Stability Behavior Of Steel Elliptical Hollow Sections Under Axial Compression

Elliptical hollow sections (EHS) have attracted significant attention from engineers and architects owing to their complementary qualities of aesthetic appearance and structural efficiency. But there is currently a lack of design guidance for elliptical cylindrical tubes inhibiting more widespread use in construction. The present paper is focused on the stability behavior of steel elliptical hollow sections by laboratory test and numerical analysis. A research was carried out mainly as following:(1)The local and global buckling behavior of elliptical cylindrical tubes are researched by the eigenvalue buckling analysis. In the local buckling research, the present paper analyzes how the aspect ratio and thickness have an effect on the local buckling model shape, then the critical stress of local buckling formulas are analyzed and compared with each other. And in the global buckling research, based on a large amount of numerical analysis results, the formulas of gyration radius and the critical stress of global buckling are fitted.(2)Laboratory tests of short elliptical cylindrical shell is implemented to study the effect of aspect ratio a/b on the stability behavior of EHS. Geometric and material nonlinear finite element models were developed by ABAQUS, while based on the multimodal buckling characteristics of elliptical cylindrical shells under the axial compression, the improved consistent imperfect buckling analysis method was used in this paper. Regarding the first several buckling modes separately as the initial geometrical imperfection, nonlinear stability analysis of elliptical cylindrical shells were carried out by the finite element method and then the least favorable geometrical imperfection distribution was found, finally the numerical models were validated against the generated test data.(3)How the aspect ratio a/b, the equivalent radius to thickness ratio and the geometrical imperfection effect the elliptical short column’s stability behavior are studied by parameter analysis. Based on the studying of the specification of steel structure at home and abroad, the classification of circular cross sections and strength and stability of cylindrical shell specification can be used for EHS design by the equivalent diameter method.(4)For long column under axial compression, based on the stability capacity calculation formula of Structural Euro codes, the stability capacity calculation formula of circular axial compression columns can be converted into the stability capacity calculation formula of elliptical axial compression columns by using the gyration radius formula of elliptical hollow sections. Then the design equation is shown to be accurate and reliable by comparing the formula results with FEM results.