PSI - Issue 78

Giuseppe Santarsiero et al. / Procedia Structural Integrity 78 (2026) 560–567

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Bridge 6 shows the lowest levels of deterioration among the three, with most IDeg values between 0.4 and 3.3. However, an inverse trend is observed in some spans: internal beams (T2 and T3) of span C1 are more degraded than the edge beam T1, highlighting that degradation is not necessarily limited to peripheral elements. This behaviour may be linked to the lack of waterproofing and water infiltration issues affecting the entire deck slab. These differences suggest that degradation patterns are influenced by both structural location (internal vs. edge beams) and local conditions, such as water drainage efficiency and maintenance history.

Fig. 2. Degradation Index (IDeg) for individual beams across spans in Bridges 4, 5, and 6.

The photographs in Fig. 3 provide visual confirmation of the degradation trends identified through the computed IDeg values in Fig. 2. In Bridge 4 (on the left), degradation is mostly limited to the edge beams, where superficial stains and minor concrete spalling are visible. This supports the trend observed in the graph, where edge beams (e.g., T1 and T3 in spans C1 and C2) exhibit higher degradation indices compared to internal beams.