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Similaire à Composite structure of concrete and steel.(20)


Composite structure of concrete and steel.

  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)
  17. 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%.
  18. THANK YOU!