US2637895A - Method of tensioning and anchoring wire bundles for prestressed concrete structural elements - Google Patents

Description

May 12, 1953 AL A. BLATON 2,637,395

METHOD OF TENSIONING AND ANCHORING WIRE BUNDLES FOR PRESTRESSED CONCRETE STRUCTURAL ELEMENTS 4'7 .4 Sheets-Sheet 1 Filed Jan. 23, 19

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May 12, 1953 A BLATQN 2637,895

A. E. METHOD OF TENSIONING AND ANCHORING WIRE BUNDLES F01 PRESTRESSED CONCRETE STRUCTURAL ELEMENTS Filed Jan. 25, 1947 4 Sheets-Sheet 2 Arry y 1953 A. E. A. BLATON 2,637,395

- METHOD OF TENSIONING AND ANCHORING WIRE BUNDLES FOR PRESTRESSED CONCRETE STRUCTURAL ELEMENTS Lled Jan. 25, 1947 4 Sheets-Sheet s A. E. A.

BLATON 2,637

s FOR 4 SheetsSheet 4 May 12, 1953 METHOD OF TENSIONING AND ANCHORING WIRE BUNDLE PRESTRESSED CONCRETE STRUCTURAL ELEMENTS 1947 Filed Jan. 25

Arly) Patented May 12, 1953 TENS O AND I ANCHOBING WIRE-BUNDLES FOR- PRESTRESSED. .CON- CBETE STRUCTURAL ELEMENT Armand- Eugene-Adolphe Elaton; Woluwe-Sainb Pierre, Brussels, Belgium,assignor of one-half toxEniileiJules Lucien Blaton Bz'ussels Belgiumr Application January 23, 1947;-Serial .N0 723/Z 18 In. B lsiumM r .2 1 .421.

Section 1, Public Law 690; "'August 8, 1946 Patent expires March 21', 19627 6 Claims. (01. 251 -148).

The: nresen-txinvention relates.to.:.:a :meljhQdwofn producing; a predetermined tensile%stress:betweenu wosfixedpointsef a eonoreteg-structure -byimeans;

ofea tensionegi wire abundlezeonsisting:10f;a 11111-1 ralityggof -:,high.'tensilezstrength-metal wires ex-.1- tendin adjacentutouone another betweenvsaidi;

fixed m im.

The sprincipalriaobjeotg Oflifth iinventionuis to obylatethe difiiculties -whieh;heretoiorehavelbeen; eneeunteredima'theuuniiorm; :tensionini; or wire bundlesend particularlya-imthe uniiormitension inst 0 "wirer lnundles 50f a :lengthexceecling.:sev-;

mtllfeetqiandz;:containing a sv-considera-blevnumben ofrindividual wires;

Another object "19f ltherimrentiomis togprov-ide a imethmi; whereby-seven, ima rmultiawire; bund-lez oft; great; lengthuanducontainings a -large number; suolrzas 2Q:erzunore-wwires xan rexactl-y mniform; nsionmetoir all theuinriividual wires can-beleacomplished.

A,, stil 1ii;furthen; :objectwofmthe invention: is. to

nevrideia methodfonthe tensioning of m ultiewirez bundlesewhieh' be married: into rseiiect easily: and;iwith,%-sma11en ranch .less-rtexpensive tensioning machinery; than-.jhadhtqbelused: heretofore.

Still another object of the invention :istonpro-L videaa rmethmiuwhielr canxbeuused .wvithout inc e sedardifficuities:regardless:of the vnumber of; Wires: iniathezbundlegso ,thatawire bundles contains A ingza greatnumber: ofiwires-can he) employed anelzi niformly?tensionerhjust as easily; as: WiIBibllllw-r dlesycontainingla small numbenoi wires. 5

GGHQ'IZfiHYwaGQOITdlngazto theupresenninvention,"

these objects are accomplished Joya-a methoclxcom-i prising :the; i o1lowing-,.-steps:i

First:tlxemntensionedaviresforming thebundlei anenarrangedethroughout theumain longitudinal l pq fliiqn-rofiaithe'agwire:bundle; which extends be weemtwoatransversewplaneslocated near the respfieechsubstan iell-yparalleltlayers each 1 inclurl-9: ing a ;;rplurality wofg closely, spaced substantially parallel wireszimsuch a mannenthat at any cross: section-lomsaiutmain portion.=.ofzthe Wire n l the wires are substantially uniformlyldistribute'd oventheentire: area of vthe cross section. Then,

anethenthesame as=.in said main" portion of; thebundleiu Thengswa predetermin eol, tun "ln, l.l)'l"itudinal tensioning stress is exerted at the other' enduofuthe bundle-ona fraction otthe total'numbee of -wires: thebundle so as to tension one,

tw aor; 55 11541 numberzl fknwi ese such ass-f ur. W re :at .zone/ut mei-iwh -le mainta nin a l: ether wires th ou hout said. main porti n t-t eb ndle in -their mutually spaced parallel positions.

Eaoh-tensioned wire is anchored at the 013,- posite end, of the: bu n i1e:i against t longitudinal, movement arelativel ,to the; rfixede 1points of the. structure in a relative position i with, respect to the .other wires the sameasin said maim portion,

' of the undle, andv th t i ine; ndeanchorin steps-are repeated rwith respeotto a small mim ber ofttheorder from onelto; founata time, ofithe ma ning; Wire f. h b ndle,untile lutheiw ese of th bu e av b en.:uniform1y. t nsion ci, and: chored:

Th invention. is p r icularl applicablet the;- anufac ure: of ar cles, su h.-asconeret b am e to which a certain pre-tension is to be imparteqi;

An ,eleme t'f r d tributing, the-W r s. i ;p1 ef-' ablya ho izontalonfs n pqseiifll e emay 3 .7;- or l s; uth spresen inventionbencunstitutem by superposed plates, Y which are 1 connected ito-e t r; f exam 1e y a t, ande h nf w ich is provided .with trapezoidal reeesses in; whiehjuhe, wires afterhavingv beenstretchedlcan bellockedl and anchored i for example means) of. Wed-. now per se-e Numerous variationsin .thedes n of t ese e -i ments can naturally be conceived aqcording to the appl ication envisaged without dep arting from the principles which form the basis of--thevention.

The accompanyingdrawings show themanner in which the invention can :be-carried into'effeot: 1

Figure -l is a plan viewyand Figure 2 an elevation :of:thewholeeinstallationz serving to stretch theametaliwires:

ures 3,: .4 and 5 re: 1 C iQn cQH'J Q'T lQSF III--III, and,, V-,-.V,-; respectively 01?. Fig:- ure l v Figuresrfi :ancl-J? 'relate .to a modifieation which the wires are tension,ect=imzlividual,ly.r

Figures 8 to 13.,relateto,eertain modifications ofthe methodflaccording tothe, invention and to, certain. details of t the structural elements which: may be usedin itsexecutionm InWFie re 1 0.v5, 1.. ignates,.rqund,wiresm f r example. of s ee1,. ,f ermine. a wire, bundl n which a tensile force to be exerted; as is1shown" particularly in Figure 3, according to the in-- vention, the wires I are disposed in the bundle in closelyadjacent horizontal parallel layers each including a plurality of closelyspaced 'substan tially parallel wires The Various layers are maintained attainstance from one another by the interposition of horizontal pins 5 which are inserted at intervals during the preparation of the cable so as to effect a preliminary grouping. Vertical pins 5 are also provided in order to separate the wires. 2 is a thin metal envelope in the form of a truncated pyramid, which is provided at its extremity directed towards the main portion of the wire bundle with a metal ring 3, through which pass the wires I (Figure 3). The envelope 2 directs the wires towards a wire anchoring element 4, which may vary in design according to the purpose of the arrangement. Preferably, the wires l are enclosed in a sheath 2 of sheet iron connected to the ring 3. It will be understood that the wires in the main portion of the wire bundle which extends to the left from the ring 3, as shown in Figures 1 and 2, for instance, to a similar ring near the other end of the bundle (not shown), are arranged and maintained throughout in the positions indicated by the cross section shown in Fig. 3, so that at any cross section of said main portion of the wire bundle the wires are substantially uniformly distributed over the entire area of the cross section. It will also be understood that the wires l are anchored at the other end of the bundle, for instance, in an anchoring element (not shown) corresponding substantially to the wire-anchoring element 4.

The wires I may be, for instance, steel wires 2 with a high elastic limit. Wire bundles consisting of such steel wires are particularly suitable for the reinforcement of concrete structures. Part of a concrete block reinforced by a wire bundle tensioned according to the present invention is indicated by the reference numeral P in Fig. 1. However, the invention is not limited to this application.

In the examples shown in Figures 1 to 5, the wire anchoring element 4 comprises a series of superposed metal plates 6 provided with recesses 1 having a trapezoidal form in plan view and two locking plates 8 rigidly connecting all the plates 6 with the aid of bolts 9 (Figure 4). Between the plates 6 provided with notches are interposed thin metal sheets l serving to avoid friction of the wires against one another when they are placed under tension.

The traction device, which is shown by way of example in the right hand part of Figures 1 and 2, comprises a metal cross-piece H having on one of its faces two recesses E2 of trapezoidal form and forming with two rods !3 and a crosspiece I 4 a coupling system permitting of exerting a tractive force on the wires. The rods [3 form at their extremities forks i5 bearing against the cross pieces II and I4, and bolts l6 connect the rods l3 to the cross-pieces H and M.

The cross-piece M bears against a traction device ll which may be a hydraulic jack or any other lifting apparatus.

A metal plate :8 having slots [9 for the passage of the rods [3 serves as a seat for a base supporting the traction device II. This plate I8 is in addition provided with securing members 2| for stays 22 connected to an annular plate 23 adapted to bear against the anchoring element 4.

The suspension of the jack I! may be effected with the aid of metal plates 25 reinforced by angle irons 26. These angle irons have apertures 21 which may be brought into register with apertures 28 in the base 20. Pins 29 may be inserted into these apertures to secure the jack H at difierent heights. During vertical adjustment of the jack ll the rods I3 move vertically in the slots [9 of the plate 18. I,

As will be seen from Figure 4, owing to the design of the anchoring element 4 which is formed by superposed plates having recesses therein, the wires, on leaving the envelope 2, are distributed in parallel, horizontal layers which, in the case illustrated, each comprise four wires I penetrating in pairs into the recesses 1. Each layer could comprise a larger number of pairs of wires or only two wires. The number of layers will depend upon the tensile force to be exerted.

In order to exert a tensile stress on the wires and to maintain this pull for as long as desired, the following procedure is adapted in the case where it is desired to tension two wires at a time.

Two of the wires I passing through a recess 1 in the element 4 are brought into a recess I! in the cross member H and are secured therein by means of a key or wedge 36. The jack I1 is then set in operation, and this jack, by exerting a thrust in the direction of the arrow on the= cross piece l4 moves the entire coupling systemand exerts on the pair of wires secured in the cross piece II the pull to be produced. When the elongation of these two wires is such that it corresponds to the force which it is desired to produce, the two wires l are keyed in the ele-' ment E in known manner by means of a wedge 3|, whereupon the jack I? is slackened and the wedge which has served to secure the two wires 1 to the coupling system H, l3, i4 is removed. .The operation is repeated as many times as there are pairs of wires in the bundle and it is thus possible by multiplying the number of wires to obtain a total tensile force of any desired strength as shown in Fig. 1, up to 4 wires may be tensioned simultaneously.

When all the wires of the bundle have been placed under tension, the coupling system II|3I4 is removed, as also the members |82223, and the tensile force will be main.

tained in the wires as long as the wedges 3| are left in position.

If it is desired to remove the tensile force in the wires 1, the coupling system is replaced in position and a further pull is exerted on each pair of wires until the keys or wedges 31 can readily be removed. The device employed for applying the tensile force is slackened, the wedges 3B are removed and the various pairs of wires are released.

Instead of measuring the tensile force to be;

produced in wires by calculating their elongation,

it is possible to insert between the coupling system and the device for tensioning the wires, a.

dynamometer indicating at each instant, the intensity of the tensile force produced. A manometer indicating the pressure obtained in the jack ing one another and they also permit that when the tensile force is exerted on some of the Wires this arrangement be maintained and that none of the wires which are tensioned become wedged between wires which are not tensioned.

In the embodiment shown in Figures 1 to 5, it

has been assumed that the tensile force has been.

applied to two wires or to four wires at a time.

L to 4 at a time while maintaining all the wires throughout said main portion of the bundle in their mutually spaced, parallel positions, anchoring each tensioned wire at said opposite end of the bundle against longitudinal movement in the direction toward said first end of the bundle in a relative position of said wire with respect to the other wires the same as in said main portion of the bundle, and repeating the tensioning and anchoring steps with respect to a small number of the order of 1 to 4 at a time of the remaining wires of the bundle until all the wires of the bundle have been uniformly tensioned and anchored.

2. In the manufacture of load-carrying structural concrete elements pre-stressed to a high tension by means of at least one bundle of high tensile strength metal wires which extend closely adjacent to one another in a longitudinal cavity of the structural element and cooperate to form a single unit for the maintenance of the desired high tension in the structural element, a method of forming the wire bundle and imparting thereto the desired high tension, said method comprising the steps of arranging .a plurality of untensioned high tensile strength wires to extend, throughout the main longitudinal portion of the wire bundle formed by said wires between two transverse planes located near the respective ends of the bundle, in several closely spaced substantially parallel layers, each including a plurality of closely spaced substantially parallel wires in such a manner that, at any cross-section of said main portion of the wire bundle, the wires are substantially uniformly distributed over the entire area ofsuch cross-section, anchoring the wires at one end of the bundle against longitudinal movement in the direction toward the other end of the bundle in relative positions of the several wires with respect to one another the same as in said main portion of the bundle, exerting at the other end of the bundle a predetermined, uniform, longitudinal tensioning stress on a fraction of the total number of wires in the bundle so as to tension a small number of wires of the order from 1 to 4 at a time while maintaining all the wires throughout said main portion of the bundle in their mutually spaced, parallel positions, anchoring each tensioned wire at said opposite end of the bundle against longitudinal movement in the direction toward said first end of the bundle in a relative position of said wire with respect to the other wires the same as in said main portion of the bundle, and

repeating the tensioning and anchoring steps I with respect to a small number of the order of 1 to 4 at a time of the remaining wires of the bundle until all the wires ofthe bundle have been uniformly tensioned and anchored.

3. In the manufacture of load-carrying struc- 300 tural concrete elements pre-stressed to a high tension by at least one bundle of high tensile strength metal wires which extend closely adjacent to one another in a longitudinal cavityof the structural element and cooperate to form a-single unit for the maintenance of the desired high tension in the structural element, a method of forming the wire bundle and imparting thereto the desired high tension, said methodlongitudinal movement in "the direction toward the other end of the structural element in relative positions of the several wires with respect to one another the same as in said main portion of the bundle, exerting at the other end of the bundle a predetermined, uniform, longitudinal tensioning stress on a fraction of the total number of wires in the bundle so as to tension a small number of wires of the order from 1 to 4 at a time while maintaining all the wires throughout said main portion of the bundle in their mutually spaced, parallel positions, anchoring each tensioned wire at the opposite end of the structural concrete element against longitudinal movement relative to the structural element in a relative position of said wire with respect to the other wires the same as in said main portion of the bundle, and repeating the tensioning and anchoring steps with respect to a small number of the order of 1 to 4 at a time of the remaining wires of the-bundle until all the wires of. the bundle have been uniformly tensioned and anchored.

. 4.; In. the manufacture of load-carrying structural concrete elements pre-stressed to a high tension bymeans of at leastone bundle of high tensile strength metal wireswhichcooperate to form a single .unit for the maintenance of the desired high tension in the structural element, a. method of formingrthe wire bundle and impartingthereto the desired high tension, said.

method comprising the steps of arranging a pluralityof untensioned. high. tensile strength wires to. extend throughout the main longitudinal portion of the wire bundle formed by such-wires between two transverse planes located near the respective ends of the bundle, in several closely' spaced substantially parallel layers each including a plurality of closely spaced substantially parallel wires in such a manner that, at any cross-section of said main portion of the wire bundle. the wires are substantially uniformly distributed over the entire area of such crosssectionanchoring the wires at one end of the bundle against longitudinal movement in the direction toward the other end of the bundle in relative positions of the several wires with respect to one another the same as in said'main' portion of the'bundle, guiding the wires from theend of the main portion of the bundle near the opposite end of the latter through a transverse anchoring plane located between said end 'of said main portion and said opposite end of the bundle along diverging lines to define animaginary truncatedv pyramid having its smaller base at the end of the main portion of the bundle and its larger base in said anchoring plane, the wires being located in said anchoring plane in relative positions the same as in the main portion of the bundle with the spacing between adjacent wires in the anchoring plane being considerably greater than the spacing between the same wires in the main portion of the bundle, exerting at the other end of the bundle a predetermined, uniform, longitudinal tensioning stress ona fraction of the total number of wires in the $59 bundlesso as to tension afr'sniall number iof wires bfthe orderfrom llto 4 at a tim'e izzhileomaint'ainng an the: wires throughouiasaid mainuportion tithe bundlein theirmutually-rspaced-sparallel wpositions, anchor-ingeach tensioned wirevin said 'eianchoring plane-against longitudinal "movement 'in the d-ircctiontoward saidfirst ehdw bf xthe fibundle in a relative-position of saiid wiretvlthnespect to the other'wires the-sam as in said main portion of the bundle, and repeating the tensioning and anchoring'st'eps' with respect-rte" a wsniallnumberof 'theorder of lto 4 at atime of "s'the remainingwiresofthe 'buifdle ufitildll the wires'bf the bundle havedoeenmniforirfly tensioned and anchored.

5. In the manufacture of load-carrying structural concrete elements pre-stressed to a high tension by means of at least one bundle of high tensile strength metal wires which extend closely adjacent to one another in a longitudinal cavity of the structural. element and cooperate to form a single unit for the maintenance of the desired high tension in the structural element, a method of forming the wire bundle and impart ing thereto the desired high tension, said method comprising the steps of arranging a plurality of untensionecl high tensile strength wires to extend, throughout the main longitudinal portion of the wire bundle formed by said wires between two transverse planes located near the respective ends of the bundle, in several closely spaced substantially parallel layers, each including a plurality of closely spaced substantially parallel wires in such a manner that, at any cross-section of said main portion of the wire bundle, the wires are substantially uniformly distributed over the entire area of such cross-section, anchoring the wires at one end of the bundle against longitudinal movement in the direction toward the other end of the bundle in relative positions of the several wires with respect to one another the same as in said main portion of the bundle, guiding the wires from the end of the main portion of the bundle near the opposite end of the latter through a transverse anchoring plane located between said end of said main portion and said opposite end of the bundle along diverging linesto define an imaginary truncated pyramid having its smaller base at the end of the main portion of the bundle and its larger base in said anchoring plane, the wires being located in said anchoring plane in relative positions the same as in the main portion of the bundle with the spacing between adjacent wires in the anchoring plane being considerably greater than the spacing between the same wires in the main portion of the bundle, exerting at the other end of the bundle a predetermined, uniform, longitudinal tensioning stress on a fraction of the total number of Wires in the bundle so as to tension a small number of wires of the order from 1 to 4 at a time while maintaining all the wires throughout said main portion of the bundle in their mutually spaced, parallel positions, anchoring each tensioned wire in said anchoring plane against longitudinal movement in the direction toward said first end of the bundle in a relative position of said wire with respect to the other wires the same as in said main portion of the bundle, and repeating the tensioning and anchoring steps with the respect to a small number of the order of 1 to 4 at a time of the remaining wires of the bundle until all the wires of the bundle have been uniformly tensioned and anchored.

6. In the manufacture of load-carrying struc- 20i .1 thewstructural element and cooperate-.- to

-.i.tor1m a's'mgle unit for thesmaintenance oflthe :rlesired high tension in thesstructural(element, raimethodsof forming thelh irabundlewand imrpartins thereto the desiredlhigh tension said imethodtcomprising the stepsanf arranging a apluralitysofz high tensile st-rength metal-swims: in

. alongitudina1 cavity leftin apre-castconcrete element uto extend, throughout. ithe imainslonigitudinal portion of'the wire'bundle .tormedvby said wires between two transverse planes located near the respective ends of the bundle, in several closely spaced substantially parallel layers each including a plurality of closely spaced substantially parallel wires in such a manner that, at any cross-section of said main portion of the wire bundle, the wires are substantially uniformly distributed over the entire area of such crosssection, anchoring the wires at one end of the hardened structural concrete element against 1ongitudinal movement in the direction toward the other end of the structural element in relative positions of the several wires with respect to one another the same as in said main portion of the bundle, guiding the wires from the end of the main portion of the bundle near the opposite end of the structural concrete element through a transverse anchoring plane located substantially at said opposite end of said structural element along diverging lines to define an imaginary truncated pyramid having its smaller base at the end of the main portion of the bundle and its larger base in said anchoring plane, the wires being located in said anchoring plane in relative positions the same as in the main portion of the bundle with the spacing between adjacent wires in the anchoring plane being considerably greater than the spacing between the same wires in the main portion of the bundle, exerting at the other end of the bundle a predetermined, uniform, longitudinal tensioning stress on a fraction of the total number of wires in the bundle so as to tension a small number of wires of the order from 1 to 4 at a time while maintaining all the wires throughout said main portion of the bundle in their mutually spaced, parallel positions, anchoring each tensioned wire in said anchoring plane at the opposite end of the structural concrete element against longitudinal movement relative to the structural element in a relative position of said wire with respect to the other wires the same as in said main portion of the bundle, and repeating the tensioning and anchoring steps with respect to a small number of the order of 1 to 4 at a time of the remaining wires of the bundle until all the wires of the bundle have been uniformly tensioned and anchored.

.ARMAND EUGE NE ADOLPHE BLATON.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 149,553 Weston Apr. 7, 1874 165,705 Brown July 20, 1875 661,615 Marwick Nov. 13, 1900 767,798 Clark Aug. 16, 1904 1,465,307 Keogan Aug. 21, 1923 1,538,293 Loyeau May 19, 1925 (Other references on following page) Number 11 UNITED STATES PATENTS Name Date Hendry June 14, 1927 Woodward Feb. 21, 1928 Schafer Aug. 1, 1933 Smith Feb. 18, 1936 Strange Mar. 30, 1937 Lapinskas June 21, 1938 Stromberg Nov. 15, 1938 Bullard Aug. 29, 1939 Freyssinet Sept. 12, 1939 Dunoyefi Mar. 5, 1940 Freyssinet Jan. 20, 1942 Schorer Dec. 1, 1942 Number Number Name Date Scharer Aug. 31, 1943 Freyssinet Mar. 20, 1945 Schorer June 19, 1945 Cueni Aug. 14, 1945 Muntz Jan. 7, 1947 Fitzpatrick June 28, 1949 Barber June 13, 1950 FOREIGN PATENTS Country Date Great Britain Dec. 15, 1941 Great Britain Feb. 16, 1942 Switzerland Apr. 16, 1951

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