US2150982A - Expansion and contraction joint - Google Patents

Description

March 21, 1939. F. R. M FARLAND 2,150,982

EXPANSION AND CONTRACTION JOINT Filed June "26, 1936 2 Sheets-Sheet l INVENTOR 500/? EN Mr/maf March 21, 1939. F. R. M FARLAND 2,150,982

EXPANSION AND QONTRACTION JOINT Filed June 26 1936 2 Sheets-Sheet 2 7 H w an 1. I. e. I b

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Patented Mar. 21, 1939 UNITED STATES PATENT. OFFICE 2,150,982 EXPANSION AND CONTRACTION JOINT Application June 26, 1936, Serial No. 87,434

5 Claims.

or pavement aligning means, in parallelism and grade alignment during pouring of the concrete so that all of the dowels are freely active in permitting expansion and contraction of the paving after it has set; to provide for distribution of live loads, acting on any one of the dowels across the width of the paving, to the other dowels; and to provide a joint reinforcement that automatically conforms to the sub-grade incidental to its inherent flexibility in one direction but which has ample rigidity in lateral directions to maintain alignment of the filling strip and load distributing bars as well as the dowels so that the relative positions thereof cannot become altered during pouring and setting up of the concrete.

It is also an important object of the invention to provide an all welded reinforcement which which is of light weight and readily handled.

In accomplishing these and other objects of the invention, as hereinafter pointed out, I have provided improved details of structure, the preferred forms of which are illustrated in the accompanying drawings, wherein:

Fig. 1 is a perspective view of a portion of adjacent sections of paving equipped with an expansion joint embodying the features of the present invention, parts of the paving sections being broken away to, better illustrate the construction.

Fig. 2 is a plan view with the adjacent ends of the paving sections broken away to illustrate the construction of the expansion and reinforcement features of the joint.

Fig. 3 is a crosssection through one side of the paving on the line 33 of Fig. 2.

Fig. 4 is an enlarged section taken transversely of the joint at one of the dowels.

Fig. 5 is a similar section through the joint taken at. a point intermediate the dowels.

Fig. 6 is a perspective viewsirnilar to Fig. 1 but showing a modified form of construction.

Referring more in detail to the'drawings:

, I designates a roadway or similar paved surface formed of monolithic material, such as concrete, and which must be divided into sections '2 and 3 to provide expansion joints 4 whereby the respective sections may expand and contract in accordance with temperature and road conditions. The joints 4 are usuallyfilled with a. plastic m terial 5 to fill the expansion space and prevent entrance of dirt, water and other elements, that would interfere with expansive and contractive movement of the sections.

The adjacent paving sections 2 and 3 are ordinarily retained in alignment by means of dowel rods 6 imbedded in the concrete and extending transversely across the joint in parallel spaced relation. Alternate ends of adjacent dowels usually are fixed in their respective paving sections, while the other ends are freeto telescope in suitable sockets 1 sleeved thereon and imbedded in the sections as shown in Figs. 1 and 4. Unless the dowels 6 are supported in parallel spaced alignment and in a plane with the grade while the concrete is poured, they become disarranged and are moved out of parallelism consequently the disarranged dowels will tend to prevent or at least resist expansive and con- 3. tractive movement of the sections, and thereby result in cracking of the pavement. It is also necessary that the filling strips 5 be supported in transverse alignment and in a plane extending at right angles to the subgrade while the concrete is being poured.

As above pointed out, it is a principal object of the present invention to.positively retain these parts against independent relative movement while the concrete is being poured, and to provide reinforcing means for distributing the load across the width of the paving adjacent the edges of the joint so that the live load acting above any one of the dowels is distributed proportionately to the other dowels, thereby obviating any 40 tendency for the paving to crack because of unevenly distributed loads.

In accomplishing these results I provide an all Welded unitary reinforcement and support for the dowel rods, as well as for thefllling strip, so that they are retained in fixed relative pc-sition during pouring of the concrete, as now to be described.

8 designates a reinforcement and support embodying the present invention and which includes a plurality of spaced primary chairs 9 locatedjin correspcnding relation to the desired spacing of the dowels, and each chairincludes' a bar or"-rod l0 bent to'provide transverse footing portions II and upturned ends I! and I3 to which are at tached load distributing and reinforcing bars l4 and l5 that extend across the paving on the respective sides of the expansion joint to connect the chairs. The bars are secured to the chairs by welding or the like, as indicated at I6, at the desired depth below the surface of the paving when the footing portions II rest upon the sub'grade indicated at H.

The ends l2 and I3 extend above the load distributing bars and have 'reversely bent terminals I3 and I9 of hook-like shape or loop. The terminals have ends 20 welded to the bars I4 and H5 at a point spaced from the welding points it, as indicated at 2|. The hook-like terminals thus cooperate with the bars to provide bearing openings 22 and 23 for slidabiy retaining the dowels 6, as clearly illustrated in Fig. 1.

Extending longitudinally of the bars l4 and I5 and welded to the under side of the footing portions II at points midway between the ends thereof, is a bar or rod 24 carrying a plurality of forks 25 located thereon midway between the chairs for supporting the premolded filling strip 5. The forks 25 include horizontal bar portions 26 welded to the rod 24 as indicated at 21, and have upstanding arms 23 and 23 cooperating with the bar portions to form seats 30.to support the strip 5 in parallel alignment with the'load distributing bars.

The strip 5 is preferably premolded of plastic materialv having resilient characteristics so that it is compressible upon expansion of the paving 'sections and expandable when the sections contract to keep the joint filled. The strip 5 is of sufllcient length to extend across the paving and has openings 3| therethrough that are positioned in alignment with the bearing openings of the ,chairs to accommodate the dowel rods. Cooperating with the chairs and preferably located in alignment with the forks are supplemental sub; stantiallyv L-shaped chairs 32 including rods having vertical leg portions 33 welded to the load distributing bars as at 34, and having lateral footing portions 35 extending in the direction of the forks for support on the subgrade. The dowels are so .spaced that those adjacent thesides of the paving are inset fromthe sides thereof, however, the bars l4 and I5 and rod 24 extend across the entire width of the paving, making it desirable to support the ends of the bars by pairs of supplemental chairs 32 and to provide the ends of the rods with forks 25 to engagingly support the outer ends of the filling strip.

The form of the invention illustrated in Fig. 6 is substantially the same as the preferred constructionsexcept that the supplementary chairs are omitted and rods 33 and 31 are welded adjacent the ends'of the'footing portions of the chairs as at 33 and 33 respectively.

, The reinforcements above described, compris ing the load distributing bars l4 and I5, the fork carrying bar 24, together with the primary. and supplementary chairs, are welded together at the factoryto form a solid unit which is shipped to the place of use. When-received at the job they are distributed along the subgrade. and. placedin the position they are to assume in the finished paving. When placed on the subgrade the units are freely flexible in a perpendicular direction .so that they readily take the curvature of the grade, however, the construction is such that the bars I4 and I5 and rod 24 will retain their parallel relationship. The reinforcements may thus be applied without the use of stakes or other means for'holdingthem'in set position.- The filling strips are then applied so that the lower edges other monolithic material forming the paving is I poured on the subgrade and levelled oi! as in conventional practice.

After the concrete has set, the paving sections are free to move to and from each other guided by the dowels which retain the surface of the paving in horizontal alignment.

Attention is directed to the fact that the chairs are. formed of relative light gauge material so that the footing portions thereof do not interfere with movement of the paving sections. Loads acting on'one portion of the paving are trans- 'mitted across the width thereof by means of the load distributing bars l4 and I5 so that the paving does not tend to' crack. Likewise load forces acting on any one of the dowels are distributed to the other dowels through the bars i4 and l5to spread and distribute the strains across the length of the joint. Since the dowel rods ,are' retained in parallelism during the pouring and setting of the concrete, it is obvious that they are free to guidingly support the sections during their expansive and 'contractive movement and thereby permit full expansion and contraction of the sections without imparting strains on the edges of the joint tending to crack or break the concrete.

From the foregoing, it is obvious that I have provided a reinforcement and support for expansion joints which is of light weight construction,

and which accurately retains the dowel rods, as

well as the filling strip, in-their correct relation during pouring of the concrete. It is also obvious that the reinforcing is readily fabricated and in corporated in a paving construction in exact conformity with the subgrade, however, the structure has'sufiicient rigidity in a lateral direction toprevent displacement f the parts supported plurality of spaced chairs, each comprising a bar fOII'nd to provide a horizontal footing portion having upturned ends, terminating in loop portions, loaddistributin'g bars fixed to said upturned ends to connect said chairs,. dowels slidablyj engaged in said loop portions, a fork supporting rod fixed to the horizontal. footing portionsof said chairs, and-forksrigidly supported on said rod to cooperate with the dowels in supporting a joint filling strip in rectilinear alignment,

3. A unitary joint reinforcement including a joint reinforcement including plurality of, spaced chairs, eachcomprising a bar tions of said-chairs, and forks fixed on said rod formed to provide a horizontal footing portion having upturned ends, load distributing bars attached to said upturned ends and connecting the chairs, a rod rigidly connecting the footing portions of said chairs, and seating means on said rod for aligningly supporting a joint filling memher.

4. A unitary joint reinforcement including a plurality of spaced chairs, each comprising a bar formed to provide a horizontalfooting portion having upturned ends, load distributing bars attached to said upturned ends and connecting the chairs, a rod rigidly connecting the footing porto aligningly support a joint filling member.

5. A unitary joint reinforcement including a. plurality of spaced chairs, each comprising a "bar formed to provide a horizontal footing portion having upturned ends, load distributing bars rigidly connected with said upturned ends to space said chairs, forks for aligningly seating a joint filling member, and means rigidly connecting the forks with the horizontal footing portions of said 10 chairs.

FRANK R. MOFARLAND.

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