PSI - Issue 62

Francesco Bencardino et al. / Procedia Structural Integrity 62 (2024) 972–982 Bencardino/ Structural Integrity Procedia 00 (2019) 000 – 000

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Peer-review under responsibility of Scientific Board Members Keywords: reinforced concrete, FRP, bridge, strengtehning, bending, shear

1. Introduction Bridges are “ vital ” elements of a country ’ s infrastructure, connecting regions, facilitating transportation, and ensuring economic development. Italy, a nation renowned for its valuable historical and architectural constructions heritage, boasts a vast network of bridges, many of which are reinforced concrete (RC)-based structures. Over the decades, these bridges have served as essential links in the country ’ s transportation system. However, with the passage of time and the increasing load-demands placed upon, they face now a pressing issue: maintenance and structural rehabilitation, Obe et al. (2001), Calvi et al. (2019) and Pellegrino et al. (2011). RC-bridges in Italy, like their counterparts worldwide, experience wear and tear due to various factors such as environmental conditions, heavy traffic loads, and aging materials. The degradation of these bridges can lead to safety hazards when they exhibit damage and/or decay (Figs. 1 a and b, respectively), leading to the deterioration of critical transportation routes. Addressing this issue is not only a matter of preserving historical and cultural assets, but also ensuring the safety and functionality of Italy ’ s infrastructure network. The necessity for maintaining and rehabilitating RC-bridges in Italy arises from several interconnected challenges: • aging infrastructure : Italy ’ s bridges, many of which were built many decades ago, are now showing signs of wear and aging. The durability of the materials used in their construction has become a concern, necessitating interventions to ensure their continued serviceability. • Increased traffic loads : the volume of traffic on Italian bridges has grown substantially over the years. Heavier loads, both in terms of vehicular traffic and cargo transportation, exert greater stresses on these structures, accelerating their deterioration. • Environmental factors : Italy ’ s diverse climate, characterized by both extreme temperatures and exposure to marine environments, places additional stress on bridge materials. This leads to corrosion and weather related damage. To address the challenges of maintaining and rehabilitating RC-bridges in Italy, engineers and researchers have explored a variety of techniques. Two prominent approaches have emerged: traditional methods such as “ beton plaque ” and innovative techniques employing fiber-reinforced polymers (FRPs) materials. Both methods offer advantages and disadvantages. Beton plaque involves applying a new layer of steel to the existing bridge structure, effectively encasing it in a protective shell. This method offers advantages such as enhanced durability of the structure, improved resistance to environmental factors, and a relatively low cost compared to other rehabilitation options. However, it may add significant weight to the bridge, potentially affecting its load-carrying capacity and requiring additional structural adjustments. Moreover, the corrosion of the “ new steel ” is an issue to face. FRP-materials, including carbon or glass fibers embedded in a polymer matrix, have gained recognition for their high strength-to weight ratio and corrosion free. When used for strengthening concrete structures, FRP-composites can provide efficient load-bearing capacity enhancements without significantly increasing the structural mass, Okeil et al. (2013) and Hu et al. (2020). However, they may come with higher initial costs and require specialized expertise for installation and maintenance. This work focuses on the critical rehabilitation and enhancement of an existing three spans RC-bridge, which was severely compromised by material decay (both steel corrosion and concrete carbonatization), through the use of FRP strengthening techniques. By addressing the structural vulnerabilities caused by material deterioration ( state-of-play ), this study aimed to extend the service life and improve the overall safety and performance of this aging infrastructure asset ( state-of-design ). In fact, applying epoxy coatings to the steel bars provide protection of them from direct exposure to moisture and corrosive environment elements. Definitely, by wrapping corroded steel bars with FRP materials an additional strength and a further protection of both the steel and concrete from further decay is achieved. More in detail, the FRP strengthening was designed in order to enhance both shear and bending capacity, thereby increasing the structural resilience of the case-study.