An elastic 1^st order 3D beam finite element is used and it has twelve degrees of freedom as shown in Figure Below. These are the three rotations and three translations at each of the beam element. Axial, bending and torsional deformations are considered in the stiffness formulations. In addition, shear deformations are also integrated into the formulation considering equivalent shear area concept (McGuire, W., Gallagher, R.H., and Ziemian, R.D., 2000). The effects of rigid end zones are accounted for in the formulation and transformation of beam elements.

The beam element can model only prismatic sections. Some beam members may have more than two nodes. This is due to the fact that beam types such as cantilevers, beams in chevron and eccentric braces or beams with columns or girders framing to a point along their span are in fact divided into beam finite elements internally by the program. However, as far as member force outputs and summaries are concerned, these beams will still be treated as single beams.