PSI - Issue 84

Angela Diana et al. / Procedia Structural Integrity 84 (2026) 623–629

624

1. Introduction Transportation infrastructure, and bridges in particular, constitute essential components of national road networks, contributing decisively to the efficiency, reliability, and safety of mobility systems. In this context, continuous structural monitoring emerges as an advanced methodology for early damage detection, influencing the improvement of infrastructure resilience and safety. This approach can be defined, in broad terms, as the systematic implementation of damage identification strategies, where damage is understood as any alteration that reduces the performance capacity of the structure, including material degradation, variations in geometric properties, and modifications to boundary conditions. A central aspect of continuous structural monitoring is the analysis of the dynamic response of structures through Operational Modal Analysis (OMA) (Zahid et al., 2020). Dynamic parameters, such as natural frequencies, damping ratio and modal shapes, are closely related to the stiffness, mass and constraint characteristics of the structural system which, in turn, are affected by the health state of the structure as well as the external thermo-hygrometric conditions. Identifying and monitoring these parameters over time allows for detection of even slight variations in the overall behaviour of the structures. A distinctive element of continuous monitoring through OMA is its non-destructive nature and limited invasiveness. In this work, continuous monitoring of reinforced concrete bridges is implemented through software called P3P, specifically designed for continuous monitoring of highway bridges and represents an evolution from a previous software suite called MOVA/MOSS (García-Macías & Ubertini, 2020). This new platform has been developed within a research project funded by Anas Spa, the main Italian company dedicated to highway system management. The software includes automated OMA functionalities, frequency tracking, environmental effects filtering, and potential damage detection. Several studies document the effective application of this technology across various structural typologies, including bridges (García-Macías et al., 2023). This study aims at interpreting the main characteristics of the dynamic behaviour of a set of bridges involved in continuous monitoring programme and investigating how simplified formulations can be employed to estimate the natural frequencies as functions of selected geometric parameters. Once validated, these simplified formulations may be potentially used for preliminary screening of potential outliers as well as large-scale vulnerability analyses of bridges aimed at prioritisation of intervention activities. 2. Sample Description The infrastructures analysed in this study are part of a broader national program called Programma SHM developed by the FABRE Consortium, of which the University of Campania is founding member, in collaboration with ANAS S.p.A. This program involves the implementation of continuous monitoring systems on over 1,000 bridges and viaducts distributed throughout Italy, with the aim of supporting the assessment of structural performance and monitoring their health state over the long term. This work focuses on a subset of reinforced concrete bridges located in different areas of Italy. The bridges considered are simply supported multi-span structures, consisting of three to six spans ranging from 20.5 m to 32.6 m. The main characteristics are summarised in Table1. In particular, the table reports the static scheme, the number of spans, the span length (SL), the number of beams and the deck width (DW), as well as first and second bending natural frequencies of the deck, discussed later.

Table 1. Geometric and dynamic characteristics of the sample bridges analysed.

Bridge Structural scheme

No.

SL

No.

DW (m)

I Mode f OMA (Hz)

II Mode f OMA (Hz)

of spans

of beams

(m)

29 28 29

A

Simply supported

3

4

11.96

4.48 4.51 4.49 4.39

16.40 16.97 17.50 16.58

B

Simply

3

28.9

4

11.96