PSI - Issue 84

Andrea Nino Consiglio et al. / Procedia Structural Integrity 84 (2026) 914–921

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with time (Bonopera et al. 2022). The two PC beams were tested according to the destructive and the non-destructive method previously presented (Sections 2.1–2.2). Specifically, in accordance with the pre–tensioning force and types of the bottom tendon, the PC beam subjected to the “cracking” method was herein named as “specimen B2”. More detailed information on the laboratory experiments and evaluation of the concrete mechanical properties were illustrated in Consiglio et al. (2026).

Table 1. Geometric properties of the PC beam specimens (B1–B2). l / h S f c f ptk σ p,0 (-) cm 2 cm 4 - - cm 3 MPa MPa MPa B1 643,0 63906,3 72,4 24,1 3209,0 42,0 1860,0 1488,0 B2 643,0 63906,3 72,4 24,1 3209,0 42,0 1860,0 1488,0 Specimen ID A J λ

3.2. Test setup and procedures of the destructive method (“cracking” method) The PC beam specimens were tested using a four-point static bending configuration. Each PC member was simply supported by two steel frames interposing a rubber layer of 10 mm in thick and 450 mm in side length between beam and supports, thus allowing free rotations in the vertical plane (while restraining out-of-plane displacements). The vertical load ( F ) – which was measured through a 300 kN load cell between the actuator and loading frame – was imposed using a steel beam with two loading points, and with a clear distance of 1,450 mm. The corresponding midspan deflections ( δ e ) due to the induced vertical loading were instead obtained by a vertical Linear Variable Differential Transducer (LVDT) at the supports, respectively, and three LVDTs along the span axes. Such transducers were of 0–25.0 mm in measurement range, whilst 0.001 mm in resolution. Vice versa, five inclinometers, of 0.001° in resolution, were fixed at the midline of each PC beam’s height. More detailed information on the test layout, deformation measurement and loading system were described in Consiglio et al. (2026).

(a)

(b)

Fig. 3. (a) PC beam specimens cast in 2003 (B1–B2); (b) Four-point bending test setup.

3.3. Results The first PC beam (B1) was only loaded to evaluate the torsional effects generated by the test setup and deflections measured with different types of instruments, according to the configuration depicted in Fig. 3(b). The vertical load ( F ) was arbitrary set to ensure that the beam behavior was elastic. Furthermore, a second loading phase was executed to evaluate the PC beam’s deformed configuration. The maximum vertical loading was set to avoid flexural cracking. The “load-displacement” relation was reported in Fig. 4(b); LVDT transducers (TR) at the midspan are considered in the graph. Specifically, the load indicated in “ y-axis ” refers to the recording of the load cell measurements, in turn positioned between the reaction frame and the steel beam and in contact with the PC beam.

(a) (b) Fig. 4. (a) Deformed configuration of the B1 specimen; (b) “Load-displacement” relation.