power point presentation on Numerical studies on corroded steel angle members

1. GUIDED BY PREPARED BY
Roshni K G Sushendhu K C
Assistant Professor M.Tech S2
Thejus Engineering TJE16CESE10
College
1

2.  Steel angle section members are used in various
structures such as bridges, trusses and other
structures
 Corrosion is one of the most common problems of
steel structures
 Corroded angle sections can be strengthened by
CFRP
2

3.  Numerical studies such as ABAQUS can be used
for the study of corroded steel angles
 Experimental test is conducted to check the
efficiency of numerical studies
3

4.  High strength per unit mass
 Quality and high durability
 Speed of construction
 It can be strengthened at any later time
 Reusable
4

5.  It is susceptible to corrosion
 Steel members are costly
 Maintenance cost is high
5

6.  Corrosion is the destructive degradation of metals in
presence of any medium
 It reduces the gross cross sectional area which leads
to higher stresses in the corroded area
6

7.  Formation of hydroxide ions
O2 + 4e- + 2H2O → 4OH
Fe → Fe2+ + 2e-
 Overall equation is as follows
2Fe + 2H2O + O2 → 2Fe2+ + 4OH-
 Formation of Rust
Fe2+ + 2OH- → Fe(OH)2
Fe(OH)2 + O2 → Fe(OH)3
Fe(OH)2 dehydrates to Fe2O3.nH2O (rust)
7

8.  Uniform corrosion
 Pitting corrosion
 Crevice corrosion
 Stress corrosion
 Galvanic corrosion
 Erosion corrosion
8

9.  Distributed uniformly over an exposed surface
 Easy to measure, predict and design
 Resulting from the contact with strong acidic or
alkaline electrolytes
 Most serious form of corrosion observed on steel
structures
9

10. Materials used for experimental studies are:
1. Steel Angle Sections
Totally nine angle specimens were considered.
Each set contains
Angle Un-Corroded (AUC)
Angle corroded (AC)
Angle corroded and retrofitted (ARC)
10

11. 11

12. 2. CFRP
Excellent tensile properties, low densities, chemical
stabilities, good thermal and electrical conductivities,
excellent creep resistance
Particulars Values
Modulus of
Elasticity
295600 MPa
Tensile strength 378.2 N/mm2
Density 1.69 ton/mm3
Poisson’s ratio 0.33
12

13. 3. Adhesive
Used for binding CFRP to steel angle section
Araldite AW 106 resin/Hardener HV 953Uepoxy
adhesive
Property Resin Hardener
Colour/Appearance Creamy,
viscous/ liquid
Amber liquid
Specific gravity 1.17 0.92
Viscosity @ 25°C (cP) 50000 35000
13

14.  Specimens were initially subjected to natural
corrosion by immersing in 3.5% NaCl solution
14

15.  Then accelerated using Galvanostatic corrosion
method
15

16.  Member which was subjected to corrosion acted as
the anode and same steel was used as the cathode
16

17.  Anode got oxidized and the cathode got reduced
resulting in a corroded section at the anode
17

18.  Retrofitted with one layer of CFRP strip by using
Araldite AW106 resin and HV 953U epoxy as
hardener
18

19.  CFRP was properly pasted to the corroded portion
of the specimen
19

20.  One more coat of the resin-hardener mix was
applied over the CFRP to have proper binding and
to protect the fibers from getting damaged
20

21. Specime
n
Size
(mm)
Length
(mm)
Initial
thickness
(mm)
Final
thickness
(mm)
Initial
weight
(kg)
Final
weight
(kg)
Leg
1
Leg
2
Leg
1
Leg
2
AUC-
100
100X100
X6
1000 6.27 6.76 - - 16.55 16.55
AC-100 100X100
X6
1000 6.45 6.33 5.59 5.27 16.49 15.87
ARC-
100
100X100
X6
1000 6.6 6.54 4.9 5.49 16.94 -
100X100
X6
- - - 8.22 8.16 - 16.61
21
Thickness and weight measurement of 100x100x6 mm

22. 22
Specime
n
Size
(mm)
Length
(mm)
Initial
thickness
(mm)
Final
thickness
(mm)
Initial
weight
(kg)
Final
weight
(kg)
Leg
1
Leg
2
Leg
1
Leg
2
AUC-75 75X75X
5
1200 5.20 5.17 - - 15.65 15.65
AC-75 75X75X
5
1200 5.27 5.25 4.09 4.15 16.51 15.75
ARC-75 75X75X
5
1200 5.27 5.33 4.44 4.53 16.56 -
75X75X
5
- - - 6.89 6.86 - 16.26
Thickness and weight of 75x75x5xmm

23. 23
Specime
n
Size
(mm)
Length
(mm)
Initial
thickness
(mm)
Final
thickness
(mm)
Initial
weight
(kg)
Final
weight
(kg)
Leg
1
Leg
2
Leg
1
Leg
2
AUC-70 70X70X
5
1000 5.05 5.06 - - 13.91 13.91
AC-70 70X70X
5
1000 5.01 5.09 4.29 4.40 13.55 12.05
ARC-70 70X70X
5
1000 5.00 5.03
4
4.68 4.57 13.51 -
70X70X
5
- - - 8.40 8.51 - 13.31
Thickness and weight of 70x70x5 mm

24. 24

25.  Flange plates of diameter 200 mm and thickness
16mm were fixed at both the ends
 Then subjected to axial compressive force of
500 kN
 The axial and lateral direction displacements were
measured using linear variable differential
transducer
 LVDT were placed at corroded region
25

26.  Numerically modeled with ABAQUS
 Uniform corrosion is modeled by thickness
reduction
 The solid element used is element C3D8R
26

27. Boundary conditions:
All translation degrees of freedom at top nodes
except the vertical displacement as fixed and all
degrees of freedom restrained at bottom
Particulars Values
fu 360 N/mm2
fy 466 N/mm2
modulus of elasticity 210000 N/mm2
density 7850 kg/m3
27

28.  Load magnitude is considered as unknown and
loads and displacements are solved
Typical finite element model Discretised column model
28

29.  Specimens were modelled using ABAQUS and the
results were compared with experimental analysis
 The ultimate strength as well as deflection for
various specimens was studied
 CFRP coating increases strength by15% to 35%
29

30.  Load bearing capacity of specimens
Specimen No. Numerical method
(kN)
Experimental
method (kN)
AUC-100 338.04 327.470
AC-100 204.150 203.50
ARC-100 244.980 242.140
AUC-75 186.913 187.759
AC-75 117.709 111.839
ARC-75 180.981 184.564
AUC-70 168.397 172.153
AC-70 126.142 123.27
ARC-70 158.038 159.750
30

31.  Load vs. Axial Displacement behavior curves for
100x100x6 specimens
31

32.  Load vs. Axial Displacement behavior curves for
70x70x5mm and 75x75x5mm specimens
32

33. 33

34.  Both numerical and experimental results match
well for un-corroded, corroded, and retrofitted
specimens
 Load vs. axial displacement graph shows that, as
the percentage of corrosion increases, the ultimate
capacity of the members decreases
34

35.  Corrosion has a major impact on the failure mode
of the member
 The capacities of corroded members were
observed between 20% to 40% of un-corroded
capacities
 For the un-corroded members, buckling was
observed at mid height
35

36.  For corroded members, the critical region of
failure shifted towards the location of minimum
thickness region
 CFRP coating increases strength by15%-35%
compared to the corroded specimen
 As the percentage of corrosion increases, the
ultimate capacity decreases
 Numerical studies results in less time, reduced
cost and less error compared to experimental
program
36

37.  Aparna Ben, Vikraman.R, Cinitha.A, Umesha.P.K, Eapen Sakaria,
(2014) “Compressive Strength of Uniformly Corroded Steel Angle
Members Retrofitted with CFRP”, International Journal of
Emerging Technology and Advanced Engineering - ISSN2250-2459,
Vol. 4.
 Cinitha. A, Umesha.P. K, and Nagesh R. Iyer, (2014) “An Overview
of Corrosion and Experimental Studies on Corroded Mild Steel
Compression Members”, KSCE Jl. of Civ. Engg., Vol. 18, pp 1735–
1744.
 Katalin Oszvald, (2014) “Behaviour of corroded steel angle
compression members – numerical study”
 Katalin Oszvald, “Finite element analysis of corroded steel angles
under compression”, BME Department of Structural Engineering,
Conference of Junior Researchers in Civil Engineering.
 Sharon John1, C. Banu Priya, Y. Preethy Dharanya, Meera
Muthulakshmi, R. Suresh, M. S. Dinesh Kumar and M. S. Hari
Krishnan, (2016), “Numerical Investigation on Corroded and
Uncorroded Structural Steel Coupons”, Indian Journal of Science
and Technology, Vol 9
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