| Summary: | Subject: investigation of local stability of cellular beams with circular openings, which are widely used in civil engineering. The main problem in this field is the absence of analytical relations for evaluation of critical load of perforated beams. Research objectives: show effectiveness of studying the local stability of perforated beams on small-scale models made of tin; obtain a relationship for recalculating the results of the model tests onto the full-scale structure; check the reliability of numerical calculations of the critical load by the finite element method (FEM). Materials and methods: tests were performed on the tin models of small beams of 32 cm length and on the full-scale steel structure of 4 m length. As for research methods, we used similarity theory, experiments and numerical modeling of stability by the finite element method with help of the software package ANSYS. Results: it was shown that the tests of small-scale models give reliable results for estimation of critical load for full-scale structures that experience local buckling in elastic stage of loading. Obtained relationship for recalculation of critical load of the model onto the full-scale structure does not require strict observance of similarity with respect to Poisson’s ratio and size of flanges because their influence on the critical load is small. Comparison of data obtained from the model tests with the results of structure analysis by the finite element method showed that FEM calculations give reliable results for prediction of stability, and the testing of models is needed only for examining the effect of initial imperfections in the form of small buckles, inaccuracy of manufacture or variation in thicknesses, or the influence of residual stresses due to welding. Discrepancy between the results of tests of the models and numerical calculations of the critical load by FEM does not exceed 6 %. Conclusions: the relationship obtained on the basis of similarity theory allows us to efficiently recalculate the critical load of the model onto the full-scale structure, for which only similarity of geometry of the perforated web from the side view, identity of boundary conditions and the loading type should be respected. Critical load of the cellular beam is proportional to the cube of the web thickness.
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