This document summarizes a presentation on prestressed concrete. It begins with an introduction to prestressed concrete and how it overcomes weaknesses in concrete in tension. It then describes the principles of prestressing by inducing compressive stresses with high-strength tendons before loads are applied. The document compares reinforced concrete with prestressed concrete and describes the methods of pre-tensioning and post-tensioning. It provides examples of prestressed concrete structures like beams, bridges and discusses advantages like reduced size and increased spans as well as disadvantages like higher material costs.
This document provides an introduction to the subject of estimating and costing for the 2nd year intermediate vocational course in construction technology. It discusses key definitions like estimating, costing, and procedures for estimating. The importance of estimation and costing is explained. The data required for preparing an estimate like drawings, specifications, and rates is described. The document also discusses complete estimates, lump sum items, and work charged establishment. Measurement units for different construction items like earthwork, concrete, masonry, woodwork, and finishing works are listed with the applicable unit of measurement and payment.
Prestressed concrete is concrete that is placed under compression using tensioned steel strands, cables, or bars. This is done through either pre-tensioning or post-tensioning. In pre-tensioning, the steel components are tensioned before the concrete is poured, while in post-tensioning, the steel components are tensioned after the concrete has hardened. Prestressed concrete provides benefits over reinforced concrete like lower construction costs, thinner structural elements, and longer spans between supports.
This document discusses different methods of prestressing concrete, including pretensioning and post-tensioning. Pretensioning involves stressing steel tendons before placing concrete around them, while post-tensioning involves stressing tendons after the concrete has cured using hydraulic jacks. Post-tensioning allows for longer spans, thinner slabs, and more architectural freedom compared to conventional reinforced concrete or pretensioned concrete. Common applications of post-tensioning include parking structures, bridges, and building floors and roofs.
Prestressing Concept, Materilas and Prestressing SystemLatif Hyder Wadho
The document discusses prestressing concepts and materials used in prestressed concrete. It describes how prestressing applies an initial compressive stress to concrete prior to service loads to improve strength and durability. Common prestressing materials include high-strength steel strands/wires, which are assembled into tendons and anchored internally or externally before or after concrete casting for pre-tensioning or post-tensioning. Grout is also discussed for transmitting stress between steel and concrete.
This document discusses column jacketing, which is a method of retrofitting and strengthening existing columns. It involves adding reinforced concrete, steel, or fiber-reinforced polymer around the column. The key steps are preparing the column surface, adding shear keys and reinforcement, applying a bonding agent, and casting the new concrete or installing the jacket. Column jacketing increases the strength and seismic capacity of the column. It improves confinement and increases axial, shear, and foundation load capacity without significant weight addition.
This document discusses the working stress method for designing reinforced concrete structures. It defines key terms like neutral axis, lever arm, and moment of resistance. It describes the assumptions and steps of the working stress method, including designing for under-reinforced, balanced, and over-reinforced beam sections. The document also discusses limitations of the working stress method and introduces the limit state method as a more modern approach.
This document provides an introduction to the subject of estimating and costing for the 2nd year intermediate vocational course in construction technology. It discusses key definitions like estimating, costing, and procedures for estimating. The importance of estimation and costing is explained. The data required for preparing an estimate like drawings, specifications, and rates is described. The document also discusses complete estimates, lump sum items, and work charged establishment. Measurement units for different construction items like earthwork, concrete, masonry, woodwork, and finishing works are listed with the applicable unit of measurement and payment.
Prestressed concrete is concrete that is placed under compression using tensioned steel strands, cables, or bars. This is done through either pre-tensioning or post-tensioning. In pre-tensioning, the steel components are tensioned before the concrete is poured, while in post-tensioning, the steel components are tensioned after the concrete has hardened. Prestressed concrete provides benefits over reinforced concrete like lower construction costs, thinner structural elements, and longer spans between supports.
This document discusses different methods of prestressing concrete, including pretensioning and post-tensioning. Pretensioning involves stressing steel tendons before placing concrete around them, while post-tensioning involves stressing tendons after the concrete has cured using hydraulic jacks. Post-tensioning allows for longer spans, thinner slabs, and more architectural freedom compared to conventional reinforced concrete or pretensioned concrete. Common applications of post-tensioning include parking structures, bridges, and building floors and roofs.
Prestressing Concept, Materilas and Prestressing SystemLatif Hyder Wadho
The document discusses prestressing concepts and materials used in prestressed concrete. It describes how prestressing applies an initial compressive stress to concrete prior to service loads to improve strength and durability. Common prestressing materials include high-strength steel strands/wires, which are assembled into tendons and anchored internally or externally before or after concrete casting for pre-tensioning or post-tensioning. Grout is also discussed for transmitting stress between steel and concrete.
This document discusses column jacketing, which is a method of retrofitting and strengthening existing columns. It involves adding reinforced concrete, steel, or fiber-reinforced polymer around the column. The key steps are preparing the column surface, adding shear keys and reinforcement, applying a bonding agent, and casting the new concrete or installing the jacket. Column jacketing increases the strength and seismic capacity of the column. It improves confinement and increases axial, shear, and foundation load capacity without significant weight addition.
This document discusses the working stress method for designing reinforced concrete structures. It defines key terms like neutral axis, lever arm, and moment of resistance. It describes the assumptions and steps of the working stress method, including designing for under-reinforced, balanced, and over-reinforced beam sections. The document also discusses limitations of the working stress method and introduces the limit state method as a more modern approach.
This document discusses several special concreting techniques:
- Pumped concrete is concrete that can be pushed through a pipeline and must have a design that prevents blockages.
- Shortcrete or gunite is a mortar or fine concrete pneumatically projected at high velocity, used for thin sections with less formwork.
- Underwater concrete requires special mixes placed via bagging, buckets, tremie pipes, or grouted aggregates to prevent water intrusion.
- Other techniques include pre-packed concrete placed underwater and special considerations for hot/cold weather concreting. Proper mix design and placement methods are essential for successful implementation of special concreting applications.
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.
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
Coffer dams are temporary structures built to exclude water from an area where permanent structures will be constructed. They allow construction to occur in dry conditions. There are several types of coffer dams depending on the depth of water, soil conditions, and available materials. Earthfill coffer dams use earthen embankments for shallow water, while more complex designs like braced sheet pile or cellular coffer dams are needed for deeper waters. Properly designed coffer dams prevent leakage and ensure the enclosed area remains dry for construction work.
Prestressed concrete is concrete that is placed under compression prior to service loads being applied through tensioning of steel tendons. This counteracts tensile stresses from loads to improve the performance of the concrete. Eugene Freyssinet is considered the father of prestressed concrete, developing techniques like high strength steel wires and conical wedges for post-tensioning in the 1930s-1940s. Prestressing can be through pre-tensioning or post-tensioning, depending on if the steel is tensioned before or after the concrete is cast. Popular post-tensioning systems include Freyssinet, Magnel Blaton, Gifford-Udall, and Lee-McCall methods. Prestressed concrete provides
The document discusses composite construction using precast prestressed concrete beams and cast-in-situ concrete. It describes how the two elements act compositely after the in-situ concrete hardens. Composite beams can be constructed as either propped or unpropped. Propped construction involves supporting the precast beam during casting to relieve it of the wet concrete weight, while unpropped construction allows stresses to develop under self-weight. Design and analysis of composite beams involves calculating stresses and deflections considering composite action. Differential shrinkage between precast and in-situ concrete also induces stresses.
It is used as a mould for a structure in which fresh concrete is poured only to harden subsequently.
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Pre-stressed concrete uses tensioned steel strands or bars to place concrete in compression before application of service loads. This counters the tensile stresses induced by loads and prevents cracking. There are two main methods: pre-tensioning applies tension before pouring concrete, while post-tensioning tensions strands after concrete curing. Pre-stressed concrete allows for smaller and lighter structures that resist loads, deflection, and cracking better than reinforced concrete.
Prestressed concrete has several advantages over reinforced concrete including being more crack-resistant, durable, and requiring smaller cross-sectional areas, allowing for longer spans and easier transport. However, it also has some disadvantages such as requiring specialized equipment, advanced technical knowledge, and skilled labor for construction, as well as more expensive prestressing reinforcement bars.
The document discusses different types of pavements. It describes flexible pavements as having multiple layers that distribute loads through aggregate interlock. Rigid pavements distribute loads through the beam strength of concrete slabs. Flexible pavements are composed of surface, base, and sub-base layers over a subgrade, while rigid pavements typically only require a concrete surface layer. Both pavement types are designed to reduce loads from vehicles to prevent damage to the subgrade. The document compares advantages and disadvantages of flexible and rigid pavements.
This document discusses prestressed concrete bridges. It begins with definitions of prestressed concrete as concrete with internal stresses introduced to counteract external loads. It then provides a brief history of prestressed concrete, noting key innovators. Examples of prestressed concrete bridges in India are given, including the famous Pamban Road Bridge. The document goes on to explain the basic principles, terminology, types, and methods of prestressing, as well as the advantages and disadvantages of prestressed concrete.
Prestressed concrete is a combination of steel and concrete that uses compressive stresses applied during construction to oppose tensile stresses that occur in use. There are three main types: pre-tensioned concrete uses steel tendons tensioned before concrete is placed; bonded post-tensioned concrete uses unstressed steel placed then tensioned after curing; and unbonded post-tensioned concrete provides freedom of movement between steel and concrete. Pre-tensioned concrete requires molds that can resist internal forces and calculations to account for losses over time. Prestressed concrete provides benefits like reduced cracking and corrosion, higher strength, and more economical construction for bridges compared to steel.
Introduction about Repair & Rehabilitation of Structures
Repair of Structures
Rehabilitation of Structures
Maintenance of Structures
Various Methods of Maintenance
Planning analysis design the overhead circular water tank in seerapalayam pan...Subash thangaraj
To forecasting the population of the seerapalayam panchayat. To calculate the estimation of water quantity need in Domestic, and industrial purpose. After the calculation planning analysis and design the overhead circular water tank in economically.
This document discusses prefabricated modular structures. Some key points:
1. Prefabricated structures have standardized components that are produced off-site in a controlled environment and then transported for assembly. This allows for faster, more efficient construction.
2. Precast concrete offers advantages like higher quality, less weather dependency, and unlimited design possibilities compared to site-cast construction.
3. There are different precast systems like large panel, frame, and lift-slab. Precast components include walls, floors, beams, and more.
The document discusses different methods of post-tensioning concrete structures. It describes the Freyssinet system as the first introduced method using steel wires grouped into cables with a helical spring. The Magnel Blaton system stresses wires two at a time using sandwich plates and wedges. The Gifford Udall system uses single wires stressed independently with double-acting jacks and tube or plate anchorages. The Lee McCall system prestresses steel bars using threaded bars tightened with nuts against bearing plates.
This document discusses prestressed concrete, which uses tensioned steel cables or bars to put concrete members into compression and increase their strength. It describes three main methods: pre-tensioned concrete where the steel is tensioned before the concrete is cast; bonded post-tensioned concrete where steel is tensioned after casting to compress the concrete; and unbonded post-tensioned concrete where greased steel is used to allow individual adjustment. Applications include buildings, bridges, nuclear reactors and earthquake resistant structures. Advantages are lower costs, thinner members, and increased spans.
Rigid pavements are concrete slabs that distribute vehicle loads through beam action. They have high flexural strength and small deflections compared to flexible pavements. The presentation discusses the types of rigid pavements including jointed plain concrete, jointed reinforced concrete, and continuously reinforced concrete pavements. It also covers the design factors for rigid pavements such as traffic loading, subgrade strength, environmental conditions, and material properties. Rigid pavements are designed to last 30 years with minimal maintenance required over the design life.
This document discusses methods of prestressing concrete, including pretensioning and post-tensioning. Pretensioning involves stressing steel tendons before concrete is poured around them. Post-tensioning involves stressing steel tendons inserted into voids in cured concrete using jacks. Both methods put the concrete in compression and improve its tensile strength. Common applications include building floors/roofs, bridges, and parking structures.
The document provides information on methods of prestressing in concrete, including pretensioning and post-tensioning. It discusses:
- Pretensioning involves stressing steel tendons before the concrete is cast around them.
- Post-tensioning involves stressing steel tendons after the concrete has cured using jacks, then grouting the voids.
- Both methods put the concrete in compression and increase its strength and durability compared to conventional reinforced concrete.
This document discusses several special concreting techniques:
- Pumped concrete is concrete that can be pushed through a pipeline and must have a design that prevents blockages.
- Shortcrete or gunite is a mortar or fine concrete pneumatically projected at high velocity, used for thin sections with less formwork.
- Underwater concrete requires special mixes placed via bagging, buckets, tremie pipes, or grouted aggregates to prevent water intrusion.
- Other techniques include pre-packed concrete placed underwater and special considerations for hot/cold weather concreting. Proper mix design and placement methods are essential for successful implementation of special concreting applications.
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.
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
Coffer dams are temporary structures built to exclude water from an area where permanent structures will be constructed. They allow construction to occur in dry conditions. There are several types of coffer dams depending on the depth of water, soil conditions, and available materials. Earthfill coffer dams use earthen embankments for shallow water, while more complex designs like braced sheet pile or cellular coffer dams are needed for deeper waters. Properly designed coffer dams prevent leakage and ensure the enclosed area remains dry for construction work.
Prestressed concrete is concrete that is placed under compression prior to service loads being applied through tensioning of steel tendons. This counteracts tensile stresses from loads to improve the performance of the concrete. Eugene Freyssinet is considered the father of prestressed concrete, developing techniques like high strength steel wires and conical wedges for post-tensioning in the 1930s-1940s. Prestressing can be through pre-tensioning or post-tensioning, depending on if the steel is tensioned before or after the concrete is cast. Popular post-tensioning systems include Freyssinet, Magnel Blaton, Gifford-Udall, and Lee-McCall methods. Prestressed concrete provides
The document discusses composite construction using precast prestressed concrete beams and cast-in-situ concrete. It describes how the two elements act compositely after the in-situ concrete hardens. Composite beams can be constructed as either propped or unpropped. Propped construction involves supporting the precast beam during casting to relieve it of the wet concrete weight, while unpropped construction allows stresses to develop under self-weight. Design and analysis of composite beams involves calculating stresses and deflections considering composite action. Differential shrinkage between precast and in-situ concrete also induces stresses.
It is used as a mould for a structure in which fresh concrete is poured only to harden subsequently.
formwork for concrete slab
beam formwork
steel formwork
doka h20
types of formwork
formwork for concrete
what is formwork in construction
building formwork
plywood disadvantages
advantage plywood
advantages and disadvantages of wood
best plywood for formwork
plywood formwork for concrete
mdf advantages and disadvantages
examples of advantages and disadvantages
advantage steel and construction
advantages of steel
disadvantages of steel structures
examples of advantages and disadvantages
advantages and disadvantages of surveys
wiki advantages and disadvantages
steel formwork design
steel formwork system
Pre-stressed concrete uses tensioned steel strands or bars to place concrete in compression before application of service loads. This counters the tensile stresses induced by loads and prevents cracking. There are two main methods: pre-tensioning applies tension before pouring concrete, while post-tensioning tensions strands after concrete curing. Pre-stressed concrete allows for smaller and lighter structures that resist loads, deflection, and cracking better than reinforced concrete.
Prestressed concrete has several advantages over reinforced concrete including being more crack-resistant, durable, and requiring smaller cross-sectional areas, allowing for longer spans and easier transport. However, it also has some disadvantages such as requiring specialized equipment, advanced technical knowledge, and skilled labor for construction, as well as more expensive prestressing reinforcement bars.
The document discusses different types of pavements. It describes flexible pavements as having multiple layers that distribute loads through aggregate interlock. Rigid pavements distribute loads through the beam strength of concrete slabs. Flexible pavements are composed of surface, base, and sub-base layers over a subgrade, while rigid pavements typically only require a concrete surface layer. Both pavement types are designed to reduce loads from vehicles to prevent damage to the subgrade. The document compares advantages and disadvantages of flexible and rigid pavements.
This document discusses prestressed concrete bridges. It begins with definitions of prestressed concrete as concrete with internal stresses introduced to counteract external loads. It then provides a brief history of prestressed concrete, noting key innovators. Examples of prestressed concrete bridges in India are given, including the famous Pamban Road Bridge. The document goes on to explain the basic principles, terminology, types, and methods of prestressing, as well as the advantages and disadvantages of prestressed concrete.
Prestressed concrete is a combination of steel and concrete that uses compressive stresses applied during construction to oppose tensile stresses that occur in use. There are three main types: pre-tensioned concrete uses steel tendons tensioned before concrete is placed; bonded post-tensioned concrete uses unstressed steel placed then tensioned after curing; and unbonded post-tensioned concrete provides freedom of movement between steel and concrete. Pre-tensioned concrete requires molds that can resist internal forces and calculations to account for losses over time. Prestressed concrete provides benefits like reduced cracking and corrosion, higher strength, and more economical construction for bridges compared to steel.
Introduction about Repair & Rehabilitation of Structures
Repair of Structures
Rehabilitation of Structures
Maintenance of Structures
Various Methods of Maintenance
Planning analysis design the overhead circular water tank in seerapalayam pan...Subash thangaraj
To forecasting the population of the seerapalayam panchayat. To calculate the estimation of water quantity need in Domestic, and industrial purpose. After the calculation planning analysis and design the overhead circular water tank in economically.
This document discusses prefabricated modular structures. Some key points:
1. Prefabricated structures have standardized components that are produced off-site in a controlled environment and then transported for assembly. This allows for faster, more efficient construction.
2. Precast concrete offers advantages like higher quality, less weather dependency, and unlimited design possibilities compared to site-cast construction.
3. There are different precast systems like large panel, frame, and lift-slab. Precast components include walls, floors, beams, and more.
The document discusses different methods of post-tensioning concrete structures. It describes the Freyssinet system as the first introduced method using steel wires grouped into cables with a helical spring. The Magnel Blaton system stresses wires two at a time using sandwich plates and wedges. The Gifford Udall system uses single wires stressed independently with double-acting jacks and tube or plate anchorages. The Lee McCall system prestresses steel bars using threaded bars tightened with nuts against bearing plates.
This document discusses prestressed concrete, which uses tensioned steel cables or bars to put concrete members into compression and increase their strength. It describes three main methods: pre-tensioned concrete where the steel is tensioned before the concrete is cast; bonded post-tensioned concrete where steel is tensioned after casting to compress the concrete; and unbonded post-tensioned concrete where greased steel is used to allow individual adjustment. Applications include buildings, bridges, nuclear reactors and earthquake resistant structures. Advantages are lower costs, thinner members, and increased spans.
Rigid pavements are concrete slabs that distribute vehicle loads through beam action. They have high flexural strength and small deflections compared to flexible pavements. The presentation discusses the types of rigid pavements including jointed plain concrete, jointed reinforced concrete, and continuously reinforced concrete pavements. It also covers the design factors for rigid pavements such as traffic loading, subgrade strength, environmental conditions, and material properties. Rigid pavements are designed to last 30 years with minimal maintenance required over the design life.
This document discusses methods of prestressing concrete, including pretensioning and post-tensioning. Pretensioning involves stressing steel tendons before concrete is poured around them. Post-tensioning involves stressing steel tendons inserted into voids in cured concrete using jacks. Both methods put the concrete in compression and improve its tensile strength. Common applications include building floors/roofs, bridges, and parking structures.
The document provides information on methods of prestressing in concrete, including pretensioning and post-tensioning. It discusses:
- Pretensioning involves stressing steel tendons before the concrete is cast around them.
- Post-tensioning involves stressing steel tendons after the concrete has cured using jacks, then grouting the voids.
- Both methods put the concrete in compression and increase its strength and durability compared to conventional reinforced concrete.
The document provides information on methods of prestressing concrete, including pretensioning and post-tensioning. It discusses:
- Pretensioning involves stressing steel tendons before the concrete is cast around them.
- Post-tensioning involves stressing steel tendons after the concrete has cured using jacks, then grouting the voids.
- Both methods put the concrete in compression and increase its strength and durability compared to conventional reinforced concrete.
This document provides an overview of prestressed concrete presented by Sayan Saha from Silliguri Institute of Technology. It introduces prestressed concrete as a method to overcome concrete's weakness in tension. The principle is that compressive stresses induced in concrete by high-strength steel tendons before loading will balance tensile stresses during use. There are two main methods: pre-tensioning where tendons are stressed before concreting, and post-tensioning where tendons are stressed after concrete curing. Advantages include reduced member thickness, deflections, weight, and cracking, while disadvantages require specialized equipment, technical knowledge, and skilled labor.
This document provides information about prestressed concrete, specifically focusing on post-tensioning methods. It defines post-tensioning as a method of reinforcing concrete with high-strength steel strands called tendons. After the concrete cures, the tendons are tensioned using hydraulic jacks and wedged into place to transfer pressure to the concrete. There are benefits to post-tensioning like allowing longer spans, thinner structures, and reduced cracking compared to conventional reinforced concrete. The document discusses bonded and unbonded post-tensioning methods and provides examples of applications like buildings, bridges, and parking structures.
This document discusses prestressed concrete, which uses steel that is tensioned to put concrete in compression and increase its strength. There are two main types: pre-tensioned concrete, where steel is tensioned before the concrete is poured; and post-tensioned concrete, where steel is tensioned after the concrete has hardened. Post-tensioned concrete can be bonded or unbonded. Prestressed concrete allows for longer spans, thinner sections, and increased strength over traditional reinforced concrete. It has applications in buildings, bridges, parking structures, and other structures.
This document discusses prestressed concrete and defines key terms like pretensioning and post-tensioning. Pretensioning involves stretching steel tendons before concrete is poured, while post-tensioning stretches steel inserted into hardened concrete. The document covers advantages of prestressing like reduced cracking and member sizes. It also discusses design considerations like prestress losses from shrinkage, creep, and relaxation. Both pretensioning and post-tensioning methods are outlined, along with tendon types like bars, wires, and strands.
This document provides an outline for lectures on prestressed concrete, including basic concepts, materials, flexural analysis, design considerations, shear/torsion, loss of prestress over time, composite beams, and deflections. Key points covered include how prestressing controls cracking by applying compressive stresses to concrete before service loads; common prestressing methods of pre-tensioning and post-tensioning; estimating stresses in uncracked concrete beams using elastic theory; and accounting for various load stages in analysis and design.
This document provides information on prestressed concrete and the Freyssinet prestressing system. It discusses the principles of prestressing, including pre-tensioning and post-tensioning methods. It also describes the key components of the Freyssinet post-tensioning system, including prestressing steels, anchorages, ducts, supports, and couplers. The anchorages can be mono-strand or multi-strand and are designed to transfer prestressing forces to the concrete structure.
Comparison of reinforced concrete and prestressed concreteSpice Shuvo
This document compares reinforced concrete and prestressed concrete. Reinforced concrete uses steel reinforcement embedded in concrete to increase its tensile strength. Prestressed concrete applies compression to concrete before loading to counteract tensile stresses when in use. For construction, reinforced concrete requires steel bars and formwork while prestressed concrete uses steel tendons stressed after the concrete reaches strength. Prestressed concrete allows for thinner sections, reduced self-weight, and less deflection compared to reinforced concrete. However, it requires higher quality materials and specialized equipment. In summary, the document outlines the key differences in material composition and behavior between the two composite concrete materials.
This document discusses prestressed concrete and provides details on:
- The definition and principle of prestressing concrete by applying compression prior to external loads
- Common prestressing methods like hydraulic, mechanical, electrical, and chemical prestressing
- Tests conducted on prestressed concrete components like post-tensioned splices and cast-in-place splices
- Advantages of prestressed concrete like reduced materials and increased strength
- Applications in bridges, buildings, water tanks, and more
- A case study on widening the Harrods Creek Arch Bridge using prestressed concrete
Pre-stressed concrete was a major innovation that replaced conventional reinforced concrete, allowing for longer spans, higher impact resistance, and greater load capacity without tensile stresses. It involves casting concrete around high-strength steel that is placed under compression before use to counteract tensile stresses when in service. There are two main types: pre-tensioning applies tension before casting, while post-tensioning does so after casting, using ducts to hold the steel. Pre-stressed concrete enables more efficient structures through factory casting and reduced material needs.
Pre-stressed concrete uses tensioned steel cables or rods to put concrete members under compression and increase their strength. It allows for longer spans than reinforced concrete. There are three methods: pre-tensioned concrete uses tensioned tendons before pouring concrete; bonded post-tensioned concrete uses tendons tensioned after pouring; unbonded post-tensioned concrete uses individually coated tendons without bonding to the concrete. Prestressed concrete has advantages like less cracking and material efficiency but also disadvantages like higher costs.
1. The document discusses parameters that affect the strength of concrete in externally prestressed bridges. It examines factors like tendon layout, prestressing method, effective depth and eccentricity of external tendons, and materials used for tendons.
2. Studies have found that draped tendon profiles provide higher strength than straight profiles. External prestressing requires more prestressing force than internal prestressing, except for very deep girders. Increased effective depth and eccentricity of external tendons enhances strength.
3. Carbon fiber reinforced polymer tendons are an alternative to steel but have issues with brittleness and cost. Overall, optimizing tendon layout and placement can improve the strength of externally prestressed concrete bridges
This document discusses prestressed concrete, including:
- The basic concepts of prestressing including using metal bands, pre-tensioned spokes, and introducing stresses to counteract external loads.
- Design concepts like losses in prestressing structures from elastic shortening, creep, shrinkage, relaxation, friction, and anchorage slip.
- Provisions for prestressing in the Indian Road Congress Bridge Code and Indian Standard Code.
- Construction aspects like casting of girders, post-tensioning work, and load testing of structures.
Prestressed concrete uses high-strength steel tendons or cables to put concrete members into compression prior to stresses from service loads being applied. This counters the tensile stresses induced by loading and improves the behavior of the concrete. There are two main methods - pretensioning and post-tensioning. Pretensioning involves stressing steel tendons before concrete is cast, while post-tensioning stresses steel tendons after the concrete has hardened. Losses in prestress over time include elastic shortening, anchorage slip, friction, creep, shrinkage, and steel relaxation. Proper material selection and design can minimize these losses and optimize the performance of prestressed concrete.
Post-tensioning is a technique for reinforcing concrete structures. The prestressing steel cables inside the sleeves or plastic ducts are positioned in the forms before placing the concrete. As the concrete gains strength, the cables are stressed to design forces before the application of the service load and are anchored att the outer edge region of the concrete.
Here are the key steps in concrete frame construction:
1. Excavation and foundation work - This involves excavating the land and laying the foundation system such as raft or pile foundations.
2. Erection of formwork - Formwork is erected to give shape to the concrete elements like columns, beams, slabs, etc. It is designed to bear the pressure of wet concrete.
3. Reinforcement cage - Steel reinforcement bars are cut, bent and assembled into cages and placed accurately in position in the formwork.
4. Concreting - Concrete is poured, compacted and finished after placing the reinforcement cages in position.
5. Curing - After concreting, the concrete elements
Pre stressed & pre-cast concrete technology - ce462Saqib Imran
1) Precast concrete consists of concrete elements that are cast and cured off-site and then transported for assembly. Prestressed concrete uses high-strength steel strands or bars that are tensioned to put the concrete in compression and improve its strength.
2) Common precasting techniques include pre-tensioning, where steel is tensioned before the concrete is poured, and post-tensioning, where steel is tensioned after the concrete cures.
3) Advantages of prestressed concrete include reduced cracking, lighter weight, and improved durability; disadvantages include higher material costs and need for specialized equipment.
Better Builder Magazine brings together premium product manufactures and leading builders to create better differentiated homes and buildings that use less energy, save water and reduce our impact on the environment. The magazine is published four times a year.
Cricket management system ptoject report.pdfKamal Acharya
The aim of this project is to provide the complete information of the National and
International statistics. The information is available country wise and player wise. By
entering the data of eachmatch, we can get all type of reports instantly, which will be
useful to call back history of each player. Also the team performance in each match can
be obtained. We can get a report on number of matches, wins and lost.
We have designed & manufacture the Lubi Valves LBF series type of Butterfly Valves for General Utility Water applications as well as for HVAC applications.
An In-Depth Exploration of Natural Language Processing: Evolution, Applicatio...DharmaBanothu
Natural language processing (NLP) has
recently garnered significant interest for the
computational representation and analysis of human
language. Its applications span multiple domains such
as machine translation, email spam detection,
information extraction, summarization, healthcare,
and question answering. This paper first delineates
four phases by examining various levels of NLP and
components of Natural Language Generation,
followed by a review of the history and progression of
NLP. Subsequently, we delve into the current state of
the art by presenting diverse NLP applications,
contemporary trends, and challenges. Finally, we
discuss some available datasets, models, and
evaluation metrics in NLP.
Covid Management System Project Report.pdfKamal Acharya
CoVID-19 sprang up in Wuhan China in November 2019 and was declared a pandemic by the in January 2020 World Health Organization (WHO). Like the Spanish flu of 1918 that claimed millions of lives, the COVID-19 has caused the demise of thousands with China, Italy, Spain, USA and India having the highest statistics on infection and mortality rates. Regardless of existing sophisticated technologies and medical science, the spread has continued to surge high. With this COVID-19 Management System, organizations can respond virtually to the COVID-19 pandemic and protect, educate and care for citizens in the community in a quick and effective manner. This comprehensive solution not only helps in containing the virus but also proactively empowers both citizens and care providers to minimize the spread of the virus through targeted strategies and education.
Data Communication and Computer Networks Management System Project Report.pdfKamal Acharya
Networking is a telecommunications network that allows computers to exchange data. In
computer networks, networked computing devices pass data to each other along data
connections. Data is transferred in the form of packets. The connections between nodes are
established using either cable media or wireless media.
Sri Guru Hargobind Ji - Bandi Chor Guru.pdfBalvir Singh
Sri Guru Hargobind Ji (19 June 1595 - 3 March 1644) is revered as the Sixth Nanak.
• On 25 May 1606 Guru Arjan nominated his son Sri Hargobind Ji as his successor. Shortly
afterwards, Guru Arjan was arrested, tortured and killed by order of the Mogul Emperor
Jahangir.
• Guru Hargobind's succession ceremony took place on 24 June 1606. He was barely
eleven years old when he became 6th Guru.
• As ordered by Guru Arjan Dev Ji, he put on two swords, one indicated his spiritual
authority (PIRI) and the other, his temporal authority (MIRI). He thus for the first time
initiated military tradition in the Sikh faith to resist religious persecution, protect
people’s freedom and independence to practice religion by choice. He transformed
Sikhs to be Saints and Soldier.
• He had a long tenure as Guru, lasting 37 years, 9 months and 3 days
2. CONTENT
INTRODUCTION
PRINCIPLE OF PRESTRESSING
COMPARISION BETWEEN R.C.C. AND P.S.C
METHODS OF PRESTRESSING
PRE-TENSIONING
POST-TENSIONING
PRESTRESSED CONCRETE STRUCTURE.
LOSSES
ADVANTAGES
DISADVANTAGE
CONCLUSION
REFERENCE
3. INTRODUCTION
Prestressed concrete is method for
overcoming 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 .It is often to use
in commercial and residential
construction as a beam and slab
4. PRINCIPLE OF PRESTRESSED
The principle behind Prestressed concrete is that
compressive stresses induced by high strength steel
tendons in a concrete member before loads are applied
will balance the tensile stresses imposed in the member
during services.
Prestressed concrete is basically concrete in which internal
stresses of a suitable magnitude and distribution are
introduced so that the stresses resulting from the external
loads are counteracted to a desired degree.
5. Comparison between R.C.C. and P.S.C.:-
R.C.C P.S.C.
1)30%-40% of total cross section is
used.
1)100% cross section is used.
2)Economical upto 12m 2)Economical from 12-30m
3)Self weight of section is more. 3)Self weight of section is less.
4)Cracking and corrosion problems
are more.
4)No cracking or corrosion
problem.
5)Reinforcement is straight. 5)Tendons can be bent or parabolic.
6)Tension is developed below
neutral axis.
6)Whole cross section is in
compression.
7)Stresses develop after loading. 7)Stresses develop before loading.
9. PRE-TENSIONING
Pre-tensioning is a method where
prestressing steels are prestressed,prior
to concreting against two rigid
abutments .This method is most widely
use for mass production of short span
structures, where prestressing is also a
prerequisite, such as railway slippers,
electric poles, fencing poles,
pretensioned slab and I-section bridge
gurders etc.
11. POST-TENSIONING
Post-tensioning is method where prestressing steels are stressed
after concrete attains its preliminary strength. Two extreme ends
of the structures are considered as a reaction face, against which
force is applied. Ducts are placed inside the formwork along with
reinforcement and the concreting is completed. After achieving
required concrete strength, stipulated
numbers of prestrssing steel is then inserted in each duct for
stressing purpose. After achieving elongation
and stresses they are blocked at two ends with the help of anchor
plates and grip.
17. ADAM VIADUCT
This is one of the first
prestressed bridge.Itt is
situated in WALGATE
,UK.
It is a concrete railway
bridge.
Total length=37m
Width= 9.07m
Year= 1946
No. of spans=4
18.
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27. ADVANTAGES OF
PRESTRESSED STRUCTURE
• The size or dimensions of structural members are reduced, which may increase the
clearances or reduce storey heights.
• It permits the use of large spans (greater than 30 m) with shallow members, even when
heavy load are encountered.
• In addition to general advantages, such as excellent fire resistance, low maintenance costs,
elegance, high corrosion-resistance, adaptability etc, the prestressed concrete is found to
sustain the effects of impact or shock and vibrations.
• Because of smaller loads due to smaller dimensions being used, there is considerable saving
cost of supporting members and foundations.
• The prestressing technique has eliminated the weakness of concrete in tension and hence
crack free members of structure are obtained.
• Because of better material (i.e. controlled concrete and high tension steel) being used and
nullifying the effect of dead loads, smaller deflections are caused.
28. DISADVANTAGES
• The unit cost of high strength materials being used is
higher.
• Extra initial cost is incurred due to use of
prestressing equipment and its installation.
• Extra labour cost for prestressing is also there.
• Prestressing is uneconomical for short spans and
light loads
29. CONCLUSION
This Technical Seminar program was an excellent
opportunity to get to the knowledge of particular a topic
and experience the things that we would have never
gained through going straight into a job. I am very much
grateful to my college for giving us this wonderful
opportunity.
I have learnt various concept of prestressed concrete and
its applications.
Future scope of it is very large and it will surely help to
build a world with safe use of concrete.
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