Regarding basics of prestressed such as inventor, types of prestressing systems, methods of prestressing, types of grouting, types of cables used for prestressed structure and method of construction etc..
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 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.
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.
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
Prestressed concrete combines high-strength concrete and high-strength steel in an active manner by tensioning steel tendons and holding them against the concrete, putting it into compression. This transforms concrete from a brittle to a more elastic material. It allows for optimal use of each material's properties and better behavior under loads. Prestressed concrete was pioneered in the 1930s and its use has expanded, finding applications in bridges and other structures. Common methods are pretensioning and post-tensioning, using various tendon types, with bonded or unbonded configurations. Tensioning is done using mechanical, hydraulic, electrical or chemical devices.
This document summarizes the precast segmental construction method for bridges. It was first used in Western Europe in the 1950s and involves casting concrete segments off-site, transporting them to the construction location, and erecting them using various methods like balanced cantilever, progressive placement, span-by-span, or incremental launching. Machinery like launchers, girders, cranes, and hydraulic jacks are used for erection. Additional steps include external prestressing and grouting. Precast segmental construction allows for longer spans, faster construction times, increased quality control, and is most suitable for long bridges.
This document provides information on a syllabus for a course on prestressed concrete. It outlines the course objectives which are to understand the principles, necessity, techniques, losses, and analysis and design of prestressed concrete members. The course outcomes are for students to acquire knowledge on the evolution of prestressing, prestressing techniques, and skills in analyzing and designing prestressed structural elements per code provisions. The syllabus then outlines 5 units that will be covered which include introduction, methods and systems, losses of prestress, flexure, shear, transfer of prestress, composite beams, and deflections. Relevant textbooks and codes are also listed.
The document discusses the principles and applications of prestressing in construction. It describes how prestressing uses tensioned steel strands or wires to put concrete members into compression through pre-tensioning or post-tensioning. This counters the tensile stresses experienced by concrete and allows for longer spans, reduced member depth, crack control, and cost savings. Common applications of prestressing include bridges, flyovers, buildings, parking structures, and industrial structures.
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 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.
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.
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
Prestressed concrete combines high-strength concrete and high-strength steel in an active manner by tensioning steel tendons and holding them against the concrete, putting it into compression. This transforms concrete from a brittle to a more elastic material. It allows for optimal use of each material's properties and better behavior under loads. Prestressed concrete was pioneered in the 1930s and its use has expanded, finding applications in bridges and other structures. Common methods are pretensioning and post-tensioning, using various tendon types, with bonded or unbonded configurations. Tensioning is done using mechanical, hydraulic, electrical or chemical devices.
This document summarizes the precast segmental construction method for bridges. It was first used in Western Europe in the 1950s and involves casting concrete segments off-site, transporting them to the construction location, and erecting them using various methods like balanced cantilever, progressive placement, span-by-span, or incremental launching. Machinery like launchers, girders, cranes, and hydraulic jacks are used for erection. Additional steps include external prestressing and grouting. Precast segmental construction allows for longer spans, faster construction times, increased quality control, and is most suitable for long bridges.
This document provides information on a syllabus for a course on prestressed concrete. It outlines the course objectives which are to understand the principles, necessity, techniques, losses, and analysis and design of prestressed concrete members. The course outcomes are for students to acquire knowledge on the evolution of prestressing, prestressing techniques, and skills in analyzing and designing prestressed structural elements per code provisions. The syllabus then outlines 5 units that will be covered which include introduction, methods and systems, losses of prestress, flexure, shear, transfer of prestress, composite beams, and deflections. Relevant textbooks and codes are also listed.
The document discusses the principles and applications of prestressing in construction. It describes how prestressing uses tensioned steel strands or wires to put concrete members into compression through pre-tensioning or post-tensioning. This counters the tensile stresses experienced by concrete and allows for longer spans, reduced member depth, crack control, and cost savings. Common applications of prestressing include bridges, flyovers, buildings, parking structures, and industrial 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 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 different systems used for prestressing steel, which are grouped into four categories: mechanical, hydraulic, electrical/thermal, and chemical. It provides details on common tensioning devices within each category. Mechanical devices use weights, pulleys, and screw jacks. Hydraulic jacks ranging from 5-600 tonnes are widely used. Electrical/thermal heating of wires before concreting is another option. Chemical devices use expanding cement. The document also describes several popular prestressing systems including Freyssinet, Gifford Udall, Lee-McCall, Magnel Blaton, BBRV, and Baur Leonhardt.
Pile foundation are essential in case where SBC is low or the load coming from superstructure is too heavy,
Topics covered includes Materials used for making piles, Type of piles, load transfer mechanism, factors affecting selection of piles, Installation methods, load carrying capacity of piles, different load tests performed and the behavior of piles as a group.
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.
Deep foundations are used when the bearing stratum is located at a significant depth below the surface. The most common types of deep foundations are pile foundations, cofferdams, and caisson foundations. Pile foundations support structures using vertical piles that transfer loads either through end bearing or skin friction. Piles can be made of timber, concrete, steel, or a composite. Cofferdams are temporary structures used to exclude water from a construction site to allow work below the water level. Common types include earthfill, rockfill, single-walled, and cellular cofferdams. Caissons are watertight structures that become part of the permanent foundation. Types are open caissons, box caissons
There are three main bridge construction launching techniques: balanced cantilever, span by span, and progressive placement. The balanced cantilever method involves building outward from both sides of each pier simultaneously. The span by span method assembles all segments for a span together before lifting into place. The progressive placement method builds the bridge in one direction by placing segments at the tip of a advancing cantilever arm.
This document discusses quality control and durability factors in concrete. It defines quality as conformance to requirements and durability as a concrete's ability to resist deterioration when exposed to the environment. Several factors influence concrete durability, including the materials used, water-cement ratio, compaction, curing and the physical and chemical conditions of the service environment. Common durability issues include corrosion, cracking from sulfate attack or alkali-silica reaction, and carbonation reducing alkalinity. Proper quality control of materials and construction processes is needed to produce durable concrete.
This document provides information on diaphragm walls, including:
- Diaphragm walls are reinforced concrete walls constructed using the slurry trench technique, reaching depths of up to 50m.
- They are commonly used as retaining walls, for supporting deep excavations, and as basement or underground structure walls.
- Construction involves excavating trenches using bentonite slurry, installing reinforcement cages, and pouring concrete to form wall panels either successively or alternately.
- Proper specifications are required for bentonite slurry, reinforcement, and construction methods to ensure continuity and water-tightness of the completed diaphragm wall structure.
Design of Reinforced Concrete Structure (IS 456:2000)MachenLink
This is the 1st Lecture Series on Design Reinforced Cement Concrete (IS 456 -2000).
In this video, you will learn about the objective of structural designing and then basic properties of concrete and steel.
Concrete properties like...
1. Grade of Concrete
2. Modulus of Elasticity
3. Characteristic Strength
4. Tensile Strength
5. Creep and Shrinkage
6. Durability
Reinforced Steel Properties....
1. Grade and types of steel
2. Yield Strength of Mild Steel and HYSD Bars
The document provides an overview of prestressed concrete structures including:
- Definitions of prestressing where internal stresses counteract external loads.
- The key terminology used including tendons, anchorage, pretensioning vs post-tensioning.
- The materials used including cement, concrete, and steel types.
- The stages of loading and advantages of prestressing over reinforced concrete.
- Details of pretensioning and post-tensioning systems including equipment, processes, and differences between the two methods.
Pre-stressed concrete builds in compressive stresses during construction to oppose tensile stresses that occur when in use. There are two main types: pretensioning and post-tensioning. Pretensioning involves stretching wires or strands called tendons between anchorages before concrete is placed, while post-tensioning stresses tendons after concrete has gained strength. Common prestressing systems include Freyssinet, Magnel, Lee-McCall, and Gifford-Udall. Prestressed concrete is more durable and requires less material than reinforced concrete, but requires specialized techniques and quality control. It is widely used in bridges and building construction.
This document discusses post-tensioning devices and systems. Post-tensioning involves applying tension to tendons placed in ducts within hardened concrete. There are two main types: bonded uses grout in the ducts while unbonded does not. Key devices include ducts, anchoring devices, jacks and optional couplers and grouting equipment. Common anchoring principles are wedge action, direct bearing and looping wires. More than 64 post-tensioning systems have been patented worldwide with the Freyssinet system most common in India.
This document discusses different methods for soil stabilization, including mechanical, physical, chemical, and bituminous stabilization. Mechanical stabilization involves compacting soil to increase density and strength. Physical stabilization involves blending soils or adding admixtures to improve properties. Chemical stabilization uses lime, cement, or other chemicals like calcium chloride to react with soils and modify their characteristics. Bituminous stabilization involves adding bitumen or asphalt to seal soil pores and increase cohesion between particles. The document provides details on appropriate soil types, required quantities, and construction methods for each stabilization technique.
This document outlines the advantages of using post-tensioning in building structures. Post-tensioning allows for longer spans, reduced floor thickness, increased floor area, faster construction speeds, and reduced material usage. It discusses common post-tensioning systems used in building floors and specialized structural elements. Post-tensioning provides more flexible and economical building structures compared to other methods.
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.
Vibro replacement stone columns are a ground improvement technique to improve the load bearing capacity and reduce the settlement of the soil. On many occasions, it is noted that the local soil is, by nature, unable to bear the proposed structure, so the use of ground improvement techniques may be necessary. Use of stone columns is one such technique. The stone column consists of crushed coarse aggregates of various sizes. The ratio in which the stones of different sizes will be mixed is decided by design criteria
This document discusses methods for solving indeterminate structural problems, specifically the matrix method. It provides advantages and disadvantages of matrix methods, including that they are formalized, versatile, and applicable to both determinate and indeterminate problems. The document also outlines the process of the matrix method, including classifying members, assembling member stiffness matrices into a global stiffness matrix, transforming between local and global coordinate systems using transformation matrices, and solving for displacements and forces. An example application to a truss structure is presented.
This document discusses pile foundations. It begins by listing the topics that will be covered, including types of piles, pile spacing, pile caps, load testing, and failures. It then defines a pile foundation as using slender structural members like steel, concrete or timber that are installed in the ground to transfer structural loads to deeper, stronger soil layers. The document goes on to classify piles based on their function, material, and installation method. It describes common pile types such as precast concrete, driven steel, and cast-in-place piles. The document provides details on pile uses, selection factors, and installation procedures.
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.
Tall Structures
Usually structure or building having height more than 80m is considered as a tall structure.
Generally tall structure may be defined as one that because of its height it is affected by lateral.
Classification: 1. Multi storeyedresidential building.
2. Multi storeyedcommercial building.
3. Tall chimneys.
4. Transmission Towers
5. Cooling towers
Prestressed Concrete
•Prestressis defined as a method of applying pre-compression to control the stresses resulting due to external loads below the neutral axis of the beam tension developed due to external load which is more than the permissible limits of the plain concrete.
Demolition
•The action or process of destroying(demolishing)the building or other structures.
•In congested area, in particular, the quality of demolition technique becomes an essential element which determines the success of revitalization of city.
•In addition to efficiency in demolition, strategies must be adopted to avoid noise, vibration and dust which affect the surrounding environment and there must be efficient disposal of waste products
Prestressed concrete is concrete in which internal stresses are introduced to counteract external loads. Tendons are stretched elements that impart prestress, and anchorage devices enable the tendons to impart and maintain prestress. There are two main methods - pretensioning, where tendons are tensioned before concrete is cast, and post-tensioning, where tendons are tensioned against hardened concrete. Prestressed concrete uses high-strength materials like cement, concrete, and steel tendons or strands to achieve its compressive strength and durability advantages over reinforced concrete.
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 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 different systems used for prestressing steel, which are grouped into four categories: mechanical, hydraulic, electrical/thermal, and chemical. It provides details on common tensioning devices within each category. Mechanical devices use weights, pulleys, and screw jacks. Hydraulic jacks ranging from 5-600 tonnes are widely used. Electrical/thermal heating of wires before concreting is another option. Chemical devices use expanding cement. The document also describes several popular prestressing systems including Freyssinet, Gifford Udall, Lee-McCall, Magnel Blaton, BBRV, and Baur Leonhardt.
Pile foundation are essential in case where SBC is low or the load coming from superstructure is too heavy,
Topics covered includes Materials used for making piles, Type of piles, load transfer mechanism, factors affecting selection of piles, Installation methods, load carrying capacity of piles, different load tests performed and the behavior of piles as a group.
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.
Deep foundations are used when the bearing stratum is located at a significant depth below the surface. The most common types of deep foundations are pile foundations, cofferdams, and caisson foundations. Pile foundations support structures using vertical piles that transfer loads either through end bearing or skin friction. Piles can be made of timber, concrete, steel, or a composite. Cofferdams are temporary structures used to exclude water from a construction site to allow work below the water level. Common types include earthfill, rockfill, single-walled, and cellular cofferdams. Caissons are watertight structures that become part of the permanent foundation. Types are open caissons, box caissons
There are three main bridge construction launching techniques: balanced cantilever, span by span, and progressive placement. The balanced cantilever method involves building outward from both sides of each pier simultaneously. The span by span method assembles all segments for a span together before lifting into place. The progressive placement method builds the bridge in one direction by placing segments at the tip of a advancing cantilever arm.
This document discusses quality control and durability factors in concrete. It defines quality as conformance to requirements and durability as a concrete's ability to resist deterioration when exposed to the environment. Several factors influence concrete durability, including the materials used, water-cement ratio, compaction, curing and the physical and chemical conditions of the service environment. Common durability issues include corrosion, cracking from sulfate attack or alkali-silica reaction, and carbonation reducing alkalinity. Proper quality control of materials and construction processes is needed to produce durable concrete.
This document provides information on diaphragm walls, including:
- Diaphragm walls are reinforced concrete walls constructed using the slurry trench technique, reaching depths of up to 50m.
- They are commonly used as retaining walls, for supporting deep excavations, and as basement or underground structure walls.
- Construction involves excavating trenches using bentonite slurry, installing reinforcement cages, and pouring concrete to form wall panels either successively or alternately.
- Proper specifications are required for bentonite slurry, reinforcement, and construction methods to ensure continuity and water-tightness of the completed diaphragm wall structure.
Design of Reinforced Concrete Structure (IS 456:2000)MachenLink
This is the 1st Lecture Series on Design Reinforced Cement Concrete (IS 456 -2000).
In this video, you will learn about the objective of structural designing and then basic properties of concrete and steel.
Concrete properties like...
1. Grade of Concrete
2. Modulus of Elasticity
3. Characteristic Strength
4. Tensile Strength
5. Creep and Shrinkage
6. Durability
Reinforced Steel Properties....
1. Grade and types of steel
2. Yield Strength of Mild Steel and HYSD Bars
The document provides an overview of prestressed concrete structures including:
- Definitions of prestressing where internal stresses counteract external loads.
- The key terminology used including tendons, anchorage, pretensioning vs post-tensioning.
- The materials used including cement, concrete, and steel types.
- The stages of loading and advantages of prestressing over reinforced concrete.
- Details of pretensioning and post-tensioning systems including equipment, processes, and differences between the two methods.
Pre-stressed concrete builds in compressive stresses during construction to oppose tensile stresses that occur when in use. There are two main types: pretensioning and post-tensioning. Pretensioning involves stretching wires or strands called tendons between anchorages before concrete is placed, while post-tensioning stresses tendons after concrete has gained strength. Common prestressing systems include Freyssinet, Magnel, Lee-McCall, and Gifford-Udall. Prestressed concrete is more durable and requires less material than reinforced concrete, but requires specialized techniques and quality control. It is widely used in bridges and building construction.
This document discusses post-tensioning devices and systems. Post-tensioning involves applying tension to tendons placed in ducts within hardened concrete. There are two main types: bonded uses grout in the ducts while unbonded does not. Key devices include ducts, anchoring devices, jacks and optional couplers and grouting equipment. Common anchoring principles are wedge action, direct bearing and looping wires. More than 64 post-tensioning systems have been patented worldwide with the Freyssinet system most common in India.
This document discusses different methods for soil stabilization, including mechanical, physical, chemical, and bituminous stabilization. Mechanical stabilization involves compacting soil to increase density and strength. Physical stabilization involves blending soils or adding admixtures to improve properties. Chemical stabilization uses lime, cement, or other chemicals like calcium chloride to react with soils and modify their characteristics. Bituminous stabilization involves adding bitumen or asphalt to seal soil pores and increase cohesion between particles. The document provides details on appropriate soil types, required quantities, and construction methods for each stabilization technique.
This document outlines the advantages of using post-tensioning in building structures. Post-tensioning allows for longer spans, reduced floor thickness, increased floor area, faster construction speeds, and reduced material usage. It discusses common post-tensioning systems used in building floors and specialized structural elements. Post-tensioning provides more flexible and economical building structures compared to other methods.
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.
Vibro replacement stone columns are a ground improvement technique to improve the load bearing capacity and reduce the settlement of the soil. On many occasions, it is noted that the local soil is, by nature, unable to bear the proposed structure, so the use of ground improvement techniques may be necessary. Use of stone columns is one such technique. The stone column consists of crushed coarse aggregates of various sizes. The ratio in which the stones of different sizes will be mixed is decided by design criteria
This document discusses methods for solving indeterminate structural problems, specifically the matrix method. It provides advantages and disadvantages of matrix methods, including that they are formalized, versatile, and applicable to both determinate and indeterminate problems. The document also outlines the process of the matrix method, including classifying members, assembling member stiffness matrices into a global stiffness matrix, transforming between local and global coordinate systems using transformation matrices, and solving for displacements and forces. An example application to a truss structure is presented.
This document discusses pile foundations. It begins by listing the topics that will be covered, including types of piles, pile spacing, pile caps, load testing, and failures. It then defines a pile foundation as using slender structural members like steel, concrete or timber that are installed in the ground to transfer structural loads to deeper, stronger soil layers. The document goes on to classify piles based on their function, material, and installation method. It describes common pile types such as precast concrete, driven steel, and cast-in-place piles. The document provides details on pile uses, selection factors, and installation procedures.
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.
Tall Structures
Usually structure or building having height more than 80m is considered as a tall structure.
Generally tall structure may be defined as one that because of its height it is affected by lateral.
Classification: 1. Multi storeyedresidential building.
2. Multi storeyedcommercial building.
3. Tall chimneys.
4. Transmission Towers
5. Cooling towers
Prestressed Concrete
•Prestressis defined as a method of applying pre-compression to control the stresses resulting due to external loads below the neutral axis of the beam tension developed due to external load which is more than the permissible limits of the plain concrete.
Demolition
•The action or process of destroying(demolishing)the building or other structures.
•In congested area, in particular, the quality of demolition technique becomes an essential element which determines the success of revitalization of city.
•In addition to efficiency in demolition, strategies must be adopted to avoid noise, vibration and dust which affect the surrounding environment and there must be efficient disposal of waste products
Prestressed concrete is concrete in which internal stresses are introduced to counteract external loads. Tendons are stretched elements that impart prestress, and anchorage devices enable the tendons to impart and maintain prestress. There are two main methods - pretensioning, where tendons are tensioned before concrete is cast, and post-tensioning, where tendons are tensioned against hardened concrete. Prestressed concrete uses high-strength materials like cement, concrete, and steel tendons or strands to achieve its compressive strength and durability advantages over reinforced concrete.
In post-tension, the concrete units are first cast by incorporating ducts or grooves to house the tendons .when the concrete attains sufficient strength, the high-tensile wires are tensioned by means of jack bearing on the end face of the member and anchored by wedges or nuts.
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.
The document discusses various types of wood floor systems and concrete floor systems. It explains the advantages of precast concrete over site-cast concrete, such as better quality control and the ability to steam cure. It also defines one-way and two-way concrete floor systems and lists different types of each, including solid slab, joist, flat plate, and waffle slab systems.
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
This document provides an introduction to prestressed concrete, including:
- Prestressing concrete involves applying an initial compressive load to counteract tensile stresses during use. Ancient examples include metal bands on wood.
- Prestressing provides advantages over reinforced concrete like reduced cracking, increased strength and stiffness, and suitability for precast construction.
- It describes prestressing materials, common systems like pre-tensioning and post-tensioning, and concepts in the analysis and design of prestressed concrete like stress conditions and load balancing.
The document discusses the history and development of pre-stressed concrete. It notes that Eugene Freyssinet is often referred to as the Father of Pre-stressed concrete and developed techniques like high-strength steel wires and conical wedges in the late 1930s. It provides examples of early pre-stressed concrete structures like the Pamban Road Bridge in India. It also discusses the basic concepts of pre-stressing including the materials used and different types of pre-stressing.
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.
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.
Prestressing is a technique where tension is applied to concrete before hardening to improve its performance. There are two main types - pre-tensioning and post-tensioning. Pre-tensioning involves tensioning steel tendons before casting concrete, while post-tensioning tensions tendons after casting. There are losses in prestress over time from factors like elastic shortening, shrinkage, creep, and steel relaxation. Proper materials and design are needed to account for these losses and ensure structures perform as intended.
This document discusses practical aspects of pre-stressed concrete (PSC) construction. It explains that PSC uses the intrinsic properties of steel and concrete, with concrete good for compression and steel for tension. Reinforcement is still needed in PSC for shear transfer, crack control, and stress distribution. Proper detailing and positioning of prestressing cables and reinforcement is important. Common issues in PSC construction include honeycombing, cracking, and stresses exceeding design limits. Solutions involve modified forms, grouting, additional reinforcement, and adjusted cable profiles. Proper material handling, stressing sequences, and construction methods are essential for successful PSC projects.
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.
A bridge is a structure built over an obstacle like a body of water or valley to allow crossing. It must support its own and traffic loads. Bridges are classified by material, structure type, construction method, and function. Common types include beam, girder, arch, truss, suspension, and cable-stayed bridges. Selection depends on span length, site conditions, cost, construction speed, and aesthetics. Proper investigation of soil, stream conditions, and alternatives is needed to select the best bridge site.
The Kurilpa Bridge in Brisbane, Australia utilizes a tensegrity structure comprising a series of staggered masts, major cables, and a tensegrity array of steel ties and flying struts to support a 6.5m wide composite steel and concrete deck across a 128m main central span. The tensegrity structure produces strength from the synergy of balanced tension and compression and allows the bridge to be constructed via balanced cantilever without relying on temporary supports.
This document discusses reinforced concrete and its properties. It explains that concrete is weaker in tension than compression, while steel has high tensile strength and bonds well with concrete. When combined, they form reinforced concrete which is strong and durable. The steel carries tensile forces while the concrete resists compression. Proper placement of reinforcement during construction is important for bond. Methods of bending, tying, and installing rebar are also outlined.
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.
1) Prestressing of concrete involves applying permanent compressive stresses to the member before external loads using high-strength steel wires or strands. This reduces or eliminates tensile stresses from the loads.
2) Prestressing is applied by pulling wires or strands with hydraulic jacks and anchoring them. When the steel tries to regain its length, it exerts compressive forces on the concrete, creating a negative bending moment in the beam.
3) Higher strength concrete is typically used for prestressed members as it reduces losses of prestressing force from elastic shortening, creep, and shrinkage, improving efficiency. It also allows for faster construction.
Design of tension and compression members – Tanks, pipes and poles – Partial prestressing –
Definition, methods of achieving partial prestressing, merits and demerits of partial prestressing.
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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.
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Sachpazis_Consolidation Settlement Calculation Program-The Python Code and th...Dr.Costas Sachpazis
Consolidation Settlement Calculation Program-The Python Code
By Professor Dr. Costas Sachpazis, Civil Engineer & Geologist
This program calculates the consolidation settlement for a foundation based on soil layer properties and foundation data. It allows users to input multiple soil layers and foundation characteristics to determine the total settlement.
Particle Swarm Optimization–Long Short-Term Memory based Channel Estimation w...IJCNCJournal
Paper Title
Particle Swarm Optimization–Long Short-Term Memory based Channel Estimation with Hybrid Beam Forming Power Transfer in WSN-IoT Applications
Authors
Reginald Jude Sixtus J and Tamilarasi Muthu, Puducherry Technological University, India
Abstract
Non-Orthogonal Multiple Access (NOMA) helps to overcome various difficulties in future technology wireless communications. NOMA, when utilized with millimeter wave multiple-input multiple-output (MIMO) systems, channel estimation becomes extremely difficult. For reaping the benefits of the NOMA and mm-Wave combination, effective channel estimation is required. In this paper, we propose an enhanced particle swarm optimization based long short-term memory estimator network (PSOLSTMEstNet), which is a neural network model that can be employed to forecast the bandwidth required in the mm-Wave MIMO network. The prime advantage of the LSTM is that it has the capability of dynamically adapting to the functioning pattern of fluctuating channel state. The LSTM stage with adaptive coding and modulation enhances the BER.PSO algorithm is employed to optimize input weights of LSTM network. The modified algorithm splits the power by channel condition of every single user. Participants will be first sorted into distinct groups depending upon respective channel conditions, using a hybrid beamforming approach. The network characteristics are fine-estimated using PSO-LSTMEstNet after a rough approximation of channels parameters derived from the received data.
Keywords
Signal to Noise Ratio (SNR), Bit Error Rate (BER), mm-Wave, MIMO, NOMA, deep learning, optimization.
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In the world with high technology and fast
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Key Words : Talent Management, Talent Acquisition , E-
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Effectiveness of Talent Acquisition through E-
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An In-Depth Exploration of Natural Language Processing: Evolution, Applicatio...DharmaBanothu
Natural language processing (NLP) has
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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
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Cricket management system ptoject report.pdfKamal Acharya
The aim of this project is to provide the complete information of the National and
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13. Concrete
• Minimum grades of concrete for
prestressed applications are as follows.
– 30 MPa for post-tensioned members
– 40 MPa for pre-tensioned members.
• Maximum grade of concrete is 60 MPa.
14. Forms of Prestressing Steel
Wires - single unit made of steel.
Strands – 2,3 or 7 wires wound to form a
prestressing strand.
Tendon - group of strands or wires wound to
form a prestressing tendon.
16. Cable - 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.
21. Advantages of Prestressing
Section remains uncracked under
service loads
• Reduction of steel corrosion
• Increase in durability.
• Full section is utilised
• Higher moment of inertia (higher stiffness)
22. • Less deformations (improved
serviceability).
• Increase in shear capacity.
• Suitable for use in pressure vessels, liquid
retaining structures.
• Improved performance (resilience) under
dynamic and fatigue loading.
29. Limitations of Prestressing
• Prestressing needs skilled technology. •
• use of high strength materials is costly.
• additional cost in auxiliary equipments.
• need for quality control and inspection.
30. Pre-tensioning or Post-
tensioning
Pre-tensioning
• The tension is applied to the tendons
before casting of the concrete.
• The pre-compression is transmitted from
steel to concrete through bond over the
transmission length near the ends.
32. Post-tensioning
• The tension is applied to the tendons
(located in a duct) after hardening of the
concrete.
• The pre-compression is transmitted from
steel to concrete by the anchorage device
(at the end blocks).
34. Stages of the pre-tensioning
operation
• Anchoring of tendons against the end
abutments
• Placing of jacks
• Applying tension to the tendons
• Casting of concrete
• Cutting of the tendons.
38. Advantages of Pre-tensioning
• Pre-tensioning is suitable for precast
members produced in bulk.
• In pre-tensioning large anchorage device
is not present.
39. Disadvantages of Pre-tensioning
• prestressing bed required for the pre-
tensioning operation.
• There is a waiting period in the
prestressing bed, before the concrete
attains sufficient strength.
• There should be good bond between
concrete and steel over the transmission
length.
40. Devices
• Prestressing bed
• End abutments
• Shuttering / mould
• Jack
• Anchoring device
• Harping device (optional)
46. various stages of the post-
tensioning operation
• Casting of concrete.
• Placement of the tendons.
• Placement of the anchorage block and
jack.
• Applying tension to the tendons.
• Seating of the wedges.
• Cutting of the tendons.
50. Advantages of Post-tensioning
• Post-tensioning is suitable for heavy cast-
in-place members.
• The waiting period in the casting bed is
less.
• The transfer of prestress is independent of
transmission length.
55. Properties of Grout
Grout = water + cement + sand + (water-
reducing admixtures, expansion agent and
pozzolanas.
w/c = 0.5.
Fine sand - used to avoid segregation.
56. Desirable properties of grout
1) Fluidity
2) Minimum bleeding and segregation
3) Low shrinkage
4) Adequate strength after hardening
5) No detrimental compounds
6) Durable.
57. Durability
• Prestressing steel is susceptible to stress
corrosion and hydrogen embrittlement in
aggressive environments.
• Hence, prestressing steel needs to be
adequately protected.
58. • Bonded tendons - alkaline environment of
the grout provides adequate protection.
• Unbonded tendons - corrosion protection
is provided by the following methods:
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