US3447784A - Apparatus for prestressing concrete - Google Patents

Apparatus for prestressing concrete Download PDF

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Publication number
US3447784A
US3447784A US518315A US3447784DA US3447784A US 3447784 A US3447784 A US 3447784A US 518315 A US518315 A US 518315A US 3447784D A US3447784D A US 3447784DA US 3447784 A US3447784 A US 3447784A
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US
United States
Prior art keywords
bar
concrete
plate
anchoring device
tube
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
US518315A
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English (en)
Inventor
Pierre Launay
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.)
IND DE TRAVAUX CIE
TRAVAUX COMP IND DE
Original Assignee
TRAVAUX COMP IND DE
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
Priority claimed from FR735A external-priority patent/FR1428554A/fr
Priority claimed from FR43216A external-priority patent/FR89271E/fr
Application filed by TRAVAUX COMP IND DE filed Critical TRAVAUX COMP IND DE
Application granted granted Critical
Publication of US3447784A publication Critical patent/US3447784A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
    • B28B23/02—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members
    • B28B23/04—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members the elements being stressed
    • B28B23/046—Post treatment to obtain pre-stressed articles
    • 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
    • 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
    • E—FIXED CONSTRUCTIONS
    • E04—BUILDING
    • E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
    • E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
    • E04G21/12—Mounting of reinforcing inserts; Prestressing

Definitions

  • the present invention has for an object apparatus for prestressing concrete by placing high resistance steel rods under tension in the concrete.
  • the present invention particularly applies where the rods are disposed within tubes in the concrete.
  • Another object of the present invention is to obtain correct centering of the rods in their tubes with anchorage devices for the rods in tensioned condition.
  • the apparatus comprises a rod, an anchoring device for the rod, a tube surrounding the rod, a centering device for the rod in the tube and an element associated with the anchoring device bearing on the concrete.
  • FIGS. 2 and 3 show in perspective respectively a part of a collar and a part of a key, a collar and two keys comprising an anchoring device for the bar;
  • FIG. 4 shows another embodiment of the present indrawings, in which like reference parts, FIG. 1 is a partial section a plane passing through the axis vention in which the anchoring device is located within a receptacle in the concrete;
  • FIGS. 5 and 6 show variations analogous to the embodiments of FIGS. 1 and 4;
  • FIG. 7 is another embodiment of the present invention in which the anchoring device includes a nut mounted on threads on the bar;
  • FIG. 8 is an enlarged detail of a part of the threaded portion of the bar of FIG. 7;
  • FIG. 9 is another embodiment of the present invention analogous to that of FIG. 7;
  • FIGS. 10 and 11 show variations of the device of the present concept in which the bars are replaced by cables.
  • FIGS. 1 to 3 show an embodiment of the invention in which the bar 1 is placed in associated structure before pouring of the concrete.
  • Bar 1 is surrounded by tube 2 which is covered by the concrete.
  • Tube 2 is extended at its extremities by an element 3 of tubular form of reduced diameters at 4 spaced about the periphery thereof in such a manner as to form protuberances which center bar 1 accurately within element 3.
  • a hearing plate 5 surrounds the extremity of element 3.
  • Plate 5 is secured to the structure surrounding bar 1 and centers bar 1 and tube 2.
  • Plate 5 serves as a support for the apparatus for placing bar 1 under tension if this apparatus has no other base for this purpose and serves as a base for the apparatus maintaing the tension of bar 1.
  • bar 1 3,447,784 Patented June 3, 1969 is not subject to parasitic bending when it is under tension.
  • Tube 3 can include an extension 6 through which a duct 7 is attached which opens to an etxerior of the concrete and may serve for the injection of liquid mortar into th space 8 between bar 1 and tube 2.
  • the anchoring device for bar 1 which bears on plate 5 includes a collar 9 shown partly broken away in perspective in FIG. 2 in such a way as to show the interior thereof.
  • Two cylindrical grooves are formed within collar 9, as seen at 10, making an angle a with the axis 11 of collar 9 with the axes intersecting at a joint within the mass of concrete.
  • the two cylindrical grooves 10 are symmetrical with respect to the axial plane 12 of collar 9.
  • Each of grooves 10 of collar 9 receives a key 13 having an exterior surface corresponding to the interior surface of a groove 10.
  • each key 13 is formed as a circular half cylinder 14 to bear upon bar 1.
  • each surface 14 can be toothed or receive a special treatment giving it a greater hardness than that of bar 1.
  • the anchoring device as described above, is used as follows. Bar 1 is first put in place with collar 9 and keys 13 mounted in grooves 10. The tensioning apparatus is then connected to bar 1 to place it under tension, the other end of bar 1 being held in place by any suitable means including another anchoring device as described above.
  • FIG. 4 shows an embodiment of the present invention as seen in FIGS. 1 and 3 in which tubular piece 3' is surrounded at an extremity by plate 5 and is extended by a metallic box 16 mounted within the concrete 17. Box 16 provides a cavity in the concrete to receive the anchoring device 9-13.
  • FIG. 5 shows another variation of the present concept in which bar 1 is put into position after the concrete is poured. In this situation, bar 1 is introduced into tube 2 and bearing plate 5 is put in place. A washer 18 is placed on plate 5 and is of a malleable material which is not susceptible to flow such as, for example, soft steel. Collar 9 is mounted on washer 18 and bar 1 is placed under tension. Bar 1 is then anchored under tension by keys 13.
  • Washer 18 compensates for any misalignment of the axes of plate 5 and of collar 9 and provides perfect centeringof bar 1 in tube 2.
  • FIG. 6 shows another variation of the present con ceptanalogous to that of FIG. 4 including a box 16 receiving the anchoring device.
  • plate 5 is placed at the bottom of box 16 and not at the extremity of the centering element 3.
  • FIG. 7 shows still another variation of the present concept in which the anchoring device as shown in FIG. 1 is not used and the device includes a thread and nut.
  • a thread 19 is formed on an extremity of bar 1 and a nut 20 is mounted on this thread.
  • Thread 19 of bar "1 is obtained by flow of the metal of the bar with a special profile of the thread which is rounded to provide minimum reduction of the diameter of the bar at the bottom of the thread to provide a bar diameter closely approximating the normal diameter thereof.
  • This construction is particularly suitable to the diameter closely approximating the normal diameter high mechanical characteristics of the steel of the bars.
  • the radius of the bottom of thread 21 is preferably approximately three times the value of the radius of the top of thread 22.
  • the flats of the threads preferably form an angle of about 90 with each other.
  • the radius of the height of the thread is preferably equal to H being the height of the thread.
  • FIG. 9 shows a still further variation of the present invention including an anchoring device analogous to that shown in FIGS. 7 and 8 but applied to the situation in which bar 1 is put in position after casting of the concrete.
  • plate 5 is not mounted in the concrete as shown in FIG. 7 but rests on the surface of the concrete.
  • This embodiment includes a washer 22 of malleable material not susceptible to flow, analogous to washer 18 shown in FIG. 5. Washer 22 assures coincidence of the axes of plate 5 and bar 1.
  • FIG. shows a concrete mass in which conduits 24 are formed covering a sheath 2. receiving twisted tensioning cables 25 and 26.
  • Plate 27 is mounted on the concrete and has orifices therein receiving cables 25 and 26. Collars 9 bear on plate 27 and keys 13 lock the cables in the collars.
  • FIG. 11 illustrates the situation in which the interior surfaces of the collars are formed directly in a bearing plate 28 and in which the axes of the keys 13 are parallel. Cables 25 and 26 are then spread by spacer 29 and held together by a ring 30.
  • the cables open into space 31 in the concrete.
  • Apparatus for prestressing concrete including a tube in the concrete, a tension element in said tube, an anchoring device at each end of said element, said anchoring device including a ring, the interior portion of said ring being formed as two circular portions of cylinders having axes intersecting the axis of said ring, the point of intersection of said taxes being within the concrete mass, and two keys having circular cylindrical exterior surfaces of the same diameter as the interior cylindrical surfaces of said ring mounted in said ring, said keys having circular cylindrical interior portions of the same diameter as and engaging said element.
  • Apparatus as described in claim '1 including a device for centering said element comprising protuberances in said tube centering said element.
  • said element being a cable and said anchoring device including a plate resting upon the concrete and openings in said plate forming said rings receiving said keys anchoring a plurality of said cables.

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  • Engineering & Computer Science (AREA)
  • Architecture (AREA)
  • Civil Engineering (AREA)
  • Structural Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing Of Tubular Articles Or Embedded Moulded Articles (AREA)
US518315A 1965-01-04 1966-01-03 Apparatus for prestressing concrete Expired - Lifetime US3447784A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR735A FR1428554A (fr) 1965-01-04 1965-01-04 Dispositif de réalisation de béton précontraint
FR43216A FR89271E (fr) 1965-12-21 1965-12-21 Dispositif de réalisation de béton précontraint

Publications (1)

Publication Number Publication Date
US3447784A true US3447784A (en) 1969-06-03

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US518315A Expired - Lifetime US3447784A (en) 1965-01-04 1966-01-03 Apparatus for prestressing concrete

Country Status (4)

Country Link
US (1) US3447784A (forum.php)
BE (1) BE674339A (forum.php)
CH (1) CH430135A (forum.php)
NL (1) NL6517239A (forum.php)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3638909A (en) * 1970-11-13 1972-02-01 Herbert Oliver Richard Dew Gripping means
US5141356A (en) * 1989-06-27 1992-08-25 Alain Chaize Locking device for elongated reinforcement under tension
US5345742A (en) * 1992-03-24 1994-09-13 Vsl International Ag Force transfer body for an anchorage

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2045703B1 (forum.php) * 1969-06-24 1973-10-19 Stup Procedes Freyssinet
DE2816933A1 (de) * 1978-04-19 1979-10-31 Haller & Co E Befestigung von kontakt- bzw. rueckstellfedern bei relais und verfahren hierfuer
US4223497A (en) * 1978-06-26 1980-09-23 Ccl Systems Limited Coupling assembly
CH662595A5 (de) * 1983-08-22 1987-10-15 Losinger Ag Verankerung von freischwingenden zugelementen aus stahl eines dynamisch beanspruchten bauteiles.

Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2270240A (en) * 1939-08-26 1942-01-20 Freyssinet Eugene Anchoring of tensioned cables in concrete constructions
DE879293C (de) * 1951-07-12 1953-06-11 Wayss & Freytag A G Verankerung eines Vorspanngliedes fuer ein Betonbauteil
US2728978A (en) * 1950-03-10 1956-01-03 Birkenmaier Max Method for pretensioning and anchoring reinforcements of concrete
US2763464A (en) * 1952-07-26 1956-09-18 Leonhardt Fritz Apparatus for anchorage of concrete reinforcements
GB764197A (en) * 1954-10-13 1956-12-19 P S C Equipment Ltd A new or improved hydraulic jack
US2988794A (en) * 1957-12-18 1961-06-20 George Rackle & Sons Company Socket for post stressed concrete wires
FI32183A (fi) * 1958-03-17 1961-11-10 Dyckerhoff & Widmann Ag Vahviketanko betonia etenkin jännitettyä betonia varten
US3137971A (en) * 1959-07-15 1964-06-23 Cable Covers Ltd Stressed concrete structures
US3176961A (en) * 1962-03-05 1965-04-06 John P Glass Hydraulic jack apparatus

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2270240A (en) * 1939-08-26 1942-01-20 Freyssinet Eugene Anchoring of tensioned cables in concrete constructions
US2728978A (en) * 1950-03-10 1956-01-03 Birkenmaier Max Method for pretensioning and anchoring reinforcements of concrete
DE879293C (de) * 1951-07-12 1953-06-11 Wayss & Freytag A G Verankerung eines Vorspanngliedes fuer ein Betonbauteil
US2763464A (en) * 1952-07-26 1956-09-18 Leonhardt Fritz Apparatus for anchorage of concrete reinforcements
GB764197A (en) * 1954-10-13 1956-12-19 P S C Equipment Ltd A new or improved hydraulic jack
US2988794A (en) * 1957-12-18 1961-06-20 George Rackle & Sons Company Socket for post stressed concrete wires
FI32183A (fi) * 1958-03-17 1961-11-10 Dyckerhoff & Widmann Ag Vahviketanko betonia etenkin jännitettyä betonia varten
US3137971A (en) * 1959-07-15 1964-06-23 Cable Covers Ltd Stressed concrete structures
US3176961A (en) * 1962-03-05 1965-04-06 John P Glass Hydraulic jack apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3638909A (en) * 1970-11-13 1972-02-01 Herbert Oliver Richard Dew Gripping means
US5141356A (en) * 1989-06-27 1992-08-25 Alain Chaize Locking device for elongated reinforcement under tension
US5345742A (en) * 1992-03-24 1994-09-13 Vsl International Ag Force transfer body for an anchorage

Also Published As

Publication number Publication date
BE674339A (fr) 1966-04-15
NL6517239A (forum.php) 1966-07-05
CH430135A (fr) 1967-02-15

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