Robustness evaluation and design of steel and steel‐concrete buildings according to current standards and recent research results

In terms of mitigation of progressive collapse, structural robustness is a specific safety consideration, which requires particular attention from all professionals involved in the construction industry, including architects, designers and constructors. The design of buildings considering robustness has evolved considerably over the last two decades, during which different research activities have been developed, leading to new methods and design processes. These practice‐oriented methods and concepts have been recently summarized in a design manual prepared in the framework of the FAILNOMORE RFCS project (grant No 899371), providing to the designer a general design strategy for robustness based on these methods as well as easy to follow worked examples. The proposed design strategy allows to ensure the global stability and the mitigation of progressive collapse of steel and composite structures when subjected to exceptional events, such as vehicle impact, explosion, cascading events involving localized fire or events which are not explicitly specified in the typical structural design process. In this paper, the application of these recommendations is demonstrated by means of realistic worked examples. Typical steel and steel‐concrete composite office buildings, designed according to the current European standards, are evaluated for robustness against identified and unidentified threats. The results obtained with simple and more advanced verification approaches are compared, and possible solutions to improve the robustness of the structures are provided.