PSI - Issue 64

Edward Steeves et al. / Procedia Structural Integrity 64 (2024) 1975–1982 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

1981

7

improvement, further research is currently underway to optimize upgrade schemes to increase structural robustness and structural redundancy, while minimizing the volume of material needed to perform the upgrade.

Table 2. Structural robustness and structural redundancy indices for damaged and upgraded bridges. State of Structure , (4) (5) Intact N/A 0.008 Damage 0.406 0.008 Upgrade 0.631 0.139

5. Conclusion It is imperative from a safety perspective that structures are able to absorb an initial damage and not collapse. Arising from no universal consensus, many definitions of structural robustness have been provided in structural engineering literature. This paper first offers a critical review of the various definitions provided for collapse, robustness, and redundancy found in peer-reviewed journals and technical documents. Next, deterministic, probabilistic, and risk-based measures are reviewed, showcasing the limitations of structural robustness quantification in existing research. Of all the existing measures, the structural robustness and structural redundancy indices formulated by Steeves and Oudah (2024), along with the associated framework of analysis, are emphasized as the only holistic and user-friendly measures, and are thus selected for the case study. The framework of analysis proposed by Steeves and Oudah (2024) is then demonstrated on a steel truss bridge based off a real-life structure in NB, Canada, subjected to corrosion damage from a 75-year exposure time. The structural robustness and structural redundancy of the damaged bridge are first quantified as 0.406 and 0.008 respectively. Based on the system performance of the damaged structure, an upgrade is recommended that changes the failure mode of the critical element from buckling to strain hardening, consequently increasing the structural robustness to 0.631 and the structural redundancy to 0.139. This case study sheds light on the application of a structural robustness index when improving the safety of existing bridges, and highlights the value of the ongoing research to optimize upgrade schemes to maximize robustness and redundancy while minimizing the cost and carbon footprint of structural repairs. Acknowledgements The author would like to acknowledge the financial support provided by the Natural Sciences and Engineering Research Council of Canada (NSERC), the Nova Scotia Graduate Scholarship (NSGS), the Dr. Robert Gillespie Graduate Scholarship, and Mathematics of Information Technology and Complex Systems (MITACS). The author would also like to extend his gratitude towards his MITACS industry supervisor Colin Jim, PEng, along with the entire Bridge Department at CBCL Limited for their continued support and mentorship throughout the research program. References American Association of State Highway and Transportation Officials: The Manual for Bridge Evaluation. AASHTO, Washington, DC, 2018. American Society of Civil Engineers: ASCE/SEI 41-17, Seismic Evaluation and Retrofit of Existing Buildings. ASCE Standard, Structural Engineering Institute, ASCE, Reston, VA, 2017. Argyroudis, S. A., 2022. Resilience Metrics for Transport Networks: A Review and Practical Examples for Bridges. Proceedings of the Institution of Civil Engineers – Bridge Engineering 175(3), 179 – 192. Baker, J. W., Schubert, M., Faber, M. H., 2008. On the Assessment of Robustness. Structural Safety 30(3), 253 – 267. Bhattacharya, B., 2021. A Reliability Based Measure of Structural Robustness for Coherent Systems. Structural Safety 89, 102050. Buitrago, M., Bertolesi, E., Calderón, P. A., Adam, J. M., 2021. Robustness of Steel Truss Bridges: Laboratory Testing of a Full-Scale 21-Metre Bridge Span. Structures 29, 691 – 700. Adam, J. M., Parisi, F., Sagaseta, J., Lu, X., 2018. Research and Practice on Progressive Collapse and Robustness of Building Structures in the 21st Century. Engineering Structures 173, 122 – 149.