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Concrete
Pre-tension
Post-tension
Presented by:
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What is Prestressed Concreted?
A pre-stressed 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.
Steel reinforcement introduce in combination
with concrete as reinforce concrete were ideal to
become a very strong and cheap buildingconstrual members
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PRESTRESSED CONCRETE
PRINCIPLE
Using high tensile strength steel alloys producing
permanent pre-compression in areas subjected to
Tension A portion of tensile stress is counteracted thereby
reducing the cross-sectional area of the steel
reinforcement
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The factors in chosen Prestressed
Concreted
RAPID
CONSTRUCTION
LONG SPAN
MAINTANANCE
FEE & SERVICES
SPACE
TO CONSERVE
HEAVY LOAD
VERSATILITY
DESIGN
FIRE RESISTANT
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TWO METHODS OF PRESTRESSED
CONCRETE
PRE-TENSIONED
HARPING/STRINGING
POST TENSIONED
BONDED POST-TENSION CONCRETE
UNBONDED POST-TENSION CONCRETE
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PRE-TENSIONING
The tendons of the reinforcement are stressed
and anchored at the mould before the concrete
is poured
Tendon are release from the abutment and the
pre stress is transferred into the concrete
member.
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PRE-TENSIONING
Pre-tension drawing detail.
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POST TENSIONING
It is one in which the reinfor cement is tens ioned after
the conc rete has fu l ly hardened.
A post-tensioning tendon is made up of one or more
pieces of pre-stressing steel, coated with aprotective coating, and housed inside of a duct or
sheathing. A tendon will have anchors on each end
to transmit the forces into the structure.
Long tendons may also have intermediate anchors
along their length. The pre-stressing steel can be a
high strength steel strand (typical in horizontal
applications) or a high strength steel bar (typical in
vertical applications).
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Typical post tensioning system
POST TENSIONING
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POST TENSIONING
Materials &
Components
Steel Wire Strand
Standard Couplers
Anchor Head And Wedges
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Steel Mould Ducting
POST TENSIONING
Material & Component
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POST TENSIONING
Machines
HYDRAULIC
STRESSING PUMP
GROUTING
MACHINE
MOBILE CRANE
HYDRAULIC JACK
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POST-TENSIONING
BONDED & UNBONDED
BONDED UNBONDED
The concrete is castaround a plastic, steel or
aluminium curved duct, to
follow the area where
otherwise tension would
occur in the concrete
element.
Each individual tendons iscoated with a grease
(generally lithium based)
and covered by a plastic
sheating formed in an
extrusion process.
USUAL PROBLEM AND
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USUAL PROBLEM AND
FAILURE
PRESTRESSED CONCRETEPRESTRESSING COMPONENT
Wire, strands and Tendons Failure
Tendons Extension Grouting and Ducts
Corrosion
CONCRETE AND REINFORCEMENT
Concrete Cracking
Concrete Spalling
Honeycombing
Concrete Cover
USUAL PROBLEM AND
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USUAL PROBLEM AND
FAILURE
PRESTRESSED CONCRETEPROBLEMS DURING CONSTRUCTION
Failures Due To Design
Construction Procedures Structural Behavior Problem
PROBLEMS AFTER OPENING
Durability
Rehabilitation and Meditation
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SITE LAYOUT
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PROJECTDETAIL
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BRIDGE.
PRESTRESSED
CONCRETEPost tension Segmental Box Girders The precast segmental box girder is designed as a continuous
single twin box of 14.08m width,4.0m length and 3.20m depth
structure with match cast joints, multiple shear keys and
prestressing tendons.
This type of box-girder was selected because of its size that
does not require extensive casting facilities, special heavy lifting
equipment and storage as compared to a precast full-length box
girder.
Total 7 types of Segmental Box Girder are designed for each
span.
Total 8,092 nosof segmental box girder are constructed along
the bridge.
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Typical Cross section of
SBG
16m is enough for th ree lane highway.
4.0m length and 3.20m depth s truc ture with
match cast jo ints, mul t ip le shear keys and
prestressing tendons.
Width 10-16m Width 10-16m
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CASTING
SEQUENCE
Tying rebar and ducting to in
dedicated reinforcement jig
Placement of reinforcement
cage in the SBG mould
Final inspection beforeconcreting
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Concreting the SBG
CASTING SEQUENCE contd
Completed SBG transported to
yard
SBG storage yard
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Span by Span
Method
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Installation of duct and anchor
head
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Stressing SBG process has beendone on site.
Setting the
Hydraulic Jack
with good position
to SBG tendons.
Hydraulic Jack
Lifting Cable
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Stressing SBG process has beensupervised by Engineer.
Tendon stress is
controlled by
Hydraulic Pump.
Hydraulic Pump
Hydraulic Jack
Fi ll G ti th SBG
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Finally, Grouting the SBGGrouting Machines & High pressure of pump
are used to grouting the SBG completely.
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Application of Epoxy as the Glue
for the connection of SBG
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SUPERSTRUCTURE PENANG BRIDGE.
POST TENSION BEAM AND SLAB D
The cable stayed bridge utilizes post
tensioned concrete beam-and-slab
decks.
Typical beam height:
2.8m
Deck slab thickness:
28cm
Post tension slab deck at stayed
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Post tension slab deck at stayed
cable Penang Bridge II
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structure
Prestessing in
progress.
Marked the strand before
stressing
Install the anchor
Post tension Beam structure
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Post tension Beam structurePrestessing in
progress.
Setting the Hydraulic Jack Install the wedges
Prepare to be stressed
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structure
Prestessing in
progress.
Set up the Hydraulic Pump
Record the result of stressing
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Pre-stressed Beam launchingprogress
Pre-stressed beams and deck slabs have also been
launched for the superstructure of bridge at the Mainland(Batu Kawan & Batu Maung)
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The launching of Pre-stressed
Beam
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References
(Enc ik Am inudin Al i , Prestressed Concrete: 2013)
(Matt Carter, 2nd Internat ional Seminar on Design &
Constru ct ion of Second Penang B ridge: 2008)
(Dato Prof Ir Dr. Ism ai l , Sust ainable Br idge Asia
Constru ct io n Pract ices, 2009)
(Dr. Bi jan O. Aalam i, Unbo nded and b ond ed Post-
Tensio ning System :1994)
(Mod jeski & Master, Inc , Prestressed Concrete Girder
Superst ructu re B ridge Design :2003)
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