US2189156A - Joint - Google Patents

Description

Feb. 6, 1940. '0; E. WILLARD JOINT Filed April 30, 1955 2 Shets-Shegat 1- Feb. 6, 1940. D, E MLLARD 2,189,156

JOINT Filed April 30, 1935 2 Sheets-Sheet 2 Patented Feb. 6, 1940 UNITED STATES .PATENT' OFFICE 25 Claims.

My invention relates to joints, preferably of the expansion type, for roadways, pavements, concrete slabs, wall sections and similar structures, and is concerned more particularly with a structure of this type in which means are provided to efie'ctively protect the concrete around the reenforcing bars between adjoining slabs against the so-called tunneling action due to load pressures on the slabs, and to generally provide a more efiicient reenforcing for slab constructions in theregion of joints.

In the building of roadways, for example, it is customary to bridge reenforcing or dowel bars between adjoining slabs to prevent their relative vertical movement. The passage of trafilc over the roadway and the upward pressure of the subsoil in conjunction with the condition of the latter, however, set up heavy localized pressures in m the concrete around the bars adjacent the opposed faces of the slabs. This actioneventually crumbles the concrete and creates a funnel-like cavity around the bar which permits definite relative movements of the slab sections annd frequetly enlarges the cavity to such an extent that the slabs eventually crack.

It is, therefore, one object of my invention to associate with such a reenforcing bar a pair of members located on opposite sides of the joint which prevent crinnbling of the concrete in the funneling region by a more eflicient distribution of the operating stresses, particularly with respect to the stresses that would-be otherwise transmitted directly from the concrete into the bar, and also with respect to an adequate lateral support for that portion of the concrete in the funneling region which transmits vertical force to the bar, and generally to provide an improved structure for transmitting the load across the joints of concrete roadway slabs.

A further object is to provide for use in conjunction w'.th a joint a reenforcing member shaped and arranged to carry the stresses normally set up in the funneling region around the dowel bar into the main body of the slab by appropriate arms or prongs and directly into the dowel bar.

A further object is to devise a joint for concrete slab construction employing dowel bars between adjacent slabsin which a reenforcing member having arms or prongs extending into the concrete is associated with each bar on opposite sides of the joint, the arms being securely anchored in the concrete and the member having a portion covering the barin the funneling region to thereby decrease the unit pressure of the concrete on the portion.

A' further object is to provide a joint of the character indicated in which the arms and associated bar are located in substantially the same 5 vertical plane to better resist the application of vertical loads, such as commonly encountered in roadway construction, and which develop the maximum shearing strength of the concrete from the top to the bottom of the slab and vice versa. 10

A further object is to provide a reenforcing member made from stampings which are subsequently shaped and formed to accommodate the dowel bars and thereafter welded or otherwise secured together to form the complete reenforcing member.

These and further objects of my invention will be set forth in the following specification, reference being bad to the accompanying drawings, and the novel means by which said objects are efiectuated will be definitely pointed out in the claims.

In the drawings:

Figure 1 is an end elevation, partly in section, of my improved joint showing the relation of the reenforcing member to the dowel bar and the expansion strip, the upper surface of the slabs proper being shown in dotted outline.

Fig. 2 is a plan view of a portion of the joint as shown in Fig. 1. 0

Fig. 3 is an elevation of the reenforced portion of the joint, as viewed in the direction of the arrow 3 in Fig. 2.

Fig. 4 is a section along the line 4-4 in Fig. 2, looking in the direction of the arrows, and show ing the arrangement of the reenforcing member for insuring a fair and continuous bearing around the dowel bar, including the top and bottom portions thereof.

Fig. 5 is a .plan view, corresponding to that shown in Fig. 2, but illustrating a modified type of reenforcing member.

Fig. 6 is a side elevation of the modified member, looking in the direction of the arrow 8 in Fig. 5.

Fig. 7 is an end view of the modified member, looking in the direction of the arrow 1 in Fig. 6.

Fig. 8 is an elevation, partly in section, showing a portion of a modified type of joint wherein provision is made for lubricating the dowel bar from time to time after the roadway is laid.

Figs. 9 and 10 illustrate further modifications of a joint structure, only one-half of the structure being shown, the former illustrating a simple association of a reenforcing member with a dowel bar without any provision for lateral support of the concrete in the funneling region and the latter showing a similar structure, but including the use of-a sleeve which encircles the dowel bar within the reenforcing member for the purpose of providing a continuous bearing around the bar.

For purpose of illustration and as exemplifying one use of my improved joint, the same will be described in connection with a roadway. It will be understood, however, that the essential conception involved is likewise susceptible of adaptation to structural sections in general, regardless of their composing material, where such sections are subject to expansion and contraction and it is desired to prevent buckling or cracking of adjoining sections by inserting a yielding member therebetween, or where such sections are subject to transverse pressures and it is desired to prevent any funneling action around the reenforcing bars which extend between adjoining sections.

Referring to Figs. 1 to 4, inclusive, of the drawings, the numerals i and Ii designate a pair of adjoining concrete slabs which are spaced by an expansion strip l2. This strip may be composed of a bituminous composition mixture, such as is now commonly employed in the industry for strips of this nature, or it may be formed of cork or rubber, or the expansion may be accommodated by the so-called metal walled joint in which thin metal walls provide faeings for the opposed ends of slabs, the walls being separated by an air space or other yieldable filling. All of the foregoing expansion members or strips are well known in the art and in and of themselves form no part of the present invention. In any case, it is contemplated that the strip will be arranged so that it will not only yield in response to movements of the slabs, but will be composed of a material that is resistant to water, earth acids, or any other decomposing influences which are commonly met with in the use of structures of this type. The thickness of the strip may be varied as desired and may be as low as A".

A reenforcing or dowel bar 13 extends through a suitable aperture provided in the strip l2, and its ends are carried in passages ll, l4 provided in reenforcing members l5, l5 that are located on opposite sides of the expansion strip. As noted more particularly in Fig. 3, each of the members I5 is composed of a pair of plates or stampings l6 and I! which are originally cut from flat stock to the profile shown in Fig. l and subsequently formed or shaped intermediate their upper and lower edges to provide the semi-circular portions I8 and I9 which together form the passages I! when the stampings are afterwards secured together. The member l5 may be cast, forged or otherwise formed without affecting the essential conception involved.

Each of the stampings i6 and I1 is provided on the end remote from the expansion strip with an upper arm and alower arm having an enlarged end, or the arms may be formed with a tapering profile, the upper arms together forming an arm or prong on the assembled reenforcing members, and the lower arms form a similar prong 2|. The opposite endsof these stampings that is, the ends adjacent the expansion strip [2, are cut at the junction of the fiat and curved portions to provide recesses 22 that are originally channel-shaped in section and concentric with the passage l4 and are afterwards deformed to the dove-tail shape illustrated in Fig. 1 in the manner hereinafter described.

loss of the cover strip. Upward movement of The joints shownin Fig. 1 may be assembled before being positioned in the course of laying the roadway and in so doing, a pair of the stampings is secured together, as by the indicated spot welds 24, or possibly rivets or other securing devices, and a washer 23 is seated in the pair of associated recesses 22, each then having a channel section. The outer peripheral surface of each washer is beveled and slopes towards the axis of the passage I4 and away from the arms 20 of the particular reenforcing member. After being thus seated, the ends of the stampings l6 and I1 adjacent the outer walls of the recesses 22 are upset, as by swedging or hammering, to thereby deform the outer wall into close contact with the beveled surface of the washer 23 and firmly hold the latter in the recesses which then have the dove-tailed shape as indicated. Each of the washers is apertured and closely fits around the curved portions of the stampings, and to this end, 5,- the ends of these curved portions adjacent the recesses are bent into abutting relation, oras near thereto as practicable. The'purpose of the washers is to provide a lateral support for the concrete in the tunneling region because, since each washer is securely held to its associated reenforcing member, any tendency of the concrete to spread toward the expansion strip under vertiical load is eifectively prevented. The washers also reenforce the tube formed by the curved portions of thestampings and render possible the close fitting and forming of the tube at this important point.

After the stampings have been secured together to form the reenforcing members l5, they, together with the dowel bar l3 and expansion strip H are assembled in the arrangement shown in Fig. 1. Each of the stampings is further swedged or hammered along the length thereof and substantially at the junctions of the rounded portions l8 and IS with the fiat portions of the stampings l6 and I! to provide the portions 25, for a purpose presently explained.

The weight of the dowel bar across the width of the slab, plus the weight of the reenforcing members, may be adequately carried by legs 26 which rest directly on the sub-soil through the provision of feet 21 and whose upper end is cut to provide a pair of spaced tongues 28 which are separated by a third tongue 29, the latter being slightly ofi'set, as clearly shown in Fig. 3 and bent upwardly and around the adjacent lower prong 2|, with the tongues 28 engaging the opposite side of the same prong.

In certain roadway constructions, it is desirable that the upper face of the expansion strip l2 be protected and, for this purpose, a cover strip 30 having an inverted channel section, encases the upper portion of the expansion strip above the reenforcing members, the web II of the cover strip being deflected transversely toward the expansion strip and longitudinally of the cover strip to provide a construction that will readily. yield under the expansive forces of the concrete. The sides of the cover strip extend downwardly along the sides of the expansion strip and are then bent outwardly to provide flanges 82 which are subsequently embedded in the concrete when poured to thereby prevent upward movement and the cover strip due to the buoyant action of the concrete while being poured is prevented by a wire 33 which is bound over the web ll of the strip with its en'ds secured to hooks 34 provided on the reenforcing members, it being understood arcane that these books need only be formed on one of the original stampings from which the reenforcing members are formed, that is, either the stamping N or the stamping I].

It will also be understood that the hammered or swedged portions 25 will be driven into contact with the top and bottom surfaces'of the dowel bar in order to provide a fair and adequate bearing of the reenforcing members on the dowel bar in these locations, the surfaces of the passages Il closely fitting the other surface portions of the dowel bar. Due to the manner in which the reenforcing members are made, that is, from the stampings I6 and I1 and the necessity for intermediately bowing the stampings l6 and I1 to receive the dowel bar, the comparatively large fillets or curved surfaces formed at the junction of the curved portions l8 and IS with the flat portions of the stampings would decrease the contacting and transmitting area of the passages H with respect to the dowel bar. The provision of the portions 25 to a large extent eliminates this difliculty, since they are driven into full contact with the peripheral surface of the dowel bar, as clearly indicated in Fig. 4.

The dowel bar i3 may havethe relatively short length indicated in Fig. 1, that is, with its right end terminating at the right end of the passage in the right-hand reenforcing member l5 and with its left end terminating some distance from the left end of the left end passage M to provide a space that may be filled with a suitable lubricant that facilitates movement of the dowel bar during expansion and contraction. This lubricant may be retained in position by a cap 35 that is suitably held in position on the indicated end of the reenforcing member, as by forming the cap of a thin, spring-like material and cutting two suitable notches in the annular wall of the cap to fit over the flat portions of the stampings, as clearly indicated in'Fig. 2. If the dowel bar is symmetrically disposed relative to the joint strip i2, the ends of the bar terminate short of the outer ends of the passages.- The bar i3 is intended to resist any relative vertical movement of the adjoining slab sections, that is, in conjunction with other dowel bars spaced at convenient intervals across the width of the slab, and also to transmit from one slab section to an adjoining slab section, a portion of the load being applied to the one section. The space in the passage it between the cap 35 and the end of the dowelbar l3 permits expansion and contraction of the slab sections with respect to each other and to the dowel bar, since the bar may move for a substantial distance before abutting against the concrete forming the slab section III, for example. It will-be understood, however, that longer dowel bars may be employed, as disclosed in my copending application for a Joint, Serial No. 715,384, filed March 14, 1934, or, in other words, the dowel bar may extend for some distance beyond the ends of the passages It, or even beyond the ends of the prongs 20 and 2|.

After the joint has been assembled and positioned in the path of the roadway, it may be definitely held against sidewise movement due to' poured, the web of the covering strip will be substantially fiush with, or preferably, as indicated in Fig. 1, a short distance below the surface of the roadway. Under the latter condition, it will be obvious that a filling of pitch or other bituminous substance may be poured along the slight depression above the web of the cover strip but, even in the absence of this pitch filling, the covering I strip will protect the expansion strip against wear and the former is preferably composed of a material that will resist corrosion and is ductile. It is also considered to be within the range of my invention to entirely eliminate the cover strip 30 and merely to fill the depression above the expansion strip with a suitable bituminous sub-- stance.

Due to the location relation of the reenforcing members to the dowel bar, it is obvious that the cylindrical portion of each reenforcing member, as formed by the curved portions 18 and I9. will adequately reenforce and protect that, portion of the concrete which encircles the bar adjacent the opposing faces of the adjoining slab sections. I This construction, which practically amounts to an enlargement of the dowel bar in the indicated location, substantially reduces the unit pressure on the adjoining concrete and so reduces the possibility of any funneling action of this material. The action is enhanced by the presence of the washers 23, since they provide lateral support for the concrete in an important location, this result being due to the fact that the washers are securely anchored to the reenforcing members and are therefore subject to horizontal tension. The washers also reduce the unit pressure on that portion of the concrete which they contact.

The stresses'whlch are set up in the funneling region are carried into the body of the slab sections by the arms 20 and 2| as further reenforced by the dowel bar l3. These elements serve to better distribute the imposed stresses and to more adequately utilize the compressivestrength of the concrete and, further, due to the presence of the prongs 20 and 2|, it is possible to develop substantially the maximum shearing strength of the concrete, one of the arms being always in I tension and the other-in compression, dependent upon the, location of the load and the slab to which it is applied. Any tendency of one of the slabs to move downwardly is not only resisted by the dowel bar [3, but also by the engagement of the arms 20 and 2! in the adjacent slabs. As indicated, the arms 20 and 2! are located in substantially the same vertical plane as the dowel bar and so are in the most eificient position for resisting the vertical loads commonly encountered in roadway construction. 1!

The dowel bar is positioned at mid-depth, or in the neutral plane of the slabs and parallel to the top surface and normal to the joint faces of the slabs. Therefore, the arms 20 and 2! extend into the compression and tension regions of each slab, respectively.

In Figs. 5, 6, and .7 are illustrated a modified type of joint which is'identical with that heretofore described, as regards the use of an ex-, pansion strip, sub-soil supports, cover strip, and the washers which encirclethe dowel bar adjacent the expansion strip to provide lateral support for the concrete. The essential distinction in thismodiflcation resides in the shape and arrangement of the stampings from which the reenforcing member is made, as well as the length of the dowel bar and the provision for carrying lubricant for the bar.

In Figs. 6.and '7, each reenforcing member is composed of a pair of stampings 36 and 31 which i are originally cut to the profile indicated in Fig. 6 to provide the arms or prongs 38 and 39 which, in edgewise view and as shown in Fig. 5, may be slightly bowed as at to provide a suitable anchorage in the concrete. This bowing of the arms may be in addition to the tapering shape shown, or the arms may be provided with parallel sides and be simply bowed as at 40. The stamping 36 is intermediately curved as at 4|, while the stamping 31 is intermediately curved as at 42 so that, when the stampings are accurately secured together, a passage 43, similar to the passage i4, is formed. Instead of forming the prongs 38 and 39 of a double thickness of metal, however, the stamping 36 below the curved portion 4| terminates as at 44, and a similar provision is made in the stamping 31, as indicated by the numeral (see Fig. 7). Accordingly, each arm 38 and 39 is composed of a single thickness of material.

These-stampings are assembled in the manner hereinbefore indicated, it being understood that washers similar to 23 are first positioned, as indicated in Fig. 6, after which the dowel bar 46 is inserted through the passages 43. Lubrication provision is taken care of by the cap 41 which extends beyond the left end of. the passage 43 and its annular edge is beveled for reception within an appropriately shaped undercut provided in the left-hand reenforcing member. In this type of joint, the dowel bar 46 is symmetrically disposed with reference to the expansion strip, that is, it extends completely through the passages 43.

In all other respects, this modified type of joint is the .same as-that illustrated in Fig... 1, and it functions in the same manner as regards the distribution of operating stresses through the adjoining slab sections.

In Fig. 8 is illustrated a still further modification wherein either of the reenforcing members heretofore described may be employed and the change consists essentially in an arrangement for introducing lubricant into the cavity, within which the dowel bar slides, from time to time after the roadway is completed. In this form, the numeral 46 designates a dowel bar which is mounted within a suitable passage provided in a reenforcing member 4'l ,'one end of the dowel bar being so disposed that a lubricant chamber 48 is provided in the passage, the adjacent open end of the passage being closed by a cap 49. Extending upwardly towards the surface of the roadway from the chamber 48 is a tube 50 whichterminates in a grease-gun attachment, or 'other lubricant receiving device 5|, which is located in a suitable recess or depression 52 provided in the surface of the roadway. This arrangement provides for a subsequent filling of the chamber 48 with grease, such as may be required some years after the roadway has been laid. P

In Figs. 9 and 10 are illustrated two further modifications which are concerned essentially with a type of joint in which the washers 23 are not employed. In Fig. 9, the numeral 53 designates a dowel bar which is received within a passage provided in a reenforcing member 54 that may be arranged and shaped according to any of .the designs heretofore discussed. In Fig. 10, the

only additional element consists in a sleeve 51 which encircles the dowel bar 55, the sleeve being positioned in a suitable pass-age provided in a reenforcing member 56. The purpose, of the sleeve 51 is to provide a full-continuous bearing over the entire surface of the dowel bar which is located within the passage of the reenforcing member. Excepting for the absence of the washers 23, these reeniorcing members operate in substantially the same manner as those heretofore described, relative to the distribution of the imposed stresses.

I claim:

. F 1. A reenforced joint for concrete slab construction comprising a reenforcing bar for extending between adjacent slabs, and reenforcing means operatively associated with the bar on each side of the joint and having a pair of stress-carrying arms adapted to extend into the body of the associated slab above and below and substantially in the same vertical plane as the bar for transmitting stresses between the bar and slabs.

2. A reenforced joint for concrete slab construction comprising a reenforcing bar for extending between adjacent slabs, and reenforcing means operatively associated with the bar on each side of the joint and having a pair of stress-carrying arms adapted to extend into the body of the associated slab above and below the bar for transmitting stresses between the bar and slabs, the arms being shaped to provide anchorage in the concrete for resisting endwise movement toward the adjacent slab face.

3. A reenforced joint for concrete slab construction comprising a reenforcing bar for extending between adjacent slabs, and reenforcing means on each side of the joint comprising a pair of stampings secured together and intermediately formed to provide a passage for the bar and having stress-carrying arms adapted to extend into the body of the associated slab above and below the bar for transmitting stresses between the bar and slabs.

4. A- reenforced joint for concrete slab construction comprising a reenforcing bar for extending between adjacent slabs, and reenforcing means on each side of the joint comprising a pair of stampings secured together and intermediately oilset to provide a closely fitting passage for the bar and having stress-carrying arms adapted to extend into the body of the associated slab above and below and substantially in the same vertical plane as the bar for transmitting stresses between the bar and slabs, and swedged portions extending inwardly from the offset portions of the stampings to bear on the upper and lower surfaces of the bar.

5. A reenforced joint for concrete slab construction comprising a reenforcing bar for extending between adjacent slabs, and reenforcing means on each side of the joint comprising a pair 01' stampings secured together and intermediately formed to provide a passage for the bar and having stress-carrying arms adapted to extend into the body 01' each slab above and below the bar for transmitting stresses between the bar and slabs, and a plate firmly held to the end of each means immediately adjacent the associated slab face and apertured to closely fit the passage-forming portion of the stampings.

6. A reenforced joint for concrete slab construction comprising a reenforcing bar for extending between adjacent slabs, and reenforcing means adapted to extend into the slabs on each side of the joint and having immediately adjacent the associated slab face an enlarged portion including a passage for closely fitting the bar and adapted to transmit stresses between the bar and slabs through the reenforcing means, the portion reducing the unit pressureon the surrounding 10 "means, a conduit extendingfrom the chamber the associatedslab face an enlarged portion including a passage' for closely fitting the bar, a lubricating chamber carried by the reenforcing and adapted to terminate at the surface of the slab, and means on the last named end of the conduit adapted to connect the conduit with a lubricatingdevice.

8. A reenforced joint for concrete slab .con-

struction comprising a reenforcing bar for extending between adjacent slabs, and reenforcing means having a sleeve portion fitting and extending the full length of the'bar on each side of the joint and each means having stress-oarrying'devices adapted to extend into the body of each slab for transmitting stresses between the bar and slabs. 9. A reenforced joint for concrete slab construction comprising a reenforcing bar for extending between adjacent slabs, and reenforcing means having a sleeve portion fitting and extending the full length of thebar on each side of the joint and each means having arms extending from and beyond an end of the sleeve portion for embedding in the body of the slab, the arms being adapted to transmit stresses between the bar and slabs.

10. A reenforced joint for concrete slab construction comprising a reenforcing bar for extending between adjacent slabs, and reenforcing means having a sleeve portion fitting and extending the full length of the bar on each side of the joint, each means having stress-carrying devices adapted to extend into the body of the associated slab above and below the bar for transmitting stresses between the bar and slabs.

11. A reenforcing member for concrete slab joint construction having a reenforcing bar between adjoining slabs comprising a sleeve portion for fitting and having a length not less than the length of the bar on one side of the joint, and arms extending from the portion for embedding in the slab and adapted to transmit stresses between the bar and slab.

12. A reenforcing member for concrete slab joint construction having a reenforcing bar between adjoining slabs comprising a sleeve. portion for fitting and having a length not less than the length of the bar on one side of the joint; and a pairof arms extending from the portion in substantially the same plane for embedding in the slab and adapted to transmit stresses between the bar and slab.

13. A reer-orcing member for concrete slab joint construction having a reenforcing bar between adjoining slabs comprising a pair of stampings secured together and intermediately formed to provide a sleeve portion for fitting the bar on one side of the joint and having stress-carrying arms adapted to extend into the body of the associated slab for transmitting stresses between the bar and slab.

14. A reenforcing member for concrete slab joint construction having a reenforcing bar between adjoining slabs eomprising a pair of stampings secured together and intermediately formed to provide a sleeve portion for fitting the bar on one side of the joint and having stress-carrying arms above and below the sleeve portion adapted to extend into the body of the associated slab for transmitting stresses between the bar and slab.

15. A reenforcing member for concrete slab joint construction having a reenforcing bar between adjoining slabs comprising a sleeve portion for fitting and having a length not less than the length of the bar on one side of the joint, and arms extending from the portion for embedding in the slab and adapted to transmit stresses between the bar and slab, the ends of the arms being shaped to provide anchorage therefor in the concrete.

16. A reenforcing member for concrete slab joint construction having a reenforcing bar between adjoining slabs comprising a sleeve portion for fitting and having a length not less than the length of the bar on one side of the joint, arms extending from the portion for embedding in the slab and adapted to transmit stresses between the bar and slab, the ends of the arms being shaped to provide anchorage therefor in the concrete, and a plate firmly held to the end of the sleeve portion immediately adjacent the associated slab face and apertured to closely fit the portion, the plate providing a lateral support for the concrete in the tunneling region.

17; A reenforcing member for concrete slab joint construction having a reenforcing bar between adjoining slabs comprising a sleeve portion for fitting and having a length not less than the length of the bar on one side of the joint, and arms extending from and beyond an end of the sleeve portion for embedding in the slab. and adapted to transmit stresses between the bar ahd slab.

8. A reenforcing member for concrete slab joint construction having a reenforcing bar beretain said resilient means in predetermined position with respect to said retainers, said second mentioned means being slidable with respect to said retainers and said slabs to permit free movement of said edges caused by expansion and contraction of said slabs.

20. A compensable joint for an expansible ribbon having spaced apart cuts transversely thereof, the edges of each of said cuts being spaced apart, blocks being positioned in said cuts, respectively, and adjacent the edges thereof, means to retain said blocks in predetermined positions with respect to said edges of said cuts, said means being. slidably mounted in said edges of said cuts, whereby said ribbon is adapted to move by expansion and contraction independently of said means and said block.

21. A joint for connecting adjoining concrete sections comprising a separating strip, a plurality of dowelsprojecting from opposite sides thereof, a rigid bearing for each end of each dowel, said bearing being increasedin cross section at this point of contact with the strip, and the opposite end of each bearing being extended to provide an anchor continuing at an angle to the plane of the dowel.

2. Means for bridging a joint in concrete slab construction comprising a load carryin bar for extending between adjacent slabs, and reenforcing means operatively associated with the bar on each side of the joint and having a pair of load carrying arms adapted to extend into the body of the associated slab above and below and substantially in the same vertical plane as the bar for transmitting loads between the bar and slabs.

23. Means for bridging a joint in concrete slab construction comprising a load distributing bar for extending between adjacent slabs, and slab reenforcing means adapted to extend into the slabs on each side of the joint and having immediately adjacent the associated slab face an enlarged portionincluding a passage for closely fitting the bar for transmitting load between the bar and slabs through the was]; means,

the portion reducing the unit pressure on the surrounding concrete, and the bar not extending beyond the extremities of the passage.

24. A bridging member for concrete slab joint construction having a load carrying bar between adjoining slabs comprising a sleeve portion for fitting and having a length not less than the length of the bar on one side of the joint, and arms extending from the sleeve portion for embedding in the slab and adapted to transmit load between the bar and slab.

25. A bridging member for concrete slab joint construction having a load carrying bar between adjoining slabs comprising a sleeve portion for fitting and having a length not less than the length of the bar on one side of the joint, and

arms extending from and beyond an end of the sleeve portion for embedding in the slab and adapted to transmit load between the bar and slab.

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