PSI - Issue 84

Donatella de Silva et al. / Procedia Structural Integrity 84 (2026) 1353–1360

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the same performance thresholds. This trend is evident in Fig. 4 and 5 and becomes more pronounced as the thickness of the protective layer increases, reflecting an overall enhancement of structural resilience under fire exposure. Overall, the comparison between unprotected and protected configurations clearly demonstrates the effectiveness of passive fire protection for the SCC bridge. Fire scenarios that are critical for the unprotected structure lead to a markedly lower probability of performance level exceedance when protection is applied. These results further confirm the usefulness of fragility curves as a robust tool for assessing fire vulnerability and for quantifying the benefits of fire protection measures in both design and performance-based evaluation frameworks. 5. Conclusions Improving fire resilience through passive fire protection systems represents a strategic measure not only for enhancing structural performance under extreme thermal conditions, but also for mitigating long-term economic losses. Although the implementation of passive protection involves additional initial investment, its effectiveness must be evaluated in terms of overall cost efficiency, considering both direct and indirect consequences over the bridge life cycle. Cost–benefit analysis provides a rational framework in which costs associated with the installation, maintenance, and potential replacement of protection systems are balanced against the expected benefits derived from risk reduction. These benefits can be quantified by linking the economic consequences of fire-induced damage and failure to the probabilities obtained from fire fragility curves, which express the likelihood of exceeding specific damage states as a function of fire intensity. By integrating cost evaluation with probabilistic vulnerability assessment, the economic convenience of alternative passive fire protection strategies can be consistently compared within a performance-based fire safety design perspective. Future developments will focus on completing the cost analysis and on estimating direct and indirect structural losses through the derived fragility curves, in order to compare the economic performance of the different protection configurations. This approach is intended to support a performance based selection of the optimal passive fire protection thickness at the design stage. References V.R. Kodur, L. Gu, M.E. Garlock, Review and Assessment of Fire Hazard in Bridges Journal of the Transportation Research Board No. 2172, Transportation Research Board of the National Academies, Washington D.C. (USA), 2010. M. Garlock, I. Paya-Zaforteza, V. Kodur, L. Gu, Fire hazard in bridges: review, assessment and repair strategies, Eng. Struct. 35 (2012) 89–98, https://doi.org/ 10.1016/j.engstruct.2011.11.002.0 G.M. Calvi, M. Moratti, G.J. O’Reilly, N. Scattarreggia, R. Monteiro, D. Malomo, et al., Once upon a time in Italy: the tale of the Morandi bridge, Structural Engineering International, 29(2), 198-217. Battelle, Comparative risks of hazardous materials and non-hazardous materials truck shipment accidents/incidents, Federal Motor Carrier Safety Administration, Washington D.C., USA, 2004 Naser, M. Z., & Kodur, V. K. R. (2015). A probabilistic assessment for classification of bridges against fire hazard. Fire Safety Journal, 76, 65–73. https://doi.org/10.1016/j.firesaf.2015.06.001 Saxena, R. C. (1992). Thermal conductivity and its temperature dependence in selected steel samples. International Journal of Energy Research, 16(6), 577–584. https://doi.org/10.1002/er.4440160606 M. Neuenschwander, C. Scandella, M. Knobloch, M. Fontana, Modeling elevated temperature mechanical behavior of high and ultra-high strength steels in structural fire design, Mater. Des. 136 (2017) 81–102. J. Chen, B. Young, B. Uy, Behavior of high strength structural steel at elevated temperatures, J. Struct. Eng. 132 (12) (2006) 1948–1954. G.C. Lee, S.B. Mohan, C. Huang, B.N. Fard, A Study of U.S. Bridge Failures (1980- 2012), 2013. Miano, A., Sezen, H., Jalayer, F., & Prota, A. (2019). Performance-based assessment methodology for retrofit of buildings. Journal of Structural Engineering, 145(12), 04019144. Xie, F., & Levinson, D. (2011). Evaluating the effects of the I-35W bridge collapse on road-users in the Twin Cities metropolitan region. Transportation Planning and Technology, 34(7), 691–703. https://doi.org/10.1080/03081060.2011.602850 Aydin, S. G., Shen, G., & Pulat, P. (2012). A retro-analysis of I-40 bridge collapse on freight movement in the U.S. highway network using GIS and assignment models. Int Journal of Transportation Science and Technology, 1(4), 379–397. https://doi.org/10.1260/2046-0430.1.4.379 Arkansas Department of Transportation. (2022). Daily impacts of a bridge closure: A case study of the 2021 I-40 Mississippi River Bridge closure. https://www.ardot.gov/wp-content/uploads/2022/01/13-PS-Daily-Impacts-of-a-Bridge-Closure.pdf J. Zhuang, V.M. Payyappalli, A. Behrendt, K. Lukasiewicz, Total Cost of Fire in the United States, Fire Protection Research Foundation Buffalo, NY, USA, 2017. R. Van Coile, A. Lucherini, R.K. Chaudhary, S. Ni, D. Unobe, T. Gernay, Economic impact of fire: cost and impact of fire protection in buildings, Technical Report FPRF-2022-13, NFPA Fire Protect 125 (2023).