theorem. You need to use the formulas in my paper (inertial and elastic properties of composite beams) to compute properties with a parallel shift.