Reliability background of the Eurocodes

EN 1990 defines structural reliability as the ability of a structure to fulfil the specified requirements during the service life for which it has been designed; the notion covers safety, serviceability and durability. According to this definition, reliability is the concern of all parts of the whole suite of Eurocodes. In a more narrow sense of the word, reliability refers to the way uncertainties are dealt with in design and assessment by the use of partial factors or more advanced probabilistic methods. 

This JRC Technical Report introduces relevant basic notions such as uncertainty, probability, risk, member and system failure, time dependency, effects of deterioration and inspection; it focuses on the basic reliability requirements in EN 1990 related to the persistent as well as the accidental and seismic design situations, paying special attention to the new materials included in the second generation of the Eurocodes (glass, fibre reinforced polymers and membrane structures). Attention is also given to the special problems that may arise in assessment of existing structures - observations, the various decision options and of typical reliability issues (updating, reduced targets). The report also describes explicit risk and full probability methods, and gives background for code calibrations. Finally, the annexes propose an overview of probabilistic models for actions, material properties and model uncertainties, as a reflection of the present state of knowledge in the various Eurocode subcommittees, working groups and horizontal groups, and a number of example applications.