Abstract:The behaviour of buildings and other constructions under critical events is widely recognised to be an important part of structural design. Still, the problem is often addressed in a qualitative way by many current codes and regulations and designers cannot refer to specific methodologies for the assessment or the achievement of the structural integrity of constructions. The term structural integrity is intended here as the ability of a construction to sustain extreme actions, which directly affect the structural system, without developing a major collapse.In this paper, two main methods are outlined for the achievement of structural integrity: a bottom-up approach, where the effects of element failures are investigated, disregarding the modelling of the specific action that could have triggered them; and a top-down approach, where the response of the structure to a particular accidental action is sought.The use of the first approach is proposed for assessing, by means of a set of non-linear static analyses, the robustness of structural systems, intended as the ability of a structure to sustain local failures (Starossek, 2009) without developing a major collapse.