A RELIABLE METHOD FOR THE STABILITY ANALYSIS OF STRUCTURES

A space truss is in an unstable configuration if it can displace incrementally without an incremental change in its loading and its supports. The load path which follows after an unstable configuration can be unique (snap-through), or there can be several possible load paths (bifurcation). This paper presents a method to detect nearly unstable configurations of a truss, a method to determine the loading, displacements and reactions of the unstable configuration and a method to traverse the load path which follows after the unstable configuration. The detection of structural configurations with singular tangent stiffness matrix is essential because they can be unstable. The secondary paths, especially in unstable buckling, can play the most important role in the loss of stability and collapse of the structure. A new method for reliable detection and accurate computation of singular points on load paths is presented and applied to a space truss subjected to symmetric and asymmetric snow loads. Keywords: space structure, stability, snap-through, bifurcation, nonlinear behaviour.