The document discusses advanced building construction techniques focusing on pre-tensioning and post-tensioning of prestressed concrete structures. It details the components used in prestressing, the methods of pre-tensioning and post-tensioning, their applications, and the differences between them. Additionally, it highlights the advantages of using prestressed concrete in large-span constructions like bridges and office buildings.

1. ADVANCED BUILDING CONSTRUCTION-IX
LONG SPAN STRUCTURES
RISHABH JAIN
B.ARCH(9THSEM)
1/16/FPA/B.ARCH/005

2. Pre-Tensioning
and
Post-Tensioning

3. FORMS OF THE PRESTRESSED STEEL:
1: Wires:
It is a single unit made of steel.
2:Strands:
Strands are two, three or seven wires that are wound to form a prestressing strand.
3: Tendons:
Tendons are wires and a group of strands is wound to form a prestressing strand.
4: Cable:
Cables are the series or group of tendons.
5: Bars:
The tendons are simply made up of a single steel bar and the diameter of this steel bar us
larger than that of wire.

4. Pre-Tensioning :
 In Pre-tensioning,wires or strands, called tendons( cables inside plastic ducts or
sleeves), are tensioned before the concrete is cast.
 The tendons are temporarily anchored using hydraulic jacks against some
abutments and then cut or released after the concrete has been placed and
hardened.
 The prestressing force is transferred to this concrete by the bond along
the length of the tendon.

8. A method of prestessing concrete in which tendons
are tensioned before the concrete is placed.
SO WE CAN ALSO DEFINE PRE TENSIONING AS :

9. Post-Tensioning :
 After adequate curing of concrete, reinforcing tendons (placed in side the
voids of the structure) are tensioned/stretched by jacks on the sides
 These spaces are then pumped full of grout to bond steel tightly to the
concrete.
 tendons are coated with grease or a bituminous material to prevent them
from becoming bonded to concrete. Another method used in preventing
the tendons from bonding to the concrete during placing and curing of
concrete is to encase the tendon in a flexible metal hose before placing it
in the forms. The metal hose is referred to as sheath or duct and remains in
the structure.

12. A method of prestessing concrete in which tendons
are tensioned after the concrete is placed.
SO WE CAN ALSO DEFINE POST TENSIONING AS :

13. Application
 This concrete is used in large-span distance between
which is not possible through the normal RCC
construction because rcc will make slab thickness more.
 Prestressed concrete is used in bridges to increase the possible
span of the bridge and to make the structure more durable
under moving traffic conditions.
 Used for office buildings where larger span, column free
spaces are required.

14. WATER TANKS

15. RETAINING WALL

16. RAILWAY SLEEPERS

17. PILES

18. Difference Between Pre-Tensioning and Post-Tensioning
PRE-TENSIONING POST-TENSIONING
 Pre-tensioning is done in the factories
thus suitable for precast construction
works
 Post-tensioning can be done in
factories as well as on the site
 Small sections are to be constructed  Size of a member is not restricted,
long-span bridges are constructed
by post-tensioning
 It is cheaper because the cost of
sheathing is not involved
 It is costlier because of use of
sheathing
 It is more reliable and durable  The durability depends upon the
two anchorage mechanism

19. BIBLOGRAPHY
• civiljungle.com
• theconstructor.org
• GOOGLE IMAGES
• SLIDE SHARE
• wikipedia.org
• steelconstruction.info