PSI - Issue 64

Konrad Bergmeister et al. / Procedia Structural Integrity 64 (2024) 14–20 Konrad Bergmeister / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction 1.1. General remarks

Distinct elements of critical infrastructure, such as bridges, are not just structures but lifelines for communities. Their high-stake societal and economic impact is evident in the immediate loss of utility and the series of cascading effects that follow a bridge failure. The consequences are often disproportionately negative and underscore the urgency and importance of bridge design and maintenance (Pregnolato 2019). The design, construction, maintenance, repair, and life-cycle cost-benefit analysis of bridges are complex tasks. They require informed decision-making, accurate assessment of uncertainties and balancing conflicting criteria of improved performance versus low cost. The complexity of these tasks necessitates continuous research and innovation in the corresponding fields (e.g., Thoft-Christensen 2009, Frangopol et al. 2019). In the study of Deng et al. (2016), human and natural hazard factors are investigated as contributing mechanisms that lead to bridge collapse. Among others, the lack of inspection and maintenance is pointed out as critical in prolonging the deterioration process. Currently, the most common approach is performing routine (i.e., frequently recurring) visual inspections to identify any changes from previous ones. However, research and innovation in the field continuously change the state of practice (Abdallah et al., 2022). The following section discusses the necessity of structural risk assessment of existing bridges and the importance of leveraging digital tools. Finally, the envisioned scope of an automated bridge inspection procedure involves easy to-obtain data and artificial intelligence (AI). 1.2. Structural risk assessment of existing bridges The protection of bridges in pursuing the resilience of cities and communities is a highly researched field that emphasizes the need to identify bridges at high risk of failure, use high-quality data, and deliver risk-based assessments (Pregnolato 2019). Moreover, it is crucial to establish national and international roadmaps of policies leading to unified bridge databases that allow for informed strategic risk assessments. In line with these requirements, multiple efforts in Italy are investigating the structural risk of existing bridges through systematic procedures (e.g., De Matteis et al. 2021, Buratti et al. 2021, Mazzatura et al. 2023). In the work of De Matteis et al. (2021), such national guidelines are reviewed and applied to a case study of 75 bridges in Caserta (Italy), forming a preliminary informative study regarding the involved hazards, exposure and vulnerability aspects. In the work of Buratti et al. (2021), a visual inspection-based methodology for the structural risk estimation of existing bridges is shown. Following their methods, collected data are displayed and statistically analysed regarding these structures' main characteristics and state of preservation. The inspections were carried out by the Department of Civil and Industrial Engineering of the University of Pisa, involving 586 existing bridges located in the Massa and Pisa Provinces in the Tuscany region (Italy). The visual and quantitative frameworks mentioned above are often chosen when data and resources are limited. However, qualitative approaches for assessing existing bridges, such as numerical and/or experimental studies (e.g., Consolazio and Cowan 2005, Decò and Frangopol 2011, Bagge et al. 2019, O’Reilly and Monteiro 2019 ), are more commonly preferred. These methods provide a structural risk assessment that reflects the underlying vulnerability of a given structure under specific hazards and impacts. The work of Bagge et al. (2019) quantifies the high demand in Europe and the United States for structural inspections and bridge replacement, underscoring the need to prioritise inadequate resources. 1.3. The importance of digitalization, automation and AI-enhanced bridge inspection Significant limitations in current routine visual inspections of bridges are scrutinized in the work of Abdallah et al. (2022). In particular, their extensive state-of-the-art review raises concerns regarding a series of critical safety- and cost-related issues, including thorough training and expertise required for inspectors; high risk of injury during inspections, even when the necessary measures are met; disruptive traffic arrangements; use of demanding equipment such as aerial platforms and scaffoldings (Mandirola et al. 2022). More importantly, it is noted that the quality of visual