Evaluation of fatigue properties using estimation methods for puddled iron (pre-1900) and mild steel (post-1900)

Research identifies that Mitchell's, modified Mitchell's, and Manson's universal slopes methods provide the most accurate and robust estimates for predicting fatigue properties of historic metallic bridge materials—puddled iron (pre-1900) and mild steel (post-1900)—using monotonic tensile strength data. These findings are critical for assessing the structural integrity of heritage sites like Oporto's Luiz I Bridge, where experimental fatigue data is often unavailable. The study evaluated 10 estimation methods, revealing that while modified Park–Song's method performs well for puddled iron, it lacks general robustness. Conversely, modified four-point correlation and GP-symbolic regression showed poor agreement with experimental data, particularly in high- and low-cycle regimes. This work establishes reference fatigue properties for these materials, advancing conservation efforts by bridging known monotonic strength behaviors with fatigue resistance predictions.

Correia, J. A., Oliveira, I., Horas, C., Mourão, A., Jesus, A. d., Pardal, J., Tavares, S., & Lesiuk, G. (2026). Evaluation of fatigue properties using estimation methods for puddled iron (pre-1900) and mild steel (post-1900). International Journal of Structural Integrity, 17(5), 1138–1167. https://doi.org/10.1108/ijsi-02-2026-0021