EP0108558A2 - Wedge type anchorage device - Google Patents
Wedge type anchorage device Download PDFInfo
- Publication number
- EP0108558A2 EP0108558A2 EP83306527A EP83306527A EP0108558A2 EP 0108558 A2 EP0108558 A2 EP 0108558A2 EP 83306527 A EP83306527 A EP 83306527A EP 83306527 A EP83306527 A EP 83306527A EP 0108558 A2 EP0108558 A2 EP 0108558A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- wedge
- strand
- diameter
- wire
- coating
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
- E04C5/08—Members specially adapted to be used in prestressed constructions
- E04C5/12—Anchoring devices
- E04C5/122—Anchoring devices the tensile members are anchored by wedge-action
Definitions
- This invention relates to a wedge type anchorage device of the kind used in prestressing of concrete structures.
- wedge type anchorage device is meant a device in which a stressing wire or strand may be anchored in a conical, or part conical, bore by means of two or more arcuate wedge elements, the bore being formed in a cylindrical barrel which provides a so-called anchor grip, or being formed, as one of a plurality of bores, in a plate or the like forming part of a concrete structure, or of a stressing jack or other stressing apparatus.
- a wedge type anchorage device having a protective.anti-rust coating of a relatively low viscosity.
- a suitable rust preventative is one having a viscosity of the order of 73 centistokes at 20°C. Fluids of higher viscosity e.g. greasy or wax films are not suitable as the efficiency of such coated wedges is too low.
- a strand anchored by a wedge of the invention will, when stressed using the hydraulic jack of our co-pending Application, have an efficiency of 95% of more, i.e. the strand will not fail until it reaches 95% of its ultimate tensile strength.
- the wedges may be adapted for use with strands ranging from about 12 mm to about 18 mm in diameter. For a 13 mm diameter the wedge may weigh about 45 - 60 grams, a saving of about 35% by weight; for a 16 mm diameter wedge the weight may range from about 65 to 85 grams, a saving of about 50% by weight.
- the invention specifically includes wedges having a coating and measuring about 39 mm and about 23 mm average diameter; and about 44 mm long and about 31 mm average diameter.
- the conical surfaces of the wedge elements only, or the conical surfaces of the barrels or plates, or the conical surfaces of both the wedges and the barrels or plates may be coated. Alternatively, all of the surfaces of the wedges and/or the barrels may be coated.
- the wedge of Figure 1 comprises two identical wedge elements 2. Each element is formed of case hardened steel. The element is conical and has a wider end 3, the right hand end as seen in Figure 2, and tapers to a narrower end 4, the left hand end as seen in Figure 2. A groove is formed adjacent the wider end 3, to receive a wire or spring 6, by which the two wedge elements 2 are held together. The wedge elements together define a bore 10 for gripping a wire, strand etc 7. The wedge 1 is received in a socket 8 in a plate 9 abutting a concrete structure. The outer surface of the wedge elements is, according to the invention, coated with RUSTBAN 335, a rust preventative marketed by ESSO and having a viscosity of 73 centistokes at 20°C. The wedge is about 44 mm long, and has a bore 10 which is about 15 mm in diameter at the wider end 3 and about 18 mm at the narrower end 4. The overall diameter at the wider end 3 is about 28 mm. The wedge weighs about 80 grams.
- the invention is illustrated by the following comparative Example. Wedges having the dimensions and weight indicated in the Table were coated as indicated and then used to tension a strand of 13 mm or 15 mm diameter as indicated. The efficiency was then measured when the strand was tensioned.
- the results show that to achieve an efficiency of 95% with a known 13 mm wedge having a waxy film, the wedge must weigh 83 grams. Decreasing the size of the wedge while using the same coating drops the efficiency.
- the wedge can be smaller and weigh 55 grams and having a coating as defined and still have an efficiency of 95%. In other words, one can have a weight saving of 31%. In the case of 15 mm wedge, the invention works in the same way but the weight saving is 152 - 80 grams, i.e. 72 grams, i.e. 47%.
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- Engineering & Computer Science (AREA)
- Architecture (AREA)
- Civil Engineering (AREA)
- Structural Engineering (AREA)
- Reinforcement Elements For Buildings (AREA)
Abstract
Description
- This invention relates to a wedge type anchorage device of the kind used in prestressing of concrete structures.
- By "wedge type anchorage device" is meant a device in which a stressing wire or strand may be anchored in a conical, or part conical, bore by means of two or more arcuate wedge elements, the bore being formed in a cylindrical barrel which provides a so-called anchor grip, or being formed, as one of a plurality of bores, in a plate or the like forming part of a concrete structure, or of a stressing jack or other stressing apparatus.
- It is well known that precautions have to be taken to avoid the wedge elements becoming locked in the bore or bores of the device where the wires or strands are subjected to contact pressure of several thousand, for example 40 - 50,000, pounds per square inch. To reduce the co-efficient of friction between the wedge elements and the conical bore, it is known to coat the mating surfaces with wax or, for example, with some form of molybdenum disulphide which provides a wax-like surface. It has also been proposed in British patent 1,434,716 (ref: 7196) to apply a coating of a material consisting of a polyfluorocarbon dispersed in a thermosetting resin.
- In our co-pending Application (ref: ) there is described and claimed a hydraulic jack of light weight. With such a jack it becomes possible to use a wedge type anchorage device formed of less metal i.e. smaller dimensions and weight. Unfortunately however the usual coating applied to such a wedge will not do, because the anchorange formed is weakened when excessive radial pressure is applied.
- According to one aspect of the invention there is provided a wedge type anchorage device having a protective.anti-rust coating of a relatively low viscosity.
- A suitable rust preventative is one having a viscosity of the order of 73 centistokes at 20°C. Fluids of higher viscosity e.g. greasy or wax films are not suitable as the efficiency of such coated wedges is too low. In our evaluations we have been able to show that a strand anchored by a wedge of the invention will, when stressed using the hydraulic jack of our co-pending Application, have an efficiency of 95% of more, i.e. the strand will not fail until it reaches 95% of its ultimate tensile strength.
- The wedges may be adapted for use with strands ranging from about 12 mm to about 18 mm in diameter. For a 13 mm diameter the wedge may weigh about 45 - 60 grams, a saving of about 35% by weight; for a 16 mm diameter wedge the weight may range from about 65 to 85 grams, a saving of about 50% by weight. The invention specifically includes wedges having a coating and measuring about 39 mm and about 23 mm average diameter; and about 44 mm long and about 31 mm average diameter.
- The conical surfaces of the wedge elements only, or the conical surfaces of the barrels or plates, or the conical surfaces of both the wedges and the barrels or plates may be coated. Alternatively, all of the surfaces of the wedges and/or the barrels may be coated.
- In order that the invention may be well understood, it will now be described with reference to the accompanying diagrammatic drawings, in which
- Figure 1 is an end view of a wedge in use; and
- Figure 2 is a side elevation of a wedge element.
- The wedge of Figure 1 comprises two
identical wedge elements 2. Each element is formed of case hardened steel. The element is conical and has awider end 3, the right hand end as seen in Figure 2, and tapers to a narrower end 4, the left hand end as seen in Figure 2. A groove is formed adjacent thewider end 3, to receive a wire or spring 6, by which the twowedge elements 2 are held together. The wedge elements together define abore 10 for gripping a wire, strand etc 7. The wedge 1 is received in asocket 8 in aplate 9 abutting a concrete structure. The outer surface of the wedge elements is, according to the invention, coated with RUSTBAN 335, a rust preventative marketed by ESSO and having a viscosity of 73 centistokes at 20°C. The wedge is about 44 mm long, and has abore 10 which is about 15 mm in diameter at thewider end 3 and about 18 mm at the narrower end 4. The overall diameter at thewider end 3 is about 28 mm. The wedge weighs about 80 grams. - The invention is illustrated by the following comparative Example. Wedges having the dimensions and weight indicated in the Table were coated as indicated and then used to tension a strand of 13 mm or 15 mm diameter as indicated. The efficiency was then measured when the strand was tensioned.
- The results of this Table show that when a waxy film is applied to a wedge of reduced dimensions the efficiency falls whereas when a coating of the invention is applied to such a wedge the efficiency rises to an acceptable level.
- In particular, the results show that to achieve an efficiency of 95% with a known 13 mm wedge having a waxy film, the wedge must weigh 83 grams. Decreasing the size of the wedge while using the same coating drops the efficiency. In contrast and in accordance with the invention the wedge can be smaller and weigh 55 grams and having a coating as defined and still have an efficiency of 95%. In other words, one can have a weight saving of 31%. In the case of 15 mm wedge, the invention works in the same way but the weight saving is 152 - 80 grams, i.e. 72 grams, i.e. 47%.
Claims (6)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB8231273 | 1982-11-02 | ||
GB8231273 | 1982-11-02 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0108558A2 true EP0108558A2 (en) | 1984-05-16 |
EP0108558A3 EP0108558A3 (en) | 1985-06-05 |
Family
ID=10533989
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP83306527A Withdrawn EP0108558A3 (en) | 1982-11-02 | 1983-10-27 | Wedge type anchorage device |
Country Status (4)
Country | Link |
---|---|
EP (1) | EP0108558A3 (en) |
AU (1) | AU557176B2 (en) |
IN (1) | IN160946B (en) |
ZA (1) | ZA838017B (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004094745A1 (en) * | 2003-04-18 | 2004-11-04 | Sumitomo (Sei) Steel Wire Corp. | Wedge for fixing pc steel |
WO2004094744A1 (en) * | 2003-04-18 | 2004-11-04 | Sumitomo (Sei) Steel Wire Corp. | Deviation preventing structure for wedge |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB811573A (en) * | 1955-05-18 | 1959-04-08 | Ionic Plating Company Ltd | Improvements in or relating to screw threaded fastenings |
US3588045A (en) * | 1969-01-31 | 1971-06-28 | Allan H Stubbs | Prestressing apparatus |
US3755880A (en) * | 1969-09-26 | 1973-09-04 | J Simms | Tensioning devices |
DE2550137A1 (en) * | 1975-11-07 | 1977-05-12 | Rehm Gallus | Wedge anchorage for cable load on concrete members - has inside serration pressing in at full height and high transverse pressure |
US4114505A (en) * | 1977-01-31 | 1978-09-19 | Loeser William J | Coatings and methods of application |
GB2077343A (en) * | 1980-05-24 | 1981-12-16 | Strabag Bau Ag | Anchorage devices for a bundle of tension wires |
-
1983
- 1983-10-27 EP EP83306527A patent/EP0108558A3/en not_active Withdrawn
- 1983-10-27 ZA ZA838017A patent/ZA838017B/en unknown
- 1983-10-31 AU AU20844/83A patent/AU557176B2/en not_active Ceased
-
1984
- 1984-03-08 IN IN220/DEL/84A patent/IN160946B/en unknown
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB811573A (en) * | 1955-05-18 | 1959-04-08 | Ionic Plating Company Ltd | Improvements in or relating to screw threaded fastenings |
US3588045A (en) * | 1969-01-31 | 1971-06-28 | Allan H Stubbs | Prestressing apparatus |
US3755880A (en) * | 1969-09-26 | 1973-09-04 | J Simms | Tensioning devices |
DE2550137A1 (en) * | 1975-11-07 | 1977-05-12 | Rehm Gallus | Wedge anchorage for cable load on concrete members - has inside serration pressing in at full height and high transverse pressure |
US4114505A (en) * | 1977-01-31 | 1978-09-19 | Loeser William J | Coatings and methods of application |
GB2077343A (en) * | 1980-05-24 | 1981-12-16 | Strabag Bau Ag | Anchorage devices for a bundle of tension wires |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004094745A1 (en) * | 2003-04-18 | 2004-11-04 | Sumitomo (Sei) Steel Wire Corp. | Wedge for fixing pc steel |
WO2004094744A1 (en) * | 2003-04-18 | 2004-11-04 | Sumitomo (Sei) Steel Wire Corp. | Deviation preventing structure for wedge |
KR101037258B1 (en) | 2003-04-18 | 2011-05-26 | 스미토모 덴코 스틸 와이어 가부시키가이샤 | Wedge for fixing pc steel |
Also Published As
Publication number | Publication date |
---|---|
AU557176B2 (en) | 1986-12-11 |
EP0108558A3 (en) | 1985-06-05 |
ZA838017B (en) | 1984-12-24 |
IN160946B (en) | 1987-08-15 |
AU2084483A (en) | 1984-05-10 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
AK | Designated contracting states |
Designated state(s): AT BE CH DE FR GB IT LI LU NL SE |
|
RBV | Designated contracting states (corrected) |
Designated state(s): BE DE FR GB IT NL |
|
PUAL | Search report despatched |
Free format text: ORIGINAL CODE: 0009013 |
|
AK | Designated contracting states |
Designated state(s): BE DE FR GB IT NL |
|
17P | Request for examination filed |
Effective date: 19851203 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN |
|
18D | Application deemed to be withdrawn |
Effective date: 19870430 |
|
RIN1 | Information on inventor provided before grant (corrected) |
Inventor name: SMITH, MICHAEL ARTHUR Inventor name: BREARLEY, DAVID |