How to include the self weight loads of frame.

[Eigen]

Hi community members,

My question is not directly related with OpenSEES but with the general FEM theory itself. Suppose that arbitrarily oriented frame element exist in space which has 12x12 stiffness and mass matrices, how am I supposed to include the self weight of that element into the general solution of linear algebraic equations K*U = F.

It's obvious that self weight matrix should be something like 12x1 matrix and should be added to the RHS of equation as long it is a scalar matrix. But the glitch is that self weight loading should be element oriented, that is, if element is inclined in spatial coordinates then it's supposed to induce the V shear force (q*l/2) and bending moment (q*l^2/12), whereas if element is vertical, then it shouldn't induce bending moment nor shear force simply it should be as axial load and be applied at the ends of frame element. I'm bit puzzled here whether my resonig is correct or not, or should I follow completely different mechanism to include the self weight loads?

Your comments will be appreciagted,