A SHORT PRESENTATION ON PRE STRESSED CONCRETE

1. ADVANCE
CONSTRUCTION
TECHNOLOGIES
UNIT 1 _
CONSTRUCTION SYSTEMS AND DESIGN ,PLANNING – PRE
STRESSED CONCRETE CONSTRUCTION,PRE- CAST
CONCRETE.

2. PRE – STRESSED CONCRETE

3. PRE – STRESSED CONCRETE
• Pre stressed
concrete is the one in
which there have
been introduced
internal stresses OF
such that the
magnitude and
distribution that the
stresses resulting
from external loading
are counter balanced
to a desired degree.

4. PRE – STRESSED CONCRETE

5. WHY DO WE PRESTRESS ?

6. Tendons may consist of single wires , multi-wire strands or threaded bars that
are most commonly made from high-tensile steels , carbon fiber.
Steel Wires – wire is a single unit made of steel.
Strands – Group of wire not more than 7 wounded to form a prestressing
strand.
Tendon – Number of strands or wires are packaged together to form a
prestressing tendon.
Cable – When a number of tendons are grouped together and form single wire
then it is called Cable.
PRE – STRESSED CONCRETE

7. Thin Concrete Floor Constructed Using
Pre-stressed Concrete
Prestressed Concrete Bridge

8. TYPES

9. PRE- TENSIONIONING
PRE- STRESS TYPE
Pre-tensioning is a method of introducing prestress to the concrete structure
through the bond between concrete and tendons. Firstly, tension is applied to
the Tendon before casting concrete. Then the concrete is cast, and after it
hardens, the tension in the Tendon is gradually released, transferring prestress
to the concrete member. Tensioning is possible for one girder or several girders
depending on the length of the prestressing bed.

11. POST- TENSIONIONING
PRE- STRESS TYPE
IN POST-TENSIONING, THE STEEL TENDONS ARE TENSIONED AFTER
THE CONCRETE HAS BEEN CAST AND HARDENED. IN THE POST-
TENSIONING PROCESS, THE STEEL TENDONS ARE PLACED IN THE
FORMWORK BEFORE THE CONCRETE IS CAST, AND THE TENDONS
ARE PREVENTED FROM BONDING TO THE CONCRETE BY
WATERPROOF PAPER WRAPPING OR A METAL DUCT (SHEATH).
TENDONS BONDED TO THE CONCRETE ARE CALLED BONDED
TENDONS. UNBONDED TENDONS, LEFT WITHOUT GROUT OR
COATED WITH GREASE, HAVE NO BOND THROUGHOUT THE LENGTH
OF THE TENDON.

12. POST- TENSIONIONING
TYPES