Abstrakt
In the present paper, an analysis uf lower bound estimation of the load carrying capacity of structures with intermediate stiffeners is undertaken. Thin-walled structures with intermediate stiffeners in the elastic range, being under axial compression and a bending moment, are examined on the basis of the Byskov and Hutchinson's method [4] and the co-operation between all the walls of the considered structures is shown. The structures are assumed to be simply supported at the ends. The study is based on the numerical method 01· the transition matrix using Godunov's orthogonalization [2]. Instead of the finite strip method, the exact transition matrix method is used in this case. In the presented method for lower bound estimation uf the load carrying capacity of structures, it is postulated that the reduced local critical load should be determined taking into account the global pre-critical bending within the first order non-linear approximation to the theory of the interactive buckling of the structure. The results are compared to those obtained from the design code and the data reported by other authors. The present paper is a continuation of papers [9], [ 11], [ 19], where the interactive buckling of thin-walled beam-columns with central intermediate stiffeners in the first and the second order approximation was considered. The most important advantage of this method is that it enables us to describe a complete range of behaviour ot· thin-walled structures from all global (flexural. flexural-torsional, lateral, distortional and their combinations) to local stability. In the solution obtained, the effects of interaction of modes, the transformation of buckling modes with an increase in load, the shear lag phenomenon and also the effect of cross-sectional distortions arc included.
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