PSI - Issue 62

Massimiliano Bregolin et al. / Procedia Structural Integrity 62 (2024) 916–923 M. Bregolin et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction The European Directive 2019/1936/EC underlined the importance of protecting vulnerable users and Italy, with the Legislative Decree n.35/2011, focused attention also on cyclists and pedestrians in particular. Furthermore, Italy adopted a National Road Safe ty Plan “Piano Nazionale per la Sicurezza Stradale” (PNSS) (MIT, 2022) with the aim to decrease the amount of road accidents. One of the main priorities of the Plan focus on road safety in the urban environment. The main problem in urban areas are the lack or insufficiency of protection for the most vulnerable road users, the poor separation of traffic flows, the recurrent interference between paths for pedestrians and cyclists and vehicles lanes. In 2018, was established the Italian National Agency for Safety of Railway and Road Infrastructures (ANSFISA), that have the task of promoting safety the national land trasportation system on the basis of annual programs of activities, thereby compelling the managing entities to implement the necessary risk control measures and safety upgrading interventions if required. The Italian Government has recently adopted the “Guidelines for the risk Management of Existing Bridges” (Cutrone et al., 2023), referred to as “Italian Bridge Guidelines” which according to the Ansfisa operating instructions constitute a reference of proven validity even if they are not legally binding (Natali er al, 2023). For the premises illustrated above, a cycle-pedestrian bridge with considerable span is of interest from a transport point of view, because it is an urban mode of transport for vulnerable users and it is an infrastructure whose structural safety and comfort standards must be monitored (Chiacchiari et al., 2016, 2017; Romera et al.,2020; Yang et al.,2023). The significance of footbridges for citizens, humanity and civilization in general goes beyond the aspects of structural safety (Siviero et al., 2019 ; Siviero, 2013), so that restoration works are often started as in the case of the Bersted Crossing footbridge (Macfarlane, 2006). This structure should be designed to accommodate every type of users, including children and elders. It should be designed in a way that focuses more on human needs as a priority rather than the other two elements of transportation system: road and vehicle (Hasan, 2017 ; Antinori et al., 2017). In this paper, particular emphasis is on the example of the Goito footbridge, one of the three Romaro suspended bridges in Padua (Romaro, 2022). Despite being outdated, it perfectly embodies the archetypal modern footbridge anticipating the vision of a future city with a sustainable approach (Siviero et al., 2019). This work is based on the need to assess the impact of the structure from a social, architectural, and urban planning point of view (Università Degli Studi di Padova, 2022; Lion & Pellegrino, 2016) . The decision regarding the possible replacement or preservation of the footbridge should consider multiple aspects, e.g., the economic cost of safety measures compared to demolition and replacement, the social aspect of depriving the community of architecturally valuable work, the evaluation of observed deformations and the possibility of continuous monitoring at reasonable costs (Padua Walls Committee, 2014). This work aims to evaluate the possibility of structural improvements to allow a comfortable use of the pedestrian bridge. The analysis investigates (i) the possibility of constraints introduction improving the dynamic behavior in terms of first mode frequency of vibration, (ii) a detailed corrosion study to evaluate the impact on the mechanical behavior, and (iii) the historical, social, and architectural value of the footbridge. 2. Case study The Goito footbridge is located adjacent to the 16th-century walls of the city of Padua, spanning the Main Branch of the Bacchiglione River between Via Goito and Via Marco Polo. Constructed by the Romaro Company in 1956, it played a crucial role in the city’s d evelopment during those years because it created a connection between residential complexes and the city center. It is essential to note that at that time, the Saracinesca Bridge, constructed in 1961, had not yet been built. Therefore, during those years, the population had to utilize the Iron Specola Bridge or the Horse Bridge at Bassanello to cross the Main Branch of the Bacchiglione. The Goito footbridge has undergone various maintenance interventions over the years, with the full replacement of the supporting cables in 1997. In Fig. 1 the frame of the work in the urban context is explained. Fig. 1(a) reported the floor plan of the Goito cycle-pedestrian bridge, and Fig.1(b) reported the large-scale map results of a GIS analysis. The cartographic data sources represented is OpenStreetMap and a DTM made available by the Veneto Region. This map provide an immediate visualization of the urban placement of the footbridge, highlighting its strategic importance for the continuity of pedestrian and cycle paths in general, particularly between the two banks of the Main Branch of the Bacchiglione River. Querying the