PSI - Issue 62

Isabella Mazzatura et al. / Procedia Structural Integrity 62 (2024) 369–376 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

375

7

Sample 8 Sample 8_1

69

31

45% 43% 53% 22% 17% 33% 33% 24% 18% 18% 1% 16% 6% 15% 44% 7% 24% 17% 48% 13% 25% 22% 27%

122

98

81%

Strand Extracted Strand Extracted Strand Extracted Strand Extracted Strand Extracted Strand Extracted Strand Extracted Strand Extracted Strand Extracted

4 2 5 5 8 7 6 6 5 3 3 3 3 3 3 3 5 3 3 3 5 3 3 4 3 3 3 3 3 3

Sample 8_2 Sample 8_3 Sample 8_4 Sample 9_2 Sample 9_3 Sample 9_4 Sample 9_5

264

113

46

24 24 43 33 41 48 18 30 13 16 17 13 64 36 38 44 43 94 63 22 15 31 30 26 37 8 2 25 6 8

108 257 100 127 200 103

Sample 9 Sample 9_1

157

69

44%

Sample 10 Sample 10_1 160

138

25

18%

Wire Wire Wire Wire Wire Wire Wire Wire Wire Wire

New - not stabilized 3 New - not stabilized 3 New - not stabilized 3 New - not stabilized 3

Sample 10_2 131 Sample 10_3 154 Sample 10_4 105 Sample 11_2 -30 Sample 11_3 -14 Sample 12_2 -73 Sample 12_3 -80 Sample 13_2 277 Sample 13_3 151 Sample 13_4 205 Sample 13_5 160 Sample 14_2 206 Sample 14_3 244 Sample 14_4 198 Sample 14_5 170 Sample 15_2 236 Sample 15_3 263 Sample 15_4 286 Sample 15_5 176

Sample 11 Sample 11_1 -55

-33

20

62%

New New New New New New

111%

Sample 12 Sample 12_1 -111

-88

20

23%

Sample 13 Sample 13_1 134

186

58

31%

Strand New Strand New Strand New Strand New Strand New Strand New Strand New Strand New Strand New Strand New Strand New Strand New Strand New Strand New Strand New

Sample 14 Sample 14_1 36

260% 30%

171

80

47%

9% 7%

18% 13% 11% 14% 3% 35%

Sample 15 Sample 15_1 237

240

41

17%

8

61

Excluding measurement points higher than the mean value increased by 30% or lower than the mean value decreased by 30% (as an assumption), the mean residual stresses results associated with each sample considering all measurement points became those shown in Fig. 6. Even if in that way the standard deviations associated are lower, and therefore also the CoVs, the variations in terms of residual stresses became significantly higher considering homogeneous group of samples (not stabilized wires, stabilized wires, and strands).

100 150 200 250 300

240

191

163

163

137

138

88

-250 -200 -150 -100 -50 0 50

Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 Sample 7 Sample 8 Sample 9 Sample 10 Sample 11 Sample 12 Sample 13 Sample 14 Sample 15

-42

-72

-84

-88

Residual stress [MPa]

-93

-111

-130

-187

Fig. 6. Mean values of residual stresses on each specimen (purified data). The error bars represent the standard deviations.

4. Conclusions In conclusion, although the technique is promising in the current field of application, i.e., defining prestressing in PT elements, many variables must be studied thoroughly. Residual stresses seem to be a crucial parameter to be