PSI - Issue 84

Giulia Rossini et al. / Procedia Structural Integrity 84 (2026) 1183–1190

1186

1.1.1. Bridge 2: detailed description The bridge 2 is a pretensioned girder bridge built in 1973. The structure is rectilinear but features an obliquity of 13°. It consists of three simply supported spans, with a total length of 54.71 m. The two side spans are identical, each 15.52 m long and made by ten longitudinal PRC girders and two RC transverse beams at the beam ends. The central span, measuring 24.16 m, consists of fourteen longitudinal PRC girders and four RC transverse beams. The stress release tests are carried out only on the span 3 (S3) and therefore only the sides span details are shown in Figure 2. The girders are made of prefabricated reinforced concrete, while the transverse beams and the deck slab are cast in situ. Concrete classes C45/55 and C35/45 were adopted for the girders and for the transverse members, piers and abutments, respectively. From in-situ tests carried out on girder concrete, an average compressive strength f cm of 57,8 MPa was detected. The harmonic steel used for strands has an ultimate characteristic strength f ptk of 1860 MPa from design drawings. Prestressing was applied using 50 strands 5/16” for the girders of the side spans. Among these, 44 strands are straight, while the remaining 6 strands are deviated by means of deflection points located approximately at one-third of the span length (L/3). These data were confirmed both by the original design documents and by diagnostic investigations. The prestressing layout is shown in Figure 3. An initial stress of 1300 MPa was assumed by the design calculations for all strands, from which short- and long-term prestress losses were deducted. To define the non-structural dead load 2 , local scarifications of the pavement were performed to measure the thickness and unit weight of the surfacing materials, and the weights of secondary elements were also included. The resulting distributed non-structural dead load was 5.1 kN/m.

Figure 2: transverse section: span 1 and 3- bridge 2 assumed by inspection and by design drawings. Dimensions are in cm. (a) (b)

Figure 3: (a) tendons’ profile for girders of span 3 (S3) and (b) tendons’ layout at the test section – bridge 2. Dimensions are in cm.