DESIGN OF STEEL STRUCTURES FOR DIFFERENTIATED RELIABILITY LEVELS

摘要

Principles and rules given in the standard EN 1990 "Basis for structural design" are interpreted and supplemented for steel structures. The distribution parameters of basic variables are identified by means of calibration rules disclosed in the EN 1990. Differentiated reliability classes and working life categories are analysed for the log-normal variables. Optional reliability measures are analysed: the global safety factor γ, the global safety index β and the hazard ratio κ. Three methods of verification of structural safety are available: the partial factor design amendable thanks to β-index checking, the conventional β-theory and a new hybrid κ-theory. Both requirements: β=const and κ_R = κ_E for resistance R and action effect E will be satisfied when the hybrid κ-mefhod is applied. The new κ-method emanates from the optimum safety theory where a constant hazard ratio κ has been given for each reliability class. The κ-theory delimits responsibility fields of the relevant individuals.