How does analysis of space frames differ from plane frames?

Space frame analysis considers six degrees of freedom per node (3 translations, 3 rotations) versus three for plane frames. The stiffness matrix is 12x12 per element including torsion, biaxial bending, and axial effects. Transformation matrices convert local to global coordinates using direction cosines in 3D. Additional considerations include warping torsion for open sections, biaxial moment interaction, and 3D stability. Matrix methods and finite element analysis are essential due to complexity.