Analysis On Overall Stability Of Monosymmetrical Two-span Continuous Steel I-beams

Stability is one of the most crucial indicators of steel structure and steel components capacity, which we study for has theoretical and engineering application value. So far, the study of overall stability of single span steel under various working conditions is comparatively complete, and the comparatively accurate calculation formula of integral stability has been worked out.Recently, there is no perfect theory method to solve the buckling problem of continuous steel beam, because of the negative bending moment which exist intermediate bearings. Although the continuous steel beam has been experimented by foreign scholars, they just studied for the steel beam with axis symmetric section. The bearing capacity calculation method of continuous steel beam has been proposed by domestic scholars, but it also just suit for the steel beam with axis symmetric section. However, the research results of integral stability of the steel beam with monosymmetry section are rare, and the height of load point has not been considered and theoretical has not been deduced.The numerical model of two-span continuous steel beam with monosymmetry shape and cross section has firstly been made with ANSYS in this paper. And the eigenvalue buckling analysis of the beam on overall stability has been done, and obtained the critical load and the buckling mode relative to the first eigenvalue in different load conditions, such as different load form (concentrated load and distributed load), load point (on top flange and bottom flange), section dimension (different width of strengthened flange and height of web),span ratio and so on. On that basis, the influence of different load conditions on the buckling load was discussed. The buckling of continuous beam under different proportional loading was studied, and got the correlation of the dimensionless critical load on two spans.On the basis of predecessors theoretical research,the analytical critical moment of the single span simply-supported beam deduced. And then the analytical critical load of monosymmetry two-span continuous steel I-beam was deduced under concentrated load and distributed load respectively. Using energy variational principle. The analytic solutions were relatively close to the numerical results, and can consider load point.Lastly, the instability forms of the steel beam belong to limit point buckling in practical engineering. It is nonlinearly analyzed that the overall stability of the continuous beams with initial geometric imperfection. The influence of different section form, main span width and span ratio on the limit load of beam under concentrated load.