US3378965A

US3378965A - Prestressed concrete reinforcing arch structure

Info

Publication number: US3378965A
Application number: US496864A
Authority: US
Inventors: Alben V Broquist
Original assignee: Individual
Current assignee: Individual
Priority date: 1965-10-18
Filing date: 1965-10-18
Publication date: 1968-04-23
Anticipated expiration: 1985-04-23

Description

April 23, 1968 A. v.- BROQUIST 3,378,965

` PRESTRESSED CONCRETE REINFORCING ARCH STRUCTURE -Filed OC'L. 18, 1965 INVENTOR.

ALBEN V. BROQUIST ATTORNEYS United States Patent O 3,378,965 PRESTRESSED CNCRETE REINFORCING ARCH STRUCTURE Alben V. Broquist, Chisago City, Minn. 55013 Filed oei. is, 196s, ser. No. 496,864 3 Crarms. (el. s2s8 ABSTRACT F THE DISCLOSURE A reinforced concrete arch structure having a prestressed core imbedded in the concrete and Acomprising a number of sections consisting of parts adapted to he assembled in the field and to he pre-stressed during or after erection.

The herein disclosed invention relates to concrete reinforcing structures and has for an object to provide a prestressed reinforcing structure having both a compression member and a number of tension members.

Another object of the invention resides in providing a structure which may be stressed in the field or during its fabrication.

A still further object of the invention resides in providing stressing means forming a part of the reinforcing structure and embedded with the same in the concrete.

A feature of the invention resides in constructing the compression member in sections of ceramic or similar material and preferably hollow and in the form of a tube with the ends of adjacent sections a-butting one another.

Another object of the invention resides in providing a construction by means of which a number of reinforcing structures may be arranged in the form of an arc of a circle whereby the reinforcing members may be used in arches.

An object of the invention resides in Iproviding plates bearing against the ends of the compression member and with the tension members extending through the plates and threaded to receive nuts which when tightened up, stress the reinforcing structure.

Other objects of the invention reside in the novel combination and arrangement of parts and in the details of construction hereinafter illustrated and/or described.

In the drawings:

FIG. 1 is a perspective view of a concrete reinforcing structure illustrating an embodiment of the invention.

FIG. 2 is a longitudinal sectional view of ya beam or joist in which a reinforcing structure similar to that shown in FIG. 1 has been employed and taken on line 2 2 of FIG. 3.

FIG. 3 is a cross sectional view taken on line 3 3 of FIG. 2.

FIG. 4 is a view similar to FIG. 2 showing a section of an arch with a number of reinforcing structures arranged in the form of an arc.

FIG. 5 is a sectional view taken on line 5 5 of FIG. 4 and drawn to a greater scale.

FIG. 6 is a plan sectional view of the stressing means shown in FIG. 5 and taken on line 6 6 of FIG. 5.

FIG. 7 is a fragmentary of a modi-cation of the reinforcing structure shown in FIGS. 4, 5, `and 6.

In the construction of pre-stressed reinforced concrete construction the common practice has been to pre-stress the tension members while they were erected in the forms and to cast the concrete about the same while so held. This requires rather complicated and heavy machinery and slows down the process of casting the concrete building -components in which the reinforcing structures are used. With applicants invention the reinforcing structure is pre-stressed before insertion in the forms with the stressing means forming part thereof.

ICC

Applicants reinforcing structure las used in beams and joists is best shown in FIGS. 1, 2, and 3 and comprises a compression member 10 and a plurality of tension members 20. Cooperating therewith is stressing means 30 and which is disposed at the ends of the compression member 10.

The compression member 10 consists of a number of sections 11 which are tubular in form and which have tubular walls 12 with a bore 13 therein. These sections have

ends

14 and 15 which abut each other and which taken in their entirety form the elongated compression member 10. The sections 11 of the compression member 1t) are preferably constructed of a non-ferrous material such as a ceramic material or of con-crete. Ordinary sewer tile have been found suitable for the purpose.

The tension members consist of rods formed of metal and which have ends 21 extending outwardly beyond the

ends

14 and 15 of the

end sections

16 and 17 of compression member 10.

The stressing means of the reinforcing structure includes two caps or

plates

31 and 32 which are constructed of metal and which butt up against the

ends

14 and 15 of the

last sections

16 and 17 of the compression member 10. These plates have holes 33 drilled in the same and through which the ends 21 of the rods 20 extend. These ends are threaded to receive nuts 34 which bear against the outer surface 35 of the

plates

31 and 32.

By tightening up the nuts 34 on the ends of the rods 20, the compression member 10 is placed in compression and the tension members 20 are stressed in tension. Thus a pre-stressed concrete reinforcing structure is provided which may be inserted into the forms for the concrete building components prior to the casting of the same.

For the purpose of illustrating the application of the invention a portion of a building component has been shown in FIGS. 2 and 3. This component may be used in 4constructing a floor or a roof. This component is elongated in

form having sides

41 and 42,

ends

43 and 44, a top 45 and a bottom 46. The pre-stressed reinforcing member is imbedded in the concrete 47 forming said component with the entire reinforcing member covered with concrete. The same may if desired be placed nearer the bottom 46 to bring more of the upper portion of the component in compression. In the sides 41 of the component are formed grooves 48 and on the sides 42 are tongues 49. The tongue 49 of one component ts into the groove 48 of the adjacent component to lock the parts together and provide an interlock between the various components and an unitary Iconstruction.

In FIGS. 4, 5, and 6 the reinforcing structure indicated by the reference numeral 50 has been shown as applied to an arch. Instead of a long straight reinforcing structure, several short units are employed, which are connected together to form a composite structure arcuate in form. Four of the units of this structure have been shown in FIG. 4 and designated by the reference numerals Si, 52, 53, and 54. Each of these units consists of a -compression member formed with three

tubular sections

56, 57, and 58. These units also have tension members, the

units

51 and 53 having

tension members

61, 62, and 63 and the

units

52 and 54 having

tension members

64, 65, and 66. Each unit has three tension members, and the tension members of one unit are interposed between those of the other unit, so that the members are sixty degrees apart. If desired, however, the tension members of one unit may be placed closer to those of the adjoining unit.

The stressing means of the reinforcing structure 50 consist of

plates

67 and 68 for each section having holes through which the

tension members

61, 62, 63, 64, 65, and 66 and nuts 69 screwed on the threaded ends of the tension members extend, the same as with the other form of the invention. Due to the curvature of the completed reinforcing structure the

plates

67 and 68 of adjoining units become spaced at the convex portion of the ar-ch and contact one another at the concave portion of the arch. In order to transmit stresses from one unit to the other, the two adjoining caps between the units are made integral with a connecting portion 71 therebetween. The parts may be welded together or a single plate ernployed, bent at 72 and 73 to form the connecting portion 71 and with the opposite edges contacting and welded together. If desired the composite structure may be cast from malleable iron or similar material.

Opposite the nuts 69 and in the plates Opposite the plates engaged by the nuts 69 are openings 74, and through which a wrench may be inserted to engage the nuts and manipulate the same.

Concrete indicated at 76 is poured into the forms in which the reinforcing structure is positioned to form building components similar to those previously described.

In FIG. 7 is shown a modification of the reinforcing structure for use in arches. This structure is similar to the foregoing structure, and the same reference numerals will be used to designate like parts. The

plates

67 and 68 are the same except the connecting portion 7l is dispensed with. Also holes 75 have been substituted for the openings 74. In this form of the invention the tension members extend through both of the

plates

67 and 68. These members, between the

plates

67 and 68 have sleeves '77 mounted on them and which form spacers serving the same purpose as the conne-cting portion 71 of the other form of the invention. Beveled washers 78 underlying the nuts 69 provide a square seat for said nuts.

The method of using the invention is obvious. The parts can be assembled at the factory and shipped in an erected form or the parts can be erected at the site where the reinforcing structure is to be used. In either case a trough is provided of the desired length and the compression member sections arranged in the trough in abutting relation. The end plates are then held in position while the tension members 20 are threaded through the holes 53 in the end plates and the nuts 54 applied. The nuts can then be tightened to give the desired initial stress.

The advantages of the invention are manifest. Heavy cumbersome equipment for the purpose of stressing the tension members is dispensed with and also the supporting structure for temporary stressing the tensile members is done away with. By the use of hollow tubes for the compression members less concrete is employed than would otherwise be necessary. The reinforcing structure i may be rapidly assembled and stressed and when placed in the forms, may be completely covered with concrete to form the ultimate building component.

Changes in the specific form of the invention, as herein described, may `be made within the scope of what is claimed without departing from the spirit of the invention.

Having described the invention, what is claimed as new and desired to he protected by Letters Patent is:

1. In a reinforced concrete arch structure having a prestressed core imbedded in the concrete, said core comprising a number of sections cach having:

(a) an elongated compression member,

(b) a plurality of elongated rods, threaded at their ends and disposed about the compression member,

(c) end plates at the ends of the compression member and against which the compression members bear,

(d) said rods extending through said plates,

(e) nuts on said rods engaging said plates to compress the compression member and tension the rods,

(f) the plates at the adjoining ends of the sections being arranged in V-shaped formation and (g) connecting members between the adjoining plates for holding the plates in fixed relation.

2. A reinforced concrete arch structure according to claim 1 in which:

(a) at least one of the connecting members is integral with both adjoining end plates.

3. A reinforced concrete arch structure according to claim 1 in which:

(a) at least one of the connecting members utilizes one of the rods which extends through both of the adjoining plates and (b) a sleeve encircling said red and engaging both of said plates.

References Cited UNITED STATES PATENTS 25,537 9/1855 Van Duzer 52-87 2,307,215 l/l943 Graef 52-86 X 2,874,812 2/1959 Clevett 52-86 X FOREIGN PATENTS 26,284 6/1923 France. 928,623 6/1947 France.

2,428 l0/l863 Great Britain. 452,126 1936 Great Britain. 511,262 1/1955 Italy.

FRANK L. ABBOTT, Primary Examiner.

A. C. PERI-IAM, Examiner.