Comparison of theories for stability of truss structures. Part 1: Computation of critical load

Two largely different theories, i.e. the geometric nonlinear eigenvalue theory and the geometric nonlinear critical point theory, of the stability analysis for truss structures are reviewed by the authors. In this paper, it is pointed out through numerical examples as well as thoroughly theoretical investigations that the eigenvalue theory leads to mistakenly very large solutions of critical load. Though it is correct in theory, the applicability of the critical point theory was inadequately extended to all shallow trusses. To overcome the shortcomings of the stability theories, the authors present two theories of their own with two new approaches for geometric nonlinear analysis and for finding the critical loads for shallow truss structures. Several conclusions are drawn, including: (1) the geometric nonlinear eigenvalue theory is mistaken and (2) the capabilities of various theories are discussed.