PSI - Issue 64

Stefano Belliazzi et al. / Procedia Structural Integrity 64 (2024) 612–620 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Structural health monitoring (SHM) (Mishra et al. 2022) is an important process that involves the continuous monitoring and assessment of the condition of structures such as bridges, buildings, dams, and other infrastructures. The primary objective of SHM is to ensure the safety, reliability, and longevity of such structures by detecting and evaluating any changes or damages that may occur over time due to various factors such as aging and environmental conditions in structural elements made not only of stone, but also of timber (Romano et al. 2016). SHM systems typically use sensors and data acquisition systems to obtain real-time data on structural behavior, performance, and integrity. This data is then analyzed to identify any anomalies, defects, or potential risks to the structure's stability or functionality. By providing early detection of structural issues, SHM helps to facilitate timely maintenance, repair, or retrofitting activities, ultimately enhancing the safety and resilience of critical infrastructure systems. The main goal of this research is to evaluate the potential of Satellite-based Synthetic Aperture Radar (SAR) technology (Shinozuka and Mansouri 2009, Ma et al. 2021) for monitoring the structural health of masonry structures. In particular, the aim is to determine if the magnitude of displacements potentially measured by SAR is sufficient to detect the activation of failure mechanisms inducted by settlements in typical masonry structures. The SAR technology is a tool for monitoring the structural health of masonry structures where SAR uses microwave pulses to image the Earth's surface from space, providing high-resolution data that can be used to detect and track changes in structures over time. In addition to structural monitoring, SAR data can also be used for a variety of other applications related to masonry structures, such as mapping masonry structures or archaeological sites by high-resolution maps which can be used for planning and maintenance purposes. Discussion of SAR technology is out of the scope of present paper. Settlements in masonry structures (Verstrynge et al. 2016) refer to the gradual sinking or subsidence of the buildings foundation. This phenomenon can occur due to various factors such as soil settlement, changes in groundwater levels, or the aging of the building materials. Settlements can lead to visible cracks in the walls, floors, or ceilings, compromising the structural integrity of the masonry. In severe cases, excessive settlements can result in structural instability, posing risks to the safety of occupants and requiring costly repairs or reinforcement measures. Therefore, monitoring and addressing settlements in masonry structures are essential for ensuring their long-term stability and safety. The monitoring of settlement in masonry structures allow to prevent failure with the adoption of strengthening systems for masonry wall (Fabbrocino et al. 2021, Ramaglia et al. 2022 and Belliazzi et al. 2024). 2. Structural analyses A large-scale approach (Belliazzi et al. 2021a, Sandoli et al. 2021) is assumed to assess the magnitude of displacements that activate failure mechanisms inducted by settlements in masonry structures. Due to the low knowledge achieved on existing buildings, local mechanisms activation is taken into account while global mechanisms are not considered in this work. The structural models are modelled using an equivalent frame approach (Augenti et al. 2009) assuming different configurations of plane frames as preliminary analysis. The structural analyses of models characterized by single-storey and two-storeys with 1 or 2 spans have highlighted that the model with single-storey and 1 span yields the lowest stress values. Therefore, it appears to be the most interesting model to study due to the fact that higher settlements are required to activate local mechanisms in masonry walls. Shear and flexural stiffnesses of masonry walls have been considered in structural analyses to define the stiffness matrix of the structural model. Each frame is characterized by two piers (AB, PQ), a spandrel (DL) at the top, and a vertical settlement δ at point Q as shown in Fig. 1. In addition, each masonry wall is modelled with a deformable element (AB, DL, PQ) and a rigid offset (BC, CD, LO, OP). Linear analyses are performed; advanced models were not considered at this stage due to the low achieved knowledge of structures and for the purposes of this study. The resolution of the static scheme was carried out using the displacement method in Wolfram Mathematica. The matrix of unknowns consists of the rotation unknowns φ C and φ O (respectively at nodes C and O) and the displacement δ of the equivalent beam CO.