An orthogonal self-stress matrix for efficient analysis of cyclically symmetric space truss structures via force method

The analysis of structures is normally carried out through displacement method while the force method is considered as an alternative approach for this purpose and used on occasion. The generation of compatibility conditions (the transpose of self-stress matrix) is one of the major and complicated parts of any structural analysis using force method. In this paper, an efficient method is proposed for producing orthogonal self-stress matrix related to space truss structures with cyclic symmetry. This is actually performed by eigen-decomposition of a special matrix having the same null basis as in equilibrium matrix. Then, the advantages of the obtained compatibility conditions are demonstrated with respect to different formulations such as standard force method, eigen force method and integrated force method. Finally, the efficiency of the presented method is comprehensively compared with three well-known numerical methods and tested on a set of practical examples. The results indicate clearly the significant superiority of the proposed approach in terms of both computational time and the accuracy of the results. (C) 2010 Elsevier Ltd. All rights reserved.