STABILITY ANALYSIS OF SPACE TRUSSES

A space truss is unstable if the determinant of its incremental stiffness matrix is . A numerical method is presented that predicts unstable configurations (singular states) by computing the nonlinear load- displacement behavior of the truss prior to instability, detecting nearly singular configurations and then computing the singular state. The method is robust since the parameters which control the computation can be chosen over a wide range without impairing the convergence of the algorithm. The stability analysis of space trusses in this paper is derived by specialization of the nonlinear theory of elastic bodies. The initial value formulation of the governing equations is derived analytically and transformed to the algebraic form by the finite element method. The equations are solved by the constant arc increment method outside the singularity range and by a new method of limit analysis near a singular point.