Global sensitivity analysis of lateral-torsional buckling resistance based on finite element simulations

The article examines a hot-rolled steel I-beam subjected to lateral-torsional buckling (LTB) due to bending moment. The paper describes a non-linear finite element (FE) model and numerical approximation and simulation methods used for the global sensitivity analysis of the static resistance of a beam under major axis bending. The presented geometrically and materially non-linear FE model based on solid elements models in detail the LTB and the effects of initial imperfections on the ultimate limit state of a steel beam. Simulation runs of random imperfections are generated using the Latin Hypercube Sampling (LHS) method. Polynomial approximation of the model output helped minimise the number of runs of the non-linear finite element model. The approximation polynomial then facilitated the evaluation of sensitivity indices using a high number of simulation runs. The relationships between the slenderness and the first and second-order sensitivity indices are plotted in graphs. The graphs show the results of global sensitivity analyses of stochastic effects of initial imperfections and residual stress on the resistance of the investigated steel beam.