Case Studies


The monitoring system has been specifically designed in terms of number and positioning of sensors to capture the complex dynamic response of the structure. By means of FEM modeling of damage scenarios, appropriate dynamic thresholds have been calculated for the continuous monitoring of the state of the stays and the evolution over time of the response of the footbridge deck.

Location: Italy
Project type: Pedestrian footbridge
Sensor type: Triaxial accelerometers
Number of measurement points: 37
Number of sensors: 37
Installation period: August 2020


  • Detailed design of the monitoring system
  • Installation assistance
  • FEM modeling, model updating and continuous structural diagnostics with automatic alerts


  • Continuous monitoring of the state of the stays
  • Monitoring of the evolution over time of the response of the footbridge deck
  • Early detection of the first signs of cable damage
  • Determination of expected dynamic thresholds of the cables corresponding to adequate levels of safety of the structure
  • Planning of targeted maintenance interventions.


The pedestrian bridge has a steel structure consisting of two parts separated by a structural joint: a cable-stayed part and a statically independent supported part.

The planimetric layout of the structure has a curved path; the carriageway has a width of about 4 m, while the total dimension of the deck in the transverse direction, including the paneling of the edge beams, is about 6 m. The cable-stayed part has a total length of 262 m, the deck geometry is defined by a circular arc with a radius of about 630 m and is composed of edge beams with an asymmetric "I" section, HEA section transverse and diagonal members, and a mixed deck made of corrugated sheet metal and concrete with a total height of 10 cm. In addition, there are steel sheet cladding elements in triangular shape corresponding to the edge beams. The piers on which the cable-stayed part rests are tubular steel profiles, assembled in the form of 'N' and 'V'. Finally, the cable-stayed structure is supported by cables from a metallic arch, 62 m high, 55 m wide and inclined relative to the vertical plane by 25°, making the cables support the arch itself. The transverse section, in equilateral triangle shape, is made of welded steel sheet and stiffened by longitudinal ribs. The suspended portion of the walkway is supported by 38 steel cables, of which 34 are anchored to the arch and 4 anchor the deck to the ground. There is also a pre-tensioning system consisting of a curved cable that runs longitudinally along the entire suspended portion of the walkway. The cable is made up of 3 steel cables with a cross-sectional diameter of 60 mm. Two tuned mass dissipative devices are present at the intrados of the deck, and damping devices, of the stockbridge type, are installed on the cables to suppress wind-induced vibrations (TMD dampers).

The monitoring system, consisting of triaxial accelerometers installed on the deck and cables, has been designed in number and positioning to best capture the dynamic response.


The complex geometry of the pedestrian bridge required a non-linear FEM modeling approach, aimed at simulating in detail the reference dynamic response of the structure, obtained through a dynamic model updating process carried out with respect to signal analyses both in the time and frequency domains. In addition to the analysis of the average and peak vibration levels of the deck and cables, comfort analyses were carried out for pedestrians against vertical and lateral actions, as well as dynamic identification through Operational Modal Analysis (OMA) techniques.

By modeling appropriate reference damage scenarios, dynamic thresholds corresponding to adequate levels of safety of the structure were determined for the continuous monitoring of the state of the cables and the evolution over time of the deck response of the pedestrian bridge. The diagnostics support the early detection of the first signs of cable damage for the planning of targeted preventive maintenance interventions.


Case history

The monitoring system consists of 28 transverse measurement sections aimed at controlling the tensile and deformation evolution of the tunnel lining over time. The monitoring system, consisting of MEMS inclinometers integrated with post-installed local tension-deformation sensors within the lining, allows for both local and global monitoring of the structure's response. The diagnostics are complemented by nonlinear FEM modeling and a real-time alert service for any structural issues.
The monitoring aims at analyzing the behavior of post-tensioned cables during the bridge's operation, through time and frequency domain analyses. Real-time monitoring is a key tool to provide useful information for the detection of possible effects induced by ongoing deterioration or fatigue processes. The analysis allows a comparison between the expected modal parameters and the measured natural frequencies in the initial monitoring conditions, with consequent definition of corresponding attention and alarm threshold levels set for automatic alerting of the operator.
The structural monitoring and diagnostics of the two tunnel tubes are supported by a complex non-linear FEM modeling, through which, for each monitoring section, the deformation and the evolution of its ovalization with respect to the evolution of the ongoing landslide phenomenon are evaluated. In cable sections where the mechanical characterization and the surrounding stratigraphic conditions are completely similar, a Data-Driven approach is used to extend the Performance Indicators and monitor the most significant structural response parameters at all measurement sections.
The monitoring allowed the real-time control of the response of the deck of a span during open traffic restoration works, and was subsequently extended to the entire viaduct for static and dynamic behavior control over time. The Model Driven monitoring approach allowed the investigation of the main damage scenarios of the structure and the definition of Performance Indicators on which to set threshold values and conditions.
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