US2133553A

US2133553A - Dowel support for concrete pavement expansion joints

Info

Publication number: US2133553A
Application number: US116898A
Authority: US
Inventors: Chester A Lord
Original assignee: UNIVERSAL FORM CLAMP CO
Current assignee: UNIVERSAL FORM CLAMP CO
Priority date: 1936-12-21
Filing date: 1936-12-21
Publication date: 1938-10-18
Anticipated expiration: 1955-10-18

Description

C. A. LORD DOWEL SUPPORT FOR CONCRETE PAVEMENT EXPANSION JOINTS Filed Dec. 21, 1936 Patented Oct. 18, 1938 UNITED STATES PATENT OFFICE DOWEL SUPPORT FOR CONCRETE PAVE DIENTEXPANSION JOINTS tion of Illinois Application December 21, 1936, Serial No. l16,898

6 Claims- This invention relates to the art of concrete pavement expansion joints of the known type wherein the meeting ends of the pavement at the joint have embedded therein dowels extending across the joint and usually coated with grease on one side of the joint to permit relative slip as the concrete expands or contracts under temperature changes. In the use of such dowels it is essential to the proper functioning that they be located accurately parallel to the axis of the pavement.

It has been the practice heretofore to rest the end portions of the dowel bars on supports known as chairs, either directly, or on cross rods extending between and seated on the chairs of each row on each side of the joint. The chairs include a pointed leg or legs that are driven into the dirt bed or floor on which the concrete is spread, and if, as often happens, the chairs of a row are not set to the same depth or one or more of them accidentally gets depressed too far into the bed or vide an improved chair structure by which the leg or legs of the latter can penetrate the bed only to a predetermined distance. Another object has been to provide an improved structure of dowel bar support by which the several chairs of each row are tied to each other in fixed spaced relation and so that adjacent chairs in the same row cannot tilt toward or from each other. Still another object has been to provide an improved dowel bar support wherein the two rows of chairs are maintained parallel and at fixed distances from each other and from the pavement joint.

Other objects and advantages of the invention will be apparent to persons skilled in the art from the following detailed description, taken in connectionwith the accompanying drawing wherein I have illustrated preferred embodiments of the invention, and in which- Fig. 1 is a perspective view of the preferred Fig. 4 is a fragmentary section, crosswise of the the form of chair shown in Figs. 1 and 2, said.

chair is preferably a one-piece structure consisting of a single length'of heavy wire bent to form a pair of downwardly divergent legs I, a lateral support II for a dowel bar laid between the limbs thereof, said limbs being continuous with the upper ends of the legs Ill, and a. seat 12 formed by contiguous twin limbs for a cross bar extending between adjacent chairs of a. single row and itself forming a direct support for the dowel bar.

The lower ends of the legs III are, of course, de-' signed to be impressed into the dirt bed on which the pavement is laid.

As shown in Fig. 2, round cross bars or rods ii are laid in the seats I! of the chairs of each row, and the dowel bars ll, which extend across the joint are directly supported adjacent to their ends on the, cross bars i3 and extend through the lateral dowel bar supports H. P and P (Fig. 4) designate the end portions of the pavement sections on the two sides of the joint, and S designates the usual flat slab of asphalt or like material that is commonly inserted as a packing between the meeting ends of the concrete sections. This slab is formed with transverse holes l5 .through which the dowel bars ll extend.

In prior constructions with which I am acquainted, the chairs of each row, whatever their structure, have been independent units, entirely unconnected except for the cross bars I3 occupying the seats of the chairs. As hereinbefore stated, unless the chair seats of the two rows are kept at substantially the same level, obviously the'dowel bars It will not be in perfect parallel-' ism which is essential to a good expansion joint of this character. To obviate this fault, I provide in association with each row of chairs a rod it which extends lengthwise of the row and is secured, preferably by spot or tack welding to the legs of the chairs a slight distance above the lower ends of the legs. This rod li serves two useful functions. In the first place, it limits the depth of penetration of the chair legs into the pavementbed, so that all of the chairs will be impressed to the same .extentinto the bed, thus maintaining their seats. l2ona common level;

and in the second place, it rigidlyconnects and spaces the several chairs of each row so that the cannot tilt toward or from each other.

the joint and each other.

The two dowel bar supporting structures are preferably located at equal-or substantially equal distances from the joint and in parallelism with To insure this accurate disposition of the, two rows of supports, I employ means for rigidly connecting them across the joint. The means preferably used and herein illustrated consists of cross rods I], extending across the joint and disposed at spaced intervals lengthwise of the two supporting structures, the ends of said rods II being secured as by spot or tack welding to the rods 16. Preferably, and as herein shown, each rod H is formed substantially midlength thereof, with a downward U- shaped offset l8,'which seats and embraces the lower edge portion of the packing slab S.

In Fig. 5 I have illustrated a slightly modified form of the one-piece chair, wherein the seat II for the cross bar It, instead of being formed as a continuation of the lateral dowel bar support Ii, is formed as a lateral offset of one of the legs I0. While the form of chair illustrated in Figs. 1 .and 2 is preferred, the form shown in Fig. 5 may be substituted therefor to practically the same effect if desired.

By virtue of the described construction, the dowel bars I can never get out of true parallelism either when erecting the chairs or when pouring the concrete; and by rigidly connecting the chairs .of each row and also the pairs of rows, the entire joint reinforcing structure retains its form and correct position when'and after the concrete is spread.

While I have illustrated and described a preferred embodiment of the invention, it is manifest that many of the structural details may be varied without departing from the operative principle of the invention, and hence I do not.

limit the latter to the specific form shown, but reserve all such variations, modifications and 'mechanical equivalents as fall within the spirit and purview of the claims.

I claim:

1. A two-legged dowel bar supporting chair for concrete pavement extension joints, consisting of a single length of wire bent to form a pair of legs consisting of end portions of the wire disposed in a common plane, a lateral sup;-

port for a dowel bar located between and in the plane of said legs, and a cross bar seat latrods extending across and secured to the lower erally ofiset from-the plane of said legs and lateral support. A two-legged dowel bar supporting chair for concrete pavement expansion joints, con-.

sisting of a single length of wire bent to form a pair of legs consisting of end portions of the wire disposed in a common plane, a lateral support for a dowel bar located between and in the plane of said legs, and a cross bar seat .2,188,558 1 I I g formed by contiguous twin U-shaped limbs, continuous with said lateral support and laterally ofi'set. from the plane of said legs and lateral support.

3. A two-legged dowel bar supporting chair for concrete pavement expansion joints, consisting of a single length of wire bent to form a pair of legs consisting of end portions of the wire, a lateral support for'a dowel bar continuous with the upper ends of said legs and lying between and in the plane of the latter, and a cross bar seat formed by a laterally oifset portion of one leg located between the upper and lower ends of the latter.

4- In a continuous spacer and support for dowel bar assemblies for concrete pavement expansion joints, the combination with parallel rows of 'chairs disposed respectively on opposite 1 sides of the joint, each chair having a leg formed with a free lower end adapted to be driven into the dirt bed of the pavement and the legs of all the chairs in each row being located in a common plane transverse to the roadway, of rods extending across and secured to the lower portions of ,the legs of the chairs of the two rows respectively, and means connected to said rods extending across the joint and rigidly connecting and spacing said rows.

'5. In a continuous spacer and. support for .two rows respectively, and rods connecting and spacing said first-named rods across the joint.

6. In a continuous spacer and support for dowel bar assemblies for concrete pavement expansion joints,- the combination with parallel rows of chairs disposed respectively on opposite sides of the joint, each chair having a pair of legs formed with free lower ends adapted to be driven into the dirt bed of the pavement and the. legs of all the chairs of each row being locatedin a common plane transverse to the roadway, of

portions of the legs of the chairs of the two rows respectively, and rods connecting and' spacing said first-named rods across the joint, said last named rods formed with downwardly oifset' portions adapted to seat and embrace the lower edge portion of a joint packing slab.

' CHESTER A. LORD.