Pt Flat Slab
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Transcript of Pt Flat Slab
SEMINARON
“Construction Aspects of Post-Tensioned Flat Slab”
Presented By
Mr. Mulla Amanulla Liyakatali Department Of Civil Engineering
Sanjay Ghodawat Institute, Attigre
Guided by- Prof. Patil V S Prof. Khurth V G
Session Outline Quick review of basic prestressing
technique General applications of prestressing
What is PT flat slab & its Types Construction aspects &materials Used
in PT flat slab Benefits over conventional RCC slab Discussion References
Prestressing is process of subjecting member under compressive stresses (compression) by external longitudinal loading.
Prestressing is process of subjecting member under compressive stresses (compression) by external longitudinal loading.
What Is Prestressing????
Prestressed Concrete vs. RCC
The main difference between PC and RC is the fact that steel reinforcement in the Prestressed Concrete is ACTIVE and the same is PASSIVE in Reinforced Concrete
Prestressed concrete can most easily be defined as pre-compressed concrete. This mean that compressive stress is put into concrete member before begin its working life and its position to be in areas where tensile stress develop under working load.
Also….
Types of Prestressing.
Post-tensioning-
Pre-tensioning-
What is Pre-tensioning???Steel reinforcement are stressed prior to concrete
placement, usually at a precast plant remote from the construction site.How Pre-tensioning is done ???
What is Post-tensioning ??? Steel tendons are stressed after the concrete has been placed and gained sufficient strength at the construction sites.Example : Post – Tensioning of Floor Slab,How Post-tensioning is done ???
STRESSING AFTER CASTING
Post-Tensioning System-
Application of Prestressed Concrete
COMMERCIAL / INDUSTRIAL FLOORS
SLAB ON GROUND
Buildings
What is PT Slab ???
The slab constructed with post-tensioning technique and having top and bottom surfaces parallel to each other.
Types of Flat Slab
STEPS IN CONSTRUCTION OF PT SLAB AND
MATERIALS
Shuttering
Marking
Layout Elevation
Profiling
Stages in formwork and reinforcement
ADJUSTABLE SPANNINGSTEEL PROPS
PLACING OF BOTTOM REINFORCEMENT
POSITION OF CHAIRS FOR PROFILING OF TENDONS
Elevation
Profiling
Layout
It is the arrangement of Duct/strands +ve and –ve moment.
Setting out of the cable profile, spacing of strands.
PLACING OF TOP REINFORCEMENT
LIVE END BLOCK REINFORCEMENT
BALLOONING AT DEAD END
DEAD END R/F
STRANDS USED FOR BONDED PT CONSTRUCTION
STRANDS USED FOR UNBONDED PT CONSTRUCTION
IDENTIFICATION OF TENDONS
PLASTIC DUCTS
STEEL DUCTS
FLAT DUCTS RESTED ON CHAIRS
MONOSTRANDANCHORS FOR UNBONDED P T
MULTISTRAND ANCHORS FOR UNBONDED P T
POSITIONS OF COMPONENTS
SHEAR RESESTING STUDS
CONCRETING OF SLAB.
Before casting, some precautions are taken such as checking the sheath joints and connection of grouting vents.
To minimize manual errors in casting and compaction, equipments like concrete pumps, surface compactor, Needle Vibrator are used.
CONCRETE MIXING PLANT
Mixing Unit
Batching Unit
Pumping Unit
CONCRETING
REMOVE POCKET FORMER
CLEAN THE STRANDS
MARK THE TENDONS
STRESS TENDONS
MEASURE ELONGATION
E.O.H PUMP- This is used to give hydraulic pressure to the jack.
Gauge-1:- used to control pressure of the jack.
Gauge-2:- used to block the strand into the jack.
CLEAN END PACKETS
PATCH END POCKETS
Grouting Machine
Grout Mixer &Collection Unit
Supply Pipe
Control Valves Pump
Feeding Unit
Controlling Unit
REDUCED SHORING COST
GEOMETRIC FLEXIBILITY
Reduced construction cost Faster construction Elegant structure Improved Water resistant Early formwork stripping Floor to floor height reduction Reduced foundation loadImproved deflection control Greater column free areasReduced seismic riskFlexible planningReduced cladding cost
BENEFITS OF FLAT SLAB
HOW CONSTRUCTIONIS FASTER?
HOW SECTION SIZES GET REDUSED?
•Post-tensioning reduces overall building mass, which is important in zones of high seismicity.
•Profiled tendons result in balanced gravity loads, significantly reducing total deflections.
•Permanent compressive forces result in greater control of cracks, deflection, and camber.
• The flat-plate building clearly behaves like the strong column-weak beam mechanism
Comparative cost of PT & RCCdurability of structure. innovative technique and theunavailability of materials and if PT slab get implemented on large scale which ultimately increase demand
of materials resulting in production of PT materials. And the material will be easily available
If we observe today’s situation which is exactly in favors of PT construction that is the number of companies entering in the production of PT materials is going on increasing. Resulting in the lesser cost of material which affects the economics of PT.
Also due to advanced portable stressing equipment and sophisticated design software helping in complex tendon profile and rigorous reinforcement details promoting the construction of PT and maximizing the use of today’s engineering skill.
DISCUSSIONS
11.0 REFERENCES
ONLINE REFERENCES:http://www.pci.orghttp://pubs.asce.org/books/http://www.bassbeams.co.zahttp://www.sciencedirect.com/http://www.bbrnetwork.comhttp://www.vsl.nethttp://www.gostructural.comhttp://enr.construction.comhttp://www.noorps.comhttp://www.structureae.de.comhttp://www.wisegeek.comhttp://www.tech9.inhttp://www.concretenetwork.comhttp://www.infolink.com.auhttp://www.ntpholdings.com/projects.asphttp://www.cclstressing.com/http://www.yde.co.il/http://www.conforce.co.uk/http://www.istructe.org.uk/
OFFLINE REFERENCES:
BOOKSPrestressed concrete by krishnarajuPrestressed concrete by DayaratnamModern prestressed concrete by James
R.Libby.STANDARD CODES IS: 1343 for prestressed concreteACI 318-77 ACI Standard building code
requirements for reinforced concrete. CP 110: Part I: 1972 Code of practice for the
structural use of concrete: Part I Design, materials and workmanship.
AS 1481-1974 SAA Prestressed concrete code. Standards Association of Australia.
RESOURSES