Robustness of Structures: Danish Approach

This paper describes the background of the robustness requirements implemented in the Danish Code of Practice for Safety of Structures and in the Danish National Annex to the Eurocode 0, see (DS-INF 146, 2003), (DS 409, 2006), (EN 1990 DK NA, 2007) and (Sørensen and Christensen, 2006). More frequent use of advanced types of structures with limited redundancy and serious consequences in case of failure combined with increased requirements to efficiency in design and execution followed by increased risk of human errors has made the need of requirements to robustness of new structures essential. According to Danish design rules robustness shall be documented for all structures in high consequence class. The design procedure to document sufficient robustness consists of: 1) Review of loads and possible failure modes / scenarios and determination of acceptable collapse extent; 2) Review of the structural systems and identification of key elements; 3) Evaluation of the sensitivity of essential parts of the structure to unintentional loads and defects; 4) Documentation of robustness by ‘failure of key element’ analysis; 5) Documentation of robustness by increasing the strength of key elements if step 4 is not possible.