Safety design of steel beams with time-dependent stability

The expediency of using probability-based approaches in the analysis of rolled and welded steel beams subjected to lateral torsional buckling is discussed. Buckling resisting moments and their mechanical uncertainties for rolled and equivalent welded flanged steel sections as particular members are analyzed. Time-dependent statistics of resisting and bending moments of steel beams is considered and their essential features are determined. Instantaneous and time-dependent survival probabilities of deteriorating and non-deteriorating steel beams in consecutive and cascade levels are also considered. Probabilistic design of steel beams with time-dependent stability is based on the generalized reliability index concept. Differences in design computation results of rolled and welded steel beams under lateral torsional buckling obtained by using the consecutive and cascade approaches are illustrated by a numerical example.