US2561581A - Manufacture of reinforced hollow structures - Google Patents

Description

July 24, 1951 s. MACERATA ,MANUFACTURE OF REINF ORCED HOLLOW STRUCTURES Filed July 18, 1947 .a w A R M @AO o .n U A m Patented July 24, `1951 MANUFACTURE or REINFonoEnnoLLow STRUCTURES Stelio Macerata, Johannesburg, Transvaal,

' Union of South Africa I Application July 18, 1947, 'Serial No. 761,930 In the Union of South Africa August 12, 1946 `1o claims. (on ca -154i 'I'his invention relates to a method of manui l facturing hollow structures, and to structures produced by such method. The invention is particularly applicable to the manufacture oftanks,

silos, bins, towers (such as cooling towers), hop- K pers, chimneys, domes and the like.

The main object of this invention is to enable the application to such structures of the Hoyer method of reinforcement by means of prestressed wires.

A method according to this invention comprises the steps of so arranging a reinforcing wire that it has, in plan, the shape of an open or closed figure having a plurality of straight sides (such as a polygon) the direction of the wire being.

except at the free ends of such wire where the direction may or may not be reversed, so reversed at each corner of the figure that the wire has, at each such corner, a loop projecting beyond that cross-section of the intended hollow structure at which such loop is located; tensioning said wire by application of suitable tensioning means at its free end or ends and possibly also at one or more of said loops; casting or otherwise moulding the structure so that the sides of the wire figure are partly embedded therein and so that said loops or parts thereof project from said structure; allowing the moulded material to .harden to the required extent; and then preferably cutting olf or otherwise removing said projecting wire loops.

Generally, the wire will have the shape of a spiral which is polygonal in plan and which may extend along the whole or part of the height of the structure that is to be erected and one or `more such spirals may be incorporated in each structure. In some cases it is preferable so to incorporate in some part of the structure two or more polygonal spirals that each side of each spiral crosses, at least in plan, at least one side 4reinforced hollow structure.

of at least one other wire spiral. When two or more polygonal wire spirals are provided within the same length of the longitudinal section of the structure, the corresponding sides of the wire polygons are preferably differently or oppositely inclined with respect to the longitudinal axis of the structure and are thus also inclined with respect to one another. In thismanner, it is possible to reinforce the structure in two, preferably opposite, directions.

When the projecting loops are cut 01T, they leave all the sections of the wire or wires which remain within the shell of the structure pretensioned to the desired degree.

In a preferred form of carrying out the invention, the guiding means at each, except one, corner of the wire figure comprises a fixed sheave or a pair of lxed sheaves, whilst at Said one corner there is provided a tensioning means which vcomprises the combination of a xed sheave with a movable sheave, which is constrained for movement along a fixed rail and with means, which may be operated by a hydraulic jack, for forcing saidwmovable sheave in the direction away from said fixed sheave.

If'the hollow structure which is to be erected is polygonal in plan, at least one reinforcing wire is preferably so arranged that all the loops of that wire are formed at the corners of said structure and so that each side of the polygonal structure has a length of the reinforcing wire extending throughout the whole length of such side.

If, on the other hand, the hollow structure is round, each reinforcing wire will be arranged, in plan, in the form of an eightor more-sided polygon so that a substantial part of the length of each side of such polygon will be `embedded in 'the shell of the structure when the latter has been completed.

The invention will be further described with reference to the accompanying drawings, in which:

Figure 1 is a plan section of a gonal structure.

Figure 2 is a part of a plan section of a round reinforced poly- Figure 3 is a diagrammatic View of a polygonal structure the walls of which are reinforced in several directions.

With reference to Figure l, 2 and 3 indicate two .parallel reinforcing wires and 4 indicates the throughout the whole length of each of its sides.

' At the corner II, each wire is guided about a stationary sheave I2 and about a movable sheave I3, which is constrained for movement along a fixed' rail I4. I5 indicates a means, which may `be operated by a hydraulic jack, for forcing said movablejsheave I3 in the direction away from said fixed sheave I2.

In carrying out the invention, rst a scaffolding I6 is erected to which the sheaves are secured in is required, or it may be formed by casting, pref-V erably with the use of vibrators, in which .case internal and external shuttering walls will be" erected from which the loops I1, of pre-tensioned wire project at the corners. H

After the cementitious material has sufficiently solidied, the shuttering is removed andthe wire loops Il are cut off leaving the completed structure in which all sections of the reinforcing wire are `under tension, thus producing the required degree of compressive stress in the whole ,shell of the structure.

Instead of or in addition to the wires 2, 3, a reinforcing wire i8 may be provided which is guided about fixed sheaves I9. The one end of said wire IS may be fixed and the other end, 2 l, will be tensioned by suitable means which are not shown in the figure.

i In the arrangement of Figure 2, the structure 22 which is to be erected is circular, and the two reinforcing rods or wires 23 are so arranged that they form, in plan, two polygonal figures the the wire so that the sides of the wire figure are partly embedded therein and so that at least parts of said loops project from said material; and allowing the cementitious material to harden until it forms the hollow structure.

i. 2,y A method as claimed in claim 1, comprising the steps of removing such parts of the wire as project from the set cementitious structure.

v 3. A method as claimed in claim 1, in which the wire is bent to form a spiral which is polygonalin plan and which extends along the whole of' the height of the structure that is to be vtractati-V 4;. Al method as claimed in claim 1, in which sides of which cross one another in the Vsame Y manner as do the lines of a star of David. The direction of the wires is reversed at the stationary sheaves 24 so that portions 25 of each wire extend within the plan of the structure while wire loops Vat project beyond the plan of said structure. The.

ends 26 'of the wires are fixed as by being anchored to the scaifolding, and the ends 2'1 are tensioned by suitable means. After the structure 22 has been formed from cementitious material,

the wire loops 28 projecting from said structure.

are preferably cut off. A y A,

As shown in Figure 3, the reinforcing wires which, in plan, appear as polygonal figures, are

preferably arranged in the form of spirals. In Figure 3, two groups 29, 38 of wires are shown' which reinforce respectively the sides 3l, 32, 33, 34, 35, 36 and the sides 3|, 31, 33, 34, 33 and 356 of the structure.

Each group of wires forms, during the manufacture Vof the structure, at each ofthe corners from which said wires are shown to extend, a series of loops which project beyond said corners, said loops being cut olf after the completion of the structure leaving the wires 29, 30, pretensioned to the desired degree.

I claim:

1. A method of manufacturing hollow structures comprising the steps of bending a reinforcing wire to the shape of a figure which, in plan, has a plurality of `straight sides, the direction of the wire being so reversed at each cor.- ner of the ligure that the wire has, at each such corner, a loop projecting beyond that cross-section of the intended hollow structuregat which Yso such loop is located whereby to provvide V`a sharp a,

intersection of the reinforcing wire at eahcorner; tensioning said wire by applicationv of suitable means; applying cementitious material to the wire is bent to form a spiral which is polygonal plan and which extends along part of the height of the structure that is to be erected.

A method as claimed in claim 1, in which a plurality of reinforcing wires is used.

6. A method as claimed in claim 1, in which at least two wires are used each .of which is bent to the shape of a polygonal spiral, each side. f each spiral crossing, at least in plan, at least one `side of at least one other wire spiral.

'7'. A method as claimed in claim 1, in which at least two wires are used within the same length of the longitudinal section of the structure, each wire being bent to the shape of a polygonal spiral; the corresponding sides of the wire polygons being differently inclined with respect to the longitudinal axis of the structure and thus being also inclined with respect to one another.

8. A method as claimed in claim l, for erecting polygonal structures in which at least one reinforcing wire is so arranged that all the loops of that wire are formed at the corners of said structure and so that each side of the polygonal structure has a length of the reinforcing wire extending throughout the whole length of such side.

9. A method as claimed in claim 1, for erecting circular structures, in which at least one reinforcing wire is bent to a figure which, in plan, has the shape of a'polygon having at least six sides, av substantial part of the length Aof each side o f such polygon being arranged within the plan, at the corresponding section, of the shell of the structure that is to be erected.

' 10. A method of manufacturing hollow struc'- ytures comprising the steps of erecting scaffolding, fixing to said scaffolding a series of sheaves spirally arranged; placing a reinforcing wire so that the direction of the latter is reversed to form a loop around some of said sheaves; tensioning said wire; erecting shuttering so that parts of the prestressed wire are within an area determined by said shuttering while said sheaves are outside said area; placing cementitious material within such shuttering; allowing said material to harden; and removing said scaffolding, said sheaves and said shuttering.

STELIO MACERATA.

REFERENCES CITED Y The following references are of' record inthe le of this patent:

UNrTED STATES PATENTS r*2,444,011 Billner Jan. 7,1947

Claims (1)

1. A METHOD OF MANUFACTURING HOLLOW STRUCTURES COMPRISING THE STEPS OF BENDING A REINFORCING WIRE TO THE SHAPE OF A FIGURE WHICH, IN PLAN, HAS A PLURALITY OF STRAIGHT SIDES, THE DIRECTION OF THE WIRE BEING SO REVERSED AT EACH CORNER OF THE FIGURE THAT THE WIRE HAS, AT EACH SUCH CORNER, A LOOP PROJECTING BEYOND THAT CROSS-SECTION OF THE INTENDED HOLLOW STRUCTURE AT WHICH SUCH LOOP IS LOCATED WHEREBY TO PROVIDE A SHARP INTERSECTION OF THE REINFORCING WIRE AT EACH CORNER; TENSIONING SID WIRE BY APPLICATION OF SUITABLE MEANS; APPLYING CEMENTITIOUS MATERIAL TC THE WIRE SO THAT THE SIDES OF THE WIRE FIGURE ARE PARTLY EMBEDDED THEREIN AND SO THAT AT LEAST PARTS OF SAID LOOPS PROJECT FROM SAID MATERIAL; AND ALLOWING THE CEMENTITIOUS MATERIAL TO HARDEN UNTIL IT FORMS THE HOLLOW STRUCTURE.

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