US1071118A - Centering for concrete or masonry arches. - Google Patents

Description

UNITED sTATEs PATENT oEEIcE.

Wil-BUB I- WATSON, or EAST CLEVELAND, onto.

GENTERNG POB CONCRETE OR MASONRY ARCHES.

Specieation of Letters Patent. apuestan and January a7. `1911.v serial nu. 604,974.

Patented Aug. 26j, 191.3'.

To all' whom, it may. concern Be it known that I', WILBUR Je WarsoN, av citizen of the United States, residlng at East Cleveland, in the county of Cuyahogal center-ings for concrete or masonry arches,

and particularly for long. span arch bridges.

@ne of the objects of the invention is to lessen the cost of construction and erection 18 of centerings and to provide a centering which can be used repeatedly.

A further object is to provide a centering which has a minimum deiiection when. the load is applied and which is especially adapted for situations requiring a large-unobstructed opening for the flow of water or to avoid the obstruction of navigation in case the bridge is to be constructed` over a navigable stream.

The centering constructed in accordance withmyinvention consists of an arch which is of the three-point-pin type and is composed of two sections suitably constructed, and connected together at their upper ends in the center plane of the arch by a single pin, and at their lower ends, the said sections are each connected by a single pin to a suitable support, which I term a shoe.

The invention may be further briefly summarized as consisting in certain novel details of construction and combinations and arrangements of parts which will be described in the specication and set forth in the appended claim.y

In the accompanying sheet of drawings, the single ligure is a side elevation of a concrete arch bridge with my improved centering, or temporary false-work in position.

Referring now tothe drawing, 10 represents the two abutments or piers for the concrete arch bridge 11 which is supported until set or until self supporting by my improved centering. 0n the inner faces of the abutments 10 are bases 12 for the centering, which bases may be formed of masonry either integral with or independent of the abutments or may be formed by cantaliverin steel beams out from the abutments.

he centering or false work which I employ consists of two braced arches 13, each of-whicli is 'preferably formed of steel or combined steel and' timber and the whole structure. beingro what I term. the threepoint-pinned type,'inasmuch asit consists of two unitary/section 13, 13, which are pinned together at their upperends or at the top'of-the arch `1.?) by meansof a pin 14 and: at their lower ends are connectedby pinsV 15 to ordinary-bridge shoes 16 which restupcn lowering devices, each sectiony being connected` atits lower end by a single pin tooneof-tlie shoes 16. It is to be-understood that these pins 145 and 15 at the top and lower ends of the sectionsr are not for hingingpunposes, as the sections are not at any time intended to be moved inwardly or y y outwardlywith respect to-cach other, but the two pinned sections are employed not only for convenience in the erection and removal of: the centering but the pins confine the stresses which are transmitted between the two sections and between the lower ends of the sections and the shoes 16 to the three points. Eachof the sections 13 consists of a straight lower chord- 17, a series of comf paratively short upper chords 18 and a plurality of bracing members 19am-.anged-7 be tween the upper and lower chords. On .top of they arches 13 and arranged at regular intervals are cross beams 20 on which are placed bows 21 formed preferably of timber and on top of the bows is laid lagging 22 upon which the concrete of the main arch 11 is placed.

After the concrete arch has set, and is self supporting, it is desirable, if not necessary, that the centering be lowered from the concrete arch as a unit, so that the arch can gradually assume its permanent position, it being understood that when the centering is removed, the arch settles a Small amount, the exact amount depending upon the design and span of the arch. Consequently, between the shoes 16 and the abutments 12, I provide suitable'lowering de` vices, each of which may bedesignated as a whole by the reference character 23. These lowering devices do not constitute parts of the present invention, and need not be explained in detail, nor further illustrated. It will be understood that thereV will be employed appropriate lowering devices which will enablev the entire centering to be lowered gradually and uniformly.

I may, if desired, employ steel tie rods 28 between the ,lower ends of each of the arches 13, but except in special cases, these bled. After the cross beams, bows and lag-V ging are in position, the concrete or masonry arch 11 is built, this arch being preferably built in sections. Preferablythe top sections 11'* find 11" of the arch .11 are first i placed in position in order that the centerlng frames will be brought to a good-bearing. Then the sections at the quarterpoints are placed lin position and afterward the other sections are placed in position in a predetermined order. v

After the concrete arch has been built and the centering has been left 'in osition, the required len-h of time to enagle the arch to obtain su cient strength to be 'self sup-V porting, the centering is lowered in the manner above stated. The centering may then be -removed from the site of the bridge and used again for similar structures at other locations.

The character of the steel or steel and timber arches 13 is such that as the load is applied to them, there is a minimum deflection,

`signature in the the stresses being carried principally by the top chord members. 'This isan extremely desirable feature for this class of work. Furthermore, not only is the deection very slight, but the character of the centering is. such that a large o en space is left below the concrete arch or Athe iiow of water, the level of which i's indicated by the line 29. Furthermore, the centering need not obstruct or interfere with navigation, in view of the fact that at least at the center of the stream, the distance from the normal water level to the centering is almost the same as to the concrete arch itself.

Having thus described my invention, what I claim is A centering or temporary false work for masonry or concrete arches com rising a three-point-pinned arch comp -of two sections supported solely at their lower ends and connected together at their upper ends at the; center plane of the arch bya single pin through which stresses are transmitted from one section to the other, supports at the lower ends of thel two sections each connected to the corresponding section by a single pin.

In testimony whereof, I hereunto aiiix my presence of two witnesses. y WILBUR J. WATSON. Witnesses:

H. R. SULLIVAN, A. J. HUDSON.

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