PSI - Issue 78

Elisa Tomassini et al. / Procedia Structural Integrity 78 (2026) 1831–1838

1836

6

Author name / Structural Integrity Procedia 00 (2025) 000–000

Experimental Data Statistical Model

Fig. 3: Frequencies vs. Temperature recordings. Red dots represent the statistical model’s predictions and black dots the experimental data.

Mode 1 Mode 9 Mode 17

Mode 2 Mode 10 Mode 18

Mode 3 Mode 11 Mode 19

Mode 4 Mode 12 Mode 20

Mode 5 Mode 13 Mode 21

Mode 6 Mode 14 Mode 22

Mode 7 Mode 15 Mode 23

Mode 8 Mode 16

Training Period

10 20 30 40 50 60 70 80 90 100

8

99% UCL

6

90% UCL

4

T [-] 2

2

Frequency [Hz]

0

15/Oct/24

18/Sep/24

11/Nov/24

07/Dec/24

22/Aug/24

03/Jan/25

25/Feb/25

23/Jul/24

27/Jul/24

05/Jan/25

30/Jan/25

30/Jun/24

05/Oct/24

28/Oct/24

12/Sep/24

01/Feb/25

30/Jun/24

13/Dec/24

15/Aug/24

20/Nov/24

(a)

(b)

Fig. 4: Frequency Tracking (a) and Control Chart (b).

4. Seismic Monitoring and Response of the Spina Bridge

The Spina Bridge, located in the vicinity of Spoleto (Central Italy), is a multi-span reinforced concrete viaduct composed of eight simply supported spans, each measuring 13 meters in length and 11.5 meters in width. The bridge’s superstructure rests on piers made of three circular columns connected at the top via a common cap. The height of the piers above ground varies between 2.6 m and 3.2 m. Due to the relatively short spans and low-height piers, the overall