Safety assessment across modes driven by plasticity, stability and fracture

The European design rules for steel structures in EN1993 cover various failure modes that were developed using different methodologies in terms of accuracy and safety. Consequently, the safety level of these design rules is not homogeneous throughout their own field of application, as well as in comparison between different rules. Safety is regulated by partial factors for the various loads and resistances, respectively. EN 1990 - Annex D offers a procedure for the reliability assessment of resistance functions, based on a semi-probabilistic approach. However, its application is not straightforward in many cases concerning steel design rules and several additional assumptions are
necessary to ensure that a target probability failure is achieved. Moreover, the design rules are calibrated using certain variability values for the relevant parameters, such as material properties, geometric properties and imperfections. It is therefore required to appropriately characterize the
statistical distributions of these basic variables in order to comply with the safety assessment procedure. The present research work, carried out in the context of the European research project SAFEBRICTILE, had as a main objective the harmonization of the reliability level of design rules for steel structures covering modes driven by ductility, stability and fracture.
This paper gives an overview of the reliability assessment of the Eurocode design rules carried out within the project for the studied failure modes; presents the adjustments in these design rules proposed whenever it was necessary; it also transmits the project recommendation on the statistical distributions of the relevant basic variables for steel structures, summarized in the "European database of steel properties" that was also developed within the project framework.