ABSTRACT
There are several general assumptions made in the two-dimensional analysis of truss structures. Joints are assumed to be pinned connections, which is one of the basic assumptions made in the analysis of planar frames. It is also valid for three-dimensional truss systems. A beam element developed earlier, will be used here with a small modification. Assume that the beam element has spherical hinges at both ends. The consequence of this assumption is that the beam can freely rotate about any axes. Thus, the end rotations will be zero. For the beam element in three-dimensional analysis, the number of degrees-of-freedom is 12. Each end will have three translations and three rotations. But, in this case, the beam element is restrained with spherical hinges. Thus, the beam element will have three displacement components at each end of the member. The truss member can resist only axial deformation and axial forces, which makes the stiffness matrix of order 6 × 6.
