PSI - Issue 64

Pat Rajeev et al. / Procedia Structural Integrity 64 (2024) 523–530 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

529

7

15

1970

19

133

20.30

19.95

20.06

3.42

3

Bed log

Dry bed log (slightly cracked) Severely degraded bed log with termite attack

16

1963

19

125

20.05

19.94

19.06

9.63

1

Bed log

17 18 19

1977 1964 1966

24 19 19

125

24.33 19.00 19.17

24.05 18.06 19.11

23.89 17.89 18.96

3.58

2 2 3

Bed log Bed log Bed log

Dry bed log Dry bed log

*

11.74

129

2.17

Dry bed log (sound wood) Severely degraded bed log

20

1964

19

126

20.42

19.37

18.68

16.32

2

Bed log

21

1968

19

106

19.68

13.76

18.05

51.11

2

Bed log

Dry bed log

* Cannot measure due to corrosion

Fig.5(a) illustrates the variation of the percentage reduction in cross-sectional area of the anchor rods. Observations indicate that, with the exception of specimen #21, the most significant reduction in cross-section occurs at the bottom of the specimens. The cross-section reduction closer to the ground level is comparatively lower than that at the bottom of the specimens. Copper Chromium Arsenate (CCA) treated timber bed logs are typically used for anchoring and both Zinc and steel are aggressive with CCA with the presence of moisture content. This might be the reason for increased corrosion rates at the bottom of the specimen. Fig.5(b) illustrates the variation in measured corrosion pit depths at both the bottom and within 300 mm below the ground level of the specimens. Further, the maximum and average corrosion pit depths proposed by Romanoff (1957) using power laws are illustrated in this figure for comparison. Except for specimen #21, all the measured corrosion pits depts are far lower than the maximum corrosion pit depth proposed by Romanoff (1957). The coefficients for the power law have been determined by considering the observed soil conditions from photographs and utilizing topographic maps corresponding to the geographical locations of the infrastructure.

(a)

(b)

Fig. 5. (a) Percentage reduction in cross-sectional area (b) Corrosion analysis

4. Summary and conclusions Visual inspection and corrosion assessment of 21 in-service cable stays supporting utility poles were conducted in this study to investigate the severity of corrosion in embedded anchor rods of steel cable stays. Following observations were made based on the visual inspection, measurements undertaken and the pictures of the pertaining site conditions of the specimens which were selected for this study. • Most of the specimens showed the largest degradation due to corrosion at the bottom end of the specimens. Moreover, some of the specimens had no signs of corrosion with in ~300mm inspection depth below the ground