Prestressed concrete combines high-strength concrete and high-strength steel in an active manner by tensioning steel tendons and holding them against the concrete, putting it into compression. This transforms concrete from a brittle to a more elastic material. It allows for optimal use of each material's properties and better behavior under loads. Prestressed concrete was pioneered in the 1930s and its use has expanded, finding applications in bridges and other structures. Common methods are pretensioning and post-tensioning, using various tendon types, with bonded or unbonded configurations. Tensioning is done using mechanical, hydraulic, electrical or chemical devices.
It is the presentation based on pre- stressed concrete construction which includes each and every point and scope which may be useful to civil engineering students
Prestressed concrete ,post tensioning ,pre tensioning, where normal concrete can not be used and need of more strength is required this type of concrete are used. Metal bars are replaced by the tendoms which are generally used to create tension in concrete. So because of that beam bends in upward direction and when load is applied it come in normal conditon.
It is the presentation based on pre- stressed concrete construction which includes each and every point and scope which may be useful to civil engineering students
Prestressed concrete ,post tensioning ,pre tensioning, where normal concrete can not be used and need of more strength is required this type of concrete are used. Metal bars are replaced by the tendoms which are generally used to create tension in concrete. So because of that beam bends in upward direction and when load is applied it come in normal conditon.
Prestressed concrete structures and its applications By Mukesh Singh GhuraiyaMukesh Singh Ghuraiya
1. What is Prestressed??
2. Principle of Prestressed
3. Method of prestressing
4. Prestressed concrete structures
5. Advantages/application of Prestressed concrete
6. Disadvantages of Prestressed concrete
7. Comparison of RCC and Prestressed Concrete Flat Slabs
This presentation gives a brief introduction on FRC's history, definition and why is it used. Types of FRC's and it's applications is explained in detail in later stages.Also, it covers various properties that affects FRC and a Case study in end.
Prestressed concrete structures and its applications By Mukesh Singh GhuraiyaMukesh Singh Ghuraiya
1. What is Prestressed??
2. Principle of Prestressed
3. Method of prestressing
4. Prestressed concrete structures
5. Advantages/application of Prestressed concrete
6. Disadvantages of Prestressed concrete
7. Comparison of RCC and Prestressed Concrete Flat Slabs
This presentation gives a brief introduction on FRC's history, definition and why is it used. Types of FRC's and it's applications is explained in detail in later stages.Also, it covers various properties that affects FRC and a Case study in end.
Prestressed concrete is a structural material that allows for predetermined, engineering stresses to be placed in members to counteract the stresses that occur when they are subject to loading.
Basic concepts – Advantages – Materials required – Systems and methods of prestressing –
Analysis of sections – Stress concept – Strength concept – Load balancing concept – Effect of
loading on the tensile stresses in tendons
CFD Simulation of By-pass Flow in a HRSG module by R&R Consult.pptxR&R Consult
CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
Here's a great example: At a large natural gas-fired power plant, where they use waste heat to generate steam and energy, they were puzzled that their boiler wasn't producing as much steam as expected.
R&R and Tetra Engineering Group Inc. were asked to solve the issue with reduced steam production.
An inspection had shown that a significant amount of hot flue gas was bypassing the boiler tubes, where the heat was supposed to be transferred.
R&R Consult conducted a CFD analysis, which revealed that 6.3% of the flue gas was bypassing the boiler tubes without transferring heat. The analysis also showed that the flue gas was instead being directed along the sides of the boiler and between the modules that were supposed to capture the heat. This was the cause of the reduced performance.
Based on our results, Tetra Engineering installed covering plates to reduce the bypass flow. This improved the boiler's performance and increased electricity production.
It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Hybrid optimization of pumped hydro system and solar- Engr. Abdul-Azeez.pdffxintegritypublishin
Advancements in technology unveil a myriad of electrical and electronic breakthroughs geared towards efficiently harnessing limited resources to meet human energy demands. The optimization of hybrid solar PV panels and pumped hydro energy supply systems plays a pivotal role in utilizing natural resources effectively. This initiative not only benefits humanity but also fosters environmental sustainability. The study investigated the design optimization of these hybrid systems, focusing on understanding solar radiation patterns, identifying geographical influences on solar radiation, formulating a mathematical model for system optimization, and determining the optimal configuration of PV panels and pumped hydro storage. Through a comparative analysis approach and eight weeks of data collection, the study addressed key research questions related to solar radiation patterns and optimal system design. The findings highlighted regions with heightened solar radiation levels, showcasing substantial potential for power generation and emphasizing the system's efficiency. Optimizing system design significantly boosted power generation, promoted renewable energy utilization, and enhanced energy storage capacity. The study underscored the benefits of optimizing hybrid solar PV panels and pumped hydro energy supply systems for sustainable energy usage. Optimizing the design of solar PV panels and pumped hydro energy supply systems as examined across diverse climatic conditions in a developing country, not only enhances power generation but also improves the integration of renewable energy sources and boosts energy storage capacities, particularly beneficial for less economically prosperous regions. Additionally, the study provides valuable insights for advancing energy research in economically viable areas. Recommendations included conducting site-specific assessments, utilizing advanced modeling tools, implementing regular maintenance protocols, and enhancing communication among system components.
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Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
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• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Industrial Training at Shahjalal Fertilizer Company Limited (SFCL)MdTanvirMahtab2
This presentation is about the working procedure of Shahjalal Fertilizer Company Limited (SFCL). A Govt. owned Company of Bangladesh Chemical Industries Corporation under Ministry of Industries.
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
Instead of buying and hoping for the best, we can use data science to help us predict which products may be good fits for us. It includes various function programs to do the above mentioned tasks.
Data file handling has been effectively used in the program.
The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Overview of the fundamental roles in Hydropower generation and the components involved in wider Electrical Engineering.
This paper presents the design and construction of hydroelectric dams from the hydrologist’s survey of the valley before construction, all aspects and involved disciplines, fluid dynamics, structural engineering, generation and mains frequency regulation to the very transmission of power through the network in the United Kingdom.
Author: Robbie Edward Sayers
Collaborators and co editors: Charlie Sims and Connor Healey.
(C) 2024 Robbie E. Sayers
4. • Reinforced concrete
– Combines concrete and steel bars by simply putting them
together and letting them act together as they may wish.
• Prestressed concrete
– Combines high -strength concrete with high-strength steel in
an “active manner”.
– This is achieved by tensioning the steel and holding it
against the concrete, thus putting the concrete into
compression . This active combination results in a much
better behavior of the two materials.
– Steel is ductile and now is made to act in high tension by
prestressing.
– Concrete is a brittle material with its tensile capacity now
improved by being compressed , while its compressive
capacity is not really harmed.
– PC is ideal combination of two modern high strength
materials
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5. History….
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• Used high tensile steel wires, with ultimate strength as high as
1725 MPa and yield stress over 1240 MPa. In 1939, he developed
conical wedges for end anchorages for post-tensioning and
developed double-acting jacks. He is often referred to as the
Father of Prestressed concrete.
1938 Hoyer, E., (Germany)
Developed ‘long line’ pre-tensioning
method.
1940 Magnel, G., (Belgium)
Developed an anchoring system for post-
tensioning, using flat wedges.
Eugene Freyssinet
(France)
6. • In India, the applications of prestressed concrete diversified over
the years. The first prestressed concrete bridge was built in 1948
under the Assam Rail Link Project. Among bridges, the Pamban
Road Bridge at Rameshwaram, Tamilnadu, remains a classic
example of the use of prestressed concrete girders.
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Pamban Road Bridge at Rameshwaram,
Tamilnadu
7. General principle of prestressing-
barrel construction
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When ropes or metal bands were
wound around wooden staves to form
barrels.
When the bands were tightened,
they were under tensile prestress
which in turn created compressive
prestress between staves and thus
enabled them to resist hoop tension
produced by internal liquid pressure.
In other words, the bands and the
staves were both prestressed before
they were subjected to any service
loads.
8. Terminology
• Tendon: A stretched element used in a concrete member of
structure to impart prestress to the concrete.
• Anchorage: A device generally used to enable the tendon to impart
and maintain prestress in concrete.
• Pretensioning: A method of prestressing concrete in which the
tendons are tensioned before the concrete is placed. In this
method, the concrete is introduced by bond between steel &
concrete.
• Post-tensioning: A method of prestressing concrete by tensioning
the tendons against hardened concrete. In this method, the
prestress is imparted to concrete by bearing
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10. Definition-Prestressed concrete-
ACI Committee
• Concrete in which there have been introduced internal stresses
of such magnitude and distribution that the stresses resulting
from given external loadings are counteracted to a desired
degree. In reinforced concrete members the prestress is
commonly introduced by tensioning the steel reinforcement.
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13. Principles of prestressing..
• Pre-stressing is a method in which compression force is applied
to the reinforced concrete section.
• The effect of pre stressing is to reduce the tensile stress in the
section to the point till the tensile stress is below the cracking
stress. Thus the concrete does not crack.
• It is then possible to treat concrete as a elastic material.
• The concrete can be visualized to have two compressive force
i . Internal pre-stressing force.
ii . External forces (d.l , l.l etc )
• These two forces must counteract each other.
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14. Stress in concrete when pre stressing is applied at the
c.g of the section
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15. Stress in concrete when pre stressing is applied
eccentrically with respect to the c.g of the section .
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16. Basic Concepts
• First Concept
– Prestressing to transform concrete into a elastic material
• Second Concept
– Prestressing for combination of high strength steel with
concrete
• Third Concept
– Prestressing to achieve load balancing
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17. First Concept-
Prestressing to transform concrete into a elastic
material
• Concrete which is transformed from a brittle material into an
elastic one by the precompression given to it.
• Concrete –weak in tension- strong in compression.
• Two systems of forces: Internal prestress and external load,
with the tensile stresses due to the external load counteracted
by the compressive stresses due to the prestress.
• Cracking in concrete is prevented or delayed by precompression
produced by the tendons.
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19. Second Concept-
Prestressing for combination of high strength steel with
concrete
Case-1-Reinforced concrete & prestressed concrete
• Steel-tensile force
• Concrete- compressive force
• Two forces forming a couple with a lever arm between them.
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20. Second Concept-
Prestressing for combination of high strength steel with
concrete
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Case-2-High Tensile steel
• High tensile steel- elongated a great deal before its strength is fully utilized.
• Conventionally High tensile steel is embedded in concrete, this tends to form
cracks in surrounded concrete before the full strength is developed by steel.
• Hence it is necessary to prestretch the steel wrt concrete.
• By prestrecthing and anchoring the steel against the concrete, we produce
desirable stresses and strains in both materials: compressive stresses and
strains in concrete and tensile stresses and strains in steel.
• This permits safe and economical utilization of two materials which cannot be
done in RC.
21. Third Concept-
Prestressing to achieve load balancing
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• Overall design of a prestressed concrete structure, the effect of
prestressing is viewed as the balancing of gravity loads so that members
under bending such as slabs, beams, and girders will not be subjected to
flexural stresses under a given loading condition.
• This enables the transformation of a flexural member into a member
under direct stress and thus greatly simplifies both the design and analysis
of complicated structures.
22. Forms of Prestressing Steel
Wires
•A prestressing wire is a single unit made of steel. The
nominal diameters of the wires are 2.5, 3.0, 4.0, 5.0,
7.0 and 8.0 mm. The different types of wires are as
follows.
Plain wire: No indentations on the surface.
Indented wire: There are circular or elliptical
indentations on the surface.
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23. Strands
•A few wires are spun together in a helical form to form
a prestressing strand. The different types of strands are
as follows.
1) Two-wire strand: Two wires are spun together
to form the strand.
2) Three-wire strand: Three wires are spun
together to form the strand.
3) Seven-wire strand: In this type of strand, six
wires are spun around a central wire. The central wire
is larger than the other wires.
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24. Tendons
•A group of strands or wires are placed together to form
a prestressing tendon. The tendons are used in post-
tensioned members. The following figure shows the
cross section of a typical tendon. The strands are
placed in a duct which may be filled with grout after
the post-tensioning operation is completed
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25. Cables
•A group of tendons form a prestressing cable. The
cables are used in bridges.
Bars
•A tendon can be made up of a single steel bar. The
diameter of a bar is much larger
•than that of a wire. Bars are available in the following
sizes: 10, 12, 16, 20, 22, 25, 28 and 32 mm.
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27. Nature of Concrete-Steel Interface
Bonded tendon
•When there is adequate bond between the prestressing
tendon and concrete, it is called a bonded tendon. Pre-
tensioned and grouted post-tensioned tendons are
bonded tendons.
Unbonded tendon
•When there is no bond between the prestressing
tendon and concrete, it is called unbonded tendon.
When grout is not applied after post-tensioning, the
tendon is an unbonded tendon.
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28. Tensioning Devices
• The various types devices used for tensioning steel are grouped under four
principal categories, viz.
• 1. Mechanical devices: The mechanical devices generally used include
weights with or without lever transmission, geared transmission in
conjunction with pulley blocks, screw jacks with or without gear devices
and wire-winding machines.These devices are employed mainly for
prestressing structural concrete components produced on a mass scale in
factory.
• 2. Hydraulic devices: These are simplest means for producing large
prestressing force, extensively used as tensioning devices.
• 3. Electrical devices: The wires are electrically heated and anchored
before placing concrete in the mould. This method is often referred to as
thermo-prestressing and used for tensioning of steel wires and deformed
bars.
• 4. Chemical devices: Expanding cements are used and the degree of
expansion is controlled by varying the curing condition. Since the
expansive action of cement while setting is restrained, it induces tensile
forces in tendons and compressive stresses in concrete
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30. Types of prestressing….
1. External or internal pre-stressing.
It is based on the location of the pre-stressing tendons with respect
to concrete section.
2. Pre-tensioning or post-tensioning.
It based on the sequence of casting the concrete and applying
tension to the tendons.
3. Linear or circular pre-stressing.
It based on the shape of the member pre-stressed.
4. Full, limited or partial pre-stressing.
It based on the pre-stressing force.
5. Uniaxial, biaxial or multi-axial pre-stressing.
It based on the direction of the pre-stressing member.
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34. 02/06/18 SPK-PSG College of Technology 34
Methods of pre-tensioning:
1) Anchoring the tendons against the end
abutments.
2) Placing of jacks.
3) Applying tension to the tendons.
4) Casting of concrete.
5) Cutting of the tendons.
Methods of post-tensioning:
1) Casting of concrete.
2) Placement of tendons.
3) Placement of the anchorage block and jack.
4) Applying tension to the tendons.
5) Seating of the wedges.
6) Cutting the tendons.
35. In pre-tensioning, the tendons are tensioned even
before casting the concrete
One end of tendon is secured to abutment. The
other end is pulled with jacks
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37. In post tensioning, the beam is cast first leaving
ducts for placing the tendons
Depending upon forces, there may be number of
ducts
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38. In post tensioning, not a solid beam but a series of
blocks
Cables are inserted and will be prestressed
02/06/18 SPK-PSG College of Technology 38Post Tensioning in Blocks
39. End Block
Whatever may be the shape of beam, the end block
is a rectangular section. The entire prestressing will
be transferred by the end block
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40. Systems of prestressing
It is the process of tensioning of tendons. Secures
firmly to concrete till the lift of member. Many
systems are in practice.
i. Freyssinet system
ii. Magnel Blaton system
iii.Gifford Udall system
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47. Advantages…..
Factory products are possible.
Long span structure are possible so that saving of wt is significant & thus it
become economical.
Pre-stressed member are tested before use.
Dead load are get counter balanced by eccentric pre-stressing
It has high ability to resist the impact.
It has high fatigue resistance.
It has high live load carrying capacity.
It free from cracks from service loads and enable entire section to take
part in resisting moments.
Member are free from the tensile stresses.
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48. Limitations…..
Required skilled builders & experienced engineers.
Initial equipment cost is very high.
Availability of experienced engineers is less.
Required complicated formwork.
It requires high strength concrete & steel.
Pre-stressed concrete is less fiber resistant.
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54. References
• Prestressed concrete-K.U.Muthu, Azmi Ibrahim,
Maganti Janardhana and M.Vijayanad (Based on IS
1343-2012)
• Design of prestressed concrete structures- T.Y.Lin
and NED.H.Burns.
• Fundamentals of Prestressed Concrete –N.C.Sinha and
S.K.Roy
• Prestressed concrete –N.Rajagopalan
• Prestressed Concrete- N.Krishna Raju
• Reinforced concrete –Limit State Design-Ashok K Jain
• IS 1343-2012-Prestressed Concrete Code of Practice
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