US2405428A

US2405428A - Load transference unit

Info

Publication number: US2405428A
Application number: US498660A
Authority: US
Inventors: James H Jacobson
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-08-14
Filing date: 1943-08-14
Publication date: 1946-08-06
Anticipated expiration: 1963-08-06

Description

@9 2%, Ji. H. www mm2@ LOAD TRANSFERENCE UNIT Filed Aug. 14, 1945 Patented Aug. 6, `l 946 UNITED STATES PATENT GFFICE LOAD TRANSFERENCE UNIT J ames H. Jacobson, Chicago, Ill.

Application August 14, 1943, Serial No. 498,660

2 Claims.

The load transference unit of the present invention is designed primarily for use in the construction of concrete highways, for the purpose of connecting the ends of adjoining road slabs, and transmitting load stresses across the gaps between the adjacent faces of the slabs in such a manner as to prevent vertical displacement under the pressure of a rolling load on a highway, runway or the like.

Before discussing the mechanical details of the present invention it is proper to point out that the term load transference unit refers to the means employed for interconnecting the adjacent ends of concrete road slabs across the gap provided for expansion and contraction and which unit includes members which are movable horizontally to accommodate the advance and recession of the slabs, and which serve in conjunction with a dowel bar to bridge the gap and resist vertical displacement of either of the slabs'with respect to the other. In such an arrangement it is of primary importance to distribute the stresses imposed by an approaching load, so that a considerable portion of such stress will be resisted by the more distant slab, which thus serves to reinforce the near slab which receives the initial impact of the advancing load, and it is also important to provide against vibration or similar movements which, unless counteracted, have a cumulative tendency to wear away the concrete adjacent the unit members, and thus in time permit displacement of the unit with a resulting failure to perform the service intended. v

The load transference unit members which are especially adapted for use with thin slabs, have been designed with a view to extreme economy in production, being in the preferred form of identical stampings, which may be cut from a bar of metal with little waste of material and bent to nished form, ready for use, by a stamping operation, and which need not be cut or formed with extreme precision in order to be intertted in the intended manner for use in a road joint. It will be understood, however, that the present unit need not be formed as a stamping, but may be produced as a malleable unit or otherwise.

Further objects and details will appear from the description of the invention in conjunction with the accompanying drawing, wherein- Figure 1 is a perspective view of identical companion unit members in their assembled relation;

Fig. 2 is a face view of one of the unit members;

Fig. 3 is an edge View of the assembled unit embedded in the faces of opposed concrete slabs on opposite sides of a road joint; and

Fig. 4 is a modification showing the provision of anchoring members.

Each unit member in the form shown is formed from plate material cut or stamped to afford a flat body portion I0 having spaced arms I I extending upwardly therefrom to afford a gap I 2, the base of which is afforded by the middle edge section I3 of the body I0.

With the opposed unit members aligned as in Fig. 1, the edges I3 afford support for a at dowel bar I4, the middle portion of which bridges the 'gap across the joint between the concrete slabs I5 of a road or similar structure which present their at vertical faces I6 in opposed relation to one another.

Each of the unit members is provided with a rearwardly extending foot Il struck backwardly from one edge of the body portion to provide supporting contact with the surface of the subgrade, while the opposite edge is extended downwardly in the form of a pointed spike I8 which is driven into the subgrade as shown in Fig. 3.

The dowel bar is of a width to lie between the upstanding arms I I and is preferably, though not necessarily, secured to one of the unit members by a line of welding I9 and has sliding contact across the body of the companion member to allow for expansion and contraction of the concrete due to thermal changes. The outer free end of the dowel bar is entered into a sheath 20 which is xedly embedded in the concrete and affords clearance for the in and out sliding movements of the dowel bar.

When the unit members are embedded within the concrete slabs as in Fig. 3, the faces of the opposed members will lie iiush with the vertical faces of the slabs while the oppositely extending feet will be embedded around their top faces and edges with their under horizontally extended faces abutting flatwise with the subgrade.

While it will not ordinarily be necessary to provide additional anchoring means for holding the unit members in place within the concrete slabs, nevertheless in some cases such anchors may be desirable and in Fig. 4 I have shown upper middle and lower anchors 2|, 22, and 23 which enter deeply into the body of concrete and assist in anchoring the unit members against displacement. The upper anchors are formed by striking back the upper ends of the arms II while the lower anchor is formed by striking up the end of the foot I'I. The middle anchor is formed by striking back a tongue cut free from the arms I I.

One or more of such supplemental anchoring devices or others of similar character may be em- 3 ployed without otherwise modifying the structure or mode of operation of the device.

In use properly spaced unit members are driven into the subgrade until the feet make contact with the surface and thus afford stops for ensuring that companion members will stand at the same level so that the dowel bar, which is preferably connected with one of the members will nt properly within the other.

The free end of the dowel bar will be capped with the sheath 20 which extends beyond the end of the bar, so that space will be aiorded within the concrete for the free sliding movements of the bar. With the unit members thus staked in position, and the dowel bar in place and with suitable forms or spacers employed to provide the intended gap between the slabs, the concrete will be poured and compacted and built up to a level above the tops of the arms H, and if anchoring wings or flanges of the; character shown in Fig. 4 are employed, the same will be embedded deeply within the body of the concrete.

The device is one which combines great strength through its resistance to stresses, with tensile strength in resistance to shear. It may be readily installed by simply driving-it into the earth to any desired height of dowel bar and still function correctly While the dowel bar itself is held in place rigidly and at the same time is free to move horizontally. Although the form shown is one which combines extreme simplicity with cheapness in production, it is obvious that changes in the shape or proportions of the constituent parts may be made without departing from the spirit of the invention.

I claim:

l. In combination with concrete pavement slabs presenting opposed edge faces on opposite sides of a gap, a load transference unit comprise ing oppositely facing unit members each formed of plate material adapted to afford great resistance to load stresses, and having a body and spaced, upwardly extending arms in the plane of thebody and presenting their exposed faces ilush with the edge faces of said opposed concrete slabs, the body of each unit member being in part extended to provide a downwardly projecting spike entered into the subgrade and in part extended horizontally to provide a ilat faced foot underlying the concrete and contacting the subgrade, a dowel bar bridging the space between the slabs and the unit members and supported between the spaced arms, and rigidly secured to one of the unit members, and having its ends extended backwardly therefrom and into the respective slabs, one end portion of the dowel bar having a slidable contact with the other of said unit members, and a sheath loosely arranged on said dowel bar end portion and located beyond the adjacent unit member and positionable on the dowel bar independently of said adjacent unit member.

2. In combination with concrete pavement slabs presenting opposed edge faces on opposite sides of a gap, a load transference unit comprising oppositely facing unit members each formed of plate material adapted to afford great resistance to load stresses, and having a body and spaced upwardly extending arms in the plane of the body and presenting their exposed faces ilush with the edge faces of said opposed concrete slabs, the upper terminals of the arms being extended outward horizontally to provide upper anchors and the body of each unit member being in part extended to provide a downwardly projecting spike entering into the subgrade and in part extended horizontally to provide a flat faced foot underlying the concrete and contacting the subgrade, the terminal of the foot being extended upwardly to provide a lower anchor, a middle anchor rigid with and extending outward horizontally from the body at the lower end of the space between said arms, a at relatively broad dowel bar presenting its flat upper and lower faces in horizontal planes and rigidly secured to one of the unit members and bridging the space between the unit members and supported between the spaced arms and having its ends extended backwardly therefrom into the respective slabs, one end portion of the dowel bar having a slidable contact with the other of said unit members, and a sheath loosely arranged on said dowel bar end portion and located beyond the adjacent unit member and positionable on the dowel bar independently of said adjacent unit member.

JAMES H. JACOBSON.