PSI - Issue 44

Dora Foti et al. / Procedia Structural Integrity 44 (2023) 1506–1513 D. Foti et al./ Structural Integrity Procedia 00 (2022) 000 – 000

1507

2

agents. Thus, it is considered necessary to carry out downstream of an accurate study of the historical evolution and survey with smart instruments and techniques such as Unmanned Aerial Vehicles (UAV) (by Gioffrè et al. (2008), Sánchez-Aparicio et al. (2019) and Biscarini et al. (2020)) and operational modal analysis (OMA) (by Foti et al. (2012), Bru et al. 2015), Foti et al. (2020) and Diaferio et al. (2021)), a diagnosis to assess the current and future structural state of historical masonry bridges and, consequently, to plan adequate conservation and restoration interventions for their preservation by Marta (1989), Grelle et al. (1993) and Galliazzo (1995). The structural performance and the state of preservation of existing historical masonry structures can be evaluated using accurate FE models (by Pepi et al. (2021), Diaferio et al. (2007)). When such models are developed, two main issues need to be addressed: the geometry description and the material characterization. These two objectives, which often require complex investigations to obtain reliable models, will be achieved through a multidisciplinary approach integrated with different innovative technologies. In this framework, in fact, there are several studies aiming at characterizing masonry arch bridges at different levels (geometric level, material level, structural system level) e.g. De Marco et al. (2020). Indeed, this type of construction is typically characterized by its high complexity in terms of size, location, and internal composition. Digital photogrammetry based on high-resolution images provided by UAVs is used to overcome these difficulties and to obtain accurate three-dimensional models from point clouds. In the present paper, the UAVs technique has been applied to the masonry bridge of Santa Teresa in Bitonto, Italy. The metric survey (also with the use of drones) and the graphic restitution have been carried out, also considering the materials and construction techniques of the bridge at that time and taking into account the evolutionary phases including any interventions carried out over time. Structural Health Monitoring (SHM) will be then used to identify the actual dynamic properties of the tested masonry bridge (frequencies, modal shapes, and damping), useful to update a numerical model (Ruocci et al. (2009) and Civera et al. (2022)). Monitoring will be performed with accelerometers applied at several points of the structure, repeated several times or with continuous monitoring. A Finite Element (FE) model has been set up using the geometric data collected during the photogrammetric survey. A sensitivity analysis has been then performed to identify the FE model input parameters that most influence the dynamic response. Then, as a future aim, model updating procedures will be performed using the results obtained from the processing of in situ monitoring data to obtain an accurate FE model to be used for structural safety assessment. The final objective is to reach, through rigorous historical, diagnostic, and technical research, a critical synthesis responsible for the delicate task of safeguarding precious testimonies which, for their value as a cultural heritage, must be preserved and enhanced in balance with the protection of the complex landscape and territorial system to which they belong. 2. Description of the case-study Santa Teresa Bridge, located in the Municipality of Bitonto (Bari, Apulia, Italy) has been considered as a case study. It was built in the southern part of the town, at the edge of the historic center and a few meters away from the church of Santa Teresa and “C. Sylos” high school (Figure 1). It borders to the north with the old city walls and to the south with C. Sylos Square. On the east and west sides, it is crossed by the lama , whose course follows an eastward downstream slope.

Fig. 1. Location of the Santa Teresa bridge of Bitonto (source Google Earth Pro)