Assessing the Effectiveness of Roof-Level Retrofitting Beams in Enhancing the Robustness of Steel Building Structures
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Improving the robustness of existing buildings is essential to ensure their ability to withstand extreme events, significantly reducing the risk of progressive collapse and its consequences in terms of deaths, injuries and economic costs. The increasing frequency of extreme events combined with the large stock of buildings designed with out-of-date standards, with or without considering structural robustness, heightens the need to find effective solutions for retrofitting existing buildings. Although there are multiple solutions to improve the robustness of existing buildings, most of them are very intrusive, making their adoption costly and limited. A promising alternative is using retrofitting beams at the roof level, which can redistribute loads of failed load-bearing elements during an extreme event to the top of the building and then to neighbouring elements up to the foundations. Such an alternative is a less intrusive and more economical solution. This study presents a methodology based on optimised computational modelling to evaluate the feasibility and effectiveness of roof-level retrofitting beams in steel buildings. The developed framework enables the exploration of different retrofitting beam configurations in a set of representative buildings. The assumptions employed to improve the efficiency of the analysis are detailed in this work. The results demonstrate that retrofitting beams at the top floor of buildings can significantly enhance structural robustness while minimizing alterations and interventions in the existing structure. The methodology developed facilitates the broader application of this retrofitting technique, promoting its adoption and contributing to the protection of existing buildings against extreme events.