US3659321A - Multiple wedge anchorage device for prestressing tendons - Google Patents

Multiple wedge anchorage device for prestressing tendons Download PDF

Info

Publication number
US3659321A
US3659321A US45643A US3659321DA US3659321A US 3659321 A US3659321 A US 3659321A US 45643 A US45643 A US 45643A US 3659321D A US3659321D A US 3659321DA US 3659321 A US3659321 A US 3659321A
Authority
US
United States
Prior art keywords
wedges
units
tendon
block
frusto
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.)
Expired - Lifetime
Application number
US45643A
Other languages
English (en)
Inventor
Michel Laurent
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
SOC TECHNIQUE POUR L'UTILISATION de la PRECONTRAINTE
STUP PROCEDES FREYSSINET
Original Assignee
STUP PROCEDES FREYSSINET
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by STUP PROCEDES FREYSSINET filed Critical STUP PROCEDES FREYSSINET
Application granted granted Critical
Publication of US3659321A publication Critical patent/US3659321A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

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
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T403/00—Joints and connections
    • Y10T403/38—Laterally related rods independently joined to transverse surface
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T403/00—Joints and connections
    • Y10T403/70—Interfitted members
    • Y10T403/7047—Radially interposed shim or bushing
    • Y10T403/7051—Wedging or camming
    • Y10T403/7052—Engaged by axial movement
    • Y10T403/7054—Plural, circumferentially related shims between members

Definitions

  • ABSTRACT The units of a prestressing cable made of multiple parallel tendon units are individually clamped between two wedges of a crown of wedges clamping all the units being itself located in a frusto-conical hole of a bearing part of which the apex angle is greater than 15.
  • the present invention concerns an anchorage with multiple wedges placed in a female anchorage cone for anchoring tendons or cables made of several parallel wires or strands, which in the following description will be called tendon units.
  • An anchorage for tendons of this type is known in the prestressing technique in which each tendon unit is located between two grooves cut in wedges and parallel to the tendon unit, all of which wedges form a crown having a frusto-conical surface placed in a frusto-conical hole of a female bearing block.
  • the angle of the frusto-conical hole in the bearing block is small, i.e. of about 6 to 10.
  • the tendon units are not clamped individually between the wedges, but are arranged around a single central frusto-conical wedge, it is necessary to keep the angle of the wedge small in order to have a good clamping action and furthermore to prevent ejection of the wedge under the action of the component of the lateral force directed in the sense opposite to the thin end of the wedge, this kind of ejection is called orange pip effect.
  • n is the number of tendon units, Tis the tension of one tendon unit, is the friction angle between the set of wedges and the frusto-conical cavity and 0 the angle of the outer face of the wedges relative to the axis of the cable.
  • the clamping force is inversely proportional to the product of the radial half-angle of the wedged (11'/ n) by the half-angle of the frusto-conical cavity (0) which are both small.
  • the invention is based on the finding that in an anchorage, in which tendon units are clamped one by one between the wedges, there is no danger of orange pip effect.
  • the tendon units are in contact with the wedges along a surface parallel to their own axes and these tendon units thus only tend to pull the wedges towards the narrow end of the frusto-conical hole as soon as friction contact is established between tendon units and wedges.
  • the bearing part and the wedges being made of rigid solid metal angle of the external surface of the wedges with the tendon is selected over and above 15.
  • This value is quite superior to the usual values and can be, for example, of for a tendon made of seven units.
  • the lateral clamping force is considerably decreased and can be reduced to acceptable values.
  • this angle it becomes possible to match the clamping force with the number of tendon units, according to theabove formula. It is obvious that the larger the number of tendon units, i.e. the smaller the radial angle of the wedges, the larger may be the angle of the frusto-conical cavity.
  • the angle of the outer surface of the wedges can be advantageously chosen 20 to 2 larger than the angle of the hole of the female bearing block. In this way the clamping is stronger towards the free end of the cable.
  • this anchorage is such that the wedges can be made solid and therefore practically indeformable which gives to the difference of angle its full efiiciency for obtaining progressive clamping.
  • This difference of angle is already known, but had not always the desired efficiency because the wedges were too deformable partly because of their shape, partly because of the constituent-material (mortar).
  • the wedges have a length 50 percent greater than the height of the bearing block. Owing to the rigidity of the bearing block and of the wedges a suitable distribution of the clamping force on the tendon units can be assured in spite of the localized pressure of the bearing block on the wedges.
  • The-important industrial advantage of the'invention is the possibility of considerably increasing the strength of tendons used with this type of anchorage and thus meeting the needs of the users of prestressed concrete.
  • FIG. 1 is a plan view of a first example of anchorage.
  • FIG. 2 is a side elevation and a partial sectional view taken along the line IIII of FIG. 1.
  • FIG. 3 is a plan view of a second example of anchorage.
  • FIG; 4 is a side elevation and a partial sectional view taken along the line IVIV of FIG. 3.
  • the anchorage shown on FIGS. 1 and 2 comprises a female bearing block 2 having a frusto-conical cavity 3 bearing on the concrete 1 of a structure to be prestressed.
  • the tendon is made in this case of seven units 4 which may be strands, for instance, each made out of seven wires.
  • This cable is placed in a duct formed by means of a sheath 5 cast into the concrete.
  • Each tendon unit is clamped between two edges 6 in shape of a sector, of which the in frusto-conical periphery bears on the frusto-conical cavity 3.
  • These wedges form a crown in the center of which remains a free space which can be advantageously cylindrical.
  • Each radial surface of each wedge is provided with a groove 9, a little less deep than a half cylinder of a diameter equal to the diameter of the tendon units, so that each tendon unit is clamped between two opposite grooves.
  • grooves can be provided with serrations in the form of saw teeth machined perpendicularly to the direction of the tendon units.
  • the grooves may alternatively be coated, for example by metallization, with hard grains in order to increase the friction factor between the grooves and the tendon units.
  • the tendon units due to their friction in the grooves, tend to pull the wedges deeper into the cavity 3.
  • the radial reaction of the wall of this cavity on each of these wedges is transformed, by vault effect, in a circular pressure which is transmitted from one wedge to the other through the tendon units, because each of them is clamped between two wedges and the wedges are spaced by narrow intervals l0 and thus are not directly in contact.
  • the angle of the generatrices of the frusto-conical cavity with the axis of this cavity is greater than Moreover, the apex angle of the frusto-cones formed by the set of wedges, which is the angle of the generatrices of the surface 7 of each wedge with the axis of the tendon, is greater than the angle 0 by to 2, preferably by about 30. 5
  • the clamping of the crown of wedges by the bearing block 2 is maximum at the outer side of this bearing part and progressively decreases towards the side of the part bearing on the concrete.
  • the clamping of the tendon units is greater there, where their stress has been progressively reduced by the friction, the clamping itself, being progressive.
  • the length L of the wedges is greater than the height H of the bearing block by about 50 percent.
  • the wedges have, at the side opposite to their portion inside the frustoconical cavity 3, another frusto-conical surface 11 in opposite direction to the surface 7.
  • the reaction force exerted by the surface 3 of the cavity on the wedges 6 near the edge 12 of the intersection of the surfaces 7 and 11 is evenly distributed along the length L of the wedge.
  • pressure reaction of the hole opening against the wedge bundle is substantially uniform and each longitudinal section of the anchorage device has a resultant reaction, substantially applied midway of the block height and perpendicularly to said hole wall.
  • said resultant reaction passes through the plane of the outer face of the block substantially at the same place as the tendon units and at the level'of the edge 12.
  • the frusto-conical wedge portion ll being equal to approximately one-half the height of the wedge portion inserted in the frusto-conical hole, pressure against the tendon units is, as is well known, distributed according to the triangular law, i.e., pressure is substantially zero at the inner tip of the wedge, maximum at the outer end thereof and linearly distributed along the grooves 9 between these two extreme values.
  • the difference between the wedges and block opening wall angles provides a clamping of the units by the wedges which is greater towards the outer ends of the wedges than towards the inner ends or tips thereof.
  • the angle of the frusto-conical cavity may be determined and chosen for obtaining, on each tendon unit, a clamping force adjusted for being not detrimental for said unit whereas, with the conventional hole reduced angle, local clamping force on the tendon may be so high that the anchorage device should be lengthened for distributing said pressure and reducing the same.
  • the length of the wedges is almost double of the depth of the bearing block 2 and the angle 6 for seven tendon units can be taken at about 20.
  • an ogive 13 is located between these tendon units in order to separate them before placing the wedges 6.
  • This 0 've has a central duct 14 prolonging the axial space 8 provide between the wedges which allows, after anchoring,
  • the tendon units 4 being parallel, tensioning can be carried out in a known manner, by means of a jack provided with an axial hole for the passage of all the said tendon units and with a surface bearing on the external surface 17 of the anchorage block 2.
  • FIGSQ3 and 4 The embodiment shown on FIGS. 1 and 2, except for the following differences:
  • the number of tendon units is twelve, therefore the radial angle of each wedge 6 is l5, whereas the angle 0 is of about Moreover, the grooves 9 provided in the wedges 6 are askew relative to the axis of the tendon, which allows a tensioning of this tendon with a jack without a central hole,-but provided with means of securing the tendon units at its periphery.
  • wedges 6 are longer than the height of the, bearing block 2 and are essentially protruding from the external surface of this block.
  • the divergence of the units of the tendon at their entry in the anchorage device may require a widening of the sheath 5 which may be carried out by means of a connection piece 15.
  • a ring 16 is placed in this connection piece in order to progressively deviate the parallel tendon units until they reach the slope of the grooves 9 where they are located.
  • the ring 16 must obviously be strong enough to keep the wires or strands in position when stressed, It will be noted that the friction of the tendon units on the internal surface of the ring 16 reduces the force necessary to anchor these units.
  • anchorages which were, described are particularly suitable for large strength tendons intended to supply big prestressing forces for concrete structures of any kind, and in particular for civil enginerring works.
  • An anchorage device for prestressing a plurality of similarly shaped units comprising, a flat bearing block having a frusto-conical opening therein, the wall of said opening being greater than 15 with respect to the axis of said block; a plurality of similar sector-shaped wedges equal to the number of said units having, in gathered active condition, a first frustoconical outer surface engaging said wall of said opening, and a second frusto conical surface, said surfaces defining an apex, the slope of said second surface being greater than the slope of said first surface, the distance parallel to said block axis between said apex and the end of said first surface slope being greater than the distance parallel to said block axis between said apex and the end of said second surface slope, the slope of said first frusto-conical outer surface being slightly greater than the shape of said block opening, and a pair of adjoining ones of said wedges each having, in their opposing radial plane faces, a facing groove for accommodating one of said tendon units
  • An anchorage device wherein said distance between said apex and the end of said second surface slope is about half the said distance between said apex and the end of said first surface slope, and wherein, in active condition, a perpendicular to said first frusto-conical surface midway along the length thereof passes through the outer plane face of said block substantially in the same location as said one tendon unit.
  • An anchorage device according to claim 1 wherein said grooves are straight and, in operative condition, are parallel to the axis of said block.

Landscapes

  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Reinforcement Elements For Buildings (AREA)
  • Ropes Or Cables (AREA)
US45643A 1969-06-24 1970-06-12 Multiple wedge anchorage device for prestressing tendons Expired - Lifetime US3659321A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
FR6921121A FR2045703B1 (fr) 1969-06-24 1969-06-24

Publications (1)

Publication Number Publication Date
US3659321A true US3659321A (en) 1972-05-02

Family

ID=9036279

Family Applications (1)

Application Number Title Priority Date Filing Date
US45643A Expired - Lifetime US3659321A (en) 1969-06-24 1970-06-12 Multiple wedge anchorage device for prestressing tendons

Country Status (10)

Country Link
US (1) US3659321A (fr)
JP (1) JPS5332183B1 (fr)
AT (1) AT304836B (fr)
BR (1) BR7019960D0 (fr)
CH (1) CH524033A (fr)
DE (1) DE2031007A1 (fr)
FR (1) FR2045703B1 (fr)
GB (1) GB1313929A (fr)
NL (1) NL7009278A (fr)
ZA (1) ZA703901B (fr)

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4132129A (en) * 1977-06-03 1979-01-02 Raytheon Company Wedge lock knob assembly
US4223497A (en) * 1978-06-26 1980-09-23 Ccl Systems Limited Coupling assembly
US20090044483A1 (en) * 2002-06-26 2009-02-19 Sika Technology Ag Device and process for reinforcing bearing structures
US20110072745A1 (en) * 2008-06-12 2011-03-31 Pantelides Chris P Anchoring, splicing and tensioning elongated reinforcement members
US20110197540A1 (en) * 2008-06-12 2011-08-18 Pantelides Chris P Anchoring, splicing and tensioning elongated reinforcement members
CN102926507A (zh) * 2012-11-14 2013-02-13 柳州豪姆机械有限公司 整体挤压式钢绞线锚具拉索及其制作方法
US10006477B2 (en) 2010-04-13 2018-06-26 University Of Utah Research Foundation Sheet and rod attachment apparatus and system
US11359659B2 (en) * 2016-08-31 2022-06-14 Beijing Surgerii Technology Co., Ltd. Locking device
US11965334B1 (en) 2024-01-11 2024-04-23 King Faisal University Multi-layer wedge anchorage for fiber-reinforced polymer (FRP) plates and tendons

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5621974U (fr) * 1979-07-30 1981-02-26
DE3225723A1 (de) * 1982-07-09 1984-01-12 Ed. Züblin AG, 7000 Stuttgart Kegelstumpffoermiger keil aus drei segmenten fuer spannstahllitzen
FR2610342A1 (fr) * 1987-02-04 1988-08-05 Bielecki Stanislas Dispositif d'ancrage en nappes radiales pour armatures de precontrainte, haubans ou amarres
WO1988005851A1 (fr) * 1987-02-04 1988-08-11 Stanislas Bielecki Ancrage en nappes radiales pour armatures de precontrainte, haubans ou amarres
DE9206827U1 (fr) * 1992-05-09 1992-07-16 Bilfinger + Berger Vorspanntechnik Gmbh, 6712 Bobenheim-Roxheim, De

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2009318A (en) * 1929-10-29 1935-07-23 Highfield John Somerville Method of joining together or anchoring wire cables and apparatus therefor
GB845386A (en) * 1957-08-09 1960-08-24 Felten & Guilleaume Carlswerk An anchor for an electric cable
US3123879A (en) * 1964-03-10 Wedge anchor for tensioning and anchoring wires
GB1020432A (en) * 1961-10-04 1966-02-16 Stup Procedes Freyssinet An improved anchorage device for the prestressing elements of reinforced concrete
FR1430406A (fr) * 1965-02-02 1966-03-04 Dispositif d'ancrage des fils pour béton précontraint
CH430135A (fr) * 1965-01-04 1967-02-15 Travaux Comp Ind De Dispositif de réalisation de béton précontraint
US3449876A (en) * 1968-02-21 1969-06-17 George H Howlett Tendon anchorage

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1503134A (fr) * 1966-12-01 1967-11-24 Clavette à <<serrage circulaire>> pour le blocage d'ensemble de fils, barres ou câbles tendus
FR1556234A (fr) * 1967-10-09 1969-02-07

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3123879A (en) * 1964-03-10 Wedge anchor for tensioning and anchoring wires
US2009318A (en) * 1929-10-29 1935-07-23 Highfield John Somerville Method of joining together or anchoring wire cables and apparatus therefor
GB845386A (en) * 1957-08-09 1960-08-24 Felten & Guilleaume Carlswerk An anchor for an electric cable
GB1020432A (en) * 1961-10-04 1966-02-16 Stup Procedes Freyssinet An improved anchorage device for the prestressing elements of reinforced concrete
CH430135A (fr) * 1965-01-04 1967-02-15 Travaux Comp Ind De Dispositif de réalisation de béton précontraint
FR1430406A (fr) * 1965-02-02 1966-03-04 Dispositif d'ancrage des fils pour béton précontraint
US3449876A (en) * 1968-02-21 1969-06-17 George H Howlett Tendon anchorage

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4132129A (en) * 1977-06-03 1979-01-02 Raytheon Company Wedge lock knob assembly
US4223497A (en) * 1978-06-26 1980-09-23 Ccl Systems Limited Coupling assembly
US20090044483A1 (en) * 2002-06-26 2009-02-19 Sika Technology Ag Device and process for reinforcing bearing structures
US20110072745A1 (en) * 2008-06-12 2011-03-31 Pantelides Chris P Anchoring, splicing and tensioning elongated reinforcement members
US20110197540A1 (en) * 2008-06-12 2011-08-18 Pantelides Chris P Anchoring, splicing and tensioning elongated reinforcement members
US8904721B2 (en) * 2008-06-12 2014-12-09 University Of Utah Research Foundation Anchoring, splicing and tensioning elongated reinforcement members
US8925279B2 (en) * 2008-06-12 2015-01-06 The University Of Utah Research Foundation Anchoring, splicing and tensioning elongated reinforcement members
US10006477B2 (en) 2010-04-13 2018-06-26 University Of Utah Research Foundation Sheet and rod attachment apparatus and system
CN102926507A (zh) * 2012-11-14 2013-02-13 柳州豪姆机械有限公司 整体挤压式钢绞线锚具拉索及其制作方法
CN102926507B (zh) * 2012-11-14 2015-04-01 柳州豪姆机械有限公司 整体挤压式钢绞线锚具拉索及其制作方法
US11359659B2 (en) * 2016-08-31 2022-06-14 Beijing Surgerii Technology Co., Ltd. Locking device
US11965334B1 (en) 2024-01-11 2024-04-23 King Faisal University Multi-layer wedge anchorage for fiber-reinforced polymer (FRP) plates and tendons

Also Published As

Publication number Publication date
CH524033A (fr) 1972-06-15
DE2031007A1 (de) 1971-03-04
FR2045703B1 (fr) 1973-10-19
GB1313929A (en) 1973-04-18
AT304836B (de) 1973-01-25
BR7019960D0 (pt) 1973-04-12
JPS5332183B1 (fr) 1978-09-07
FR2045703A1 (fr) 1971-03-05
NL7009278A (fr) 1970-12-29
ZA703901B (en) 1971-02-24

Similar Documents

Publication Publication Date Title
US3659321A (en) Multiple wedge anchorage device for prestressing tendons
US4640068A (en) Anchoring and coupling device for tendons in prestressed concrete
US2371882A (en) Tensioning and anchoring of cables in concrete or similar structures
US3137971A (en) Stressed concrete structures
US4671034A (en) End-anchoring device for anchoring at least one bar made from a fibrous compound material and being used as tendon in pre-stressed concrete construction
US3935685A (en) Anchor member and method of forming same
US4092814A (en) Reinforcing rod
US5493828A (en) Stressing anchorage for prestressing elements in a part of a structure
CA1048750A (fr) Assemblage d&#39;ancrage pour la precontrainte des ouvrages en beton
US4028988A (en) Dowel
US4388014A (en) Multiple part tapered collar for a tendon anchorage system
US3449876A (en) Tendon anchorage
FI59468C (fi) Expansionsbult
USRE27954E (en) Anchor for post-tensioning frestressed concrete
US3520032A (en) Tendon anchorage
US3522682A (en) Multiple tendon anchorage
US3422592A (en) Anchor device for steel reinforcing cables
JP3445555B2 (ja) Ｐｃケーブルの定着装置
US3983606A (en) Cable anchors
US3613179A (en) Cable or rod anchoring means
AU681003B2 (en) Post-tensioning anchor head assembly
US3676900A (en) System of fixing braided cables and rods subjected to stress
US2783024A (en) Bar gripping means for use in the production of prestressed concrete
US9315998B1 (en) Cable lock-off block for repairing a plurality of post-tensioned tendons
US3965541A (en) Reinforcing strand anchorage assembly