July - AMMJ

Effective Thickness of Corroded Steel Plates
43
AMMJ
1
1
0.8
0.8
( yn / y )
0.6
0.4
Y = 0.204 + 0.795 X
R 2 = 0.911
( bn / b )
0.6
0.4
Y = 0.185 + 0.839 X
R 2 = 0.943
0.2
0.2
0 0.2 0.4 0.6 0.8 1
, (t min / t 0 )
0 0.2 0.4 0.6 0.8 1
, (t min / t 0 )
Figure 7 Relationship of (a) yield stress ratio, (b) tensile stress ratio and minimum thickness ratio ( )
Considering both yield and tensile stress conditions, it was found that the λ =0.2 gives the best agreement and
hence the representative effective thickness parameter can be defined as:
t eff = 0.2 t 0 + 0.8 t min (8)
Now, the maximum corroded depth (t c,max ) can be expressed as:
t c,max = t 0 - t min (9)
So, considering Eq. 8 and Eq. 9, the following relationship can be obtained for representative effective thickness
(t eff ), which can be used to estimate the remaining yield and tensile strengths of a corroded steel plate.
t eff = t 0 - 0.8 t c,max (10)
A further detailed study comprises with experimental and numerical analysis of more specimens with moderate and
severe corrosion is deemed necessary to understand the significance of this λ value and verify this for different
corrosion levels and environmental conditions.
10
10
( yn / y ) ( bn / b )
8
(a) Matsumoto et al. 1989
8
(b) Muranaka et al. 1998
t Matsumoto
6
4
t Muranaka
6
4
2
2
Coefficient of Correlation: R 2 = 0.88
0 2 4 6 8 10
t e_b
10
Coefficient of Correlation: R 2 = 0.04
0 2 4 6 8 10
t e_b
10
8
(c) Kariya et al. 2003
8
(d) Proposed
t Kariya
6
4
t eff (Proposed)
6
4
2
Coefficient of Correlation: R 2 = 0.81
2
Coefficient of Correlation: R 2 = 0.90
0 2 4 6 8 10
0 2 4 6 8 10
t e_b
t e_b
Figure 8 Relation between different predicted effective thickness parameters with te_b
Vol 24 No 3