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.
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.
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
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.
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.
Precast concrete construction involves casting concrete structural elements at a manufacturing facility rather than on site. This allows for rapid construction, high quality control, and easy incorporation of prestressing. Precast concrete provides advantages like speed of erection, durability, and economy, but also has disadvantages such as weight, limited flexibility in design, and need for skilled workmanship and lifting equipment on site. Common precast concrete elements include walls, slabs, beams, and structural framing using techniques like welded plates and rebar splicing.
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.
Trusses are commonly used in buildings to span long distances and carry heavy loads. Steel trusses are preferred over wood trusses for their strength, simplicity of installation, and durability without risk of rotting. Various types of trusses include king post, queen post, Howe, Pratt, and fan trusses used in roofs, as well as north light trusses traditionally used for industrial buildings to maximize natural lighting. Larger spans may use tubular steel, quadrangular, or gusset plate connected trusses, while galvanized steel sheets are often used for roofing material.
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.
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.
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
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.
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.
Precast concrete construction involves casting concrete structural elements at a manufacturing facility rather than on site. This allows for rapid construction, high quality control, and easy incorporation of prestressing. Precast concrete provides advantages like speed of erection, durability, and economy, but also has disadvantages such as weight, limited flexibility in design, and need for skilled workmanship and lifting equipment on site. Common precast concrete elements include walls, slabs, beams, and structural framing using techniques like welded plates and rebar splicing.
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.
Trusses are commonly used in buildings to span long distances and carry heavy loads. Steel trusses are preferred over wood trusses for their strength, simplicity of installation, and durability without risk of rotting. Various types of trusses include king post, queen post, Howe, Pratt, and fan trusses used in roofs, as well as north light trusses traditionally used for industrial buildings to maximize natural lighting. Larger spans may use tubular steel, quadrangular, or gusset plate connected trusses, while galvanized steel sheets are often used for roofing material.
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 provides an overview of prefabricated modular structures. It discusses the introduction and features of prefabricated structures, comparing them to site-cast structures. It outlines the design concept, components, types of precast systems including large panel, frame, and lift-slab systems. It also discusses design considerations, equipment used, assembly process, scheduling, advantages including reduced costs and time, limitations, and concludes with examples of prefabricated hospital structures.
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
Pre-stressed concrete uses tensioned steel strands or bars to place concrete in compression and improve its tensile strength. There are two main methods - pre-tensioning and post-tensioning. Pre-tensioning tensions the strands before the concrete is poured, while post-tensioning tensions strands inside ducts after the concrete has cured. This compression counteracts tensile and flexural stresses from loads to reduce cracking and increase strength, allowing pre-stressed concrete to be lighter and more durable than reinforced concrete. It is commonly used in bridges, buildings, tanks, and other structures.
Prefabrication types and Applications explainedEyad Reda
Explaining prefabrication in construction in a simple way. The contents range from steel framing, Precast concrete, Concrete prefab systems, sandwich paneling, timber framing and Real-life applications for prefabrication.
This document discusses prefabrication in construction. Prefabrication involves assembling components of a structure in a factory then transporting them to the construction site. It has advantages like reduced cost, time, and waste and allows work during poor weather. Common prefabricated components include columns, beams, waffle floors/roofs which are cast and cured off-site then erected using cranes. While prefabrication offers benefits, it also has disadvantages like potential breakage during transport and need for specialized equipment and labor. The document concludes that partial prefabrication is well-suited for Indian conditions.
This document provides an overview of different types of retaining walls, including gravity, cantilever, counterfort, sheet pile, and diaphragm walls. It discusses the key components and design considerations for gravity and cantilever retaining walls. Gravity walls rely on their own weight for stability, while cantilever walls consist of a vertical stem with a heel and toe slab acting as a cantilever beam. The document also covers lateral earth pressures, drainage of retaining walls, uses of sheet pile walls, and construction methods for diaphragm walls.
The document discusses common defects found in buildings such as cracks and dampness. It categorizes defects into pre-construction, during construction, and post-construction. Cracks can be structural or non-structural, and are caused by factors like drying shrinkage, thermal movement, elastic deformation, creep, chemical reactions, and foundation issues. Dampness is usually due to penetrating damp from gaps or rising damp without a proper damp proof course. Preventive measures include proper design, materials, construction practices, and addressing the root causes of defects.
It is the presentation based on precast concrete construction which includes each and every point and scope which may be useful to civil engineering students
Prefabrication is the practice of assembling components of a structure in a factory or other manufacturing site, and transporting them to the construction site where the structure is to be located.
Post-tensioning is an effective alternative for earthquake-prone regions and dense populations in India. It has advantages over ordinary reinforced concrete like higher seismic resilience, less concrete usage, stiffer foundations, and faster construction. Post-tensioning involves threading steel tendons through ducts and tensioning them after concrete pouring. It provides better crack control, economy, quality, and efficiency. While widely used in other countries, post-tensioning is not yet common in India but has applications in slabs, buildings, and foundations.
Prefabrication involves assembling building components in a factory and transporting them to the construction site. There are several prefabrication systems including open prefab, box type, and large prefab. Prefabricated components include panels, roofs, floors, and more which are manufactured off-site and assembled on-site. Prefabrication offers benefits like reduced construction time and costs, improved quality, and less waste. However, it also has disadvantages such as requiring specialized equipment and skilled labor for transportation and assembly. A case study on a housing project in India demonstrated how prefabrication helped complete buildings faster and with higher quality.
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.
This document discusses prefabrication in construction. Prefabrication involves assembling structural components at a factory or manufacturing site and transporting them to the construction site for assembly. It describes the advantages as less noise, dust, time and costs compared to on-site construction. Potential disadvantages include transportation costs, accuracy needs and reduced aesthetic variety. The document outlines various prefabrication components, materials, systems, joints, casting methods and the differences between on-site and off-site prefabrication.
The document discusses precast concrete construction. Some key points:
- Precast concrete components are cast off-site in a controlled environment and transported to the construction site for assembly. This allows for standardized, mass produced elements.
- Large precast concrete panels form the walls and floors, connecting vertically and horizontally. When joined, they form a rigid box structure that transfers lateral loads.
- Connections between precast elements can be either dry joints using bolts/welds, or monolithic placement with concrete poured to join components.
This document discusses prefabricated concrete columns. It defines prefabrication as assembling building components in a factory and transporting them to the construction site. Precast concrete columns can be single or double-story height and are made in modular designs to accommodate different heights. Columns have widths of 300mm, 450mm, or 600mm and can be rectangular or circular. Connection methods between the column and foundation include cast-in base plates, dowel tubes, or projections. The manufacturing process for precast concrete components involves 10 main steps including installing molds and reinforcement, pouring and vibrating concrete, curing, and removing molds.
This document discusses precast concrete construction. Some key points:
- Precast concrete elements are cast and cured off-site then transported for assembly, allowing more efficient production and quality control.
- Elements include slabs, beams, columns, and wall panels that are joined on-site through embedded bolts, plates, and grouted connections.
- The precasting process involves casting concrete around prestressing strands to add strength, then cutting sections and transporting them for erection.
Precast concrete is concrete that is cast in reusable molds or "forms" that are then cured in a controlled environment. This allows precast concrete construction to provide several benefits over traditional cast-in-place concrete including time savings, quality assurance, cost effectiveness, durability, aesthetics, and safer construction. However, precast concrete also has some disadvantages such as high initial investment costs, transportation issues, handling difficulties, limitations for modifications, and needing sensitive connection work. Overall, precast concrete can be a good solution for large construction projects where its benefits outweigh its disadvantages.
Saint Gobain Gyproc India Ltd. is a market leader in India's plasterboard market with a 48% market share. The document discusses Saint Gobain's products, financial performance, competitors like Lafarge Boral and Sai India, and the Indian gypsum market. It also presents a SWOT analysis and the results of a survey of 15 Saint Gobain dealers regarding their satisfaction with the company's products, advertising, and distribution channels.
The document contains construction documents for renovations to the Lafayette Tap Room located in Buffalo, New York. It includes general notes specifying code compliance, contractor responsibilities, and other project requirements. Floor plans show the layout and dimensions of the existing and proposed renovated space. Elevations, sections and schedules provide additional architectural details for walls, doors, finishes and fixtures to complete the renovations.
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 provides an overview of prefabricated modular structures. It discusses the introduction and features of prefabricated structures, comparing them to site-cast structures. It outlines the design concept, components, types of precast systems including large panel, frame, and lift-slab systems. It also discusses design considerations, equipment used, assembly process, scheduling, advantages including reduced costs and time, limitations, and concludes with examples of prefabricated hospital structures.
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
Pre-stressed concrete uses tensioned steel strands or bars to place concrete in compression and improve its tensile strength. There are two main methods - pre-tensioning and post-tensioning. Pre-tensioning tensions the strands before the concrete is poured, while post-tensioning tensions strands inside ducts after the concrete has cured. This compression counteracts tensile and flexural stresses from loads to reduce cracking and increase strength, allowing pre-stressed concrete to be lighter and more durable than reinforced concrete. It is commonly used in bridges, buildings, tanks, and other structures.
Prefabrication types and Applications explainedEyad Reda
Explaining prefabrication in construction in a simple way. The contents range from steel framing, Precast concrete, Concrete prefab systems, sandwich paneling, timber framing and Real-life applications for prefabrication.
This document discusses prefabrication in construction. Prefabrication involves assembling components of a structure in a factory then transporting them to the construction site. It has advantages like reduced cost, time, and waste and allows work during poor weather. Common prefabricated components include columns, beams, waffle floors/roofs which are cast and cured off-site then erected using cranes. While prefabrication offers benefits, it also has disadvantages like potential breakage during transport and need for specialized equipment and labor. The document concludes that partial prefabrication is well-suited for Indian conditions.
This document provides an overview of different types of retaining walls, including gravity, cantilever, counterfort, sheet pile, and diaphragm walls. It discusses the key components and design considerations for gravity and cantilever retaining walls. Gravity walls rely on their own weight for stability, while cantilever walls consist of a vertical stem with a heel and toe slab acting as a cantilever beam. The document also covers lateral earth pressures, drainage of retaining walls, uses of sheet pile walls, and construction methods for diaphragm walls.
The document discusses common defects found in buildings such as cracks and dampness. It categorizes defects into pre-construction, during construction, and post-construction. Cracks can be structural or non-structural, and are caused by factors like drying shrinkage, thermal movement, elastic deformation, creep, chemical reactions, and foundation issues. Dampness is usually due to penetrating damp from gaps or rising damp without a proper damp proof course. Preventive measures include proper design, materials, construction practices, and addressing the root causes of defects.
It is the presentation based on precast concrete construction which includes each and every point and scope which may be useful to civil engineering students
Prefabrication is the practice of assembling components of a structure in a factory or other manufacturing site, and transporting them to the construction site where the structure is to be located.
Post-tensioning is an effective alternative for earthquake-prone regions and dense populations in India. It has advantages over ordinary reinforced concrete like higher seismic resilience, less concrete usage, stiffer foundations, and faster construction. Post-tensioning involves threading steel tendons through ducts and tensioning them after concrete pouring. It provides better crack control, economy, quality, and efficiency. While widely used in other countries, post-tensioning is not yet common in India but has applications in slabs, buildings, and foundations.
Prefabrication involves assembling building components in a factory and transporting them to the construction site. There are several prefabrication systems including open prefab, box type, and large prefab. Prefabricated components include panels, roofs, floors, and more which are manufactured off-site and assembled on-site. Prefabrication offers benefits like reduced construction time and costs, improved quality, and less waste. However, it also has disadvantages such as requiring specialized equipment and skilled labor for transportation and assembly. A case study on a housing project in India demonstrated how prefabrication helped complete buildings faster and with higher quality.
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.
This document discusses prefabrication in construction. Prefabrication involves assembling structural components at a factory or manufacturing site and transporting them to the construction site for assembly. It describes the advantages as less noise, dust, time and costs compared to on-site construction. Potential disadvantages include transportation costs, accuracy needs and reduced aesthetic variety. The document outlines various prefabrication components, materials, systems, joints, casting methods and the differences between on-site and off-site prefabrication.
The document discusses precast concrete construction. Some key points:
- Precast concrete components are cast off-site in a controlled environment and transported to the construction site for assembly. This allows for standardized, mass produced elements.
- Large precast concrete panels form the walls and floors, connecting vertically and horizontally. When joined, they form a rigid box structure that transfers lateral loads.
- Connections between precast elements can be either dry joints using bolts/welds, or monolithic placement with concrete poured to join components.
This document discusses prefabricated concrete columns. It defines prefabrication as assembling building components in a factory and transporting them to the construction site. Precast concrete columns can be single or double-story height and are made in modular designs to accommodate different heights. Columns have widths of 300mm, 450mm, or 600mm and can be rectangular or circular. Connection methods between the column and foundation include cast-in base plates, dowel tubes, or projections. The manufacturing process for precast concrete components involves 10 main steps including installing molds and reinforcement, pouring and vibrating concrete, curing, and removing molds.
This document discusses precast concrete construction. Some key points:
- Precast concrete elements are cast and cured off-site then transported for assembly, allowing more efficient production and quality control.
- Elements include slabs, beams, columns, and wall panels that are joined on-site through embedded bolts, plates, and grouted connections.
- The precasting process involves casting concrete around prestressing strands to add strength, then cutting sections and transporting them for erection.
Precast concrete is concrete that is cast in reusable molds or "forms" that are then cured in a controlled environment. This allows precast concrete construction to provide several benefits over traditional cast-in-place concrete including time savings, quality assurance, cost effectiveness, durability, aesthetics, and safer construction. However, precast concrete also has some disadvantages such as high initial investment costs, transportation issues, handling difficulties, limitations for modifications, and needing sensitive connection work. Overall, precast concrete can be a good solution for large construction projects where its benefits outweigh its disadvantages.
Saint Gobain Gyproc India Ltd. is a market leader in India's plasterboard market with a 48% market share. The document discusses Saint Gobain's products, financial performance, competitors like Lafarge Boral and Sai India, and the Indian gypsum market. It also presents a SWOT analysis and the results of a survey of 15 Saint Gobain dealers regarding their satisfaction with the company's products, advertising, and distribution channels.
The document contains construction documents for renovations to the Lafayette Tap Room located in Buffalo, New York. It includes general notes specifying code compliance, contractor responsibilities, and other project requirements. Floor plans show the layout and dimensions of the existing and proposed renovated space. Elevations, sections and schedules provide additional architectural details for walls, doors, finishes and fixtures to complete the renovations.
This document discusses the design and construction of a post-tensioned concrete slab. It begins with objectives to summarize experience with post-tensioning in building construction and discuss design and construction of post-tensioned flat slab structures. It then provides details on prestressed concrete principles, design of the PT slabs including thickness determination and prestress calculations, and execution steps like formwork, concrete pouring, prestressing, and grouting. Post-tensioning offers advantages over reinforced concrete like longer spans, thinner slabs, and improved seismic performance.
Post-Tension Concrete - Info session for ContractorsAMSYSCO Inc.
This presentation is to help General and Concrete Contractors manage construction projects that use Post-Tensioned Concrete.
1. Intro to Post-Tension
2. Components of Post-Tension
3. Construction Team
4. Submittals
5. Pre-Installation
6. Installation Management
7. Post-Concrete Placement
8. Troubleshooting
The document discusses different types of partition walls used to divide interior spaces in buildings. It describes timber stud, metal stud, drywall, glass block, and block partitions. Timber stud partitions can be plaster skimmed, dry-lined, or partially glazed. Metal stud partitions are lightweight but strong, consisting of a metal framework covered in plasterboard or fire-resistant sheeting. Glass block partitions are made of translucent glass blocks laid in mortar, sometimes with reinforcement. Block partitions are constructed from masonry blocks.
Glass partition walls can be constructed of either glass sheets or hollow glass blocks. Glass sheet partitions use a wooden frame with glass sheets fixed into panels divided by vertical and horizontal posts. Hollow glass blocks are translucent units available in different sizes, shapes, and thicknesses that are laid with mortar. Glass partition walls provide architectural effect while being soundproof, fireproof, and heatproof. Steel partition walls can be single or double-skinned and are used to create enclosed work areas in offices and industrial environments.
Partition walls are used to divide interior spaces. They can be load-bearing or non-load bearing. Common types include timber, brick, clay block, concrete, glass, and metal partitions. Timber partitions use a wooden framework, while brick partitions come in plain, reinforced, and nogging styles. Clay block and concrete partitions use hollow blocks or precast panels. Glass partitions employ sheets or hollow blocks for visibility and soundproofing. Metal partitions make use of metal lath and plaster or steel framing. Proper installation of the chosen partition wall type is important for strength and function.
Pre-stressed concrete is a combination of steel and concrete that takes advantage of each material's strengths. There are three main types of pre-stressed concrete: pre-tensioned concrete, bonded post-tensioned concrete, and unbonded post-tensioned concrete. Pre-tensioned concrete involves stressing steel reinforcement prior to placing concrete around it, while bonded and unbonded post-tensioned concrete involve stressing steel embedded in cured concrete. Pre-stressing concrete provides benefits like increased strength, reduced cracking and corrosion, and allowing for thinner members. The pre-stressing process requires careful planning and consideration of factors like creep, shrinkage, and stress losses over time.
This document defines and compares different types of prestressed concrete, including pre-tensioned and post-tensioned concrete. Pre-tensioned concrete involves stressing steel reinforcement prior to placing concrete around it. Post-tensioned concrete uses unstressed steel placed in concrete that is later tensioned. Bonded post-tensioning bonds the steel to the concrete, while unbonded systems separate the steel and concrete. Prestressed concrete provides benefits like increased strength, reduced cracking, and improved durability over conventional reinforced 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.
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 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.
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.
prestressed concrete and precast concrete technology.pptxPRASANNABHAVANGR1
This document provides information on precast, prestressed concrete construction. It discusses how precast concrete elements are cast off-site in a controlled environment and transported to the construction site. This allows for faster, more efficient construction compared to site-cast concrete. Common precast structural elements include slabs, beams, columns, and wall panels. The document outlines the manufacturing process and how precast elements are joined together on-site. It also discusses some applications of precast concrete such as buildings, bridges, and water tanks.
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 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 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 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.
Introduction and methods of Prestressed ConcreteAthiqullakhan1
This document provides an overview of pre-stressed concrete, including:
1. It defines pre-stressed concrete as concrete in which internal stresses are introduced to counteract stresses from external loads.
2. It discusses the materials used - steel wires, strands, tendons, and cables - and whether they are bonded or unbonded.
3. It compares pre-stressed concrete and reinforced concrete, noting differences in stress levels, deflections, shear resistance, fatigue resistance, and economics.
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.
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 provides a brief history of prestressed concrete, beginning in 1824 with the development of Portland cement. It then outlines several important developments in prestressed concrete technology from the late 19th century through the mid-20th century by innovators from various countries. These include early uses of steel in concrete, prestressing methods like pre-tensioning and post-tensioning, and development of high-strength steel and anchoring systems. It also mentions increased use of prestressed concrete during World War 2 and establishment of professional organizations to support the field.
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.
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Prestressed concrete uses high-strength steel tendons to place concrete in compression before loading. This counters the tensile stresses from loads and allows for longer spans and lighter structures. There are two main methods: pretensioning, where tendons are tensioned before concrete is poured, and post-tensioning, where tendons are tensioned after concrete cures. Prestressed concrete has advantages like reduced cracking, increased load capacity, and smaller deflections under loads.
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2. The concept of prestressed concrete
appeared in 1888 when P.H. Jackson was
granted the first patent in the United States
for prestressed concrete design. Jackson’s
idea was perfect, but the technology of high
strength steel that exhibited low relaxation
characteristics was not yet available.
It was not until Eugene Freyssinet defined
the need for these materials that
prestressed concrete could be used as a
structural building material. Unfortunately,
although Freyssinet, a brilliant structural
designer and bridge builder, lacked the
teaching qualities necessary to communicate
his ideas to other engineers.
It would take Gustave Magnel to write the
first book of design in prestressed concrete,
3. “Pre-stressed concrete is a form of reinforced concrete
that builds in compressive stresses during construction
to oppose those found when in use.”
It is a combination of steel and concrete that takes
advantages of the strengths of each material.
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 .
METHODS :-
a) Pre-tensioning
b) Post-tensioning
PRETENSIONING :- Placing of concrete around
reinforcing tendons that have been stressed to the
desired degree.
POST-TENSIONING :- Reinforcing tendons are stretched
by jacks whilst keeping them inserted in voids left pre-
hand during curing of concrete.
These spaces are then pumped full of grout to bond steel
tightly to the concrete.
PRESTRESSED CONCRETE
4. FORMS
Wires
Prestressing wire is a single unit made of steel.
Strands
Two, three or seven wires are wound to form a
prestressing strand.
Tendon
A group of strands or wires are wound to form a
prestressing tendon.
Cable
A group of tendons form a prestressing cable.
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.
WHY PRESTRESSED CONCRETE?
• Concrete remains un-cracked
• Reduction of steel corrosion
• Increases durability
• Good for pressure vessels
• High span to depth ratio (ex:
45:1 vs. 28:1)
• less dead load
• More economical
5. 3 MAIN TYPES OF INTERNAL PRESTRESSED CONCRETE
1. Pre-Tension Concrete: pre-stressing steel is
tension stressed prior to the placement of
the concrete and unloaded after concrete
has harden to required strength.
2. Bonded post-tensioned concrete:
unstressed pre-stressing steel is placed
within the concrete and then tension
stressed after concrete has harden to
required strength
3. Un-bonded post-tensioned concrete: differs
from bonded post-tensioning by providing
the pre-stressing steel permanent freedom
of movement relative to the concrete.
6. PRESTRESSED PRE-TENSIONED CONCRETE
Prestressed Pre-tensioned concrete is when the
steel reinforcement is stressed prior to concrete
being placed around the steel.
Pre-tensioned concrete is cast around already
tensioned tendons.
This method produces a good bond between the
tendon and concrete, which both protects the
tendon from corrosion and allows for direct transfer
of tension.
The cured concrete adheres and bonds to the bars
and when the tension is released it is transferred to
the concrete as compression by static friction.
However, it requires stout anchoring points
between which the tendon is to be stretched and
the tendons are usually in a straight line.
Thus, most pretensioned concrete elements are
prefabricated in a factory and must be transported
to the construction site, which limits their size.
Pre-tensioned elements may be balcony elements,
lintels , floor slabs, beams or foundation piles.
Section for Pre-tensioning
7. CONCERNS WITH PRE-TENSION
• Usually uses a mould which is able to resist the
forces within the tendons. Which are more
expensive than regular moulds
• Concrete sample should be taken for every new
mix so that strength obtained may be determined
before cutting the tendons releasing the stresses
onto the concrete.
• Since pre-tension may only be set once calculations
for the camber must be correct. So, pre-stress
takes a large amount of preplanning. Must
consider self-weight deflections, pre-stress
deflections, dead load deflections, and live load
deflections.
• Since it may only tightened once and cannot be
retightened the designer must also account for
Creep of concrete, elastic shortening of concrete,
shrinkage of concrete, relaxation of steel, slip at
the anchorage, and friction losses due to intended
and unintended (wobble) curvature in the tendons
in calculations for the camber of the member in
order to have lasting quality of the structure.
8. ADVANTAGES OF PRETENSION
• Tension caused by the steel is spread
throughout the length of the concrete since it is
bonded within the concrete along the length of
the member.
9. POST - TENSIONING
• It is a method of reinforcing (strengthening) concrete or other materials with high-strength steel strands called
tendons.
• Post-tensioning allows construction that would otherwise be impossible due to either site constraints or
architectural requirements.
• Requires specialized knowledge and expertise to fabricate, assemble and install.
• After adequate curing of concrete, reinforcing tendons(placed in side the voids of the structure) are
tensioned/stretched by jacks on the sides & grouts filled with appropriate mix.
APPLICATIONS –
Structural members beams, bridge-deck panels, Roof –Slabs, Concrete Silos Etc.
• Concrete is very strong in compression but weak in tension.
• This deflection will cause the bottom of the beam to elongate slightly & cause cracking.
• Steel reinforcing bars (“rebar”) are typically embedded in the concrete as tensile reinforcement to limit the
crack widths.
• Rebar is what is called “passive” reinforcement however; it does not carry any force until the concrete has
already deflected enough to crack.
• Post-tensioning tendons, on the other hand, are considered “active” reinforcing.
• Because it is prestressed, the steel is effective as reinforcement even though the concrete may not be
cracked .
• Post-tensioned structures can be designed to have minimal deflection and cracking, even under full load.
BENEFITS-
11. BONDED POST-TENSIONED CONCRETE
Process
• Concrete is casted around a curved
duct (usually corrugated), to allow room
for the Tendon to be inserted.
• After the concrete has hardened the
tendons are pulled in tension and then
wedged.
• The duct is then injected with grout
Advantages
• Tendons are less likely to de-stress in accidents
• Tendons can be easily 'weaved' allowing more efficient designs
• Higher ultimate strength due to bond generated between the strand and
concrete
• No issues with maintaining the anchor
13. • In post-tensioning, the steel in
the concrete is stretched after the
curing process.
• Unlike bonded, un-bonded
provides tendons freedom of
movement by coating each
tendon with grease and covering
it with a plastic sheathing
• Tension on the concrete is
achieved by the cables acting
against the steel anchors that are
buried in the perimeters of the
concrete
UN-BONDED POST-TENSION
ADVANTAGES
• Post-stress grouting is
eliminated
• Ability to de-stress the
tendons
• Economical
• Replaceable
• Simple stressing equipment
14. ADVANTAGES
Post-tensioning, which is a form of prestressing, has
several advantages over standard reinforcing steel
(rebars):
•It reduces or eliminates shrinkage cracking-
therefore no joints, or fewer joints, are needed.
•It allows slabs and other structural members to be
thinner.
•It allows us to build slabs on expansive or soft soils.
•It lets us design longer spans in elevated members,
like floors or beams.
•MATERIAL SAVINGS- Thinner concrete member sizes;
reduction in concrete is approximately 20%.
• QUICKER CONSTRUCTION
•INCREASED PERFORMANCE- Improved seismic behavior
&
Reduced deflection and vibration.
• REDUCED LIFETIME COSTS- Reduced building height
also results in energy savings, especially for office
buildings.
15. POST-TENSIONING
• Can be performed at the project site as well as at precast yards.
There is relatively less loss of prestress due to concrete shrinkage as at the time of prestressing
concerete has already been cured.
• Corrosion of steel is less as compared to pre-tensioning.
• There is more flexibility in design. The prestressing tendons can be configured to almost any shape. As
per requirements the tendons may be bonded or unbonded.
• They are more prone to anchorage failure as the compressive forces are transferred at the beam ends.
Hence compressive stresses are concentrated.
PRE-TENSIONING
• Difficult to perform at site. Only done in precast yards.
• There is greater loss of prestress due to shrinkage of concrete.
• Concrete and steel tendons are in direct contact. So any moisture that slips through cracks in concrete
will cause corrosion in steel.
• Tendons can only be straight or circular.
• Since the compressive forces are transferred over a certain length of bond, they are less prone to
anchorage failure.
So to generalize post-tensioning is usually better than pre-tensioning. However this may not always be
the case. Either method has its applications.
DIFFERENCE BETWEEN POST-TENSIONING AND PRE- TENSIONING
16. IHP(Indian Hume Pipes) introduced the
• PRESTRESSED CONCRETE MONOBLOCK SLEEPERS for railways in
1970.
• PRESTRESSED CONCRETE PIPE ( PSC )
• PRESTRESSED CONCRETE CYLINDER PIPE ( PCCP)
The Freyssinet Prestressed Concrete Company Ltd (FPCC) established
in 1954 is the first company to introduce state-of-the-art Prestressing
Technology in India,
MANUFACTURER OF PRE -STRESS CONCRETE IN INDIA
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