Behaviour of Concrete encased built up steel concrete composite columns with angle sections

1. BEHAVIOUR OF CONCRETE ENCASED
BUILT-UP STEEL CONCRETE COMPOSITE
COLUMNS WITH ANGLE SECTIONS
By
S.Amudhalingam (0271101)
Under the guidance of
Tmt.V.M.Shanthi
Lecturer in Civil Engg (Sel.Grd)

2. INTRODUCTION
COMPOSITE COLUMNS
EXPERIMENTAL PROGRAMME
ANALYTICAL PROGRAMME
RESULTS
GRAPHS
CONCLUSIONS
BIBLIOGRAPHY
PRESENTATION OUTLAY

3. General
SteelSteel and concreteand concrete
 Concrete is efficient in compression and steelConcrete is efficient in compression and steel
in tensionin tension
 Concrete encasement restrain steel against bucklingConcrete encasement restrain steel against buckling
 Protection against corrosion and fireProtection against corrosion and fire
 Steel bring ductility into the structureSteel bring ductility into the structure

4. COMPOSITE COLUMNS
 Definition
Composite columns are compressive
members in which steel section acts
compositely with concrete. So that, both steel
and concrete resist the compressive force.

5. abc
bcy
y
z
tf
h hc
cz
b
y
z
h = hc
b = bc
d
c
y
z
b
y
z
t
t
h
b e
d
t
y
z
f
d
t
y
z
cy
cz
tw
tf
tw tw
h = hc
b = bc
tf
TYPES OF COMPOSITE COLUMNS

6. OBJECTIVE OF THE PROJECT
 To study the behaviour of built-up steel
concrete composite columns with angle
sections under axial load and Uniaxial bending
(two eccentricities)
 To study the effect of Fibre reinforced
concrete and Additional reinforcement.
 To find the moment interaction curves for
the built-up sections for ANGLE sections.

7. TYPES OF SECTIONS
Types of
specimens
Dimensions of
the sections
Height of the
specimens
Types of
Variation
Built up
Angle
sections
20×20×3 mm
(3 nos)
890mm Angle sections
with
Conventional
concrete
Built up
angle
Sections
20×20×3 mm
(4 nos)
890 mm Angle sections
with
Fibre reinforced
concrete
Built up
Angle
sections
20×20×3 mm
(4 nos)
890 mm Angle sections
with
Additional
reinforcement

8. BUILT UP ANGLE SECTION
WITH SINGLE LACING

9. EXPERIMENTAL PROGRAMME
 MATERIAL PROPERTIES
 Cement _ Ordinary Portland Cement
(43 grade)
 Fine Aggregate – Passing through 4.75 mm
sieve
 Coarse Aggregate – 6 mm
 Water – Potable Water
 Steel – Cold rolled Steel Sections of 3mm
thickness
 MIX DESIGN - IS METHOD
1 : 1.67 : 2.71 : 0.45

10. Concreting
Composite
columns
Built-up sections
1:1.67:2.71:0.45
Curing

11. ANALYTICAL PROCEDURE
 PLASTIC RESISTANCE OF THE ENCASED
SECTIONS
Pp =Aa fy /γa +αc Ac fck / γc
Aa, Ac = Area of steel and concrete
fy = Yield strength of steel
fck = characteristic
compressive
strength of cube
αc =strength coefficient

12.  MAXIMUM MOMENT OF RESISTANCE OF
THE SECTION
Mmax = PyZpa +0.5PckZpc
Py = Yield strength of steel
Pck = characteristic strength of concrete
Zpa,Zpc = plastic section modulus for steel and
concrete section

13. ANGLE SECTION
Sl.
no
Types of
loading
First
crack
load in
KN
Maximum load in KN
T/E
% of
increase
Maximum
deflection in mm
T/E Position
Theoretic
al
Experimen
tal
Theoret
ical
Experi
mental
1 Axial 360 406 718 0.565 12.91 1.64 1.78 0.91 L/2
2
Eccentricity
@15mm
320 406 584 0.695 18.5 1.82 1.96 0.89 L/2
3
Eccentricity
@20 mm
370 372 430 0.84 0.6 2.02 1.99 0.96 L/2

14. ANGLE SECTION WITH REINFORCEMENT
Sl.
no
Types of
loading
First
crack
load in
KN
Maximum load in KN
T/E
% of
increase
Maximum
deflection in mm
T/E Position
Theoretic
al
Experimen
tal
Theoret
ical
Experi
mental
1 Axial 480 435 758 0.574 42.6 2.24 2.36 0.92 L/2
2
Eccentricity
@15mm
640 354 656 0.539 46.1 2.59 2.89 0.86 L/2
3
Eccentricity
@20 mm
446 435 647 0.672 32.8 2.86 3.04 0.79 L/2

15. ANGLE SECTION WITH FIBRE REINFORCED CONCRETE
Sl.
no
Types of
loading
First
crack
load in
KN
Maximum load in KN
T/E
% of
increas
e
Maximum
deflection in mm
T/E
Positio
n
Theoreti
cal
Experimen
tal
Theore
tical
Experi
mental
1 Axial 618 376.72 694 0.5428 45.72 2.82 3.12 0.79 L/2
2
Eccentricity
@15mm
430 376.72 543 0.693 31.7 3.14 3.32 0.74 L/2
3
Eccentricity
@20 mm
526 376.72 532 0.708 29.2 3.35 3.64 0.71 L/2

16. RESULTS AND DISCUSSIONS
Load Deflection graph for angle section under axial load
0
50
100
150
200
250
300
350
400
450
0 0.1 0.2 0.3 0.4 0.5 0.6
Deflection in mm
LoadinKN
l/4 x direction
l/2 x direction
3l/4 x direction
l/4 y direction
l/2 y direction
3l/4 y direction

17. Load deflection graph for Angle section under e - 15mm
0
10
20
30
40
50
60
70
80
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16
Delfection in mm
LoadinKN
l/4 x
3l/4 x
l/2 x

18. Load and Deflection of angle section with 20mm eccentricity
0
50
100
150
200
250
300
350
400
0 0.5 1 1.5 2 2.5 3
Deflection in mm
Loadinmm
l/4 x direction
l/2 x direction
3l/4 x direction

19. Load deflectiongraph for angle section with additional reinforcement under
axial load
0
100
200
300
400
500
600
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Deflection in mm
LoadinKN
l/4 x direction
l/2 x direction
3l/4 x direction
l/2 y direction

20. Load - Deflection for angle-sectionwith additional reinforcement under 15
mm eccentricity
0
50
100
150
200
250
300
350
400
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6
Deflection in mm
LoadinKN
l/4 x direction
l/2 x direction
3l/4 direction

21. Load - Deflection graph for angle section with additional reinforcement
under 20 mm eccentricity
0
100
200
300
400
500
600
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8
Deflection in mm
LoadinKN
l/4 x direction
l/2 x direction
3l/4 x direction

22. Load - deflection graph for fibre reinforced angle section under axial
load
0
100
200
300
400
500
600
700
0 0.5 1 1.5 2 2.5
Deflection in mm
LoadinKN
l/4 x direction
l/2 x direction
3l/4 x direction
l/2 y direction

23. Load - deflection for fibre reinforced angle section under 15 mm
eccentricity
0
100
200
300
400
500
600
0 0.5 1 1.5 2 2.5
Deflection in mm
LoadinKN
l/4 x direction
l/2 x direction
3l/4 x direction

24. Load - deflection for fibre reinforced angle section under
20 mm eccentricity
0
50
100
150
200
250
300
350
400
450
500
0 0.5 1 1.5 2 2.5 3
Deflection in mm
LoadinKN
l/4 x direction
l/2 x direction
3l/4 x direction

25. Moment curvature for Angle section with Fibre reinforced
concrete under e-15mm
0
1
2
3
4
5
6
7
0.000000 0.000001 0.000002 0.000003 0.000004 0.000005
Curvature in Radians
MomentinKN.m

26. Moment curvature of Angle section with Fibre reinfroced
Concrete under e-20mm
0
2
4
6
8
10
12
0.000000 0.000020 0.000040 0.000060 0.000080 0.000100 0.000120
Curvature in radians
MomentinKN.m

27. Moment curvature for Angle section with reinforcement under e-15mm
loading
0
1
2
3
4
5
6
0.000000 0.000002 0.000004 0.000006 0.000008 0.000010 0.000012 0.000014 0.000016
Curvature in radians
MomentinKN.m

28. Moment Curvature diagram for Angle section with reinforcement under
e-20mm
0
1
2
3
4
5
6
7
8
9
0.000000 0.000010 0.000020 0.000030 0.000040 0.000050 0.000060 0.000070 0.000080 0.000090 0.000100
Curvature in radians
MomentinKN.m

29. Moment curvature for Angel section with 15 mm eccentricity
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0.000000 0.000002 0.000004 0.000006 0.000008 0.000010 0.000012 0.000014
Curvature in radians
MomentinKN.m

30. Moment curvature for Angle section with e-20mm
0
1
2
3
4
5
6
7
8
0.000000 0.000020 0.000040 0.000060 0.000080 0.000100 0.000120
Curvature in radians
MomentinKN.m

31. C o mp a r i s o n o f M a x . D e f l e c t i o n f o r v a r i o us s p e c i me n s
0
100
200
300
400
500
600
0 0. 5 1 1. 5 2 2. 5 3
D e f l e c t i o n i n m m
A ngl e under ax i al l oad A ngl e under e-15 mm
A ngl e under 20 mm A ngl e r ei nf or c ed under ax i al l oad
A ngl e r ei nf or c ed under e-15mm A ngl e r ei nf or c ed under e- 20mm
Fi br e angl e s ec t i on under ax i al Fi br e angl e under e-15mm
Fi br e angl e under e-20mm

32. LOAD MOMENT INTERACTION DIAGRAM FOR ANGLE SECTION
0
50
100
150
200
250
300
350
400
0 1 2 3 4 5 6
MOMENT IN kN-M
LOADINkN
C
D
B
A
Mpl Mmax
Pp
Pc
0.5Pc
M
P

33. CONCLUSIONS
 Steel elements are not yielding throughout the
complete loading condition. Instead, concrete
material failure occurred at a load level close to the
maximum axial load.
 Failure occurred by crushing of the concrete at the
compression face of the cross section.
 The maximum load was attained without any
distortion of the built-up section or slip between steel
and concrete elements.

34.  The composite column will take more loads and the
bare steel skeleton will fail by elastic instability at
lower load value.
 The concrete can be relied upon to transfer the shear
between the steel element and concrete.
 Experimental load carrying capacity is more than
the theoretical load carrying capacity .
 when eccentricity is more, variation in the
prediction of load carrying capacity is more. When
eccentricity is less, variation is also less. This
concludes that the theoretical is conservative

35.  The deflections obtained experimentally
compared satisfactorily with theoretical values.
 Theoretical solution slightly underestimated
the value of the collapse load.
 No significant torsional displacement could be
detected at mid height of the column.
 Among all the specimens, built-up angle
section with fibre reinforced concrete is found
to take more load.

36. SCOPE OF THE FUTURE STUDY
 Experimental study on behavior of composite column with
different cross-sections can be carried out.
 In this thesis work, baby chips were used as coarse
aggregate. Study can be done by varying sizes of coarse
aggregate.
 The study can be extended to slender composite columns.
 The effect of shear connectors can be studied for future
work.
 Using cold formed and hot rolled steel sections, various
other shapes can be carried out and tested.

37. REFERENCES
 Furlong R.W. “Strength of steel encased concrete beam-columns”,
Journal of Structural Division, ASCE,1967:93(ST5):pp 115- 130.
 N.E.Shanmugam,B.Lakshmi “State- of – art – report on composite
columns”, Journal of Constructional Steel Research.
 Munoz , “Biaxially loaded concrete-encased composite columns”,
Journal of Structural engineering,ASCE,1997,pp1576- 1585.
 www.fb-embureyplus.com

38. Thank you!!!