The Research On Overall Stability Behavior Of Biaxial Symmetry I-section Overhanging Beams

The theoretical and experimental data about the research on overall stability of the overhanging beams is obviously insufficient at home and abroad. All the specifications for structural steel also did not give a standard calculation method and recommendations, which affect the practical application of cantilever beams. Thus, the paper has derived the formula of critical moment and overall stability coefficient of the biaxial symmetry overhanging beams, by using Galerkin method, verified the results by ANSYS simulation, and analyzed comprehensively the impact of a variety of factors on the overall stability behavior. The main research contents include:1.Through the theoretical deduction of the overall stability of biaxial symmetry overhanging beams, educed the general formulas of critical load and moment with the lateral load acting on the shear center of the section, and given the coefficient values of the formulas to four different forms of loads, also derived corresponding range of application for the formulas. On that basis, deduced the proposed formula of overall stability coefficient ?b and the equivalent moment coefficientβb .2.To the single-span of the overhanging beams, by contrasting to ANSYS finite element analysis results, the formula value of critical moment derived by the author and the result according to simply supported beam tally with the ANSYS results, when the maximum moment section exists in the single-span. It shows that the ANSYS finite element shell model can reflect the instability of thin-walled steel beam, and calculate the critical moment of overhanging beams by simplifying as simply supported beam. However, the error of formulas derived in this paper, which is safer, is slightly less than that of the results of simplified calculation. To the extended-span of the overhanging beams, ANSYS finite element simulation results close to the formula of the paper, but deferent with the calculated results of cantilever in the same conditions. This indicates that the critical moment formula of extended-span can better reflect the overall stability of the extended section of overhanging beams and can not directly choose cantilever to research in relevant analysis.3. Using the results of numerical calculation and theoretical derivation, comprehensively analyzed the influence of overhanging length ratio g, load forms, height of load imposed, load scale factorγ, torsional stiffness coefficient K and the span of simply-span to the overall stability behavior of overhanging beam.