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 3

946

linear regression of experimental responses between the strain points 0.001 and 0.006 (American society for testing and materials (ASTM) (2021)). Specimens were named T_CFRP_8_N, where T = tensile, CFRP = bar type, 8 = nominal diameter (in mm), and N = specimen number.

Table 1 . Tensile test results of control specimens

Average tensile strain [%] (CoV)

Tensile strain  max [%]

Tensile strength  max [MPa]

Elastic modulus E [GPa]

Average elastic modulus [GPa] (CoV)

Average tensile strength [MPa] (CoV)

Specimen

T_CFRP_8_1 T_CFRP_8_2 T_CFRP_8_3

2070 2230 2260

1.21 1.30 1.34

168.40 167.30 164.70

2190 (3.77%)

1.28 (4.11%)

166.80 (0.98%)

The CFRP bars provided an average tensile strength of 2190 MPa, a corresponding average ultimate strain of 1.28%, and an average elastic modulus of 166.80 GPa. In Fig. 1, the axial load F - stroke  curves are reported for each specimen tested. Fig. 2 shows a representative failure mode observed in specimen T_CFRP_8_1. The results obtained showed that the bonded steel pipes were not sufficient to fully exploit the tensile capacity of the bars. In fact, failure occurred due to slippage of the bars within one of the two anchor pipes. This determined a sudden decrease of the applied load, whereas the bar did not show any failure.

T__CFRP_8_1 T__CFRP_8_1 T__CFRP_8_1

140

120

100

40 Axial load F [kN] 60 80

20

0

0

2

4

6

8

10

12

Stroke  [mm]

Fig. 1 Axial load F - stroke  curves of CFRP bars with bonded steel pipes.

Fig. 2 Representative failure mode of specimen T_CFRP_8_1.