PSI - Issue 84

Valentina Picciano et al. / Procedia Structural Integrity 84 (2026) 922–930

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Among traditional solutions, steel jacketing is widely used for local strengthening, particularly in the presence of impact damage or severe surface deterioration. The technique consists of bonding steel plates to the lateral and bottom surfaces of the girder by means of mechanical anchors and epoxy resins, thereby forming a composite steel–concrete section (Fig. 1a). This configuration allows for significant increases in flexural and shear capacity (Aykac et al. 2013) and can be adapted to different geometric layouts. However, it introduces a non-negligible additional permanent load and requires careful corrosion protection to ensure durability. Reinforced concrete jacketing represents another traditional and widely adopted strengthening strategy, typically applied to the lower bulb of PRC girders. This solution enhances flexural capacity and stiffness through the addition of a new reinforced concrete layer that becomes integral with the existing section (Fig. 1b). One of its main advantages lies in the use of conventional materials and construction techniques, which facilitate execution and reduces the need for specialized labor. On the other hand, the significant increase in self-weight negatively affects the overall efficiency of the intervention, and the technique is statically passive, becoming effective only after the application of additional loads. In recent decades, fiber-reinforced polymers (FRP) (Fig. 1c) have emerged as an attractive alternative for the strengthening of existing concrete structures, including PRC girders. Thanks to their high strength-to-weight ratio, corrosion resistance, and application flexibility (Chen et al. 2024), FRP systems can be used to improve both flexural and shear performance, as well as to control cracking. Their main advantages include minimal added weight, rapid installation, and limited disruption to traffic. However, their structural behavior is often governed by brittle failure mechanisms, such as debonding and delamination, which may prevent full exploitation of the material capacity (Rosenboom et al. 2007, Ary and Kang 2012). Among the most advanced and effective strategies, external post-tensioning plays a prominent role (Santarsiero and Picciano 2024). This technique involves the introduction of additional prestressing forces through external tendons anchored to the girder (Fig. 1d), leading to increases in both flexural and shear capacity, as well as reductions in cracking and service deformations (Daly and Witarnawan 1997). A key advantage of this approach is its active structural behavior, as the prestressing force directly contributes to resisting both existing and future loads. Moreover, tendons can often be installed externally with limited interference with the original structure, enabling relatively fast execution and reduced traffic disruption. The above overview highlights that the main strengthening strategies for PRC bridge girders differ not only in terms of mechanical effectiveness, but also with respect to construction complexity, material use and durability. These preliminary considerations suggest that techniques providing comparable structural performance may lead to substantially different implications when evaluated from a life-cycle perspective. This observation motivates the need for a systematic comparison capable of integrating structural, economic, and life-cycle-related aspects, which is developed in the following section.

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