PSI - Issue 84

Angelo Masi et al. / Procedia Structural Integrity 84 (2026) 321–328

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Fig. 4. Typological distribution of bearings

The analysis of defect occurrence highlights clear differences among bearing typologies (Fig. 5). Elastomeric bearings show the highest incidence of defects, with ageing-related phenomena being the most frequently reported (App_7), followed by debris accumulation (App_5), oxidation of steel components, and excessive horizontal deformation or material extrusion. These results underline the vulnerability of elastomeric materials to long-term environmental exposure and cyclic loading, especially in older structures. Pot bearings generally exhibit a more favourable condition, with a substantial proportion of devices showing no detectable defects. When present, deterioration is mainly associated with oxidation (App_2) of metallic components and, to a lesser extent, improper pre-setting (App_4). Similarly, steel bearings are largely affected by corrosion phenomena, which represent the predominant defect, while minor issues such as debris accumulation are less frequent.

Fig. 5. Defect distribution among the identified bearing typologies

For bearings with steel–PTFE sliding surfaces, oxidation remains the most common defect, followed by deterioration of the PTFE layer (App_14) and the presence of debris, whereas a non-negligible fraction of these devices appears defect-free, likely due to the partial protection offered by their configuration. Overall, the results confirm that defect patterns are strongly dependent on bearing typology and age, with elastomeric and traditional steel bearings exhibiting higher levels of degradation compared to pot and steel–PTFE devices. The analysis also reveals some inconsistencies in defect attribution, highlighting limitations of the current