Analytic Method And Finite Element Analysis Of Steel Beams Out-of-plane Buckling

The stability is a prominent issue in the design of steel structures, the steel is a good buildingmaterial because of its advantages of high strength, light weight and good mechanicalproperties; The steel structure has the characteristics of small cross-sectional dimension,slender components and plate soft-thin compared to other materials; When there iscompression of the component such as compression, bending and shear, If technically can notbe handled properly, the structural instability phenomena may be led to; Due to the damagecaused by instability of the structure which often happen suddenly, and the structure will becollapsed, resulting in higher than the strength of their degree of danger, so the stabilityproblem is more important than strength problem. Although the study of stability problemwas always a problem which many experts to study in the past hundreds of years, and thegreat achievements were obtained, but the research is continuing because of the complexityof the stability problem itself. The methods of theory and numerical simulation were adoptedin this article:1. The theoretical analysis of steel beam elastic lateral-torsional buckling’s the stability,according to the existing expression of total potential energy and modal trial function, theenergy variational method was used to solve the lateral buckling problems of simplysupported H beam under uniform distributed load, at the same time the dimensionlessparameter was introduced, and the high-precision numerical solution of correspondingproblem was given based on the principle of minimum potential energy. The formula of thecritical buckling moment was proposed.2. The calculation formula in specification about the equivalent critical the momentfactors (EUMF) can be assessed through accurate numerical solution, and the differences ofits EUMF formula were introduced in detail. The problems in the existing theory were foundthrough the analysis of other specifications. In this paper, the theory applies to any boundaryconditions and loading conditions, and the more accurate EUMF formula was put forward fordesigners reference.3. The EUMF formulas of biaxially symmetric H beams and monosymmetric H beam inthe top flange, bottom flange and shear center of the load were proposed through thecomparative analysis, and the applicability of different formula and the difference of accuracywere found in several different load position, at the same time the data result and exact solutions proposed in this paper are compared to prove the validity of the formula.4. Through the analysis of finite element can be found, in the steel beams and connected nodeof steel columns, the stiffeners of structure were setted at the connection of internal andexternal flange turning point position which was a very feasible way. It can prevent the localvibration of structure and improve the integrity of the structure effectively; at the same timethe tie-bar setting of the model can greatly improve the critical load of rigid frame, so as toimprove the stability of the structure.