PSI - Issue 64

A. Cagnoni et al. / Procedia Structural Integrity 64 (2024) 944–950 Alessandro Cagnoni, Pierluigi Colombi, Marco A. Pisani, Tommaso D’Antino / Structural Integrity Procedia 00 (2019) 000 – 000 5

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a. b. Fig. 4 (a) GFRP bar and (b) CFRP bar anchored with the novel wedge-barrel system at the beginning of the tensile test

3. Results and discussion The CFRP bar tensile tests were conducted to obtain a preliminary assessment of the novel anchor system efficiency. The tensile tests results are reported in Table 2, where the specimens were named T_A_X_8_N, where T = tensile, A = novel anchor system, X = bar type (i.e., GFRP or CFRP), 8 = nominal diameter (in mm), and N = specimen number. In Table 2 are reported the obtained tensile strength  maxA , the nominal anchor efficiency  nom computed as the ratio between  maxA and the bar nominal tensile strength, and the anchor efficiency  computed as the ratio between  maxA and the tensile strength obtained from the control samples reported in section “ 2.1 FRP bars ”. In Fig. 5, the axial load F - stroke  curves are reported for each specimen tested.

Table 2 . Tensile test results of bars anchored with the novel system. Specimen Tensile strength  maxA [MPa] Average tensile strength  maxA,avg [MPa] (CoV)

Nominal anchor efficiency  nom [-]

Average nominal anchor efficiency  nom,avg [-] (CoV)

Anchor efficiency  [-]

0.93 0.96 0.92 0.62 0.60 0.59

- - -

T_A_GFRP_8_1 T_A_GFRP_8_2 T_A_GFRP_8_3 T_A_CFRP_8_1 T_A_CFRP_8_2 T_A_CFRP_8_3

934 956 918

0.94 (1.96%)

936 (1.69%)

0.69 0.68 0.67

1517 1477 1457

0.61 (1.67%)

1484 (1.67%)

The experimental results presented highlight the good compatibility between the GFRP bars and the wedge-barrel anchor system. In fact, the average nominal anchor efficiency was close to 1, even though these bars failed due to longitudinal delamination (Fig. 6a). This failure mode may be attributed to the uneven stress distribution along the anchored portions of the bar, which eventually induced a delamination failure. On the other hand, the CFRP bars failed prematurely due to delamination (Fig. 6b), with an average nominal anchor efficiency of 0.61. Indeed, the tensile strength obtained was lower than that obtained with the bonded steel pipes (Table 1). These results should be considered a lower bound for this technology, as the tensile failure of all fiber filaments was not attained.