Abstract
The elastic load-carrying capacity and buckling trajectory of steel columns under compression with open and hollow cross-sections, whose axis is curved by spatial random fields, are studied in the article. As a result of the spatial curvature of the axis the cross-sections are subjected to compression, bending and torsion from the onset of loading. Numerical simulations are performed using the geometrically non-linear model created using the ANSYS software package. Each simulation run has input random realizations of yield strength and the random field generated using the Latin Hypercube Sampling method. In the plane perpendicular to a perfectly straight column axis, the random observations of deformation trajectories of a node in the middle of the column height are studied. The increasing compression load moves the node along the curve path (open sections) or along the linear path (hollow sections). Large discrepancies in the deformation trajectories of open sections (curvilinear paths) and hollow sections (linear paths) were observed from the comparison of simulation runs. The average and design load-carrying capacities of compressed columns with open cross-sections are lower in comparison to columns with hollow cross-sections due to the lower efficiency of open cross-sections in torsion.
Highlights
The rectangular hollow structural steel section was developed by Stewarts and Lloyds (Wardenier 2002) in 1952
Five deflection curves, which show the growth of the deformation in the process of loading the column, emanate from the point of the initial imperfection
One approach is the application of the Hermite pdf (Kala 2016a), which effectively takes into account small values of skewness and kurtosis and LCC of a steel column under compression with spatial axial curvature may be significantly influenced by torsion, which is transferred more effectively in hollow cross-sections than in open cross-sections
Summary
The rectangular hollow structural steel section was developed by Stewarts and Lloyds (Wardenier 2002) in 1952. The effect of random spatial imperfections on the structural performance of a column under compression, which in the case of open cross-sections is more or less reduced due to the effect of torsion, is analysed in the present. The load-carrying capacity of columns under compression with intermediate slenderness (non-dimensional slenderness around 0.9) is very sensitive to the initial geometric imperfection of the initial out-of-straightness of the column This was proven by sensitivity analyses of planar buckling (Kala 2009, 2016b). Common models are based on an approximation of the initial out-ofstraightness using a half-wave sinusoidal function for compressed columns (Kala 2009) or a scaling of the first eigenvalue buckling mode shape for frame structures (Kala 2016b) An advantage of these models is that the curvature of the axis of the loaded column is affine to the initial out-of-straightness. Kala et al Random fields of initial out of straightness leading to column buckling
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