US2608141A

US2608141A - Load transfer device for concrete pavements

Info

Publication number: US2608141A
Application number: US744242A
Authority: US
Inventors: James H Jacobson
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-04-26
Filing date: 1947-04-26
Publication date: 1952-08-26
Anticipated expiration: 1969-08-26

Description

Aug. 2%, 1952 JACQBSQN' 2,608,141

LOAD TRANSFER DEVICE FOR CONCRETE PAVEMENTS Filed April 26, 1947 2 SHEETS-SHEET l 1952 J. H. JACOBSON 2,603,141

LOAD TRANSFER DEVICE FOR CONCRETE PAVEMENTS Filed April 26, 1947 2 SHEETSSHEET 2 Patented Aug. 2.6, 1952 V 2,60s, 14'i LOADATRANSFER DEVICE oaooNoitE'rE PAVEMENTS James Hi Jacobson; Chi'cagoJll; AppIicationApriI-QG, 1947 -Serial-No;:7 4el,242

8 Claims.

This invention relates 'to' improvements in Portland cement concrete pavement construction and relates particularly to: improvements in devices for transferring loads across a joint separating adjacent-pavement panels. e

In, modern concrete pavement construction it is, the practice toprovide at regularly spaced intervals meansfor permitting contraction or expension. of the-pavement slabs, and the presence of such separatorsqor spacer. members-between the adjacent slabs requires the useof means for transmitting loads on .one. pavement panel into an adjacent pavementpanel across such. a joint, to :the. end that such loads may. beproperly dis.- tributed across such. a joint :and that .the 'pave ment slabs will not be misaligned vertically:

In the past it has beenthepractice to employ round-dowels made of hot rolled steel, thedowels extending across the joint and beingibondedin onepavement panel andfree of bond-inthe adjacent pavementpanel, a capbeing provided at the endofthe unbondedportion of the dowels; to provide for expansion of the concreteslab; More recent practice has been to encircle such dowelswi-th a sleeve or other means to'diminish the bearingstresses-on the concrete-caused by the load transferred by-the dowels; particularly at-the vertical-facesof the concrete adjacent the joint.-

An object-of the present invention is to provide for concrete pavement construction a load transfer device which' is made oitwo co-operating similar and symmetrical complementary members or portions; each ofwhich is positioned in the concrete mass on each side of a joint 'or spacer member, the two complementary mem-' bers or portions interlocking with each other and being in mutual bearing, each" of the comple'-' mentary-members or portions preferably havingan arm-which is struck backinto the concrete mass to anchor each portion of the load transfer device firmly into thec'oncrete.

' A yet-further object is to provide a load transfer device which isunusually-rigid and whichcomprises a pair of co-operating-.. symmetrical complementary members or portions, each mem- Another. object is to providea load transfer deyicewhich is formed of two symmetrical. com.-. plem'entary members or portions which write 2 manufactured by forging, punching; or'cas' Other objects ofthe'invention, will be apfi fro'm' 'a 'study'of the de'scription'hereinaftei"taken together with the .drawingsin which: I Figure" 1 is "a side elevation viewo'f afload transfer device according to the present inven? tionj'showing' the device positioned in a concrete slab'which is shown in secti'c'inj Figure 2' is a section taken. along theIIin sQ- -Z ofFigure 1:"

Figure s is a sec"tion"taken "along 'the' lines 3 -3 ofFigure l';' e i Figure 4 is an end view of thefload transfer 'dej vice shown in Figure 1; i Figure'5 is an isometric View showing in detail how the co-ope'rating Symmetric l'commementary members "or 'portions "of the load transfer device of Figure 1 are fitted together; and I I Figure 6 isan elevation view of anotheriorm of theinvention. Referring now'to Figures' l to'5, th'eload t'ra i fer device according to the present. invention is indicated generallypy' the ordinal ID, and is shown in"'conj'unction with a spacermmterlz whichsep'aratestwo adjacent con iete' paiasm and Hit The spacer member 12 maybeprot ectd alon'g' 'its' upper edge 'by means, of ta 'U-channell8 andalo'n'g its'lowei edee'by'a' similar "'u 5riaifiii The load transfer device "l O'a'lsb comprises "tw' similar co-operatingsymmetrical complementary member'sor portions; each member or portion ink. clu'di'ng' a channel" portion 22 which d-o' ra s with a tenon" 24' 'of the" opposite, likeiand sym metrical'mein'b'ei' or "portion, Each channel pertion"22."is provided with hearing surfacesg26'and 28" upon which the tenon 24is affordedmutual sliding bearing support with the channel portion 22.- The channel portion is composed of a web and upper "and; lower flangesand the channel thereof is open throughout its entire; length to permit'lat'eral assembly movement of the comple: menta'ry members or portions. As shownin Fig: ure 1,. the 'tenons- 24 pass through 'openingsflll,

inthe spacer member I 2 Each co-ope rating symmetricalportion of the load transfer device in isprovided withva'n-arm' 32 which extends from each channel 22-and lies' in the exposed iaces of the concrete; panelscr slabs'l l and I-E, a nd each is con'tinuouswith- PO tions 34 s'trucl: back into the concrete pane, j and It. The portions 3}} may be flared, seeiFige ures 4, and 5, as at 35' to provide more areaz'fori bond-with its 'contig iouspavement panel. -Each charmer 221s provided with a dowtwamy'airected extension 38 which lies in the faces of the concrete panels I4 and I6 when poured and adjacent the spacer member I2.

It will be apparent that the device thus far described can be anchored firmly into a concrete pavement and can be employed to transfer a load on one concrete panel, as for example panel I4 into the adjacent panel I6. The device thus far described will also operate to, permit; expansion and contraction of the panels I4 and I6 since the tenons 24 have a sliding bearing fit with the channel 22. In order to permit movement of the tenons 24 with respect to the channel 22 a portion of the channel 22 not having the tenons 24 slidable therein is provided with a plug of easily deformable material 40, see Figure 3 also, which may be made of sponge rubber, fibrous material made from bagasse, or other suitable similar material. I

Means are provided for holding the device thus far described together as a unit with the spacer member I2, to the end that the entire assembly maybe placed on the subgrade prior to the concreting operation. There is provided a basket indicated generally by the ordinal 42 which comprises a pair of stringers 44 resting on the subgrade, as shown, and extending longitudinally of the spacer member I2. The stringers 44 are connected by a stirrup 46 in the general form of an inverted W, the stirrup 46 having a pair of vertical legs 48 which springably engage the downwardly directed extensions 38 with the spacer member I2 and the channel member 20 held therebetween. Secured to each of the stringers 44 and on each side of the spacer member I2 is a saddle 50 having a pair of central legs 52 which springably engage the channel 22 and the material 40.

Referring now to Figure 6, another embodiment of the invention is shown. As shown in Figure 6 the load transfer device, according to this embodiment of the invention, is indicated generally by the ordinal I I and is shown as being used in conjunction with the spacer member I I2 which may be made of thin bituminous impregnated material, or of a steel plate, such being generally employed where joints for contraction are needed. The spacer member H2 separates adjoining pavement panels I I4 and I I6. The upper edge of the spacer member II2 may be protected by a-cap channel H8, and the lower edge of the member II2 may also be protected by a channel member I20. The load transfer device IIO comprises a pair of similar co-operating symmetrical portions, each portion having a channel I22 into which extends a tenon I24 of the opposite symmetrical portion, the tenon I24 being in close sliding bearing fit on surfaces I26 and I28 of the channel member I22. The tenons I24 are adapted to pass through a rectangular opening I30 spaced in the spacer member II2. Each channel portion I22 has a downwardly directed extension I38 which lies in the faces of the concrete panels H4 and H6 when poured and on each side of the spacer member I I2. The tenons I24 do not extend in the channels I22 for the full length thereof, and the portions of the channel I22 not occupied by the tenons I24 are filled with readily deformable material I40 in order to provide for unimpeded movement of the tenons I24 with respect to the channels I22 upon contraction or expansion of the concrete panels I I4 and I I6, and to prevent the entrance of concrete to the channels I22 during the paving operation.

- The device described with reference to Figure 6 may be held together as a unit with the spacer member II2 by means of a basket assembly indicated generally by the ordinal I42 and which, as with reference to Figure 4, comprises stringers I44 and stirrups I46 having upstanding portions I48 which engage the extension I30 with the spacer member II2 of the channel I20 therebetween. The ends of the channel I22 are held in saddles I50 in a manner exactlylike that shown in Figure 4.

The load transfer devices described above consist essentially of two similar cc-operating symmetrical portions which may be readily formed by one or more processes or methods. For example, each portion may be cast, and the channels milled to provide a bearing surface for the tenon which is milled to a size to obtain a sliding bearing fit with the channel. In order to obtain the necessary ductility for the co-operating symmetrical portions, and in order to take the impact stress caused by loads upon the concrete panels, the parts are malleableized. The load transfer device disclosed in Figures 1 to 6 inclusive may alternatively be forged, the'present date forging processes permitting the holding of tolerances which enable the tenons to have a close sliding bearing fit with the channel of the opposing symmetrical portion. The device may also be made by a punching operation which would give channelsheld to such close dimensions that they would readily provide a sliding bearing fit with a tenon also made in the punching operation.

While the invention has been described in terms of a preferred embodiment thereon, its scope is not limited in terms of the embodiment shown nor otherwise by the terms here appended.

I claim:

1. A load transfer device for use in concrete slab construction including two cooperating symmetrical complementary members each comprising a channel portion and a tenon consisting of an extension of the web of the channel portion and, the tenon of each channel portion being received within and fitting the channel of the other channel portion and supported by the same to maintain said members in mutual supporting relation, each of said channel portions being provided at its inner end with an extension of the upper flange of the channel member extending upwardly and outwardly therefrom and arranged to extend into an adjacent concrete slab when poured.

2. A load transfer device for use in concrete slab construction including two cooperating symmetrical complementary members each comprising a channel portion and a tenon consisting of an extension of the Web of the channel portion and the tenon of each channel portion being received within and fitting the channel of the other channel portion and supported by the same to maintain said members in mutual supporting relation, each of said channel portions being provided at its inner end with an arm consisting of an extension of the upper flange of the channel member and extending upwardly therefrom and having its upper portion bent back and arranged to extend into an adjacent concrete slab when poured.

3. A load transfer device for use in concrete slab construction including two cooperating symmetrical complementary members each comprising a channel portion and a tenon consisting of an extension of the web of the channel portion and the tenon of each channel portion being received within and fitting the channel of the other channel portion and supported by the same to maintain said members in mutual supporting relation, each channel portion having at its inner end a downwardly directed extension of the adjacent flange of said channel portion arranged to lie in the joint face of a contiguous concrete slab when poured.

4. A load transfer device for use in concrete slab construction including two cooperating symmetrical complementary members each comprising a channel portion having horizontal upper and lower flanges and a vertical web and a tenon consisting of an extension of the web of the channel portion and the tenon of each channel portion being received within and fltting between and engaging the flanges of the other channel portion and supported by the same to maintain said members in mutual supporting relation, each channel portion having. its upper flange extended upwardly and forming an arm bent back and arranged to extend into an adjacent concrete slab when poured, and each channel portion having its lower flange extended downwardly and forming a downwardly directed extension arranged to lie in the face of said concrete slab when poured.

5. A joint for concrete pavement construction comprising a spacer member, load transfer devices spaced longitudinally of the spacer member and adapted to transfer loads from a concrete panel on one side of the spacer member to a concrete panel on the other side of the spacer member, each load transfer device comprising two cooperating symmetrical complementary members, each member being provided with a channel portion consisting of a web and upper and lower flanges, an a tenon, the tenon of each channel portion being an extension of the web thereof and fitting between and engaged by the flanges of the other channel portion and each channel portion having a downwardly directed extension arranged to lie in the joint face of a contiguous slab when poured and adjacent the spacer member, and means for holding the spacer member and the load transfer devices together as a unit assembly comprising a basket having portions engaging the said channel portions and portions engaging said downwardly directed extensions with the spacer member therebetween.

6. A joint for concrete pavement construction comprising a spacer member, load transfer devices spaced longitudinally of the spacer member and adapted to transfer loads from a concrete panel on one side of the spacer member to a concrete panel on the other side of the spacer member, each load transfer device comprising two cooperating symmetrical complementary members, each member being provided with a channel portion consisting of aweb and upper and lower flanges, and a tenon, the tenon of each channel portion being an extension of the web thereof and fitting between and engaged by the flanges of the other channel portion and each channel portion having a downwardly directed extension arranged to lie in the joint face of a contiguous slab when poured and adjacent the spacer member, and means for holding the spacer member and the load transfer devices together as a unit assembly comprising a basket having saddles springably engaging said channels and including stirrups springably engaging said extensions with the spacer therebetween.

'7. A joint for concrete pavement construction comprising a spacer member, load transfer devices spaced longitudinally of the spacer member and adapted to transfer loads from a concrete panel on one side of the spacer member to a concrete panel on the other side of the spacer member, each load transfer device comprising two cooperating symmetrical complementary members, each member being provided with a channel portion consisting of a web and upper and lower flanges, and a tenon, the tenon of each channel portion being an extension of the web thereof and fitting between and engaged by the flanges of the other channel portion and each channel portion having a downwardly directed extension arranged to lie in the joint face of a contiguous slab when poured and adjacent the spacer member, plugs arranged within the channel portions at the outer ends thereof adjacent the outer ends of the tenons of the members, and means for holding the spacer member and the load transfer devices together as aunit assembly comprising a basket including a pair of stringers extending one each lengthwise of the spacer member, stirrups connecting said stringers and springably engaging said extensions with the spacer member between, and saddles connected to said stringers and springably engaging said plugs and the channel portions near the ends thereof and retaining the plugs in said channel portions.

8. A load transfer device for use in concrete construction comprising two cooperating symmetrical complementary members, each of said members being provided with a channel portion and a tenon, each channel portion having flanges which form a bearing surface engaging and supporting the cooperating tenon of the other member, each channel portion having its upper flange extended upwardly at its inner end and forming an arm extending upwardly and arranged to lie in the joint face of a concrete slab when poured, said arm having a portion bent back with respect to the joint face of a concrete slab when poured, and each channel portion having its lower flange extended downwardly and forming a downwardly directed extension arranged to lie in the joint face of a concrete slab.

JAMES H. JACOBSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Yeoman Aug. 15, 1944