US3372448A - Apparatus for prestressed concrete members of non-rectilinear shape - Google Patents

Description

March 12 1968 APPARATUS FOR PRESTRESSED CONCRETE MEMBERS OF NON-RECTILINEAR SHAPE Filed Nov. 18, 1964 United States Patent fifice 3,372,448 Patented Mar. 12, 1968 3,372,448 APPARATUS FOR PRESTRESSED CONCRETE MEMBERS OF NON-RECTTLTNEAR SHAPE Georges Nays, Neuiiiy-sur-Seine, France, assignor to Societe pour la Fabrication de Produits en Beton Arnie on Precontraint Bepre, Neniiiy-sur-Seine, France Filed Nov. 18, 1964, Ser. No. 412,144

5 Claims. (61. 25118) This invention relates to the production of concrete structural members of non-rectilinear, or arcuate, shape, by means of prestressed-concrete techniques.

Serious difliculty has been encountered in the past when it was attempted to cast parts of other than straight configuration including pre-tensioned reinforcement wires or cables therein, that is to say wires or cables placed under tension within the concrete mold or form prior to the pouring of concrete into the mold, the difiiculty being due to the non-rectilinear shape of the mold.

An example of a structural member in connection with which the difficulty arose and to which the present invention is particularly applicable, is provided by the concrete lamp-posts used in the illumination of highways and other public areas. Such lamp-posts include a straight vertical lower part or stem, and a curving upper part or crook merging with the stem, with one or more lamps being supported from the top of the crook. Because of the afore-mentione-d difiiculty in positioning pretensioned reinforcement wires in the arcuate or crook portion of the concrete form, the casting procedure heretofore usually adopted for the casting of such lamp-posts generally involved two stages. In a first step the crook portion of the post was cast in an arcuate mold with reinforcement wires placed in slack, untensioned condition in the mold, and projecting beyond the end of the mold a length corresponding to that of the desired straight stem section of the lamp-post. Then, in a second stage, the projecting parts of the wires were tensioned by suitable jacking means in a straight mold section, and concrete was poured into this straight mold section to produce the straight stern of the lamp-post.

The resulting precast structure was clearly heterogeneous and non-monolithic in character, and therefore lacked strength. Cracks were liable to occur at the junction between the stem and crook portions under the stresses to which the structure was subject during transportation, erection and use. The consequences of these defects are graver still in the case of arcuate structural members subjected to heavy loads in use, such as arcuate beams, arch buttresses and the like in buidings, bridges and other structures.

It is an object of this invention to provide concrete structural members of non-rectilinear or arcuate shape, which will include therein reinforcement wires or cables applied in pre-tensioned condition, extending throughout the length of the member. A more specific object is to provide such a member of part-rectilinear and part arcuate shape, erg. a lamp-post, which will be monolithic and will include pre-tensioned reinforcement wires throughout the length of the member.

Further objects are to provide improved apparatus for the precasting of non-rectilinear concrete members, embodying improved provision for the placement of reinforcing wires in pre-tensioned state in the non-rectilinear concrete mold or form.

In an important aspect, the invention provides wiresupporting plates disposed in the cavity of a non-rectilinear concrete mold transversely thereof, the plates being perforate so as to receive reinforcing wires through the perforations and thereby support the wires in properlyspaced relation across the mold cavity. Thus the wires can be pre-tensioned prior to pouring concrete into the mold.

Further objects relate to the provision of improved means for supporting the said die-plates Within the mold so that the plates wiil resist any tendency to displacement under the action of the tensioned wires, as well as means for withdrawing said supporting means out of the mold after the concrete has substantially set. Other objects will appear.

An exemplary embodiment of the invention will now be described for illustrative purposes with reference to the drawings wherein:

FIG. 1 is a simplified overhead plan view of apparatus according to the invention for precasting a large-sized arcuate lamp-post; and

FIG. 2 is a larger-scale view as seen on a transverse plane such as IIII, FIG. 1, illustrating a wire-spacer or die-plate together with its supporting means according to the invention.

Apparatus for pre-casting a one-piece concrete structure of elongated, arcuate shape, specifically a highway lamp-post in the selected example, is illustrated generally in FIG. 1 as being composed of a number of segmental sections such as 2, assembled end to end in the desired general configuration.

Each segmental section such as 2 includes a bedplate 3 which extends laterally a substantial distance in both directions and supported on the bedplate, a concrete mold section which is generally designated 1 in FIG. 1. The mold section 1 is shown in FIG. 2 as comprising a generally channel-shaped mold supported centrally of the upper surface of bedplate 3 including oppositelypositioned lower angle members 15, 16, upper angle members 18, 18, and gusset plates such as 20, assembled around the mold cavity and to bedplate 3 through suitable means not shown, such as bolts.

It will be understood that the sections 2 are supported so that the mold channel sections 1 are positioned end to end to provide a continuous molding channel from one to the opposite end of the precasting apparatus. The supporting means for the sections 2 have not been shown but may comprise conventional base-blocks positionedbeneath the bedplates 3 so as to overlap the respective planes of joint such as 4 between adjacent sections 2 and at the outer ends of the endmost sections 2 of the apparatus.

Beyond the ends of the apparatus so far described are positioned anchoring means for the respective ends of steel reinforcing wires. Said anchoring means are shown as including a wire-blocking device 14 at one end of the apparatus and an anchor plate device 15 at the opposite end, both these devices 14 and 15 being of conventional design and hence not here described in detail. Conventional jacking means may be associated with said devices for tensioning the wires.

The reinforcing wires, two of which are partly indicated at 7 in FIG. I, extend from one to the other of the blocking and anchoring devices 14 and 15 at opposite ends of the apparatus through the cavity of the continuous concrete mold 1.

Means are provided according to the invention for maintaining the wires in proper position within the mold while under pre-tension during the concrete pouring operations. These means comprise a number of wire-spacer die-plate assemblies, generally designated 1. In FIG. 1, one of the die-plate assemblies p is illustrated in small-scale general view while the remaining die-plate assemblies p have been schematically indicated as dot-dash lines. FIG. 2 shows a die-plate assembly P in greater detail.

The die-plate assemblies p are provided in those of the segmental sections 2 of the apparatus which participate in forming the curved portion of the structure, and the number of said assemblies provided in each such section is in a general way proportionate to the degree of curvature of the portion of the structure in which Said Section is located, as will be apparent from FIG. 1. The assemblies 2 may, as shown, be completely omitted from those sections 2 of the apparatus in which the concrete structure is rectilinear.

Referring especially to FIG. 2, each spacer-plate assembly P comprises a spaceror die-plate 5 formed with a generally circular series of holes 6 for the passing of the reinforcing wires 7 therethrough. As here shown, there are eight holes 6 through which eight reinforcing wires 7 are threaded. The die-plate 5 is also formed in this example with a larger central opening 8 which is used to pass an electric conductor cable, not shown, serving eventually to supply electric power to the lamp or lamps supported on the finished lamp-post.

For retaining the die-plate 5 in position, there are provided screw-pins 10, 10' which extend oppositely inwards from opposite sides of the mold structure, and are threadedly supported in holes formed in the vertical fianges of a pair of angle brackets 11, 11' having their horizontal flanges secured, e.g. bolted, to the bedplate 3 on opposite sides of the mold assembly. The screw pins 10, 10 are extended inwardly by smooth shanks 12, 12' which extend through holes formed in the opposite sides of the mold structure 1 and have tapered ends engaging cutouts formed in the related sides of the die-plate 5. The outer ends of the screw pins 10, 10' are fitted with nuts 22, 22 engaging the outer sides of the vertical flanges of brackets 11, 11 for locking the screw pins in adjusted positions.

It will be understood that in the molding process of the invention, using the apparatus described, the spacer or die-plates 5 of the assemblies 1) are positioned at prescribed locations in the mold sections 2, the reinforcement wires 7 are passed through the hole 6 of the respective plates 5 and are then pre-tensioned using conventional jacking means not shown. The screw-pins 10, 10' may then be readjusted for a correct positioning of the wires 7 in their properly spaced relation as between one another and with respect to the side surfaces of the mold. The die-plates 5 then act to take up and compensate any radial stresses created by the wires in the mold. Concrete is then poured into the continuous mold, around the reinforcing wires 7 and the die plates 5 and the inner end portions of the pins 12, 12', as well as the aforementioned central conductor cable if present. After the concrete has set, the screw pins 10, 10' are withdrawn, this operation being facilitated by the smooth and tapered shape of the shank portions 12, 12. The cavities remaining in the concrete after withdrawal of said shank portions may be subsequently filled in with cement if desired. The die plates 5, of course, remain imbedded permanently in the finished concrete structure.

It will be apparent that the invention has provided a novel apparatus for the pre-casting of concrete structural parts of arcuate form, whereby pro-tensioned steel wires can be employed for the pro-stressing of the concrete with extremely desirable results as to the ultimate strength 4 of the member. The process and apparatus are simple and economical.

It will be understood that various modifications may be introduced into the single embodiment of the invention shown and described While remaining within the terms of the ensuing claims. Moreover, it will be apparent that the invention is applicable to the casting of pre-stressed concrete parts of arcuate shape for uses other than lampposts, such as arcuate beams and joists for buildings, bridges and the like.

What is claimed is:

1. In an apparatus for casting a prestressed concrete member which is of elongated non-rectilinear shape comprising:

means defining an elongated non-rectilinear concrete form;

means for positioning reinforcing wires within the cavity of the form longitudinally thereof including means for tensioning said wires the improvements which consist in the provision of; at least one perforate Wire-supporting and spacing plate disposed in the cavity of said form transversely thereof and receiving said tensioned wires through the perforations therein, whereby to support the pretensioned wires in properly spaced relation across the cavity during the pouring of concrete into the form around the pre-tensioned wires and during the setting of said concrete; and means projecting into the cavity through opposite side walls of said form and engaging opposite sides of said plate for adjusting the transverse positions of and supporting said plate in position the pouring and setting of the concrete. 2. An apparatus as defined in claim 1 wherein said means projecting into the cavity comprises transversely aligned pins, and means for readily withdrawing said pins out of the set concrete.

3. The apparatus defined in claim 2, wherein said pins include smooth tapered inner end portions engageable with said plate and screw-threaded outer portions integral with said smooth portions, and means supporting said threaded portions for adjustable movement of said pins into and out of said form.

4. Apparatus for precasting a pre-stressed concrete member of elongated non-rectilinear shape comprising:

a plurality of sectional units each including a base and a mold section;

means supporting all said units in end-to-end juxtaposed relation with said mold sections in contiguous serial relation so as to define a continuous elongated, nonrectilinear mold corresponding in shape to that of said member;

means for positioning reinforcement wires within the cavity of said continuous mold longitudinally thereof including means for tensioning said wires; a perforate wire-supporting and spacing plate disposed in the mold cavity of at least one of said units within a non-rectilinear part of said continuous mold, said plate being disposed transversely of the mold cavity for receiving said tensioned wires through the perforations therein whereby to support said wires in spaced relation across the cavity during the pouring of concrete into the form around the pre-tensioned wires and during the setting of said concrete;

transversely aligned pins projecting into the cavity through opposite sidewalls of said mold and engageable with opposite sides of said plate for supporting said plate during the pouring and setting of the concrete; and

means upstanding from the said base of said unit on opposite sides of said mold section, and supporting said pins for adjustable movement towards and away from said mold section, whereby to permit withdrawal of said pins from out of the concrete when. set.

5. The apparatus defined in claim 4, wherein said pins 870,429 11/ 1907 Grimler 52726 include smooth tapered inner end portions engageable 1 736 531 12 1930 Rue 52 726 for adjustable movement towards and away from said 5 2874812 2/1959 Cleve 52-7726 mold section.

References Cited J. SP ENCER OVERHOLSER, Przmwry Exam-mar. UNITED STATES PATENTS R. D. BALDWIN, Assistant Examiner.

780,312 1/1905 Burkholder et a1. 25-418 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,372,448 March 12, 1968 Georges Neys It is certified that error appears in the above identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading to the drawing, line 2 and in the heading to the printed specification, line 2, before"PRESTRESSEIZI", each occurrence, insert PRODUCING column 1, lineSl, for "buidings" read buildings column 4, line 32, after the word "position" insert during Signed and sealed this 29th day of July 1969.

(SEAL) Attest:

WILLIAM E. SCHUYLER, JR.

Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer

Claims (1)

1. IN AN APPARATUS FOR CASTING A PRESTRESSED CONCRETE MEMBER WHICH IS OF ELONGATED NON-RECTILINEAR SHAPE COMPRISING: MEANS DEFINING AN ELONGATED NON-RECTILINEAR CONCRETE FORM; MEANS FOR POSITIONING REINFORCING WIRES WITHIN THE CAVITY OF THE FORM LONGITUDINALLY THEREOF INCLUDING MEANS FOR TENSIONING SAID WIRES THE IMPROVEMENTS WHICH CONSIST IN THE PROVISION OF; AT LEAST ONE PERFORATE WIRE-SUPPORTING AND SPACING PLATE DISPOSED IN THE CAVITY OF SAID FORM TRANSVERSELY THEREOF AND RECEIVING SAID TENSIONED WIRES THROUGH THE PERFORATIONS THEREIN, WHEREBY TO SUPPORT THE PRETENSIONED WIRES IN PROPERLY SPACED RELATION ACROSS THE CAVITY DURING THE POURING OF CONCRETE INTO THE FORM AROUND THE PRE-TENSIONED WIRES AND DURING THE SETTING OF SAID CONCRETE; AND MEANS PROJECTING INTO THE CAVITY THROUGH OPPOSITE SIDE WALLS OF SAID FORM AND ENGAGING OPPOSITE SIDES OF SAID PLATE FOR ADJUSTING THE TRANSVERSE POSITIONS OF AND SUPPORTING SAID PLATE IN POSITION THE POURING AND SETTING OF THE CONCRETE.

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