PSI - Issue 84

Silvia Manarin et al. / Procedia Structural Integrity 84 (2026) 231–239

234

A total of 297 measurements were collected: 96 in the single wire configuration and the remaining 201 in the strand configuration. In both phases, specimens approximately 60 cm long were used. They were anchored using conical end fittings to ensure proper gripping and were subjected to tensile loading using a Galdabini SUN60 universal testing machine. The single wire had a diameter of approximately 4.3 mm, while the outer wire of the strand had a nominal diameter of 15.2 mm. The transition from single wire to strand testing was intended both to validate the experimental setup and to gradually approach real application scenarios. It is important to note that, due to the relatively short available length (about 60 cm, with approximately 20 cm occupied by anchorage cones), it was not possible to reproduce the full-stress distribution typically encountered in-service. Following the laboratory testing, results are presented separately for the two experimental campaigns (single wire and strand wire), in line with the structure of this thesis. 4.1 Single Wire Tests In an initial phase, the results of 96 measurements performed on a single tensioned wire using a Galdabini SUN60 testing machine were analyzed. The cross-sectional area of the wire was 14.52 mm², and the loading protocol consisted of a three-step load sequence corresponding approximately to nominal stress levels of 275, 550, and 826 MPa. Measurements were first carried out on the wire in the “as-received” condition and subsequently repeated after surface cleaning with a neutral solution. No corrosion was observed on the wires. The investigated test configurations, together with the mean value of θ and the associated coefficient of variation ( CoV ), are summarized in Table 1 and represented by boxplot diagrams in figure 1. Table 1 reports for each configuration the mean value ( μ θ ), standard deviation ( SD θ ), and coefficient of variation ( CoV ) of θ , as a function of the adopted peak-fitting algorithm (Centroid (C), GNR PVII (G), Parabola(P)), cleaning condition (1 for cleaned, 0 for not cleaned), angle (in degrees), number of points (acquisition points), and acquisition time per point (in seconds).

Table 1 Results in terms of mean value of μ θ , standard deviation ( SD θ ) and coefficient of variation ( CoV ) for the single-wire configurations.

Algorithm Cleaning Angle (°)

N. Points

Time (s)

N_measure

μ θ

SD θ 0.1 0.15 0.13 0.1 0.16 0.11 0.13 0.13 0.88 0.11 0.15 0.12 0.12 0.09 0.23 0.11 0.17 0.13 0.11 0.13 0.1

CoV 0.1 0.16 0.15 0.08 0.14 0.09 0.1 0.13 0.14 0.17 0.09 0.14 0.12 0.11 0.09 0.25 0.12 0.12 0.12

CENTROID 1 CENTROID 1 CENTROID 1 CENTROID 0 CENTROID 1 CENTROID 0 CENTROID 1

35 35 35 40 40 40 40 35 35 35 40 40 40 40 35 35 35 40 40 40 40

9

60 60 60 60 120 120 120 60 60 60 60 120 120 120 60 60 60 60 120 120 120

3 6 4 7 6 3 3 3 6 4 7 6 3 3 3 6 4 7 6 3 3

1.06 0.92 0.91 1.27 1.15 1.14 1.0 0.92 0.15 1.19 1.1 1.01 1.08 1.1 0.93 0.96 1.41 1.11 1.16 1.05 1.1

11 11

9 9 9 9 9 9 9 9 9 9 9 9 9 9

GNR PVII GNR PVII GNR PVII GNR PVII GNR PVII GNR PVII GNR PVII

1 1 1 0 1 0 1

11 11

PARABOLA 1 PARABOLA 1 PARABOLA 1 PARABOLA 0 PARABOLA 1 PARABOLA 0 PARABOLA 1

11 11

0.1

0.12