Finite element method has been used in multibody dynamic analysis for flexible bodies. A conventional finite element method has employed displacement vectors and rotations as nodal variables. Absolute nodal coordinate method, proposed by A. A. Shabana et al., has employed position vectors and spatial derivatives of nodal displacements as nodal variables. Since the spatial derivatives are expressed in terms of an angle between beam axis and reference frames, they are dependent variables. The dependency of spatial derivatives has not been fully discussed in the existing papers. The effects of dependency on numerical results are discussed in this paper. An expression for internal forces has been an important issue in the absolute nodal coordinate method. An accurate expression for axial forces is proposed in this paper. The number of degrees of freedom remain unchanged in this formulation. Numerical examples show the effectiveness of the proposed formulation.