Contribution to the implementation of robustness in European design recommendations for steel and composite structures

Abstract

At present, Eurocode 1 Part 1-7 presents different strategies to deal with the problem of robustness. However, for each of these strategies, the content is limited to the statement of general principles. Consequently, in recent years, several researches have been carried out to develop calculation and design tools for robustness. Thanks to these researches, many new tools and works are available to practitioners, but the lack of comprehensive approaches limits their scope and use.

In this work, approaches for handling the robustness problem in steel and composite structures are developed for the strategies presented in the Eurocode, and based on the tools currently available. For each of the approaches developed, the tools it requires to use, the limitations it presents and the analysis and verification steps to be followed are presented in detail. In addition, all this information is summarized in a global flowchart proposed to deal with the robustness problem.

This first task highlights several inconsistencies concerning the prescriptive tying method currently proposed by the Eurocode. Proposals for improvements have actually already been made recently.

Therefore, in a second step, this thesis focuses more specifically on this tying method. To assess the relevance of the rules currently proposed by the Eurocode regarding the tying method and the degree of robustness which these rules allow to reach, a study of a braced structure undergoing the loss of a column is carried out. In the context of this study, the beam-column joints of the structure first have the resistance specified by the tying method. Subsequently, different joint configurations are studied. By comparing the results obtained, several conclusions are drawn about the tying method. Also, this study shows that simple joints such as header plate connections have a too low degree of robustness, and that it is more advantageous to use semi-rigid/rigid joints such as flush end-plate connections.