Rolled H Section Steel Bending Structures Stability Elastic-plastic Finite Element Analysis

As a new type economical section, rolled H section steel is a real environmental steel for its pollution-free, reproducible ability, safety, efficiency, energy conservation and good seismic capability, which was applied in civil engineering, railway, oil, mechanism, shipbuilding and ports etc.. So, H section steel developed quickly from its born in 1998 in China. But it is too conservative of the stability design formula for solid-web biaxial bending beam-columns in the Code for design of steel structures in China at present for the members of rolled H section steel biaxial bending beam-columns. Because the formula is only the linear combination of axial compressive and unidirectional bend members, it affects the application of H section steel greatly.For the conditions above, using software, ANSYS, to simulate the process from loading to failure of H section steel solid-web biaxial bending beam-columns members, the stability was analyzed, and a comparison of the stability bearing capability to the formula in Code for design of steel structures was made, concentrating on the contents followed.(1) Make a simply comparison and analysis between Code for design of steel structures of the U.S.A, Germany and Japan about the formulas of BC member stability design. Whether the biaxial bending beam-columns member design formula in the Code in China is suitable or not needs a study further.(2)Using analysis software ANSYS, built the models of H section biaxial bending beam-columns members and simulated its bearing progress by considering initial geometric imperfection and residual stress.The value of the simulation was found being closed to the experiments value nearly, which showed that the models in this paper were credible.(3)A parametric analysis for the stability bearings of H section biaxial bending beam-columns members was made by the data counted by ANSYS, mainly about the affection to the stability by slenderness ratio, initial geometric imperfection and residual stress under different loading. It shows that the slenderness ratio is larger, the stability bearing capability is lower, and the relative eccentricity ratio of loading is lower, the affection to the stability of members by the slenderness ratio and is more obvious. As the increase of the slenderness ratio, the affection by geometric imperfection becomes larger and larger. What's more, keeping the slenderness ratio between 50～100, the affection by residual stress to lower slenderness ratio is very small, and as the increase of the ratio, the affection increases, too.(4)Make a comparison between the analysis data and the value counted by the formula in Code for design of steel structures. Provide a conservative degree of the Code by statistics. At last, some suggestions were given on formula improving.