Short introduction about the "composite structure of concrete and steel.

1. COMPOSITE STRUCTURE
Presented by – Under the guidance of -
SUHAIL KHAN MR. ANUJ SHARMA
SURAJ MISHRA
RAVI SINGH
ANUJ KUMAR

2. CONTENT
 Objective
 About composite structure
 Elements of composite structure
 Examples of composite structure
 Advantages of composite structure
 Cost analysis
 Conclusion

3. OBJECIVE
 The two complementary materials, steel and concrete are
introduced together.
 To explain the composite action of the two different
materials and to show how the structural members are
used, particularly in building construction.
 Comparison between nominal construction and composite
construction on the basis of cost and time efficiency.

4. ABOUT COMPOSITE STRUCTURE
 In this type of construction we use Steel and Concrete as a
composite material.
 The reason why composite construction is often so good
can be expressed in one simple way - concrete is good in
compression and steel is good in tension.

5. ELEMENTS OF COMPOSITE STRUCTURE
 Main elements of composite structure as follows-
1. Composite deck slabs
2. Composite beams
3. Composite columns
4. Shear connector

6. 1. Composite deck slabs
 Composite slabs comprise reinforced concrete cast on top of profiled
steel decking, which acts as formwork during construction and
external reinforcement at the final stage.
 The decking may be either re-entrant or trapezoidal.
 Trapezoidal decking may be over 200 mm deep, in which case it is
known as deep decking.
 Slab thicknesses are normally in the range 100 mm to 250 mm for
shallow decking.
 Composite action increases the load carrying capacity and stiffness by
factors of around 2 and 3.5 respectively.

7. Re-entrant
decking
Trapezoidal
decking

8. 2. Composite beams
 Composite beams, subjected mainly to bending, consist of section
action composite with flange of reinforced concrete.
 Composite beams, subjected mainly to bending, consist of section
action composite with flange of reinforced concrete.
 also resist uplift forces acting at the steel concrete interface.
 Encased steel beam sections have improved fire resistance and
corrosion.
 Composite sections have higher stiffness than the corresponding steel
sections and thus the deflection is lesser.

9. Composite floor components –
downstand edge beam,
longitudinal trapezoidal
decking, through deck welded shear
stud, edge trim and concrete
Steel frame with |composite
beams during construction

10. 3. Composite columns
 A steel concrete composite column is a compression member,
comprising either of a concrete encased hot rolled steel section or a
concrete filled hollow section of hot rolled steel.
 It is generally used as a load bearing member in a composite framed
structure.
 Composite members are mainly subjected to compression and
bending.
 Significant economic advantages over either pure structural steel or
reinforced concrete alternatives.
 Increased stiffness, leading to reduced slenderness and increased
bulking resistance.

11. Typical composite column cross sections

12. 4. Shear connector
Types of shear connector -:
• RIGID TYPE - These connectors are very stiff and they sustain only a small
deformation while resisting the shear force. They derive their resistance from
bearing pressure on the concrete, and fail due to crushing of concrete
• FLEXIBLE TYPE - Headed studs, channels come under this category.
These connectors are welded to the flange of the steel beam.
• BOND OR ANCHORAGE TYPE - It is used to resist horizontal shear and to
prevent separation of girder from the concrete slab at the interface through
bond.

13. Shear
connector

14. Examples of composite structure
Construction started – 1997
Completed - 1999
Millennium Tower (Vienna)
Total height – 171meters
Floor count – 50
Floor area – 47200 sq.m

15. Advantages of composite structure
 In case of a composite structural system because of the lesser
magnitude of the beam end forces and moments compared to an
R.C.C system, one can use lighter section in a composite structure.
Thus, it is reduces the self-weight and cost of the structural
components.
 Under earthquake consideration because of inherent ductility
characteristics, steel-concrete composite structure perform better
than a R.C.C structure.
 In the cost estimation for building structure no savings in the
construction time for the erection of the composite structure is
included.
 In the cost estimation for building structure no savings in the
construction time for the erection of the composite structure is
included.

16. Cost analysis
Category 1 Category 2 Category 3 Category 4
Series 1 57620409 73029883 95776019 121352652
Series 2 56657375 69397893 86720189 105740009
57620409
73029883
95776019
121352652
56657375
69397893
86720189
105740009
0
20000000
40000000
60000000
80000000
100000000
120000000
140000000
160000000
Chart Title
Series 1 Series 2 Linear (Series 2)

18. CONCLUSION
 As the results show the Steel option is better than R.C.C. But the
Composite option for high rise building is best suited among all three
options.
 The reduction in the dead weight of the Steel framed structure is 32 %
with respect to R.C.C. frame Structure and Composite framed
structure is 30 % with respect to R.C.C. framed structure.
 Axial forces in column have been reduced by average 46% in steel
structure and reduced by average 7% in Composite framed structure
as compared to R.C.C. framed structure.
 Steel and composite structure gives more ductility to the structure as
compared to the R.C.C. which is best suited under the effect of
lateral forces.
 Total saving in the composite option as compared to the R.C.C. results
in 10 % so as with Steel it will be 6-7%.

19. THANK YOU!