Overall Stability Research Of Mono-symmetric Steel I-beams Under Combined Bending And Torsion

Steel owns high strength, light weight, good mechanical properties. Usually steelstructural ultimate load bearing capacity depends on the stable condition. In theopening section member development process, scholars have done a lot of researchesand experiments, but most are aimed at simple stress condition, there are few studieson the I-shaped cross-section beams in bending, and torsional stress situation.“Codefor design of steel structures”(GB50017-2003) of china also doesn,t give designformula. This text did some research in order to get a simple and clear formula.Using the traditional theory of stability, this thesis analysised monosymmetricI-beam subjected to bending-torsion complex role; got equilibrium differentialequation and the total potential energy equation; got a bending bearing capacityformula in two kinds of typical eccentric load cases, which contain an unknownconstant coefficient, by using Rayleigh-Ritz method. However, from this formula, it isvery difficult to get analytic solution. Then, drawing lessons from the load deviationshear heart but the parallel with the main shaft bending member integral stabilitycalculation formula in “cold-formed steel standard”(GB50018-2002) of china, thisthesis put forward a bending coefficient, to consider the influence of warping stresscaused by double torque on steel beam integral stability bearing capacity.Using finite element analysis software ANSYS, this thesis did nonlinear bucklinganalysis of monosymmetric I-beam in the action of combined bending and torsion, ontwo kinds of typical eccentric loads. According to the calculation results, analyzed theinfluence of the eccentric distance e, spanl, the compression flange widthb1on theintegral stability capacity and bending coefficientk t, analyzed the relationshipbetween limit bending moment and torque. From all of these, the article obtained thetorsion coefficient formula in two cases above-mentioned through regression analysisof finite element results by using the statistical software SPSS. Then, got the overallstability ultimate bearing capacity formula of monosymmetric I-beam in the action ofcombined bending and torsion.