1. PRE-STRESSED
CONCRETE
MUHAMMAD SHAHRON NIZAM
MUHAMMAD SHABERY
ZULHELMI
ROSZITA
KARTINA
NURUL NAZIRA
NUR ZANAH
2. Introduction
A prestressed concrete structure is
different from a conventional reinforced
concrete structure due to the application
of an initial load on the structure prior to
its use. The initial load or ‘prestress’ is
applied to enable the structure to
counteract the stresses arising during its
service period. The prestressing of a
structure is not the only instance of
prestressing. The concept of prestressing
existed before the applications in
concrete.
3.
4. Pre stressed 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
5. Pre stressing tendons (generally of high
tensile steel cable or rods) are used to provide
a clamping load which produces a
compressive stress that balances the tensile
stress that the concrete compression member
would otherwise experience due to a bending
load
Traditional reinforced concrete is based on
the use of steel reinforcement bars, re bars,
inside poured concrete.
6.
7. Pre – tensioned concrete
In pre – tensioning system, the high- strength
steel tendons are pulled between two end abutments
(also called bulkheads) prior to the casting of
concrete. The abutments are fixed at the end pre
stressing bed
Once the concrete attains the desires strength for
pre stressing, the tendon are cut loose from the
abutments. The pre stress is transferred to the
concrete from the tendons, due the bond between
them
During the transfer of pre stress, the member
undergoes elastic shortening. If the tendons are
located eccentrically, the member is likely to bend
and deflect (camber)
8. The various stages of the pre-tensioning
operation are summarized as follows :
Anchoring of tendons
Placing of
against the end
jacks
abutments
Cutting of the Applying tension
tendons to the tendons
Casting of
concrete
9.
10.
11. Post – tensioned concrete
Post-tensioning is a method of
reinforcing (strengthening) concrete or
other materials with high-strength
steel strands or bars, typically referred
to as tendons
Post-tensioning applications include
office and apartment buildings, parking
structures, slabs-on-ground, bridges,
sports stadiums, rock and soil anchors,
and water-tanks
12.
13.
14. Pre-tensioned Concrete
Improving the performance of the
building under various service
condition.
Allow to carry a greater load or span a
greater distance then ordinary
reinforce concrete.
It permits steel to be used at
stresses several times larger than
those permitted for reinforcing bars
15. Post-tensioned Concrete
Large reduction in traditional
reinforcement requirements as tendons
cannot distress in accidents
Tendons can be easily "woven" allowing a
more efficient design approach
Higher ultimate strength due to bond
generated between the strand and
concrete
Strong against compression
