NONLINEAR ANALYSIS OF SPATIAL FRAMES CONSISTING OF MEMBERS WITH CLOSED CROSS-SECTIONS

Abstract

A general matrix analysis for elasto-plastic spatial large deflections of thin-walled frames or arches is developed in this paper. A tangent stiffness matrix for an elasto-plastic member with closed cross-section and an initial stress matrix expressed in terms of internal forces are written with respect to so-called incremental moving coordinate. By the proposed method, the ultimate strength including buckling strength in bifurcation problems for arbitrary spatial frames or arches subjected to non-proportional loading can be analyzed under consideration of growth of plastic zones and initial imperfections such as residual stresses due to welding. Numerical examples are shown for the several problems which are presently available. Through the comparison with other authors' results, the accuracy and the efficiency of this method may be recognized.