CA1278698C - Anchor apparatus for a tendon in prestressed concrete slab - Google Patents
Anchor apparatus for a tendon in prestressed concrete slabInfo
- Publication number
- CA1278698C CA1278698C CA000520018A CA520018A CA1278698C CA 1278698 C CA1278698 C CA 1278698C CA 000520018 A CA000520018 A CA 000520018A CA 520018 A CA520018 A CA 520018A CA 1278698 C CA1278698 C CA 1278698C
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- CA
- Canada
- Prior art keywords
- tendon
- anchor
- anchor body
- conduit
- covering
- 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 - Fee Related
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Abstract
Abstract of the Disclosure An anchor apparatus which provides corrosion pro-tection for the exposed cable in a region around where the anchor body attaches to a tendon of a prestressed concrete slab is disclosed. A conduit is fastened to the inlet end of the anchor body. The other end of the conduit is taped or connected with heat shrink tubing to the covering on the ten-don. The outlet end of the anchor body is closed either with a plug at an end anchor or with a second conduit and tape or heat shrink tubing at an intermediate anchor. Fittings are provided for inserting corrosion resistant grease into interior cavities as a second line of corrosion protection.
Description
12~8Ç;~8 ANCHOR APPARATUS FOR A TENDON IN
PRESTRESSED CONCRETE SLAB
Field of the Invention The present inven~ion is directed to anchor devices for a tendon in a concrete slab and, more particularly, to such a device including mechanism for resisting corrosion in a region around where the anchor device attaches to the tendon.
Backqround of the Invention Anchor devices for holding tendons in a stressed condition in a prestressed concrete slab are known. In ~.S. Patent 3,596,330, a preexisting coating or coverin~ fox a wire tendon is sealed to one end of an anchor by a defcrmable washer which is pressed into a sealing configuration by wedges holding the stressed tendon to the anchor. A plug or cap closes the other end of the anchor. The problem with this device is that it is very difficult to make a precise stripping of the cover on a tendon so that it ends, for example, at the washer. Hence, it is likely difficult to achieve the purpose of the device. In U.S. Patent 3,95~,797, shield elements are shown which fit over one end of the anchor body and extend out over a portion of the tendon. In .S. Patent 4,053,974, a shield member is formed to extend from paper wrapped about the tendon to a tube which is installed during pouring of the concrete around the anchor and a form holding the anchor body. After the concrete hardens, the tube is removed. The shield member remains in place, but its intent is simply to prevent concrete from entering the tube and contacting the exposed cable of the tendon since after the tube is removed, the shield member does not extend to the anchor member. Over the years, this ,.~
~786~98 .
mochani~m wlll not prev~nt corro~ive flulds rom ~eeping through the concret~ and contac~ing ~he exposed cabl~. In U.
S. Patent 4,3~3,462, the space between a ~hield member and thc anchor body i~ filled ~;th a grease or ~ome other corro-~lon pro~ec~lo~ sub~tance.
~ nown device~ do not conslder the needs o~ large pres~r~6~cd sl~b~ whereln both end ancho~ ~nd lntermedi4te anchor~ are require~ and wherein corroslon pr~tect~on ~hould be provided for the exposed oable o~ a tcndon in the re~ions o each o~- the ~ever~l anchors. In thls regard, known Anchors do not show mechan$~m or prov~d~ng a~t, e~flcient ~nd po~i~ive sealin~ connectlon~ at selectively one or both end~ of an anchor.
S~m~rv o~ the Inveneion The present ;nvent~on iR directed to an anchor device ~or holdin~ a tendon ln a ~tressed cond~tion ln a prestresssd conerete slab wherein th~ tendon ha~ a corroslon resist~nt coverlng, ~ut wherein the covering i~ incomplete in a re~ion ~ro~nd where the anchor device is attached to the tendon. The d~vice incl~des wed~es and an anchor bo~y for reoeiving the wedg~. The anchor body has 8 ¢entral pass~ge ~or receiving the tendon. The pa~sage ha~ ~ longi~udlnal centerline. The pas~age furSher hes an lnl~t sectlon, an outlet sec~ion and a central ~c~lon therebetween. The een~ral sectlon includes a eonlcal portion ~or rec~iv~ng ~nd provldin~ a seat for the wedge~. The inlot sectlon has smal~er tran~verse dimension through the longi~udlnal cen-terline than the outlot section. The anchor body further lncludes a mechanlsm for re~i~tin~ longi~udin~l mov~ment w1th re~pect to ~he cemont slab. The anchor dovlce furth~r lnclu-des a fira~ conduit havlng ~ir~t and ~econd end ~ortion~. In ~ddlt~on, the ancho~ d~vi~e ~n~ludes a mech~nlsm or sealingly atta~hlng the fi~st end portion o~ the flr~t con-l27a6~s duit to the inlet section of the anchor body. Theattaching mechanism includes the inlet section having a first threaded portion and the first end portion of the first conduit being threaded to mate with the first threaded portion. Also, the anchor device includes first means for sealing the second end portion of the first conduit to the covering on the tendon to enclose one end of the region wherein the corrosion resistant covering is incomplete. The anchor device still further includes a mechanism for sealingly closing the outlet section of the anchor body with respect to the other end of the re~ion of the tendon wherein the corrosion resistant covering is incomplete. The closing means includes the outlet section having a second threaded portion. The closing means also includes a second conduit like the first conduit and second sealing means like the first sealing means. The closing means further includes a reducer having a first threaded end mating with the second threaded portion of the outlet section of the anchor body and a second threaded end for mating with a first threaded end portion of the second conduit. The reducer has a central passage for receiving the tendon therethrough. The covering of the tendon, the reducer, the second conduit and the second sealing means enclose the other end of the region of said tendon where the corrosion resisting covering is incomplete thereby protecting the entire region from outside corrosive fluids.
In end anchors, the closing mechanism includes a plug. In intermediate anchors, the closing mechanism includes the reducer which decreases the diameter of the outlet section for attachment to the second conduit by connecting with the reducer just like the first conduit which is connected to the other end of the anchor body.
The unattached ends of both conduits are taped, enclosed with a heat shrink tube or otherwise sealed to the covering on the tendon. Thus, the present anchor ~1~7~ 98 apparatus advantageously may be used for both end and intermediate anchor applications.
Of further advantage is that a grease fitting may be installed in the closure plug for an end anchor and in the reducer for an intermediate anchor for the purpose of forcing grease into the conduits and the central passage of the anchor body. Thus, the present apparatus not only provides for enclosing the region around where the anchor grips the tendon, but also provides for filling the enclosed space with a corrosion resistant grease.
In another embodiment, a heat shrink tube provides sealing between the inlet section of the anchor body and the covering on the tendon. In situations where this embodiment may be used, the conduit of the previously discussed embodiment is not necessary. With respect to the outlet section of the anchor body, a plug is used to sealingly close it when the anchor is used as an end anchor. For an intermediate anchor, a reducer is used to reduce the transverse cross section of the outlet section so that a second heat shrink tube may be used to provide a seal between the reducer and the covering on the tendon.
According to another aspect of the invention there is provided an apparatus for holding a tendon in a stressed condition in a prestressed concrete slab wherein the tendon having a corrosion resistant covering, but wherein the covering is incomplete in regions around where attachments of said apparatus are made to the tendon. The apparatus includes a plurality of anchor bodies with a pair of the anchor bodies being attached at opposite ends of the tendon to the tendon. At least one other of the anchor bodies is attached to the tendon intermediate the pair of anchor bodies attached at opposite ends. Each of the anchor bodies has a central passage for receiving the tendon~ The passage has a longitudinal centerline. The passage has an inlet section, an outlet section and a central section therebetween. The central section -4a- 1~ 78 ~8 includes a conical portion. The inlet section has a smaller transverse dimension through the longitudinal centerline than the outlet section. Each of the anchor bodies further includes means for resisting longitudinal movement with respect to the slab.
The apparatus also includes a plurality of sets of wedges, with one set of wedges fitting into each anchor body to seat in the conical portion to hold the tendon with respect to said anchor body. The apparatus further includes a pair of plug members and a mechanism for sealingly attaching a different one of the plug members to each of the o~tlet sections of the anchor bodies at the opposite ends of the tendon. A reducer has a central passage for receiving the tendon and opposite first and second ends. A second sealing mechanism sealingly attaches the first end of the reducer to the outlet section of the intermediate anchor body. A plurality of conduits have first and second end portions, with the first end portion of each of the conduits sealingly connecting with one of said inlet sections of the anchor bodies and the second end of the reducer. Means are provided for sealing the second end portions of the conduits to the covering on the tendon to enclose the regions where the corrosion resistant covering is incomplete.
Consequently, the tendon is anchored at its ends and at a location intermediate the ends and the regions of attachment are enclosed to minimize the possibility of corrosive fluids contacting the tendon at uncovered points.
According to a further aspect of the present invention, there is provided a method for using an anchor device to hold and protect a tendon in a stressed condition in a prestressed concrete slab. The tendon has a fixed end and a corrosion resistant coveriny that is incomplete in a region around where the device is attached ., ~. ' ' ~
-4b- 12786~8 to the tendon. The device includes an anchor body having a central passage for receiving the tendon and a central section for receiving wedges to hold the tendon with respect to the body. The anchor body further has means for resisting longitudinal movement with respect to the slab. The anchor body additionally has a first portion on a first side of the resisting means and a second portion on a second side of the resisting means. The device further includes a conduit having a first and second end portions, a mechanism for sealingly attaching the first end portion to the first portion of the anchor body and a mechanism for sealing the second end portion of the conduit to the covering on the tendon. The device still further includes a mechanism for sealingly closing the central passage at the second portion of the anchor body.
The method comprises the steps of:
(a) attaching with the attaching means the first end portion of the conduit to the first portion of the anchor body, fixing the anchor body at a predetermined location, and passing the tendon through the conduit and the central passage of the anchor body:
(b) sealing the second end portion of the conduit to the covering on the tendon with the sealing means:
(c) casting concrete with respect to the anchor body and the tendon on the first side of the resisting means so that the central passage at the first portion of the anchor body is free of concrete:
(d) placing wedges in the central passage of the anchor body between a wall of the central passage and the tendon and stressing the tendon with respect to the fixed end of the tendon, the wedges holding the tendon in the stressed condition, (e) fitting a reducer to the second portion of the anchor body, the reducer having first and second ends, the first end sealingly attaching to the second portion of d~
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the anchor body;
(f) fitting a second conduit into the second end of the reducer, the second conduit having first and second end portions with the first end portion sealingly attaching to the second end of the reducer; and (g) sealing the second end portion of the second conduit to the covering on the tendon with the sealing means;
whereby the tendon is held in a stressed condition and sealed against corrosive fluids in the region around where the anchor body with the wedges attaches to the tendon.
These advantages and other objects obtained by the invention are further explained hereinafter and may be better understood by reference to the more detailed description which refers to the drawings briefly described as follows.
Brief Description of the Drawings FIGURE 1 is a cross-sectional view of a concrete slab showing in side view a tendon held by an intermediate anchor and end anchors in accordance with the present invention;
FIGURE 2A, which follows FIGURE 3, is a cross-sectional view of an intermediate anchor as held by a formboard prior to having cement cast with respect to it;
FIGURE 2B is a partial cross-sectional view of an installed intermediate anchor;
FIGURE 3 is a partial cross-sectional view of an end anchor;
Similarly, FIGURES 4-8 are diagrammatic cross-sectional views showing alternative embodiments for plugs closing the outlet section of an anchor device and for mechanisms to seal between the inlet section and the tendon covering; and FIGURES 9-11 are partial cross-sectional views illustrating the use of a heat shrink tube to seal between -4d- ~2786~8 the inlet section of an anchor device and a tendon cove r i ng.
Detailed Descri~tion of the Preferred Embodiment Referring now to the drawings wherein like ref-erence numerals designate identical or corresponding parts -5- lZ786~8 throughou~ the several view~, and ~ore p~rticul~ly to FIGURE
1, an app~ra~us for holding a tendon 18 ln a ~tre~ea con-ditlon ln a pre~t~es~ed concrete slab 1~ 1~ d~ nated generally by ~he numeral 10~ Slab 12 i6 ~hown suppo~d by a plurality of beams 14. A plursllty of ~emperatu~e tendons 16 oxtend transver~ely ~hrough slab 12 with res~e~t to the ~on~ltudinal extenslon of prlmary ~endon 1~. A pair o~
anchor devlce~ 2~ hold tendon 18 at its oppo~ite onds. An intermediate anchor ~evice 20' holds tendon 18 at a locatlon b~twesn ~t~ oppo~lte end~, prefer~bly at a m~dpoint betwe~n ~djaoent anchors an~ ~r a one way ~lab ~ystem preferably near a beam 14. It ls understood that the present lnvent~on applie~ also to ~ two way sla~ sys~em. It 1B further understood that the present apparatu~ is applicable ~or any tendon anchorage, whether ~raped or not.
A~ shown in FIGURE 3, devlce 20 includos Pnchor body 22 hAving a centràl pas~age 24 therethrough~ PassPge 24 is aligned ~long a longitudinal centerline (not 6hown for clarity r~a~on~). Passage ~4 includes an lnlet ~ection 26, an outlet seotion 28 and a cen~ral ~ection 30 in ~he region betwe~n the lnlet and outlet sections 26 and 28~ ~h~ centrPl ~ectlon ha~ a conical portion 32 tor receivin~ and provlding a se~ ~or a ~e~ o~ wedges 34. Inlet section 26 18 in~er-nally threaded with a diam~ter pre~erably at least a8 lPrge as the ~mslle~S diametQr of coni~al port~on 32 to whlch it mPte~. Outlet ~ectlon 28 is al~o intornally thre~d~d.
Outlet sectlon 28 ha a lArger tran~verse d~en~ion when mea~ured throu~h the longi~udlnal centerllno of pa~sa3e 24 than inlet soction 26. With respect to conical portion 32, the d~ameter o outlet section 28 ~8 larger BO that we~ges 34 may be readily in~erted Shrough outlet ~ection 28 lnto cenSral section 24 around ~endon 18.
Anchor body 2Z has an outwardly extendlng, tran~--6- 12~ 8 6~ 8 vers~, flat surface 36 which i~ one side o ~n ou~wardly extendlng flange 38 suppor~ed on the ~lde opposlte ~rfac~ 36 by a plurallty o~ gu~set~ 40. 8urf~ce 36 m~ be located anywhere alon~ the longitudin~l dlmen6ion of body 2~.
Surface 36 is ~hown approxima~ly half way between the end~
of ~ody 22. Surace 36 b~tts against the ~oncrete o~ 81~ 12 to prevent anchor body 2~ rom movlng longi~din~lly wlth re~pect to slab 12 even thoush body 22 is holding ten~on 18 in t~nslon.
The po~ion 42 of body 22 toward inlet end 44 o body ~2 h~ a smaller tran~verse dimens;on than portion 46 extendin~ toward outlc~ end 48 ~rom ~lan~e 38. Portlon 46 must be su~floiently l~rge to provide ~t~ucture ~or the lar~er threaded portlon of outlet section 28, SimLlarly, portlon 42 must be suf~iciently large to provide 6tructure for the smaller threaded portion o~ lnlet ~ection 26.
Tendon 18 i~ ~ommonly a cablo wrapped with a treated paper or covered with a layer of a plastic materlal or 80me othe~ corrosion resistan~ eoverln~ 52. Cov~ring 52 is strippad away ~rom the c~bl~ 50 ln the reglon o~ devlce 20 ~o that ~dge~ 34 can reliably grip cabl~ S0 an~ not glip or p~e3s into any ~oft cov~r$n~ As A resul~, the unoovered re~ion of tendon 18 o~ten extends b~yond anchor body ~2. In the pa~t, such uncovered reqions ware sub~c~ to corro6ive fluids ~eepln~ through the concrete of ~lsb 12. Furthermore, slnce anchors 20 and 20' ~re gen~rally nearer the up~er sur-facQ of sla~ 12 ~han the rest of tendon 18, ~ny seepage by cor~osive fluld oftQn reached the uncovered re~ions be~ore it reached the eovered portion o~ tendon 18. ~n any ease, the present lnvention i~ directad to ~olvlng the pro~lem of pro-tectln~ ~ch uncovered reglons ~rom corrosive flu~d~.
A conduit 54 ~s threaded at a fir~t en~ portion 5~
~o mate with the thrc~dad portion of ln~ et sectlon ~6 of --'- lZ786~8 anchor body 22. Tape 5~ or o~her ~eallng me~hanl8m iS
~astened betw~en ~he seeond end portion 60 of conduit 54 and covering 52 of tendon 18.
A clo~ure plug fi2 ~eals passage 24 a~ o~tlet end 48 of anchor body 22. Plug 62 lncludes a threaded end 64 fo~
ma~ing wi~h the threaded portion o~ outlet ~ectlon 28. The othe~ end of plug 62 iB prefera~ly square or hexlgon~l 80 that it may b~ easlly en~3ged with ~ co~mon wrench. A
fittlng 68 ls installed ln the end of plug 62 so that a com-mon ~re~se ~un ~ay ~e used to foree gre~e throu~h flttin~ 68 ~nto p~s~a~e ~4 of anchor body 22 and lnto conduit 54.
Although the enclose~ Bpace bounded by pa~ age 24 ln anchor body ~2, cond~it ~4, tape 58 and plu~ 62 adequately encloses the reglon of tendon 18 having ~n lncomplete covering, n~verthe les~, a corrosion re~i~tant grea~e advantageousl~
prov~des a second mechanism or minimlzing any tendon weakonin~ due to corrosion. In ~ddition, it ls noted that the enelosed space encloses the vol~til~ gase~ vaporizlng rom the ~rease and helps to kee~ ~he vapor pressure hlgh ~nd prevent the ~rea~o ~rom b~eaklng down.
It is ~urther noted ~hat it i~ desirablo to use a seal~nt between the thre4ds o~ plug G~ And the threads o section 28~ ~s ~ell as between ~he thre~ds of condui~ 54 ~nd She threads of inle~ tion 26.
D~vice 20' has the same anchor ~ody 22 os ~evice 20 ~urthermore, device ~0' lncludes a ~et Of wedge~ 34 and h~
cond~it 54 with ~ape 60 for ~ealing one end of the uncovered reglon of tendon 1~ in the vicin1ty of devlce 20'. ~ather than ~ plug 62, howevQr ~ a reducer 70 f its into the outlet section 28 of anehor body 22 of device 20 ' . Reducer 70 has an outer threaded port~ on 72 extending to one end for mating wlth the ~hre~ded portion of outlet sectlon 28. ~educer 70, ln addi~ion, ha3 an inner threaded portlon 74 extending to -8~ 78~
~he other end for recelving ~he ~irst threaded end portlon 56' of a ~e~ond condult ~4~ whl~h 18 ex~ctly ~he s~me a~
~irst conduit 54. Anchor body 22 ;B, thus, advantageoU~ly do~L~ned ~o th~t outlet ~e~tion 2~ may be u~e~ wl~h a reduoer 70 to decrea~e tho dlame~er of the ~hrea~ed ~ort~on ln order ro~eive a ~econd conduit just llke the flrst oondult theroby sealln~ both ends of body 22 ln a ~lmil~r ~hlon.
In this regard, tape 60' seals betwoen Becond end portlon 58' o~ conduit 5~ and coverlng ~2 o~ tendon 18.
A fitting 76 i~ installed in reducer 70 ~o provi~e ~ mechani~m for in~ertln~ ~orrosion re~lstant ~e~e ~n~o the enclosed ~pa~ ~en~rally for~d within body 22, ~ondults 54 ~nd 54', ~nd reducer 70.
In u5e~ ~ tendo~ 18 may be installed durlng the ~n~tial cons~ruction o~ a ce~ent ~la~ 12 or ~nder ~ome cir cumstano0~, a new tendon 18 may replaoe a prevlously removed tendon ln an exl~ting cement ~l~b. In ~ny case, the end anchore 20 and intermedi~e anchors 20' must be located and flxed wi~h respect to tho slab 12 or the BpACe to be occupied by the slab 12. Many ti~es, no intermedia~e anohors ~re needed. On the other hand, th~re are many ~imos when one or ~ore inter~edl~te an~hors 20' are neoded~ In either ca~e, the op~osite end o~ ~endon 18 with respeot to the anchor which 1~ belng inst~lled i~ ~lxed. Gener~lly, such oppo~ite Qnd i~ ~lxed wi~h an end an~hor 20. g~ch opposite end anchor is positioned on ~ orm known to those ~o skilled. Be~ore or after fixing the end ancho~ in po~ltlon, a first ~ondult 54 8 ~hread~d ~o lt and tendon 18 ~s passed through ~he anchor ~ody ~2 ~n~ held by wedge~ 34~
With respect to instAllin~ the lntermedlAte ~nchor 20' or the second end anchor 20, #imilarly, ei~he~ before or a~ter ~ix~ng the anchor body 22 at a pr~de~ermined locatlon, ths flrst threaded end po~tion o~ fir~t condult ~4 ls .
.7~36~38 threaded into the fl~t ~h~ead~d portion of lnlet ~ection 26 o~ anchor ~ody 22. ~n ~he case of an 0%iBtln9 ~lab, ~he ten-don 1~ i8 pasged through the various anehor bodies, reducOEr~, and conduits whlle they are belng located and fixed in pl~ce.
In the case o~ new con~ruction, a tendon 18 may ~e pa~sed throu~h the appropriat~ ~lr~ cond~it 59 and the central p~a~e o~ the anchor ~ody 22 of the anchor to be ~n~talled afte~ the onchor has been positionally fixed. Th~ secon~ end portion o~ fir6t condult 54 is ~hen se~led with ~po 58 to covering 52 of tendon 18. To illu~r~te, in FIG~RE 2A, ~n intermediate anohor ~0' is shown ixed in pl~ce relative to ~orm prior ~o oa~tlng concre~e. Nalls 80 are pa~sed throu~h openings in flange 38 and extend through a block 82, for example Styrofoam, to en~age form B~, likely ~ wooden pl~nk.
Cond~it 54 i~ ~ttached ~t first end portion 56 to portion 42 of ~nohor body 22. The second end port~on 60 of c~nduit 54 ls sealed wlth tape 58 to coverlng 52 on tendon 18. Tendon 18 extends through conduit 54 ~nd the central paS~Age 24 of anchor body 22, a~ well ~5 through block 82 and form 84.
Nex~ concrete 8~ ~see FIGURE 28) is cas~ in the sp~ce between the fixed end and the anchor to be lnstalled.
In the case of ~ tendon replaced in an existiny slab, cone~ete i~ c~ hround the tendon to flll ln the ~lab wherever portion~ wQre ramoved. Only the outward end3 of the facing Anchors ~re not covered with concrete ln order ~o pro-vlde ~or subsequent tendon stres~ing. In the case o new construc~lon, concrete 1~ ca~t ln the space in which the slab i~ to ~e created and between the forms holdin~ the anchors.
A~ shown ~n ~ RE ~B, con~rete 88 at this poin~ in the pro-cess would not be pre~ent ~lnce lt would be Ca~ during a ~ubseq~ent iter~tion o th~ process ~hen anehor ~ody 20' a~
s~own in FIGUR~ 2~ fun~tion~ a~ ~ fixed anchor at one end of a new portLon o~ l~b ~o be in~t~lled. It is ole~ th~t -10- 1z786~
block 82 keepg cen~ral p~sgage ~4 and end 90 o anchor body ~2 free of concrete 86 so that wed~es 34 may be lnsertad into contr~l æ~ction 24 at the appropria~e tlme.
Before stres~;n~, wedge~ 34 are placod in central ~ect~on 32 o~ pA~age ~4. Tendon 1~ i5 then pulled in a known fashion w~th respect ~o the $1xed end to place the ten-don in a stre~ed condition, thereb~ pre-stre~slng the ~lab.
Wed~es 34, acting against the wall o~ the central pa~age of th~ anchor body, hold tho tendon ln ~he ætre~sed condltion.
If the anchor installed in this w~y 18 an lntermedia~e anchor 20', ~ a later time when a subso~uen~ end anchor 20 1 ln~talled ~nd the tendon i~ further qtressed, th~ inter-mediat~ anchor 20' will be rellcved so that w*dges 34 provide le or no holding force with r~spect to an~hor body 22.
Finally, the se~ond end of the lnst~lled ~nchor is ~ealed. For an in~ermedlate ~nchor 20', a second cond~lt 54' at first end portion 56' is threaded in~o portion 74 of reducer 70. Redueer 70 1~ threaded into the outlet gection 28 of ~nchor body 22. ~he second end por~ion 60' o~ ~econd oondult 54' i5 ~Qaled Wi th ~ap~ 58' to cover 52 o~ tendon 18 thereby oompletely encloslnq any re~ion around anehor body 22 ln which coverin~ 52 has been strlpped away. End anehor 20 i~ inst~lled in a ~imilar fA~hion, except plug 62 1~ thre~ded into outlet section 28 ln~te~d o ~educQr 70 ~nd ~econd con-dult 54' to form the ~aal ~or the outlet ~nd.
As a further step ir. the use o~ device~ 2~ and 20', a corro~ion resi~tant ~rea~e may be ~orced throu~h fitting 76 ln devic~ 20' or Çittln~ 68 in devlce ~0 to ~111 the inter-nally enclosed space thereby ~urther protectln~ the unoov~red region of tendon lR. ~ft~r all ~ncho~ have been ~a~l~d, further oement, or ex~mple, concrete 88, m~y or may not be cast ~round the anchor~ ~o encapsulate them ~nd crea~e the deslred a~ade ~or the 61Ab. In any ~e, the ~ealin~ ~e~ha-2786~8 ni~ms protect the ~nchor~ from expo~ure ~nd ~rom w~erleakage, especially salt wat~r le~kage. If the ~nchor~ are not encapsulated, lt 1~ clear thaS the anchor~ wo~ld be expo~d and v~lnerable to det~rior~ion mech~ni~m~. Thls 1 e~pecl~lly ~ignlficant where A construction ~olnt g2 1 formed.
A nu~ber o~ ~lternate embodiment~ or the pre~ent invont~on ~r~ al80 p~sslble. ~ ~hown ln FIGURE 4, ~ fir~t threaded end 96 of a connector 94 i~ threa~ed into ma'cing ~hre~ds in a rece~vlng ~avity for~ed ~t inlet s~ction 26 of anchor body ~. The second end 9B of connector 94 h~s a cyl~ndrlcal in~erior passago 100 into which conduit 102 ~its.
Cond~lt 102 may form ~ frict~on ~ ith pas~ageway loO o~ it m~y be s~lued thereto with an adhe~ive. The ~econd end por-~ion 104 o c~ndult 102 is sealed with res~ect to coverlng 52 on tendon 18 with a heat ~hrlnk tube 106.
Sever~l embodiment~ ~ho~lng different connectlon~
for a condu1t to the inlet section o~ an Anehor body are ~'hown in FIGURES 5-8. In addltion, it is understood that khese varlo~s ~hodimen~s co~ld ~lso be used with re~p~ct to the outlet sectlon, u~u~lly ln conjunctlon w~th a reducer, although not nece~arily ~lnce the v~riouq c~nnector~
discus~ed herolna~ter cou~d al80 functlon a~ reducers slmply by ch~n~lng dimcnsion~ at thG snd ~hlch connects w1~h tho anchor body.
In FIGURE ~, the fir~t end 103 o conn~ctor 110 is inser~ed in ~he rece~v~ng cavi~y 112 of the inlet sec~lon 114 o ~nchor body a2 . ~ gaske~ l16 ~ 8 it~ed between ~irst end 108 of oonduit 110 and the wall of cavlty 112. Gasket 116 compresses to provide a ~eal and f~lction flt between first end 108 and ~he wall o~ c~vlty 112. I~ necessary, an adhe-sive may be used to in~ure the attachment o~ the part~. The second end 118 of connector ll~ connects wlth ~irs~ end por--12- ~Z~8G~8 ~lon 1~0 of oondui~ 122 by receiving ~lr~t end por~ion 120 ax friction fit within the cylln~rlcal passag~ At ~econd end 11~ of oonnector 110. A~ain, lf de~ed, ~n adhe~ive may be u~ed betwecn ~he p~rts.
Ag ~hown ln FI~URE 6, a first end 124 of connecto~
126 1~ in~erted ln recelving cavl~y 128. An o-ring 130 installed be~ween first end 124 ~nd the wall of cav~y 12~
f~ms a ~e~l ~nd also provides for A fric~ion it batween the parts. The se~ond end 132 of ~onnector 126 is sealln~ly ~on-nected ~th ~he fir~t end portlon 134 o condult 136 in fAshlon ~i~ilar to the dovice of FIGUR~ S.
As shown in FIGURE 7, the ~lr~t end 133 of connec-tor 140 is fltted into receiving cavlty 142 and held in place by an adhe~ive layer 144. As ~i~h the other embodiments, the second end 146 o~ conn~ctor 140 is soalingly aonnect~d with condu~t 14~.
As ~hown in PIGURE 8, the r~ceivln~ cavity 150 of inlet sectlon 152 of anchor ~od~ 22F include~ a groovo 1$4 ln the wall o~ ~avity 150. The first end 156 o conn~ctor 15B
fi~s lnto ~avl~y 150 and lnoludes a ringular protru~ion 1~0 ~or m~tin~ with groove 154 thereby providing a ~nap 1t bet-ween connecto~ 158 and anchor body 22. With thi~ em~o~lment, flange 1~2 preforably extends radially outwardly from the ~ody o~ connector 15~ . In this way, if de~ired, adhe~lve 164 ma~ ~e ~plie~ between f~ange 162 and end 166 of anc~or body 2~ to lnsure a ~aal ~nd a ~olid attachment. The seoond end 168 of ~onnec~or 158 is ~ealin~ly connected w~th cond~lt 1?0 in a fashion prevlously described.
A further embodiment and ~thod i6 shown in FIGURES
9-11. With ref~rence to FIGUR~ 11, anchor dovice 20G is similAr to pr~ferred embodiment anchor device 20 prevlo~sly de~cribed except a~ lndicated herein~ter. ~urther~ore, simil~r ele~ent~ ~re de~ignAted by similar numerals except -13- 127 ~ 6~8 the elementg o~ the present em~odimen~ have numeral~ wlth a followlng "G" to di~lngui~h the preB~nt embo~imen~ rom device 20.
Anchor device ~OG includes anchor ~ody 2~G h~ving a centr~l passage 24G through which t~ndon 18~ passes~ T~ndon 18G incl~de~ ~ oorrosion resi~tant coverln~ 52~ exce~ in a r~gion around where anohor dovice ZOG hold~ tendon 18G.
Central passage 24G incl~de~ ~n lnlet ~ection 26~, ~n outlet sec~ion 28G, and ~ central section 30G therebe~ween. Central s~c~ion 30G 1~ formed to ln~lude a conlcal portion for recelving and pr4vlding a se~t ~or wodges 34~. It ~s polnted out that two dlfferent wod~es 34G ~re ~hown in cros~ ~ection in FIG~RE 11. Inl~t and outlet se~tions 26G ~nd 28G have surrounding walls with oute~ flrst ~nd ~econd dlameter~, resp~ctively. The fir~ diameter ~ 8 ~maller ~han the second dlameter so that the wall of inlet section 26G has a a~aller transver~e dim~nsion than the wall o~ outlet seotion 28G. A~
ind~cated hereln~e~ore, it i8 necessary ~or ou~le~ section 28G to be larger thAn inlet section 26G so that wedges 34G
may ~e inserted during the s~ressing of tendon 18G.
A re~ucer member 174 ha~ first and sacond end por-tlons 176 and 178. First end portion 176 threadin~ly mates ~ith outlet ~ectlon 28G of anchor body 22~. Sccond end por-tlon 178 h~s a w~ll with an outer third diameter ~ubstan-~lally ~imilar to the 'f$rs~ dlameter of anchor body 22G.
~ irst and second heat shrink tube~ 180 and 182 pro-vide the seAling machanl~m for anchor devico 2CG. First heat shrink tube 180 ~eals be~ween the wall o~ lnlot seotion 26G
and coverin~ 52G on ten~on 18G. Simil~rly, second heat ~hrlnk ~be ~82 ~eal~ betweon the second end portion 178 o~
reducer 174 and cove~ing 52G. In this rogard, tubes 180 and 182 contrsct the ma~t to fit snguly on covoring 52G of tendon 18G whlle the w~ll o~ ~nlet section 26G and ~econd end por-.
-14- ~Z786~
tion 178 o~ reducer member 174 hold the larger form~tlon of the heat s~rink tubes. Both the wall o~ lnlet ~ction 26G
and the ~11 of ~eeond end portion 178 of red~cer member 174 ln¢lude encirclln~ ringular protrusions 184 and 186 to better retain tube~ 180 and 182 there~o. In thl~ w~y, the 1,ncomp1e~e oovering r~g~on of S~3ndon 18G around where wed~es 34G o~ onchor devlce 20G hold tendon 18G l~ eov~r~d not only b~ ~nchor body 22G and reducer 174, but also by the fi~4~ and 6~cond haat shrink tubes 180 and 182. and, in this way, the ~ntegrlty Q~ the corrosion re~istan~ co~ering mech~nism for tendon 18G is m~lntained.
To use, ~s ~hown in FIGURE 9, tendon 18G 18 p~ssed throu~h fir~ heat shrink tube 180 and the cen~ral p~s6age 24G o~ an¢hor body 22G . Either be~ore or after passing the tendon therethrough, anchor body 22~ ixed ~t a prede~er-mine~ location~ As di~ussed wi~h respect ~o pre~erred embo-diment 20, anchor body 22G i~ fastened wlth nails BOG to a form 84~ w~h ~ block 82G to space the i~ems apa~t. 810~k 82G also prev~nts con~rete from entering outlet sectlon 28G
durlng the concrete ¢a~t~ng ~tep. Tendon 18G also passes throu~h openin~ in block ~2G and formboard 84~ a~ necQ~sary.
In o~der to prepare ~he ~sse~bly for cas~lng She ~oncrete, flr~t h~t ~hrink tube 180 is moved ~o that an ~nd 188 ~l~s around the wall of lnlet section 26G. Heat gun 190 then direct~ heat a~a~nst heat shrink tube 180 as lllustrated in FI~U~E 9. In accord~nce w~th the common ch~racterlstlo of heat shrink tubin~, hea~ ~hrink tube 180 ~hrink6 to ti~htly con~orm ~o the outer ~urface of the ~811 of lnle~ s~ction ~6G
and covering 52G of tendon 18G. In thi~ way, heat shrink t~he 180 forms A seal be~en anchor body 22G and ooverlng ~2G~
Concrete 1~2 ~ then cast ~i~h re~pect to ~nchor body ~2G and tendon 18G on the firR~ sid~ of 1an~e 38~ which lS lzq~6~8 ~aces ~ n the directlon o inlet ~ectlon 26~. Soma concrete 18 AI80 cast on the oth~r ~3ide o~ ~lange 38~3 in th~ reglon b~twoen ~lan~e 38G and block 8~;;, but the lmpor~c~nt re~lt 18 ehat 'che ~eoon~ end 194 o anchor body 22~ is froe frorn concret~ ~o th~ tendon 18G may be readily ~treseea and wedges 345 prop~rl~ in~talled. Wedge~ 34G aro then placed ln the ~onical po~tlon of central ~e~tlon 30~; ~nd tendon 18G i~
pulled in a known manner wl~h re~pe~t ~o a ~ixed end (~ot shown) of the tendon. After stro~s~ng tendon 18G, the wedges ~e forced tlgh~cly ~n~o the conical por~lon o~ c~n~x~l sec-tlon 30G tv hold tendon 1~ in the ~tressed ~onditlon.
For an end anchor~ a plu~ 62 8g previou~ly describ~d could then be ln~talled to seal o~tlet seotion 28G.
Po~ ~n intermedi~te anchor ~ ~hown, red~cer 174 having ten-don 18G pos~ln~ throu~h its centr~l passage, i~ fa~tened to the second end o~ ~nchor hody 22G. A second hea~ shrink tube 182 with tendon 18G pa~sing therethrough 1~ then moved 80 that one end enclrcles second end portlon 17~. ~ea~ ls then flirec~ed A~ainst ~econd heat shrlnk tube 1~2 to caus~ it to shrink and s~a~ second end por~lon 178 with res~ect to ~he coverln~ 5~G o~ tendon 18~.
It is noted ~hat the re~ion whereln covering ~2G
has heen removed ~y be fa~rly long ln order to provld~ ~or convenient grasp~ng and ~ulllng of tendon lSG. ~he length o the uncovered region, d~termlne~ ho~ lon~ the he~t shFink tubes must bo.
In this way, the pre~ent a~paratu~ provlde~
complete eorroslon prote~tlon for a tendon ln ~ pre~tre~ed concrete slab. The ~d~ntages di~u6~ed and the detail~ of ~tructure ~nd functlon set forth, howevor, mu~ be con~iderod exemplar~. ~on~quen'cly, it i~ not~d in summary ~h~t ~hange~
made wlth ~espect to th~ p~eerred embodlment, e6p~cially ln ~tters of ah~pe, ~ize and arrangement, ~o th~ ull extent -16- 127~36~3~
extencled by the ~n~ral meaning of ~che terms lr~ whlch ~he ap~ended cl~ims ~re e~cpres~e~, a~e wi~hin th~ ~rinciple of th~ ~ nven~lon .
PRESTRESSED CONCRETE SLAB
Field of the Invention The present inven~ion is directed to anchor devices for a tendon in a concrete slab and, more particularly, to such a device including mechanism for resisting corrosion in a region around where the anchor device attaches to the tendon.
Backqround of the Invention Anchor devices for holding tendons in a stressed condition in a prestressed concrete slab are known. In ~.S. Patent 3,596,330, a preexisting coating or coverin~ fox a wire tendon is sealed to one end of an anchor by a defcrmable washer which is pressed into a sealing configuration by wedges holding the stressed tendon to the anchor. A plug or cap closes the other end of the anchor. The problem with this device is that it is very difficult to make a precise stripping of the cover on a tendon so that it ends, for example, at the washer. Hence, it is likely difficult to achieve the purpose of the device. In U.S. Patent 3,95~,797, shield elements are shown which fit over one end of the anchor body and extend out over a portion of the tendon. In .S. Patent 4,053,974, a shield member is formed to extend from paper wrapped about the tendon to a tube which is installed during pouring of the concrete around the anchor and a form holding the anchor body. After the concrete hardens, the tube is removed. The shield member remains in place, but its intent is simply to prevent concrete from entering the tube and contacting the exposed cable of the tendon since after the tube is removed, the shield member does not extend to the anchor member. Over the years, this ,.~
~786~98 .
mochani~m wlll not prev~nt corro~ive flulds rom ~eeping through the concret~ and contac~ing ~he exposed cabl~. In U.
S. Patent 4,3~3,462, the space between a ~hield member and thc anchor body i~ filled ~;th a grease or ~ome other corro-~lon pro~ec~lo~ sub~tance.
~ nown device~ do not conslder the needs o~ large pres~r~6~cd sl~b~ whereln both end ancho~ ~nd lntermedi4te anchor~ are require~ and wherein corroslon pr~tect~on ~hould be provided for the exposed oable o~ a tcndon in the re~ions o each o~- the ~ever~l anchors. In thls regard, known Anchors do not show mechan$~m or prov~d~ng a~t, e~flcient ~nd po~i~ive sealin~ connectlon~ at selectively one or both end~ of an anchor.
S~m~rv o~ the Inveneion The present ;nvent~on iR directed to an anchor device ~or holdin~ a tendon ln a ~tressed cond~tion ln a prestresssd conerete slab wherein th~ tendon ha~ a corroslon resist~nt coverlng, ~ut wherein the covering i~ incomplete in a re~ion ~ro~nd where the anchor device is attached to the tendon. The d~vice incl~des wed~es and an anchor bo~y for reoeiving the wedg~. The anchor body has 8 ¢entral pass~ge ~or receiving the tendon. The pa~sage ha~ ~ longi~udlnal centerline. The pas~age furSher hes an lnl~t sectlon, an outlet sec~ion and a central ~c~lon therebetween. The een~ral sectlon includes a eonlcal portion ~or rec~iv~ng ~nd provldin~ a seat for the wedge~. The inlot sectlon has smal~er tran~verse dimension through the longi~udlnal cen-terline than the outlot section. The anchor body further lncludes a mechanlsm for re~i~tin~ longi~udin~l mov~ment w1th re~pect to ~he cemont slab. The anchor dovlce furth~r lnclu-des a fira~ conduit havlng ~ir~t and ~econd end ~ortion~. In ~ddlt~on, the ancho~ d~vi~e ~n~ludes a mech~nlsm or sealingly atta~hlng the fi~st end portion o~ the flr~t con-l27a6~s duit to the inlet section of the anchor body. Theattaching mechanism includes the inlet section having a first threaded portion and the first end portion of the first conduit being threaded to mate with the first threaded portion. Also, the anchor device includes first means for sealing the second end portion of the first conduit to the covering on the tendon to enclose one end of the region wherein the corrosion resistant covering is incomplete. The anchor device still further includes a mechanism for sealingly closing the outlet section of the anchor body with respect to the other end of the re~ion of the tendon wherein the corrosion resistant covering is incomplete. The closing means includes the outlet section having a second threaded portion. The closing means also includes a second conduit like the first conduit and second sealing means like the first sealing means. The closing means further includes a reducer having a first threaded end mating with the second threaded portion of the outlet section of the anchor body and a second threaded end for mating with a first threaded end portion of the second conduit. The reducer has a central passage for receiving the tendon therethrough. The covering of the tendon, the reducer, the second conduit and the second sealing means enclose the other end of the region of said tendon where the corrosion resisting covering is incomplete thereby protecting the entire region from outside corrosive fluids.
In end anchors, the closing mechanism includes a plug. In intermediate anchors, the closing mechanism includes the reducer which decreases the diameter of the outlet section for attachment to the second conduit by connecting with the reducer just like the first conduit which is connected to the other end of the anchor body.
The unattached ends of both conduits are taped, enclosed with a heat shrink tube or otherwise sealed to the covering on the tendon. Thus, the present anchor ~1~7~ 98 apparatus advantageously may be used for both end and intermediate anchor applications.
Of further advantage is that a grease fitting may be installed in the closure plug for an end anchor and in the reducer for an intermediate anchor for the purpose of forcing grease into the conduits and the central passage of the anchor body. Thus, the present apparatus not only provides for enclosing the region around where the anchor grips the tendon, but also provides for filling the enclosed space with a corrosion resistant grease.
In another embodiment, a heat shrink tube provides sealing between the inlet section of the anchor body and the covering on the tendon. In situations where this embodiment may be used, the conduit of the previously discussed embodiment is not necessary. With respect to the outlet section of the anchor body, a plug is used to sealingly close it when the anchor is used as an end anchor. For an intermediate anchor, a reducer is used to reduce the transverse cross section of the outlet section so that a second heat shrink tube may be used to provide a seal between the reducer and the covering on the tendon.
According to another aspect of the invention there is provided an apparatus for holding a tendon in a stressed condition in a prestressed concrete slab wherein the tendon having a corrosion resistant covering, but wherein the covering is incomplete in regions around where attachments of said apparatus are made to the tendon. The apparatus includes a plurality of anchor bodies with a pair of the anchor bodies being attached at opposite ends of the tendon to the tendon. At least one other of the anchor bodies is attached to the tendon intermediate the pair of anchor bodies attached at opposite ends. Each of the anchor bodies has a central passage for receiving the tendon~ The passage has a longitudinal centerline. The passage has an inlet section, an outlet section and a central section therebetween. The central section -4a- 1~ 78 ~8 includes a conical portion. The inlet section has a smaller transverse dimension through the longitudinal centerline than the outlet section. Each of the anchor bodies further includes means for resisting longitudinal movement with respect to the slab.
The apparatus also includes a plurality of sets of wedges, with one set of wedges fitting into each anchor body to seat in the conical portion to hold the tendon with respect to said anchor body. The apparatus further includes a pair of plug members and a mechanism for sealingly attaching a different one of the plug members to each of the o~tlet sections of the anchor bodies at the opposite ends of the tendon. A reducer has a central passage for receiving the tendon and opposite first and second ends. A second sealing mechanism sealingly attaches the first end of the reducer to the outlet section of the intermediate anchor body. A plurality of conduits have first and second end portions, with the first end portion of each of the conduits sealingly connecting with one of said inlet sections of the anchor bodies and the second end of the reducer. Means are provided for sealing the second end portions of the conduits to the covering on the tendon to enclose the regions where the corrosion resistant covering is incomplete.
Consequently, the tendon is anchored at its ends and at a location intermediate the ends and the regions of attachment are enclosed to minimize the possibility of corrosive fluids contacting the tendon at uncovered points.
According to a further aspect of the present invention, there is provided a method for using an anchor device to hold and protect a tendon in a stressed condition in a prestressed concrete slab. The tendon has a fixed end and a corrosion resistant coveriny that is incomplete in a region around where the device is attached ., ~. ' ' ~
-4b- 12786~8 to the tendon. The device includes an anchor body having a central passage for receiving the tendon and a central section for receiving wedges to hold the tendon with respect to the body. The anchor body further has means for resisting longitudinal movement with respect to the slab. The anchor body additionally has a first portion on a first side of the resisting means and a second portion on a second side of the resisting means. The device further includes a conduit having a first and second end portions, a mechanism for sealingly attaching the first end portion to the first portion of the anchor body and a mechanism for sealing the second end portion of the conduit to the covering on the tendon. The device still further includes a mechanism for sealingly closing the central passage at the second portion of the anchor body.
The method comprises the steps of:
(a) attaching with the attaching means the first end portion of the conduit to the first portion of the anchor body, fixing the anchor body at a predetermined location, and passing the tendon through the conduit and the central passage of the anchor body:
(b) sealing the second end portion of the conduit to the covering on the tendon with the sealing means:
(c) casting concrete with respect to the anchor body and the tendon on the first side of the resisting means so that the central passage at the first portion of the anchor body is free of concrete:
(d) placing wedges in the central passage of the anchor body between a wall of the central passage and the tendon and stressing the tendon with respect to the fixed end of the tendon, the wedges holding the tendon in the stressed condition, (e) fitting a reducer to the second portion of the anchor body, the reducer having first and second ends, the first end sealingly attaching to the second portion of d~
-4c-12786~
the anchor body;
(f) fitting a second conduit into the second end of the reducer, the second conduit having first and second end portions with the first end portion sealingly attaching to the second end of the reducer; and (g) sealing the second end portion of the second conduit to the covering on the tendon with the sealing means;
whereby the tendon is held in a stressed condition and sealed against corrosive fluids in the region around where the anchor body with the wedges attaches to the tendon.
These advantages and other objects obtained by the invention are further explained hereinafter and may be better understood by reference to the more detailed description which refers to the drawings briefly described as follows.
Brief Description of the Drawings FIGURE 1 is a cross-sectional view of a concrete slab showing in side view a tendon held by an intermediate anchor and end anchors in accordance with the present invention;
FIGURE 2A, which follows FIGURE 3, is a cross-sectional view of an intermediate anchor as held by a formboard prior to having cement cast with respect to it;
FIGURE 2B is a partial cross-sectional view of an installed intermediate anchor;
FIGURE 3 is a partial cross-sectional view of an end anchor;
Similarly, FIGURES 4-8 are diagrammatic cross-sectional views showing alternative embodiments for plugs closing the outlet section of an anchor device and for mechanisms to seal between the inlet section and the tendon covering; and FIGURES 9-11 are partial cross-sectional views illustrating the use of a heat shrink tube to seal between -4d- ~2786~8 the inlet section of an anchor device and a tendon cove r i ng.
Detailed Descri~tion of the Preferred Embodiment Referring now to the drawings wherein like ref-erence numerals designate identical or corresponding parts -5- lZ786~8 throughou~ the several view~, and ~ore p~rticul~ly to FIGURE
1, an app~ra~us for holding a tendon 18 ln a ~tre~ea con-ditlon ln a pre~t~es~ed concrete slab 1~ 1~ d~ nated generally by ~he numeral 10~ Slab 12 i6 ~hown suppo~d by a plurality of beams 14. A plursllty of ~emperatu~e tendons 16 oxtend transver~ely ~hrough slab 12 with res~e~t to the ~on~ltudinal extenslon of prlmary ~endon 1~. A pair o~
anchor devlce~ 2~ hold tendon 18 at its oppo~ite onds. An intermediate anchor ~evice 20' holds tendon 18 at a locatlon b~twesn ~t~ oppo~lte end~, prefer~bly at a m~dpoint betwe~n ~djaoent anchors an~ ~r a one way ~lab ~ystem preferably near a beam 14. It ls understood that the present lnvent~on applie~ also to ~ two way sla~ sys~em. It 1B further understood that the present apparatu~ is applicable ~or any tendon anchorage, whether ~raped or not.
A~ shown in FIGURE 3, devlce 20 includos Pnchor body 22 hAving a centràl pas~age 24 therethrough~ PassPge 24 is aligned ~long a longitudinal centerline (not 6hown for clarity r~a~on~). Passage ~4 includes an lnlet ~ection 26, an outlet seotion 28 and a cen~ral ~ection 30 in ~he region betwe~n the lnlet and outlet sections 26 and 28~ ~h~ centrPl ~ectlon ha~ a conical portion 32 tor receivin~ and provlding a se~ ~or a ~e~ o~ wedges 34. Inlet section 26 18 in~er-nally threaded with a diam~ter pre~erably at least a8 lPrge as the ~mslle~S diametQr of coni~al port~on 32 to whlch it mPte~. Outlet ~ectlon 28 is al~o intornally thre~d~d.
Outlet sectlon 28 ha a lArger tran~verse d~en~ion when mea~ured throu~h the longi~udlnal centerllno of pa~sa3e 24 than inlet soction 26. With respect to conical portion 32, the d~ameter o outlet section 28 ~8 larger BO that we~ges 34 may be readily in~erted Shrough outlet ~ection 28 lnto cenSral section 24 around ~endon 18.
Anchor body 2Z has an outwardly extendlng, tran~--6- 12~ 8 6~ 8 vers~, flat surface 36 which i~ one side o ~n ou~wardly extendlng flange 38 suppor~ed on the ~lde opposlte ~rfac~ 36 by a plurallty o~ gu~set~ 40. 8urf~ce 36 m~ be located anywhere alon~ the longitudin~l dlmen6ion of body 2~.
Surface 36 is ~hown approxima~ly half way between the end~
of ~ody 22. Surace 36 b~tts against the ~oncrete o~ 81~ 12 to prevent anchor body 2~ rom movlng longi~din~lly wlth re~pect to slab 12 even thoush body 22 is holding ten~on 18 in t~nslon.
The po~ion 42 of body 22 toward inlet end 44 o body ~2 h~ a smaller tran~verse dimens;on than portion 46 extendin~ toward outlc~ end 48 ~rom ~lan~e 38. Portlon 46 must be su~floiently l~rge to provide ~t~ucture ~or the lar~er threaded portlon of outlet section 28, SimLlarly, portlon 42 must be suf~iciently large to provide 6tructure for the smaller threaded portion o~ lnlet ~ection 26.
Tendon 18 i~ ~ommonly a cablo wrapped with a treated paper or covered with a layer of a plastic materlal or 80me othe~ corrosion resistan~ eoverln~ 52. Cov~ring 52 is strippad away ~rom the c~bl~ 50 ln the reglon o~ devlce 20 ~o that ~dge~ 34 can reliably grip cabl~ S0 an~ not glip or p~e3s into any ~oft cov~r$n~ As A resul~, the unoovered re~ion of tendon 18 o~ten extends b~yond anchor body ~2. In the pa~t, such uncovered reqions ware sub~c~ to corro6ive fluids ~eepln~ through the concrete of ~lsb 12. Furthermore, slnce anchors 20 and 20' ~re gen~rally nearer the up~er sur-facQ of sla~ 12 ~han the rest of tendon 18, ~ny seepage by cor~osive fluld oftQn reached the uncovered re~ions be~ore it reached the eovered portion o~ tendon 18. ~n any ease, the present lnvention i~ directad to ~olvlng the pro~lem of pro-tectln~ ~ch uncovered reglons ~rom corrosive flu~d~.
A conduit 54 ~s threaded at a fir~t en~ portion 5~
~o mate with the thrc~dad portion of ln~ et sectlon ~6 of --'- lZ786~8 anchor body 22. Tape 5~ or o~her ~eallng me~hanl8m iS
~astened betw~en ~he seeond end portion 60 of conduit 54 and covering 52 of tendon 18.
A clo~ure plug fi2 ~eals passage 24 a~ o~tlet end 48 of anchor body 22. Plug 62 lncludes a threaded end 64 fo~
ma~ing wi~h the threaded portion o~ outlet ~ectlon 28. The othe~ end of plug 62 iB prefera~ly square or hexlgon~l 80 that it may b~ easlly en~3ged with ~ co~mon wrench. A
fittlng 68 ls installed ln the end of plug 62 so that a com-mon ~re~se ~un ~ay ~e used to foree gre~e throu~h flttin~ 68 ~nto p~s~a~e ~4 of anchor body 22 and lnto conduit 54.
Although the enclose~ Bpace bounded by pa~ age 24 ln anchor body ~2, cond~it ~4, tape 58 and plu~ 62 adequately encloses the reglon of tendon 18 having ~n lncomplete covering, n~verthe les~, a corrosion re~i~tant grea~e advantageousl~
prov~des a second mechanism or minimlzing any tendon weakonin~ due to corrosion. In ~ddition, it ls noted that the enelosed space encloses the vol~til~ gase~ vaporizlng rom the ~rease and helps to kee~ ~he vapor pressure hlgh ~nd prevent the ~rea~o ~rom b~eaklng down.
It is ~urther noted ~hat it i~ desirablo to use a seal~nt between the thre4ds o~ plug G~ And the threads o section 28~ ~s ~ell as between ~he thre~ds of condui~ 54 ~nd She threads of inle~ tion 26.
D~vice 20' has the same anchor ~ody 22 os ~evice 20 ~urthermore, device ~0' lncludes a ~et Of wedge~ 34 and h~
cond~it 54 with ~ape 60 for ~ealing one end of the uncovered reglon of tendon 1~ in the vicin1ty of devlce 20'. ~ather than ~ plug 62, howevQr ~ a reducer 70 f its into the outlet section 28 of anehor body 22 of device 20 ' . Reducer 70 has an outer threaded port~ on 72 extending to one end for mating wlth the ~hre~ded portion of outlet sectlon 28. ~educer 70, ln addi~ion, ha3 an inner threaded portlon 74 extending to -8~ 78~
~he other end for recelving ~he ~irst threaded end portlon 56' of a ~e~ond condult ~4~ whl~h 18 ex~ctly ~he s~me a~
~irst conduit 54. Anchor body 22 ;B, thus, advantageoU~ly do~L~ned ~o th~t outlet ~e~tion 2~ may be u~e~ wl~h a reduoer 70 to decrea~e tho dlame~er of the ~hrea~ed ~ort~on ln order ro~eive a ~econd conduit just llke the flrst oondult theroby sealln~ both ends of body 22 ln a ~lmil~r ~hlon.
In this regard, tape 60' seals betwoen Becond end portlon 58' o~ conduit 5~ and coverlng ~2 o~ tendon 18.
A fitting 76 i~ installed in reducer 70 ~o provi~e ~ mechani~m for in~ertln~ ~orrosion re~lstant ~e~e ~n~o the enclosed ~pa~ ~en~rally for~d within body 22, ~ondults 54 ~nd 54', ~nd reducer 70.
In u5e~ ~ tendo~ 18 may be installed durlng the ~n~tial cons~ruction o~ a ce~ent ~la~ 12 or ~nder ~ome cir cumstano0~, a new tendon 18 may replaoe a prevlously removed tendon ln an exl~ting cement ~l~b. In ~ny case, the end anchore 20 and intermedi~e anchors 20' must be located and flxed wi~h respect to tho slab 12 or the BpACe to be occupied by the slab 12. Many ti~es, no intermedia~e anohors ~re needed. On the other hand, th~re are many ~imos when one or ~ore inter~edl~te an~hors 20' are neoded~ In either ca~e, the op~osite end o~ ~endon 18 with respeot to the anchor which 1~ belng inst~lled i~ ~lxed. Gener~lly, such oppo~ite Qnd i~ ~lxed wi~h an end an~hor 20. g~ch opposite end anchor is positioned on ~ orm known to those ~o skilled. Be~ore or after fixing the end ancho~ in po~ltlon, a first ~ondult 54 8 ~hread~d ~o lt and tendon 18 ~s passed through ~he anchor ~ody ~2 ~n~ held by wedge~ 34~
With respect to instAllin~ the lntermedlAte ~nchor 20' or the second end anchor 20, #imilarly, ei~he~ before or a~ter ~ix~ng the anchor body 22 at a pr~de~ermined locatlon, ths flrst threaded end po~tion o~ fir~t condult ~4 ls .
.7~36~38 threaded into the fl~t ~h~ead~d portion of lnlet ~ection 26 o~ anchor ~ody 22. ~n ~he case of an 0%iBtln9 ~lab, ~he ten-don 1~ i8 pasged through the various anehor bodies, reducOEr~, and conduits whlle they are belng located and fixed in pl~ce.
In the case o~ new con~ruction, a tendon 18 may ~e pa~sed throu~h the appropriat~ ~lr~ cond~it 59 and the central p~a~e o~ the anchor ~ody 22 of the anchor to be ~n~talled afte~ the onchor has been positionally fixed. Th~ secon~ end portion o~ fir6t condult 54 is ~hen se~led with ~po 58 to covering 52 of tendon 18. To illu~r~te, in FIG~RE 2A, ~n intermediate anohor ~0' is shown ixed in pl~ce relative to ~orm prior ~o oa~tlng concre~e. Nalls 80 are pa~sed throu~h openings in flange 38 and extend through a block 82, for example Styrofoam, to en~age form B~, likely ~ wooden pl~nk.
Cond~it 54 i~ ~ttached ~t first end portion 56 to portion 42 of ~nohor body 22. The second end port~on 60 of c~nduit 54 ls sealed wlth tape 58 to coverlng 52 on tendon 18. Tendon 18 extends through conduit 54 ~nd the central paS~Age 24 of anchor body 22, a~ well ~5 through block 82 and form 84.
Nex~ concrete 8~ ~see FIGURE 28) is cas~ in the sp~ce between the fixed end and the anchor to be lnstalled.
In the case of ~ tendon replaced in an existiny slab, cone~ete i~ c~ hround the tendon to flll ln the ~lab wherever portion~ wQre ramoved. Only the outward end3 of the facing Anchors ~re not covered with concrete ln order ~o pro-vlde ~or subsequent tendon stres~ing. In the case o new construc~lon, concrete 1~ ca~t ln the space in which the slab i~ to ~e created and between the forms holdin~ the anchors.
A~ shown ~n ~ RE ~B, con~rete 88 at this poin~ in the pro-cess would not be pre~ent ~lnce lt would be Ca~ during a ~ubseq~ent iter~tion o th~ process ~hen anehor ~ody 20' a~
s~own in FIGUR~ 2~ fun~tion~ a~ ~ fixed anchor at one end of a new portLon o~ l~b ~o be in~t~lled. It is ole~ th~t -10- 1z786~
block 82 keepg cen~ral p~sgage ~4 and end 90 o anchor body ~2 free of concrete 86 so that wed~es 34 may be lnsertad into contr~l æ~ction 24 at the appropria~e tlme.
Before stres~;n~, wedge~ 34 are placod in central ~ect~on 32 o~ pA~age ~4. Tendon 1~ i5 then pulled in a known fashion w~th respect ~o the $1xed end to place the ten-don in a stre~ed condition, thereb~ pre-stre~slng the ~lab.
Wed~es 34, acting against the wall o~ the central pa~age of th~ anchor body, hold tho tendon ln ~he ætre~sed condltion.
If the anchor installed in this w~y 18 an lntermedia~e anchor 20', ~ a later time when a subso~uen~ end anchor 20 1 ln~talled ~nd the tendon i~ further qtressed, th~ inter-mediat~ anchor 20' will be rellcved so that w*dges 34 provide le or no holding force with r~spect to an~hor body 22.
Finally, the se~ond end of the lnst~lled ~nchor is ~ealed. For an in~ermedlate ~nchor 20', a second cond~lt 54' at first end portion 56' is threaded in~o portion 74 of reducer 70. Redueer 70 1~ threaded into the outlet gection 28 of ~nchor body 22. ~he second end por~ion 60' o~ ~econd oondult 54' i5 ~Qaled Wi th ~ap~ 58' to cover 52 o~ tendon 18 thereby oompletely encloslnq any re~ion around anehor body 22 ln which coverin~ 52 has been strlpped away. End anehor 20 i~ inst~lled in a ~imilar fA~hion, except plug 62 1~ thre~ded into outlet section 28 ln~te~d o ~educQr 70 ~nd ~econd con-dult 54' to form the ~aal ~or the outlet ~nd.
As a further step ir. the use o~ device~ 2~ and 20', a corro~ion resi~tant ~rea~e may be ~orced throu~h fitting 76 ln devic~ 20' or Çittln~ 68 in devlce ~0 to ~111 the inter-nally enclosed space thereby ~urther protectln~ the unoov~red region of tendon lR. ~ft~r all ~ncho~ have been ~a~l~d, further oement, or ex~mple, concrete 88, m~y or may not be cast ~round the anchor~ ~o encapsulate them ~nd crea~e the deslred a~ade ~or the 61Ab. In any ~e, the ~ealin~ ~e~ha-2786~8 ni~ms protect the ~nchor~ from expo~ure ~nd ~rom w~erleakage, especially salt wat~r le~kage. If the ~nchor~ are not encapsulated, lt 1~ clear thaS the anchor~ wo~ld be expo~d and v~lnerable to det~rior~ion mech~ni~m~. Thls 1 e~pecl~lly ~ignlficant where A construction ~olnt g2 1 formed.
A nu~ber o~ ~lternate embodiment~ or the pre~ent invont~on ~r~ al80 p~sslble. ~ ~hown ln FIGURE 4, ~ fir~t threaded end 96 of a connector 94 i~ threa~ed into ma'cing ~hre~ds in a rece~vlng ~avity for~ed ~t inlet s~ction 26 of anchor body ~. The second end 9B of connector 94 h~s a cyl~ndrlcal in~erior passago 100 into which conduit 102 ~its.
Cond~lt 102 may form ~ frict~on ~ ith pas~ageway loO o~ it m~y be s~lued thereto with an adhe~ive. The ~econd end por-~ion 104 o c~ndult 102 is sealed with res~ect to coverlng 52 on tendon 18 with a heat ~hrlnk tube 106.
Sever~l embodiment~ ~ho~lng different connectlon~
for a condu1t to the inlet section o~ an Anehor body are ~'hown in FIGURES 5-8. In addltion, it is understood that khese varlo~s ~hodimen~s co~ld ~lso be used with re~p~ct to the outlet sectlon, u~u~lly ln conjunctlon w~th a reducer, although not nece~arily ~lnce the v~riouq c~nnector~
discus~ed herolna~ter cou~d al80 functlon a~ reducers slmply by ch~n~lng dimcnsion~ at thG snd ~hlch connects w1~h tho anchor body.
In FIGURE ~, the fir~t end 103 o conn~ctor 110 is inser~ed in ~he rece~v~ng cavi~y 112 of the inlet sec~lon 114 o ~nchor body a2 . ~ gaske~ l16 ~ 8 it~ed between ~irst end 108 of oonduit 110 and the wall of cavlty 112. Gasket 116 compresses to provide a ~eal and f~lction flt between first end 108 and ~he wall o~ c~vlty 112. I~ necessary, an adhe-sive may be used to in~ure the attachment o~ the part~. The second end 118 of connector ll~ connects wlth ~irs~ end por--12- ~Z~8G~8 ~lon 1~0 of oondui~ 122 by receiving ~lr~t end por~ion 120 ax friction fit within the cylln~rlcal passag~ At ~econd end 11~ of oonnector 110. A~ain, lf de~ed, ~n adhe~ive may be u~ed betwecn ~he p~rts.
Ag ~hown ln FI~URE 6, a first end 124 of connecto~
126 1~ in~erted ln recelving cavl~y 128. An o-ring 130 installed be~ween first end 124 ~nd the wall of cav~y 12~
f~ms a ~e~l ~nd also provides for A fric~ion it batween the parts. The se~ond end 132 of ~onnector 126 is sealln~ly ~on-nected ~th ~he fir~t end portlon 134 o condult 136 in fAshlon ~i~ilar to the dovice of FIGUR~ S.
As shown in FIGURE 7, the ~lr~t end 133 of connec-tor 140 is fltted into receiving cavlty 142 and held in place by an adhe~ive layer 144. As ~i~h the other embodiments, the second end 146 o~ conn~ctor 140 is soalingly aonnect~d with condu~t 14~.
As ~hown in PIGURE 8, the r~ceivln~ cavity 150 of inlet sectlon 152 of anchor ~od~ 22F include~ a groovo 1$4 ln the wall o~ ~avity 150. The first end 156 o conn~ctor 15B
fi~s lnto ~avl~y 150 and lnoludes a ringular protru~ion 1~0 ~or m~tin~ with groove 154 thereby providing a ~nap 1t bet-ween connecto~ 158 and anchor body 22. With thi~ em~o~lment, flange 1~2 preforably extends radially outwardly from the ~ody o~ connector 15~ . In this way, if de~ired, adhe~lve 164 ma~ ~e ~plie~ between f~ange 162 and end 166 of anc~or body 2~ to lnsure a ~aal ~nd a ~olid attachment. The seoond end 168 of ~onnec~or 158 is ~ealin~ly connected w~th cond~lt 1?0 in a fashion prevlously described.
A further embodiment and ~thod i6 shown in FIGURES
9-11. With ref~rence to FIGUR~ 11, anchor dovice 20G is similAr to pr~ferred embodiment anchor device 20 prevlo~sly de~cribed except a~ lndicated herein~ter. ~urther~ore, simil~r ele~ent~ ~re de~ignAted by similar numerals except -13- 127 ~ 6~8 the elementg o~ the present em~odimen~ have numeral~ wlth a followlng "G" to di~lngui~h the preB~nt embo~imen~ rom device 20.
Anchor device ~OG includes anchor ~ody 2~G h~ving a centr~l passage 24G through which t~ndon 18~ passes~ T~ndon 18G incl~de~ ~ oorrosion resi~tant coverln~ 52~ exce~ in a r~gion around where anohor dovice ZOG hold~ tendon 18G.
Central passage 24G incl~de~ ~n lnlet ~ection 26~, ~n outlet sec~ion 28G, and ~ central section 30G therebe~ween. Central s~c~ion 30G 1~ formed to ln~lude a conlcal portion for recelving and pr4vlding a se~t ~or wodges 34~. It ~s polnted out that two dlfferent wod~es 34G ~re ~hown in cros~ ~ection in FIG~RE 11. Inl~t and outlet se~tions 26G ~nd 28G have surrounding walls with oute~ flrst ~nd ~econd dlameter~, resp~ctively. The fir~ diameter ~ 8 ~maller ~han the second dlameter so that the wall of inlet section 26G has a a~aller transver~e dim~nsion than the wall o~ outlet seotion 28G. A~
ind~cated hereln~e~ore, it i8 necessary ~or ou~le~ section 28G to be larger thAn inlet section 26G so that wedges 34G
may ~e inserted during the s~ressing of tendon 18G.
A re~ucer member 174 ha~ first and sacond end por-tlons 176 and 178. First end portion 176 threadin~ly mates ~ith outlet ~ectlon 28G of anchor body 22~. Sccond end por-tlon 178 h~s a w~ll with an outer third diameter ~ubstan-~lally ~imilar to the 'f$rs~ dlameter of anchor body 22G.
~ irst and second heat shrink tube~ 180 and 182 pro-vide the seAling machanl~m for anchor devico 2CG. First heat shrink tube 180 ~eals be~ween the wall o~ lnlot seotion 26G
and coverin~ 52G on ten~on 18G. Simil~rly, second heat ~hrlnk ~be ~82 ~eal~ betweon the second end portion 178 o~
reducer 174 and cove~ing 52G. In this rogard, tubes 180 and 182 contrsct the ma~t to fit snguly on covoring 52G of tendon 18G whlle the w~ll o~ ~nlet section 26G and ~econd end por-.
-14- ~Z786~
tion 178 o~ reducer member 174 hold the larger form~tlon of the heat s~rink tubes. Both the wall o~ lnlet ~ction 26G
and the ~11 of ~eeond end portion 178 of red~cer member 174 ln¢lude encirclln~ ringular protrusions 184 and 186 to better retain tube~ 180 and 182 there~o. In thl~ w~y, the 1,ncomp1e~e oovering r~g~on of S~3ndon 18G around where wed~es 34G o~ onchor devlce 20G hold tendon 18G l~ eov~r~d not only b~ ~nchor body 22G and reducer 174, but also by the fi~4~ and 6~cond haat shrink tubes 180 and 182. and, in this way, the ~ntegrlty Q~ the corrosion re~istan~ co~ering mech~nism for tendon 18G is m~lntained.
To use, ~s ~hown in FIGURE 9, tendon 18G 18 p~ssed throu~h fir~ heat shrink tube 180 and the cen~ral p~s6age 24G o~ an¢hor body 22G . Either be~ore or after passing the tendon therethrough, anchor body 22~ ixed ~t a prede~er-mine~ location~ As di~ussed wi~h respect ~o pre~erred embo-diment 20, anchor body 22G i~ fastened wlth nails BOG to a form 84~ w~h ~ block 82G to space the i~ems apa~t. 810~k 82G also prev~nts con~rete from entering outlet sectlon 28G
durlng the concrete ¢a~t~ng ~tep. Tendon 18G also passes throu~h openin~ in block ~2G and formboard 84~ a~ necQ~sary.
In o~der to prepare ~he ~sse~bly for cas~lng She ~oncrete, flr~t h~t ~hrink tube 180 is moved ~o that an ~nd 188 ~l~s around the wall of lnlet section 26G. Heat gun 190 then direct~ heat a~a~nst heat shrink tube 180 as lllustrated in FI~U~E 9. In accord~nce w~th the common ch~racterlstlo of heat shrink tubin~, hea~ ~hrink tube 180 ~hrink6 to ti~htly con~orm ~o the outer ~urface of the ~811 of lnle~ s~ction ~6G
and covering 52G of tendon 18G. In thi~ way, heat shrink t~he 180 forms A seal be~en anchor body 22G and ooverlng ~2G~
Concrete 1~2 ~ then cast ~i~h re~pect to ~nchor body ~2G and tendon 18G on the firR~ sid~ of 1an~e 38~ which lS lzq~6~8 ~aces ~ n the directlon o inlet ~ectlon 26~. Soma concrete 18 AI80 cast on the oth~r ~3ide o~ ~lange 38~3 in th~ reglon b~twoen ~lan~e 38G and block 8~;;, but the lmpor~c~nt re~lt 18 ehat 'che ~eoon~ end 194 o anchor body 22~ is froe frorn concret~ ~o th~ tendon 18G may be readily ~treseea and wedges 345 prop~rl~ in~talled. Wedge~ 34G aro then placed ln the ~onical po~tlon of central ~e~tlon 30~; ~nd tendon 18G i~
pulled in a known manner wl~h re~pe~t ~o a ~ixed end (~ot shown) of the tendon. After stro~s~ng tendon 18G, the wedges ~e forced tlgh~cly ~n~o the conical por~lon o~ c~n~x~l sec-tlon 30G tv hold tendon 1~ in the ~tressed ~onditlon.
For an end anchor~ a plu~ 62 8g previou~ly describ~d could then be ln~talled to seal o~tlet seotion 28G.
Po~ ~n intermedi~te anchor ~ ~hown, red~cer 174 having ten-don 18G pos~ln~ throu~h its centr~l passage, i~ fa~tened to the second end o~ ~nchor hody 22G. A second hea~ shrink tube 182 with tendon 18G pa~sing therethrough 1~ then moved 80 that one end enclrcles second end portlon 17~. ~ea~ ls then flirec~ed A~ainst ~econd heat shrlnk tube 1~2 to caus~ it to shrink and s~a~ second end por~lon 178 with res~ect to ~he coverln~ 5~G o~ tendon 18~.
It is noted ~hat the re~ion whereln covering ~2G
has heen removed ~y be fa~rly long ln order to provld~ ~or convenient grasp~ng and ~ulllng of tendon lSG. ~he length o the uncovered region, d~termlne~ ho~ lon~ the he~t shFink tubes must bo.
In this way, the pre~ent a~paratu~ provlde~
complete eorroslon prote~tlon for a tendon ln ~ pre~tre~ed concrete slab. The ~d~ntages di~u6~ed and the detail~ of ~tructure ~nd functlon set forth, howevor, mu~ be con~iderod exemplar~. ~on~quen'cly, it i~ not~d in summary ~h~t ~hange~
made wlth ~espect to th~ p~eerred embodlment, e6p~cially ln ~tters of ah~pe, ~ize and arrangement, ~o th~ ull extent -16- 127~36~3~
extencled by the ~n~ral meaning of ~che terms lr~ whlch ~he ap~ended cl~ims ~re e~cpres~e~, a~e wi~hin th~ ~rinciple of th~ ~ nven~lon .
Claims (3)
1. A device for holding a tendon in a stressed condition in a prestressed concrete slab, said tendon having a corrosion resistant covering, said covering being incomplete in a region around where said device holds said tendon, said device comprising:
wedges;
an anchor body having a central passage for receiving said tendon, said passage having a longitudinal centerline, said passage having an inlet section, an outlet section and a central section therebetween, said central section including a conical portion for receiving and providing a seat for said wedges, said inlet section having a smaller transverse dimension through the longitudinal centerline than said outlet section, said body further including means for resisting longitudinal movement with respect to said slab;
a first conduit having first and second end portions;
means for sealingly attaching said first end portion of said first conduit to said inlet section of said anchor body, said attaching means including said inlet section having a first threaded portion and said first end portion of said first conduit being threaded to mate with said first threaded portion;
first means for sealing said second end portion of said first conduit to said covering on said tendon to enclose one end of said region where said corrosion resistant covering is incomplete; and means for sealingly closing said outlet section of said anchor body with respect to the other end of said region of said tendon where said corrosion resistant covering is incomplete, said closing means including said outlet section having a second threaded portion, said closing means also including a second conduit like said first conduit and second sealing means like said first sealing means, said closing means further including a reducer having a first threaded end mating with said second threaded portion of the outlet section of said anchor body and a second threaded end for mating with a first threaded end portion of said second conduit, said reducer having a central passage for receiving said tendon therethrough, said covering of said tendon, said reducer, said second conduit and said second sealing means enclosing said other end of said region of said tendon where said corrosion resisting covering is incomplete thereby protecting said entire region from outside corrosive fluids.
wedges;
an anchor body having a central passage for receiving said tendon, said passage having a longitudinal centerline, said passage having an inlet section, an outlet section and a central section therebetween, said central section including a conical portion for receiving and providing a seat for said wedges, said inlet section having a smaller transverse dimension through the longitudinal centerline than said outlet section, said body further including means for resisting longitudinal movement with respect to said slab;
a first conduit having first and second end portions;
means for sealingly attaching said first end portion of said first conduit to said inlet section of said anchor body, said attaching means including said inlet section having a first threaded portion and said first end portion of said first conduit being threaded to mate with said first threaded portion;
first means for sealing said second end portion of said first conduit to said covering on said tendon to enclose one end of said region where said corrosion resistant covering is incomplete; and means for sealingly closing said outlet section of said anchor body with respect to the other end of said region of said tendon where said corrosion resistant covering is incomplete, said closing means including said outlet section having a second threaded portion, said closing means also including a second conduit like said first conduit and second sealing means like said first sealing means, said closing means further including a reducer having a first threaded end mating with said second threaded portion of the outlet section of said anchor body and a second threaded end for mating with a first threaded end portion of said second conduit, said reducer having a central passage for receiving said tendon therethrough, said covering of said tendon, said reducer, said second conduit and said second sealing means enclosing said other end of said region of said tendon where said corrosion resisting covering is incomplete thereby protecting said entire region from outside corrosive fluids.
2. An apparatus for holding a tendon in a stressed condition in a prestressed concrete slab, said tendon having a corrosion resistant covering, said covering being incomplete in regions around where attachments of said apparatus are made to said tendon, said apparatus comprising;
a plurality of anchor bodies, a pair of said anchor bodies being attached at opposite ends of said tendon to said tendon, at least one other of said anchor bodies being attached to said tendon intermediate said pair of anchor bodies attached at opposite ends, each of said anchor bodies having a central passage for receiving such tendon, said passage having a longitudinal centerline, said passage having an inlet section, an outlet section and a central section therebetween, said central section including a conical portion, said inlet section having a smaller transverse dimension through the longitudinal centerline than said outlet section, each of said anchor bodies further including means for resisting longitudinal movement with respect to said slab;
a plurality of sets of wedges, one set of wedges fitting into each anchor body to seat in said conical portion to hold said tendon with respect to said anchor body;
a pair of plug members;
first means for sealingly attaching a different one of said plug members to each of said outlet sections of said anchor bodies at the opposite ends of said tendon;
a reducer having a central passage for receiving said tendon and opposite first and second ends;
second means for sealingly attaching the first end of said reducer to the outlet section of said at least one intermediate anchor body;
a plurality of conduits having first and second end portions, said first end portion of each of said conduits sealingly connecting with one of said inlet sections of said anchor bodies and said second end of said reducer; and means for sealing said second end portions of said conduits to said covering on said tendon to enclose said regions where said corrosion resistant covering is incomplete;
whereby said tendon is anchored at ends and at a location intermediate said ends and the regions of attachment are enclosed to minimize the possibility of corrosive fluids contacting said tendon at uncovered points.
a plurality of anchor bodies, a pair of said anchor bodies being attached at opposite ends of said tendon to said tendon, at least one other of said anchor bodies being attached to said tendon intermediate said pair of anchor bodies attached at opposite ends, each of said anchor bodies having a central passage for receiving such tendon, said passage having a longitudinal centerline, said passage having an inlet section, an outlet section and a central section therebetween, said central section including a conical portion, said inlet section having a smaller transverse dimension through the longitudinal centerline than said outlet section, each of said anchor bodies further including means for resisting longitudinal movement with respect to said slab;
a plurality of sets of wedges, one set of wedges fitting into each anchor body to seat in said conical portion to hold said tendon with respect to said anchor body;
a pair of plug members;
first means for sealingly attaching a different one of said plug members to each of said outlet sections of said anchor bodies at the opposite ends of said tendon;
a reducer having a central passage for receiving said tendon and opposite first and second ends;
second means for sealingly attaching the first end of said reducer to the outlet section of said at least one intermediate anchor body;
a plurality of conduits having first and second end portions, said first end portion of each of said conduits sealingly connecting with one of said inlet sections of said anchor bodies and said second end of said reducer; and means for sealing said second end portions of said conduits to said covering on said tendon to enclose said regions where said corrosion resistant covering is incomplete;
whereby said tendon is anchored at ends and at a location intermediate said ends and the regions of attachment are enclosed to minimize the possibility of corrosive fluids contacting said tendon at uncovered points.
3. A method for using an anchor device to hold and protect a tendon in a stressed condition in a prestressed concrete slab, said tendon having a fixed end, said tendon having a corrosion resistant covering, said covering being incomplete in a region around where said device is attached to said tendon, said device including an anchor body having a central passage for receiving said tendon and a central section for receiving wedges to hold said tendon with respect to said body, said anchor body further having means for resisting longitudinal movement with respect to said slab, said anchor body additionally having a first portion on a first side of said resisting means and a second portion on a second side of said resisting means, said device further including a conduit having first and second end portions and means for sealingly attaching said first end portion to said first portion of said anchor body, said device also including means for sealing said second end portion of said conduit to said covering on said tendon, said device still further including means for sealingly closing said central passage at said second portion of said anchor body, said method comprising the steps of:
(a) attaching with said attaching means the first end portion of said conduit to said first portion of said anchor body, fixing said anchor body at a predetermined location, and passing said tendon through said conduit and the central passage of said anchor body;
(b) sealing the second end portion of said conduit to said covering on said tendon with said sealing means;
(c) casting concrete with respect to said anchor body and said tendon on said first side of said resisting means so that said central passage at said first portion of said anchor body is free of concrete;
(d) placing wedges in said central passage of said anchor body between a wall of said central passage and said tendon and stressing said tendon with respect to said fixed end of said tendon, said wedges holding said tendon in the stressed condition; and (e) fitting a reducer to the second portion of said anchor body, said reducer having first and second ends, said first end sealingly attaching to said second portion of said anchor body;
(f) fitting a second conduit into said second end of said reducer, said second conduit having first and second end portions with said first end portion sealingly attaching to said second end of said reducer;
and (g) sealing the second end portion of said second conduit to said covering on said tendon with said sealing means;
whereby said tendon is held in a stressed condition and sealed against corrosive fluids in said region around where said anchor body with said wedges attaches to said tendon.
(a) attaching with said attaching means the first end portion of said conduit to said first portion of said anchor body, fixing said anchor body at a predetermined location, and passing said tendon through said conduit and the central passage of said anchor body;
(b) sealing the second end portion of said conduit to said covering on said tendon with said sealing means;
(c) casting concrete with respect to said anchor body and said tendon on said first side of said resisting means so that said central passage at said first portion of said anchor body is free of concrete;
(d) placing wedges in said central passage of said anchor body between a wall of said central passage and said tendon and stressing said tendon with respect to said fixed end of said tendon, said wedges holding said tendon in the stressed condition; and (e) fitting a reducer to the second portion of said anchor body, said reducer having first and second ends, said first end sealingly attaching to said second portion of said anchor body;
(f) fitting a second conduit into said second end of said reducer, said second conduit having first and second end portions with said first end portion sealingly attaching to said second end of said reducer;
and (g) sealing the second end portion of said second conduit to said covering on said tendon with said sealing means;
whereby said tendon is held in a stressed condition and sealed against corrosive fluids in said region around where said anchor body with said wedges attaches to said tendon.
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US78533385A | 1985-10-07 | 1985-10-07 | |
| US785,333 | 1985-10-07 | ||
| US87065486A | 1986-05-30 | 1986-05-30 | |
| US870,654 | 1986-05-30 | ||
| US06/916,151 US4799307A (en) | 1986-05-30 | 1986-10-07 | Anchor apparatus for a tendon in prestressed concrete slab |
| US916,151 | 1986-10-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1278698C true CA1278698C (en) | 1991-01-08 |
Family
ID=27419825
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000520018A Expired - Fee Related CA1278698C (en) | 1985-10-07 | 1986-10-07 | Anchor apparatus for a tendon in prestressed concrete slab |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1278698C (en) |
-
1986
- 1986-10-07 CA CA000520018A patent/CA1278698C/en not_active Expired - Fee Related
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| JPS5926766Y2 (en) | Temporary oil stop device for OF cable | |
| SU1379852A1 (en) | Sealed inlet |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |