US317793A - Laying artificial stone or concrete arches - Google Patents

Description

(No Model.) P. H. JACKSON.

LAYING ARTIFICIAL STONE 0R CONCRETE ARCHES. No. 317,793. Patented May 12, 1885.

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PETER H. JACKSON, OF SAN FRANCISCO, CALIFORNIA.

LAYING ARTIFICIAL STONE OR CONCRETE ARCHES.

SPECIFICATION forming part of Letters Patent No. 317,793, dated May 12, 1885.

I I Applicatim filed November 2F. 1884. (X0 model.)

To all 2217110111. it may concern.-

Be it known that I, PETER H. JACKSON, of the city and county of San Francisco, State of California, have invented certain 'new and useful Improvements in Laying Artificial Stone or Concrete Arches, Forming Sidewalks and Floors of Buildnigs; andl declare the following to be a full, clear, and exact description thereof, sufficient to enable any person skilled in the art to which my invention belongs to make and use the same, reference being had to the accompanying drawings, forming part of the specification.

Figure 1 is a perspective view of the longitudinal sectional arch. Fig. 2 is a perspective View of the longitudinal sectional arch with the intermediate section divided into transverse sections. Fig. 3 is a section through Fig. 2 on the line 00 3 z.

Myinvention relates to an improved method of forming artificial stone or concrete arches over basements, cellars,or other chambers, the top surface forming a sidewalk or floor surface, the whole resting on iron beams.

Plastic materials of which artificial stone or concrete arches are made shrink, and thereby open perpendicular cracks or joints in the thin parts at the ends of the arches over thebeams or bearers which sustain the arches. The haunches and the remaining part of the arch between the beams being much thicker than the parts over the top of the beams aggregate the particles in shrinking, so as to cause open these joints are formed,the ledges over the top of the beams are weakened by the division and liable to crack and break off when subjected to severe usage from the following cause: The shrinkage of the material of the arch between the beams draws it away from the abutting sides of the beams. This causes the arch to settle between the beams. To this is to be added the settlement caused by striking the centers that is, taking away the wooden forms upon which the arch was formed and sustained. These cause the arch to drop until the extremes reach out to meet the abutting sides of the beams, and to further settle when subjected to a load in the center of the arch. The thin ledge over the top of the beam does not participate in the settlement of the arch,but bears on the edge of the top flange of the beam h at a,

Figs. land 2, which is the fulcrum, and from there to the crack or joint it is raised from the beam h, the ledge at the crack or joint being the lever which is acted on by the load passing over it to break it off at a.

The object of my invention is not to have any separation of the artificial stone or concrete over the top of the beams, and also to produce compression of the parts.

After the beams hare set in position and the wooden centers are in place to form the botto m of the arch, the beams are then covered and filled up to the desired height with the plastic concrete material, and on each side up to the inclined stopping-off pieces of wood or metal, denoted by the lines 0 d e f, Figs. 1 and 2, and the material is rammed to a proper consistency, thick paper or any other separating material usual having been laid against the side of the stopping-off pieces 0 d 0 to prevent the plastic material from adhering to the remaining part of the arch which is to be formed, or, if the plastic material is allowed to stand a while, molders parting-sand applied or dusted on will answer the purpose. After the stopping-off pieces have been withdrawn this application will prevent sticking to the other parts of the arch to be formed. Then the mate rial is filled in between the lines 0 d and 6f, so as to form thecentral or remaining part of the arch, which is in the form of a keystone, and the sides of the arch at c d e f, first formed, are

the abutments to the keystone of the arch. ings or joints over the top of the beams. When Another mode of making the arch is to dispense with the stopping-off pieces described, and place thick stiff paper, sheet-zinc, or other sheet metallic substance or any suitable material that will divide the sections and preserve the sloping lines 0 d e f, Figs. 1 and 2,

ing of wedgform will, from its own weight, as Well as any load that may come upon it, compress itself and compress the abutments, and all parts of the artificial stone or concrete material and counteract the tendency to separate any of the parts.

Artificial stone is Portland cement concrete, and its capacity to resist compression is much greater than its capacity to resist separation, and by my construction all the parts are compressively employed, which is employing the material in its strongest resisting property.

In Gen. Gilmores work entitled Ooignet Bton, or Other Artificial Stone, on page 54, is as follows: With a mixture of Portland cement one and sand two, the ratio of the crushing to the tensile strength will generally be found between the limits of fourteen to one and nineteen to one. With cement one and sand four it reaches as high as twenty-five to one and twenty-nine to one. With cement one and sand five as high as thirty-five to one. In the work entitled Iron Arches, by W. Airy, on the ninth page, second line, referring to the voussoir arch, are these words, (of which my construction assimilates in as far as the forces exerted in the material when employed As regards the strain of the material of the arch this will be, of course, a simply compressed strain, distributed more or less ac cording to the degree of elasticity which exists in the stone. 0n the twelfthline are these words: In case of the continuous arch, it must be understood there is at every point a bending moment and a thrust force. Therefore,an arch made in one piece extending from beam to beam when employed, the lower part extending down to the intrados is subjected to separation of the parts of which concrete is so feeble to resist. In addition to this the shrinkage of the plastic material when the moisture is drying out draws away from the sides of the beams against which they abut; hence the arch must stretch out when employed to meet the abutting sides of the beams which it has drawn away from in shrinkage.

All concretes have much greater capacity to resist compression than separation. By this means of greatly strengthening the arches I am enabled to make them of less thickness and of equal strength to those made in one piece between the beams; also there is a saving in the cost of the sustaining-beams as they have to carry less weight than if thick and heavier arches were used.

Another feature of my invention, as shown in Figs. 2 and 3, is in making the arches cut through on an incline or taper prepared in a cross direction to those described, so that they may be lifted out without disturbing the side sections B, as in case of the breaking of any of the sections, instanced by the falling of the I front of the building on it in case of fire.

Section 9, Figs. 2 and 8 may be lifted out without disturbing sections 6 t or the beamsections B B; or sections i and i can be lifted out without disturbing the longitudinal beamsections B B.

At the place of the divisions of the sections, should it be necessary to provide against leakage, thin strips of wood or metal may be set forming a channel between the sections either on the top orbottom surface, and when the material has become set and hard the strips are withdrawn and the channels are filled up with plastic or other cement.

Having thus described my invention, what I claim as new, and desire to secure by -Letters Patent, is V v 1. A sidewalk or floor consisting of artificial stone or concrete longitudinal sectional arches, the side sections of the arches formed in a plastic state on the sides and over the top of the supporting-beams and supporting an intermediate separated section, substantially as herein described.

2. A sidewalk or floor consisting of artificial stone or concrete longitudinal sectional arches, the side sections of the arches formed in a plastic state on the sides of the supportingbeams and supporting an intermediate separated section which produces compression, substantially as herein described.

3. A sidewalk or floor consisting of artificial stone or'c-oncrete longitudinal sectional arches, the side sections of the arches formed in a plastic state on the sides and over the top of the supporting-beams and with sloping sides which support a separated intermediate section, also with sloping sides conforming to the sides of the side sections, substantially as herein described.

4. Asidewalk or floor consisting of artificial stone or concrete longitudinal sectional arches, the side sections formed in a plastic state on the supporting-beams and with sloping sides faced with sheet metal, thick paper, or other separating material which will permit the intermediate section formed on it to wedge and produce compression of the parts, substantially as herein described.

5. A sidewalk or floor consisting of artificial stone or concrete longitudinal sectional arches, the side sections of the arches formed in a plastic state on the sides of the supporting-beams and supporting a separate intermediate section, the intermediate section divided into transverse sections with sloping supportingedges, so that the pieces may be lifted out without disturbing the side sections, substan tially as herein described.

6. In a sidewalk or floor consisting of artificial stone or concrete longitudinal sectional arches, the side sections of the arch formed in' a plastic state on the supporting-beams, and supporting a separated intermediate section with channels between the sections on either surface filled with plastic or other cement, substantially as herein described.

PETER H. JACKSON.

Witnesses:

LINCOLN SAMTAG, JAMES B. LANE.

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