PSI - Issue 78

330 Andrea Pozè Falet et al. / Procedia Structural Integrity 78 (2026) 325–332 MAC( , , , )= 0.9785 in 2003, highlighting some non-negligible divergences between the two nominally identical span (a hint that was linked to scour effects), this was reversed after, with MAC( , , , )= 0.9988 in 2004, clearly indicating a recover of the expected dynamic behaviour. Finally, as is well-known from much experimental evidence, the damping ratios do not follow a predictable pattern (Civera et al., 2023; Reynders et al., 2008) and are thus of limited use here (both for comparison between different spans at the same instant and between the same span at different years). All these considerations are detailed in Table 3, where the differences are reported both in absolute values and as percentages ( Δ = ( 2004 − 2003 )/ 2003 for each parameter p ).

Upstream sensor Downstream sensor M.S. upstream M.S. downstream

(a)

Upstream sensor Downstream sensor M.S. upstream M.S. downstream

(c)

Upstream sensor Downstream sensor M.S. upstream M.S. downstream

(e)

Fig. 7. Mode shapes of the Strambino Bridge, all five spans (C1 to C5, left to right), as seen from upstream looking South. First bending mode, (a) 2003 (before P2 retrofitting), (b) 2004 (after P2 retrofitting), (c) 2024. The plots report both the mo de shapes estimated at the sensors’ locations and the interpolated mode shapes.