The document discusses concrete filled steel tube (CFST) columns under axial compressive loads. It summarizes that CFST columns have higher load capacity than hollow steel tubes due to the composite action between steel and concrete. Experimental tests were conducted on circular and square CFST columns with varying concrete grades and heights. The results showed that square CFST columns had higher load capacity than circular columns. Ultimate load also increased with higher concrete grade. Failure modes included local and overall buckling. CFST columns provide advantages like increased strength, reduced construction costs, and improved fire resistance compared to reinforced concrete columns.

1. CONCRETE FILLED STEEL
TUBE COLUMNS ON AXIAL
COMPRESSIVE LOADS
GUIDED BY PRSENTED BY
TINA J NANDHU.H
ASST. PROFESSOR ROLL NO. 43
VAST-TC
1

2. CONTENTS
 Introduction
 Objectives
 Experimental study
 Experimental results
 Advantages and Applications
 Conclusion
 Reference
2

3. INTRODUCTION
3

4. Concrete filled steel tube columns
(CFSTC)
 These are a type of composite structures which
uses the advantage of both steel and concrete
 They comprise of a steel hollow section of
circular or rectangular shape filled with plain or
reinforced concrete.
 They are widely used in high-rise and multistorey
buildings as columns and beam-columns, and as
beams in low-rise industrial buildings.
4

5. Contd…
 The hollow tubes alone were designed in such a way that
they are capable of supporting the floor load up to three or
four storey height.
 Once the upper floors were completed, the concrete was
pumped into the tubes from the bottom.
 To facilitate easy pumping the tubes were continuous at the
floor level.
 Modern pumping facility and high performance concrete
make pumping three or four storey readily achievable.
 Due to the simplicity of the construction sequence, the
project can be completed in great pace. 5

6. Plan and section of CFST
6
(Source:www.iosrjournals.org)

7. Various types of CFST
 Composite column systems
 Reinforced composite column systems
 Concrete-filled double skin tubes (CFDST)
 Reinforced Concrete-filled double skin tubes
 Concrete-encased CFST columns
 Stiffened CFST columns
7

8. Contd….
8(Source:www.iosrjournals.org)

9. Objectives
 To study the behaviour of CFST and HST columns
in axial compression.
 To determine the axial load carrying capacity of
CFST and HST columns.
 To study the behaviour of square and circular
CFST columns in axial compression and to
determine the axial load capacity of the respective
columns.
 To compare the experimental results of CFST with
AISC-LRFD 2005 and Eurocode-4.
9

10. EXPERIMENTAL STUDY
10

11. 1.COMPARATIVE STUDY BETWEEN HOLLOW
STEEL TUBES (HST) AND CONCRETE FILLED
STEEL TUBE (CFST) COLUMNS
 Axial load is applied on HST & CFST specimen.
 The end surfaces on which concrete filled steel
tubes keeping for testing should be the plane.
 Specimens were simply supported at both ends.
11

12. DETAILS OF COLUMN SPECIMEN
 All the steel tubes have same c/s as 145mm X 82mm X
4.8mm.
 A total of 18 columns were tested (6 HST and 12 CFST).
 2 HST and 4 CFST columns of height 0.5m were tested for
axial compression loading.
 2 HST and 4 CFST columns of height 1m were tested for
axial compression loading.
 2 HST and 4 CFST columns of height 1.5m were tested for
axial compression loading
12

13. MATERIALS USED
 Hollow steel tubular section
 Nitowrap 410 (epoxy)
 Cement
 Fine aggregate
 Coarse aggregate
 Steel bars
 Water
 Curing compound
13

14. Properties of material
 Hollow steel tubes:
14
Table 1 Dimensional and geometric properties of hollow steel
Table 2 Mechanical properties of cold formed steel section

15. Contd…
 Cement: OPC 53 grade is used
15
Table 3 Properties of cement

16. Contd…
 Fine aggregate : Manufactured sand belonging to
zone II is used.
16
Table 4 Properties of sand

17. Contd…
 Coarse aggregate :
 maximum size of crushed stone dust was 12.5mm.
 The specific gravity was found to be 2.63
 water absorption was found to be 0.72%.
 Chemical admixture: a high performance super
plasticizer which is derived from carboxylic ether.
17
Table 5 Characteristics of admixture

18. Contd…
 Concrete: Two grades of concrete M20 and M40
were used. Both the concrete had collapsible slump
so that concrete can easily flow into the steel tube
by its own.
 Curing compound: Master Kure 181 which is a
non degrading, membrane forming liquid basically
derived from the acrylic resin.
18
Table 6 Characteristics of Master kure 181

19. Contd…
 Epoxy: used for bonding the two adjoining
surfaces. This epoxy used acts as bonding agent
between the concrete which is inside the tube and
internal surface of hollow steel tube.
19
Table 7 Characteristics of Epoxy

20. FLOW CHART
20

21. MIXING OF HARDNER AND EPOXY
21(Source: www.arcjournals.org)

22. Hollow steel tubes sections of 6m long pieces
22(Source: www.arcjournals.org)

23. Gas cutting of 6m long pieces ( BEFORE & AFTER)
23
(Source: www.arcjournals.org)

24. Finishing to the concrete exposed surfaces of column
24(Source: www.arcjournals.org)

25. CFST columns before and after application of curing
compound
25(Source: www.arcjournals.org)

26. Test set up of HST and CFST Column for axial
loading
26
(Source: www.arcjournals.org)

27. Test setup for the short columns of 1m and 1.5m
27(Source: www.arcjournals.org)

28. Experimental Results
TABLE 8 RESULTS OF HSTC
SL NO.
Specimen
Designation
Height of
Column
(m)
Ultimate
Compressive
Load
(KN)
1 HSTC-01 0.5 749.48
2 HSTC-02 0.5 757.33
3 HSTC-03 1.0 688.66
4 HSTC-04 1.0 680.81
5 HSTC-05 1.5 608.22
6 HSTC-06 1.5 622.94
28

29. Contd…
TABLE 9 RESULTS OF CFSTC
29
SL NO.
Specimen
Designation
Height of
column (m)
Grade of
concrete infilled
Ultimate
Compressive
Load (KN)
1 CFST-01 0.5 M20 884.86
2 CFST-02 0.5 M20 912.33
3 CFST-03 0.5 M40 1020.24
4 CFST-04 0.5 M40 1059.48
5 CFST-05 1.0 M20 797.55
6 CFST-06 1.0 M20 808.34
7 CFST-07 1.0 M40 819.14
8 CFST-08 1.0 M40 830.91
9 CFST-09 1.5 M20 725.94
10 CFST-10 1.5 M20 741.64
11 CFST-11 1.5 M40 755.37
12 CFST-12 1.5 M40 769.10

30. Comparison of Test Results with Codes
 LRFD AISC 2005
30

31. Contd…
 EUROCODE 4
31

32. Contd…
32

33. Comparison of experimental ultimate loads and design
ultimate loads
33

34. Failure of columns
Failure of HSTC
34(Source: www.arcjournals.org)

35. Contd…
35
FAILURE OF CFSTC
(Source: www.arcjournals.org)

36. TEST RESULT ANALYSIS
 The axial load carrying capacity of CFST columns was
increased by
19.3% and 38% for M20 and M40.
17.3% and 22.2% for M20 and M40.
19.7% and 24.3% for M20 and M40.
 The failure of the CFST columns of height 0.5m was basically
due to the local buckling near the mid height compare to the
failure of Hollow Steel Tubular columns which failed due to
inward local buckling near the ends.
 The failures of the CFST columns of height 1.0m and 1.5m
were basically due to the overall buckling which was very
much similar in case of Hollow Steel Tubular columns.
36

37. 2. STUDY ON CIRCULAR AND SQUARE
CONCRETE FILLED STEEL TUBE COLUMNS
SUBJECTED TO AXIAL COMPRESSION LOADS
 Here compare the difference of the axial load
capacity of the circular and square CFST columns
of high grade of steel for different grades (M20,
M30 & M40) of concrete.
 Then,axial loading capacity of the CFST columns
as per the EC4[6]design codes are calculated
37

38. PROPERTIES OF MATERIALS USED
 STEEL
 Here grade 310 steel is used
38
Table 11 Properties of steel

39. Contd…
 CONCRETE
39
Table 12 Concrete strengths

40. SPECIMEN PROPERTIES
40
Table 13 Specimen properties

41. EXPERIMENTAL SETUP
 Three different grades of concrete i.e. M20, M30 & M40 has been used
of two different shapes (circular & square) of CFST columns and 6
specimen for each grade of concrete is evaluated.
 The columns were fixed at both ends and axial compressive load was
applied.
 A pre-load of about 5kN was applied to hold the specimen upright.
 Dial gauge was used to measure longitudinal deformations of the
columns.
 The load was applied in small increments of 50 kN.
 At each load increment, the deformations were recorded.
 All specimens were loaded up to ultimate load
41

42. EXPERIMENTAL SET UP
42
(source:www.ijret.esatjournals.org)

43. EXPERIMENTAL RESULT ANALYSIS
 FOR CIRCULAR CFST
43

44. Contd…
 FOR SQUARE CFST
44

45. Graph between axial load and grade of concrete
45

46. Curve for hollow steel tube
46

47. Axial shortening curve for square CFST
47

48. Axial shortening curve for circular CFST
48

49. Comparison with EUROCODE
49

50. Failure of columns
For M20 concrete
50
(source:www.ijret.esatjournals.org)

51. Contd…
For M30 concrete
51
(source:www.ijret.esatjournals.org)

52. Contd…
For M40 concrete
52
(source:www.ijret.esatjournals.org)

53. TEST RESULT ANALYSIS
 Ultimate load (Pu) for square shape CFST sections are
quite higher compared to circular ones.
 It can be observed that the strength to weight ratio of 80
mm hollow square column is about 35% more than that
of 88.9 mm hollow circular column. Therefore, about
30% of steel can be saved when square columns are
used to obtain the same load capacity instead of circular
columns.
 Ultimate axial shortening values for circular CFSTs are
quite large than square ones for all grades of concrete.
i.e. ductility index of circular CFSTs are better.
53

54. Advantages of CFST columns
 Local buckling of the steel tube is delayed, and the
strength deterioration after the local buckling is
moderated, both due to the restraining effect of
concrete.
 The strength of concrete is increased due to the
confining effect provided from the steel tube, and
the strength deterioration is not very severe, since
the concrete Spalding is prevented by the tube.
 Drying shrinkage and creep of concrete are much
smaller than ordinary reinforced concrete.
54

55. Contd..
 Forms and reinforcing bars are omitted and
concrete easting is done by tramline tube or pump-
up method, which lead to savings of manpower
and constructional cost and time.
 Steel of the CFT section is well plasticized under
bending since it is located on the outside the
section.
 Concrete improves the fire resistance performance,
and the amount of fireproof material can be
reduced or its use can be omitted.
55

56. Contd…
 The size of column is smaller, increases the usable
floor area by 3.3% (5500m2).
 CFST columns used concrete 62% less and steel
5%~10% less than that of RC columns.
 Compared with steel column, CFST ones used steel
is 50% less and decreases cost 45%.
 4. It is about 55% lighter than that of RC. Hence,
the foundation cost can be reduced.
56

57. Application of CFST
1. Shenzhen SEG Plaza
 source:wikipedia
 Highest tall building adopted CFST
 completed in 1999
 Highest one in China and abroad
 356 meters tall
57

58. Contd…
2. Wangchang East River Bridge
source:wikipedia
 First CFST Arch Bridge in China
 CFST has higher compression capacity and ductility and is
good for the application of arch bridge
 Span 115 m
58

59. CONCLUSION
From the experimental study, it is observed that
 The axial load carrying capacity of CFST columns
compared to hollow steel tubes was increased.
 The failure of the CFST columns was basically
due to the local buckling near the mid height
compare to the failure of Hollow Steel Tubular
columns which failed due to inward local buckling
near the ends.
59

60. Contd…
 Ultimate load (Pu) for square shape CFST
sections are quite higher compared to circular
ones. Although, they were kept of same
thickness & same resisting area under
compressive load.
 Ultimate axial shortening values for circular
CFSTs are quite large than square ones for all
grades of concrete. i.e. ductility index of
circular CFSTs are better.
60

61. REFERENCE
1.Pandu Ranga Kirankumar.T, S.V.V.K.Babu, D.Aditya Sai Ram, Comparative
Study of Concrete Filled Steel Tube Columns under Axial Compression,
International Journal of Constructive Research in Civil Engineering (IJCRCE)
Volume 2, Issue 2, 2016, PP 11-17.
2.D. R. Panchal, V. P. Sheta, EXPERIMENTAL STUDY ON CIRCULAR AND
SQUARE CONCRETE FILLED STEEL TUBE COLUMNS SUBJECTED TO
AXIAL COMPRESSION LOADS, IJRET: International Journal of Research in
Engineering and TechnologyeISSN 2321-7308
3.Beena Kumari, Concrete Filled Steel Tubular (CFST) Columns in Composite
Structures, IOSR Journal of Electrical and Electronics Engineering (IOSR-JEEE)
e-ISSN: 2278-1676,p-ISSN: 2320-3331, Volume 13, Issue 1 Ver. II (Jan. – Feb.
2018), PP 11-18
4.Eurocode 4. Design of composite steel and concrete structures. Part 1.1, General
rules and rules for buildings (with UK national application document), DD ENV
1994-1-1. London (UK): British Standards Institution; 1994.
5.AISC, Load and Resistance Factor Design Specification for Structural Steel
Buildings, American Institute of Steel Construction, 2005
61

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