For dynamic analysis of structure, the calculation of eigenvalues and eigenvectors is
necessary. When the structural models are symmetric, such calculation can be simplified using
some of the concepts of graph theory. In this paper, two methods are presented for eigensolution of
space Truss. The first method uses a graph model and employs a decomposition and healing
process for factorization of the graph model and calculating the eigenvalues of graph. The second
approach uses the canonical forms for the construction of submatrices, from which, the
eigenvalues can be obtained. Both methods lead to identical results.