Prestressed concrete - Revision history

Editor: Reverted edits by Wearobee (talk) to last revision by Designing Buildings

2022-12-22T08:58:28Z

Reverted edits by Wearobee (talk) to last revision by Designing Buildings

← Older revision		Revision as of 08:58, 22 December 2022
Line 31:		Line 31:
	== Pre-tensioning prestressed concrete ==		== Pre-tensioning prestressed concrete ==

−	Pre-tensioning prestressed concrete involves the stressing of wires or cables by anchoring them at the end of a metal form, which may be up to 120 m in length. Hydraulic jacks stress the wire as required, often adding 10% to accommodate creep and other pre-stress losses that may be incurred. Side moulds are then fixed and the concrete placed around the tensioned wires. The ~~[https://tbeexprestress.com/stressing-jack-and-pump/ Strand Jack]~~ hardens and shrinks, gripping the steel along its length, transferring the tension from the jacks to exert a compressive force in the concrete.	+	Pre-tensioning prestressed concrete involves the stressing of wires or cables by anchoring them at the end of a metal form, which may be up to 120 m in length. Hydraulic jacks stress the wire as required, often adding 10% to accommodate creep and other pre-stress losses that may be incurred. Side moulds are then fixed and the concrete placed around the tensioned wires. The concrete hardens and shrinks, gripping the steel along its length, transferring the tension from the jacks to exert a compressive force in the concrete.

	Once the concrete has reached the desired strength, the tensioned wires are released from the jacks. A typical concrete strength of 28 N/mm2 can be achieved by 24-hour steam curing, as well as using additives.		Once the concrete has reached the desired strength, the tensioned wires are released from the jacks. A typical concrete strength of 28 N/mm2 can be achieved by 24-hour steam curing, as well as using additives.

Wearobee at 06:39, 22 December 2022

2022-12-22T06:39:55Z

← Older revision		Revision as of 06:39, 22 December 2022
Line 31:		Line 31:
	== Pre-tensioning prestressed concrete ==		== Pre-tensioning prestressed concrete ==

−	Pre-tensioning prestressed concrete involves the stressing of wires or cables by anchoring them at the end of a metal form, which may be up to 120 m in length. Hydraulic jacks stress the wire as required, often adding 10% to accommodate creep and other pre-stress losses that may be incurred. Side moulds are then fixed and the concrete placed around the tensioned wires. The ~~concrete~~ hardens and shrinks, gripping the steel along its length, transferring the tension from the jacks to exert a compressive force in the concrete.	+	Pre-tensioning prestressed concrete involves the stressing of wires or cables by anchoring them at the end of a metal form, which may be up to 120 m in length. Hydraulic jacks stress the wire as required, often adding 10% to accommodate creep and other pre-stress losses that may be incurred. Side moulds are then fixed and the concrete placed around the tensioned wires. The [https://tbeexprestress.com/stressing-jack-and-pump/ Strand Jack] hardens and shrinks, gripping the steel along its length, transferring the tension from the jacks to exert a compressive force in the concrete.

	Once the concrete has reached the desired strength, the tensioned wires are released from the jacks. A typical concrete strength of 28 N/mm2 can be achieved by 24-hour steam curing, as well as using additives.		Once the concrete has reached the desired strength, the tensioned wires are released from the jacks. A typical concrete strength of 28 N/mm2 can be achieved by 24-hour steam curing, as well as using additives.

Designing Buildings at 09:30, 18 November 2022

2022-11-18T09:30:24Z

← Older revision		Revision as of 09:30, 18 November 2022
Line 1:		Line 1:
	[[File:Prestressedconcrete.jpg\|link=File:Prestressedconcrete.jpg]]		[[File:Prestressedconcrete.jpg\|link=File:Prestressedconcrete.jpg]]

−	= ~~Introduction~~ =	+	= What is prestressed concrete? =

−	Prestressed concrete is a structural material that ~~allows for~~ predetermined, engineering stresses ~~to be placed in~~ members to counteract the stresses that occur when they are subject to loading. It combines the high strength compressive properties of concrete with the high tensile strength of steel.	+	Prestressed concrete is a structural material that uses steel to create predetermined engineering stresses within concrete members to counteract the stresses that will occur when they are subject to loading. This combines the high strength compressive properties of concrete with the high tensile strength of steel.

−	In ordinary reinforced concrete, stresses are carried by the steel reinforcement, whereas prestressed concrete supports the load by induced stresses throughout the entire structural element. This makes it more resistant to shock and vibration than ordinary concrete, and able to form long, thin structures with much smaller sectional areas ~~to support equivalent loads~~.	+	= What is prestressed concrete for? =
		+
		+	In ordinary reinforced concrete, stresses are carried by the steel reinforcement, whereas prestressed concrete supports the load by induced stresses throughout the entire structural element. This makes it more resistant to shock and vibration than ordinary concrete, and able to form long, thin structures with much smaller sectional areas.
		+
		+	= When was prestressed concrete developed? =

	Prestressed concrete was patented by San Franciscan engineer P.H Jackson in 1886, although it did not emerge as an accepted building material until 50 years later when a shortage of steel, coupled with technological advancements, made prestressed concrete the building material of choice during European post-war reconstruction.		Prestressed concrete was patented by San Franciscan engineer P.H Jackson in 1886, although it did not emerge as an accepted building material until 50 years later when a shortage of steel, coupled with technological advancements, made prestressed concrete the building material of choice during European post-war reconstruction.

−	It is ~~now~~ commonly used for floor beams, piles and railways sleepers, as well as structures such as bridges, water tanks, roofs and runways. Generally, prestressed concrete is not necessary for columns and walls, however, it can be used economically for tall columns and high retaining walls with high bending stresses.	+	= When is prestressed concrete used? =
		+
		+	Prestressed concrete is commonly used for floor beams, piles and railways sleepers, as well as structures such as bridges, water tanks, roofs and runways. Generally, prestressed concrete is not necessary for columns and walls, however, it can be used economically for tall columns and high retaining walls with high bending stresses.

	As a general rule, traditional reinforced concrete is the most economic method for a span of up to 6 m. Prestressed concrete is more economical when spans are over 9 m. Between 6 and 9 m, the two options must be considered according to the particular requirements as to which is the most suitable option.		As a general rule, traditional reinforced concrete is the most economic method for a span of up to 6 m. Prestressed concrete is more economical when spans are over 9 m. Between 6 and 9 m, the two options must be considered according to the particular requirements as to which is the most suitable option.

−	= ~~Steel~~ =	+	= What sort of steel is used in prestressed concrete? =

	Steel used for prestressing may be in the form of wire or tendons that can be grouped to form cables. Solid bars may also be used.		Steel used for prestressing may be in the form of wire or tendons that can be grouped to form cables. Solid bars may also be used.
Line 19:		Line 25:
	Wire is made by cold-drawing a high carbon steel rod through a series of reducing dies. The wire diameter typically ranges from 3-7 mm and may be round, crimped or indented to give it better bond strength. Another form of tendon is strand which consists of a straight core wire around which is wound in helixes around further wires to give formats such as 7 wire (6 over 1) and 19 wire (9 over 9 over 1). Similar to wire tendons, strand can be used individually or in groups to form cables.		Wire is made by cold-drawing a high carbon steel rod through a series of reducing dies. The wire diameter typically ranges from 3-7 mm and may be round, crimped or indented to give it better bond strength. Another form of tendon is strand which consists of a straight core wire around which is wound in helixes around further wires to give formats such as 7 wire (6 over 1) and 19 wire (9 over 9 over 1). Similar to wire tendons, strand can be used individually or in groups to form cables.

−	= ~~Method~~ =	+	= How is prestressed concrete made? =

	The process of prestressed concrete can be either through pre-tensioning or post-tensioning.		The process of prestressed concrete can be either through pre-tensioning or post-tensioning.

−	== Pre-tensioning ==	+	== Pre-tensioning prestressed concrete ==

−	~~This process~~ involves the stressing of wires or cables by anchoring them at the end of a metal form, which may be up to 120 m in length. Hydraulic jacks stress the wire as required, often adding 10% to accommodate creep and other pre-stress losses that may be incurred. Side moulds are then fixed and the concrete placed around the tensioned wires. The concrete hardens and shrinks, gripping the steel along its length, transferring the tension from the jacks to exert a compressive force in the concrete.	+	Pre-tensioning prestressed concrete involves the stressing of wires or cables by anchoring them at the end of a metal form, which may be up to 120 m in length. Hydraulic jacks stress the wire as required, often adding 10% to accommodate creep and other pre-stress losses that may be incurred. Side moulds are then fixed and the concrete placed around the tensioned wires. The concrete hardens and shrinks, gripping the steel along its length, transferring the tension from the jacks to exert a compressive force in the concrete.

	Once the concrete has reached the desired strength, the tensioned wires are released from the jacks. A typical concrete strength of 28 N/mm2 can be achieved by 24-hour steam curing, as well as using additives.		Once the concrete has reached the desired strength, the tensioned wires are released from the jacks. A typical concrete strength of 28 N/mm2 can be achieved by 24-hour steam curing, as well as using additives.
Line 31:		Line 37:
	To create shorter members, dividing plates can be placed at any point along the member which, when removed, permit the cutting of the wires.		To create shorter members, dividing plates can be placed at any point along the member which, when removed, permit the cutting of the wires.

−	== Post-tensioning ==	+	== Post-tensioning prestressed concrete ==

−	~~This~~ follows the reverse method to pre-tensioning, ~~whereby~~ the concrete member is cast and the prestressing occurs after the concrete is hardened. This method is often used where stressing is to be carried out on site after casting an insitu component or where a series of precast concrete units are to be joined together to form the required member.	+	Post-tensioning prestressed concrete follows the reverse method to pre-tensioning, that is, the concrete member is cast and the prestressing occurs after the concrete is hardened. This method is often used where stressing is to be carried out on site after casting an insitu component or where a series of precast concrete units are to be joined together to form the required member.

	The wires, cables or bars may be positioned in the unit before concreting, but bonding to the concrete is prevented by using a flexible duct or rubber sheath which is deflated and removed when the concrete has hardened.		The wires, cables or bars may be positioned in the unit before concreting, but bonding to the concrete is prevented by using a flexible duct or rubber sheath which is deflated and removed when the concrete has hardened.
Line 47:		Line 53:
	The Macalloy system on the other hand, involves applying stress to the concrete by means of a solid bar, usually with a diameter of 25-75 mm. The bar is anchored at each end by a special nut which bears against an end plate to distribute the load.		The Macalloy system on the other hand, involves applying stress to the concrete by means of a solid bar, usually with a diameter of 25-75 mm. The bar is anchored at each end by a special nut which bears against an end plate to distribute the load.

−	= ~~Advantages~~ and disadvantages =	+	= What are the advantages and disadvantages of prestressed concrete? =

	The advantages of prestressed concrete include:		The advantages of prestressed concrete include:
Line 64:		Line 70:
	* Expensive equipment is needed and there are complex safety requirements.		* Expensive equipment is needed and there are complex safety requirements.

−	= Related articles on Designing Buildings ~~Wiki~~ =	+	= Related articles on Designing Buildings =

	* Bridge construction.		* Bridge construction.
Line 74:		Line 80:
	* Concreting plant.		* Concreting plant.
	* Design of durable concrete structures.		* Design of durable concrete structures.
−	* Ground anchor.
−	* Grouting in civil engineering.
	* Learning from the Genoa bridge collapse.		* Learning from the Genoa bridge collapse.
−	* Mortar.
−	* Pile foundations.
	* Precast concrete.		* Precast concrete.
	* Rebar.		* Rebar.
	* Reinforced concrete.		* Reinforced concrete.
−	* Retaining walls.
−	* Scour.
−	* Smart concrete.
	* The properties of concrete.		* The properties of concrete.

−	=== External references ===	+	= External references =

	* ‘Building Construction Handbook’ (6th ed.), CHUDLEY, R., GREENO, R., Butterworth-Heinemann (2007)		* ‘Building Construction Handbook’ (6th ed.), CHUDLEY, R., GREENO, R., Butterworth-Heinemann (2007)

Designing Buildings: Reverted edits by 129.205.113.44 (talk) to last revision by 82.46.213.47

2021-11-28T10:00:10Z

Reverted edits by 129.205.113.44 (talk) to last revision by 82.46.213.47

← Older revision		Revision as of 10:00, 28 November 2021
Line 92:		Line 92:
	* ‘Introduction to Civil Engineering Construction’ (3rd ed.), HOLMES, R., College of Estate Management (1995)		* ‘Introduction to Civil Engineering Construction’ (3rd ed.), HOLMES, R., College of Estate Management (1995)

−	~~[[Category:Articles_needing_more_work]]~~ [[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Product_Knowledge]] [[Category:Construction_techniques]] [[Category:Products_/_components]]	+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Product_Knowledge]] [[Category:Construction_techniques]] [[Category:Products_/_components]]

129.205.113.44 at 09:16, 28 November 2021

2021-11-28T09:16:47Z

← Older revision		Revision as of 09:16, 28 November 2021
Line 92:		Line 92:
	* ‘Introduction to Civil Engineering Construction’ (3rd ed.), HOLMES, R., College of Estate Management (1995)		* ‘Introduction to Civil Engineering Construction’ (3rd ed.), HOLMES, R., College of Estate Management (1995)

−	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Product_Knowledge]] [[Category:Construction_techniques]] [[Category:Products_/_components]]	+	[[Category:Articles_needing_more_work]] [[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Product_Knowledge]] [[Category:Construction_techniques]] [[Category:Products_/_components]]

82.46.213.47 at 12:57, 29 October 2021

2021-10-29T12:57:46Z

← Older revision		Revision as of 12:57, 29 October 2021
Line 3:		Line 3:
	= Introduction =		= Introduction =

−	Prestressed concrete is a ~~hello~~ structural material that allows for predetermined, engineering stresses to be placed in members to counteract the stresses that occur when they are subject to loading. It combines the high strength compressive properties of concrete with the high tensile strength of steel.	+	Prestressed concrete is a structural material that allows for predetermined, engineering stresses to be placed in members to counteract the stresses that occur when they are subject to loading. It combines the high strength compressive properties of concrete with the high tensile strength of steel.

	In ordinary reinforced concrete, stresses are carried by the steel reinforcement, whereas prestressed concrete supports the load by induced stresses throughout the entire structural element. This makes it more resistant to shock and vibration than ordinary concrete, and able to form long, thin structures with much smaller sectional areas to support equivalent loads.		In ordinary reinforced concrete, stresses are carried by the steel reinforcement, whereas prestressed concrete supports the load by induced stresses throughout the entire structural element. This makes it more resistant to shock and vibration than ordinary concrete, and able to form long, thin structures with much smaller sectional areas to support equivalent loads.
Line 9:		Line 9:
	Prestressed concrete was patented by San Franciscan engineer P.H Jackson in 1886, although it did not emerge as an accepted building material until 50 years later when a shortage of steel, coupled with technological advancements, made prestressed concrete the building material of choice during European post-war reconstruction.		Prestressed concrete was patented by San Franciscan engineer P.H Jackson in 1886, although it did not emerge as an accepted building material until 50 years later when a shortage of steel, coupled with technological advancements, made prestressed concrete the building material of choice during European post-war reconstruction.

−	It is now commonly used for floor beams, piles and railways sleepers, as well as structures such as bridges, water tanks, roofs and runways. Generally, ~~prestress~~	+	It is now commonly used for floor beams, piles and railways sleepers, as well as structures such as bridges, water tanks, roofs and runways. Generally, prestressed concrete is not necessary for columns and walls, however, it can be used economically for tall columns and high retaining walls with high bending stresses.
−		+
−	~~l][l~~	+
−		+
−	ed concrete is not necessary for columns and walls, however, it can be used economically for tall columns and high retaining walls with high bending stresses.	+

	As a general rule, traditional reinforced concrete is the most economic method for a span of up to 6 m. Prestressed concrete is more economical when spans are over 9 m. Between 6 and 9 m, the two options must be considered according to the particular requirements as to which is the most suitable option.		As a general rule, traditional reinforced concrete is the most economic method for a span of up to 6 m. Prestressed concrete is more economical when spans are over 9 m. Between 6 and 9 m, the two options must be considered according to the particular requirements as to which is the most suitable option.

82.46.213.47 at 12:56, 29 October 2021

2021-10-29T12:56:47Z

← Older revision		Revision as of 12:56, 29 October 2021
Line 3:		Line 3:
	= Introduction =		= Introduction =

−	Prestressed concrete is a structural material that allows for predetermined, engineering stresses to be placed in members to counteract the stresses that occur when they are subject to loading. It combines the high strength compressive properties of concrete with the high tensile strength of steel.	+	Prestressed concrete is a hello structural material that allows for predetermined, engineering stresses to be placed in members to counteract the stresses that occur when they are subject to loading. It combines the high strength compressive properties of concrete with the high tensile strength of steel.

	In ordinary reinforced concrete, stresses are carried by the steel reinforcement, whereas prestressed concrete supports the load by induced stresses throughout the entire structural element. This makes it more resistant to shock and vibration than ordinary concrete, and able to form long, thin structures with much smaller sectional areas to support equivalent loads.		In ordinary reinforced concrete, stresses are carried by the steel reinforcement, whereas prestressed concrete supports the load by induced stresses throughout the entire structural element. This makes it more resistant to shock and vibration than ordinary concrete, and able to form long, thin structures with much smaller sectional areas to support equivalent loads.

82.46.213.47 at 12:55, 29 October 2021

2021-10-29T12:55:50Z

← Older revision		Revision as of 12:55, 29 October 2021
Line 9:		Line 9:
	Prestressed concrete was patented by San Franciscan engineer P.H Jackson in 1886, although it did not emerge as an accepted building material until 50 years later when a shortage of steel, coupled with technological advancements, made prestressed concrete the building material of choice during European post-war reconstruction.		Prestressed concrete was patented by San Franciscan engineer P.H Jackson in 1886, although it did not emerge as an accepted building material until 50 years later when a shortage of steel, coupled with technological advancements, made prestressed concrete the building material of choice during European post-war reconstruction.

−	It is now commonly used for floor beams, piles and railways sleepers, as well as structures such as bridges, water tanks, roofs and runways. Generally, ~~prestressed~~ concrete is not necessary for columns and walls, however, it can be used economically for tall columns and high retaining walls with high bending stresses.	+	It is now commonly used for floor beams, piles and railways sleepers, as well as structures such as bridges, water tanks, roofs and runways. Generally, prestress
		+
		+	l][l
		+
		+	ed concrete is not necessary for columns and walls, however, it can be used economically for tall columns and high retaining walls with high bending stresses.

	As a general rule, traditional reinforced concrete is the most economic method for a span of up to 6 m. Prestressed concrete is more economical when spans are over 9 m. Between 6 and 9 m, the two options must be considered according to the particular requirements as to which is the most suitable option.		As a general rule, traditional reinforced concrete is the most economic method for a span of up to 6 m. Prestressed concrete is more economical when spans are over 9 m. Between 6 and 9 m, the two options must be considered according to the particular requirements as to which is the most suitable option.

Designing Buildings at 10:37, 2 September 2020

2020-09-02T10:37:52Z

← Older revision		Revision as of 10:37, 2 September 2020
Line 92:		Line 92:
	* ‘Introduction to Civil Engineering Construction’ (3rd ed.), HOLMES, R., College of Estate Management (1995)		* ‘Introduction to Civil Engineering Construction’ (3rd ed.), HOLMES, R., College of Estate Management (1995)

−	[[Category:~~Construction_techniques~~]] [[Category:~~Products_/_components~~]] [[Category:DCN_Product_Knowledge]]	+	[[Category:DCN_Definition]] [[Category:DCN_Guidance]] [[Category:DCN_Product_Knowledge]] [[Category:Construction_techniques]] [[Category:Products_/_components]]

Editor at 17:55, 3 June 2020

2020-06-03T17:55:45Z

← Older revision		Revision as of 17:55, 3 June 2020
Line 83:		Line 83:
	* Reinforced concrete.		* Reinforced concrete.
	* Retaining walls.		* Retaining walls.
		+	* Scour.
	* Smart concrete.		* Smart concrete.
	* The properties of concrete.		* The properties of concrete.
Line 91:		Line 92:
	* ‘Introduction to Civil Engineering Construction’ (3rd ed.), HOLMES, R., College of Estate Management (1995)		* ‘Introduction to Civil Engineering Construction’ (3rd ed.), HOLMES, R., College of Estate Management (1995)

−	[[Category:Construction_techniques]] [[Category:Products_/_components]]	+	[[Category:Construction_techniques]] [[Category:Products_/_components]] [[Category:DCN_Product_Knowledge]]