1. What is Prestressed?? 2. Principle of Prestressed 3. Method of prestressing 4. Prestressed concrete structures 5. Advantages/application of Prestressed concrete 6. Disadvantages of Prestressed concrete 7. Comparison of RCC and Prestressed Concrete Flat Slabs

1. Prestressed Concrete Structures
and Its Applications
by
Mukesh Singh Ghuraiya
14PCES001
M. Tech.(3rd Sem)
Structural Engineering
School of Civil Engineering
Lingaya’s University, Faridabad
December, 2015
Seminar Report

2. Contents-
1. What is Prestressed??
2. Principle of Prestressed
3. Method of prestressing
4. Prestressed concrete structures
5. Advantages/application of Prestressed concrete
6. Disadvantages of Prestressed concrete
7. Comparison of RCC and Prestressed Concrete Flat
Slabs
8. References
2

3. Prestressed concrete
 Prestressed concrete is a
method for overcoming
concrete's natural weakness in
tension. It can be used to
produce beams, floors or
bridges with a longer span
than is practical with ordinary
reinforced concrete. It is often
used in commercial and
residential construction as a
beam and slab.
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A Prestressed concrete girder

4. Principle of Prestressed
 The principle behind Prestressed concrete is that
compressive stresses induced by high-strength steel
tendons in a concrete member before loads are
applied will balance the tensile stresses imposed in the
member during service.
 Prestressed concrete is basically concrete in which
internal stresses of a suitable magnitude and
distribution are introduced so that the stresses
resulting from the external loads are counteracted to a
desired degree.
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5. 5
Method of prestressing
Prestressing system basically classified in
two types….
Post-tensioning
Pre-tensioning

6. Pre-tensioning
6
Pre-tensioning is a method where
Prestressing Steels are pre-
stressed, prior to concreting,
against two rigid abutments. This
method is most widely used for
mass production of short span
structures, where pre-stressing is
also a prerequisite, such as
Railway Sleepers, Electric Polls,
Fencing Polls ,Pre-Tensioned
Slabs and I-Section Bridge
Girders etc.
Jack
Tendon

7. Pre-tensioning
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8. Pre-stressed beam
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9. Post-tensioning
9
Post-tensioning is a method where Prestressing Steels are
stressed after concrete attains its preliminary strength.
Two extreme ends of the structure are considered as a reaction
face, against which force is applied.
Ducts are placed inside the
formwork along with reinforcement
and the concreting is completed.
After achieving required concrete
strength, stipulated numbers of
Prestressing Steel Is then inserted
each duct for stressing purpose.
After achieving required elongation
and stresses they are blocked at
two ends with the help of Anchor Plates and grip.

10. Post-tensioning
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11. Post-tensioning
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12. Pre-stressed Concrete Structures
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Chaco-Corrientes Bridge, Argentina.
The longest precast Prestressed concrete cable-stayed box girder bridge in South America.
(Courtesy, Ammann &Whitney.)

13. Pre-stressed Concrete Structures
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L.V.Prasad Eye Institute.
Location: Hyderabad
Scope : Prestressed hollow core
slabs , Prestressed beams,
precast stairs, precast landing
slabs, precast wall panels

14. Pre-stressed Concrete Structures
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Phoenix Info city , filmnagar
Location: Hyderabad
Scope : : Prestressed
hollow core slabs,
Prestressed beams,
precast stairs,
precast landing slabs,
precast retaining walls

15. 15
Bridge decks

16. Advantages of prestressing
structures
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 Reduction of member thickness (material savings)
 Reduction of deflections
 Reduction of building height
 Reduction of building weight (foundation savings)
 Because prestressing steel has higher strength then mild steel,
 PT slabs are built with approximately 60 to 70% less steel (More
space for MEP installations.)
 Reduction of cracking due to permanent pre-compression.
 Better corrosion resistance
 Architectural freedom of larger spans and irregular slab geometry.
 Reduction in construction time i.e. fast construction
 No need of form work in case of precast.

17. Disadvantages of prestressing
structures
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 The major problem with Prestressed concrete is that it needs
specialized construction machineries like jacks anchorage etc.
 Advanced technical knowledge and strict supervision is very
important.
 For concrete prestressing, high tensile reinforcement bars are
needed which costs greater than generally used mild steel
reinforcement bars.
 Highly skilled labor is needed for Prestressed concrete
constructions.

18. Comparison of RCC and Prestressed
Concrete Flat Slabs
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Based on the study conducted by
Vakas K. Rahman & Prof. A. R. Mundhada
it could be concluded that RCC flat slabs are economical up to 9m
span but beyond that Prestressed concrete flat slabs become a
better choice. The cost advantage in percentage terms goes on
increasing in favour of Prestressed concrete with increasing span.
Besides, Prestressed concrete flat slabs being thinner provide
greater headroom & result in lesser seismic forces. Better
durability of Prestressed concrete structures is already a well
established fact

19. 1) Wikipedia.org/wiki/Prestressed concrete
2) http://www.preca.in/prefabricated-structures-prefab.html
3) http://freyssinet-india.com
4) http://www.preca.in
5) http://civilengineersforum.com
6) international Journal of Modern Engineering Research (IJMER) Vol. 3,
Issue. 3, May.-June.2013pp-1727-1730- Vakas K. Rahman & Prof. A. R.
Mundhada
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 References :-

20. THANK
YOU
!! धन्यवाद !!
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