US2147001A - Bridge construction - Google Patents

Description

Feb. 14, 1939 3 Sheets-Sheet 1 Filed July l,- 1957 3 Sheets-Sheet 2 J. A. TAGGART BRIDGE CONSTRUCTION Filed July 1, 1937 Feb. 14, 1939.

Feb. 14, 1939. J. A. TAGGART BRIDGE CONSTRUCTION Filed July 1, 1937 3 Sheets-Sheet 3 Patented Feb. 14, 1939 UNITED STATES PATENT OFFICE BRIDGE CONSTRUCTION John A. Taggart, Chicago, 111. Application July 1, 1937, Serial No. 151,330

4 Claims.

This invention pertains to bridges of the type known as hinged bridges wherein provision is made to allow for hinging movement in the completed bridge between the abutmentsrand the main supporting members of the bridge.

Heretofore in the constructing of hinged bridges,it has been the common practice to provide pintles carried in the ends of the arch rings or main supports of the bridge, these pintles usually being of steel and fitting in cooperating holes in steel plates supported in the abutments. Usually the cross sectional area of these pintles isnot large, and tremendous and sometimes destructive pressures are therefore concentrated upon the relatively small areas provided in such hinges. Because of unavoidable exposure to the elements, it has been difiicult to prevent corrosion and provide lubrication for such metal hinges.

Furthermore, when these hinged arch rings were made of reinforced concrete, it has been customary to provide a temporary structure extending the entire distance between the bridge abutments for supporting the concrete forms in which these rings were poured. The cost of erecting and removing such temporary structure usually constitutes a large fraction of the total cost of a bridge, High cost is not the only disadvantage, however, as customarily it is difficult to maintain the forms in proper alignment due to settling of the supporting structure after erection and especially after receiving the weight of the poured concrete. If the structures settle while the concrete is becoming hardened, cracks may develop in the concrete and ruin it.

In a location where the river bed is deep and soft or where a deep ravine is being bridged, the cost of erecting and removing a temporary concrete form supporting structure sometimes reaches an appalling figure. In some cases it has been necessary to drive piles which are difficult and costly to remove but usually must be removed to avoid interference with navigation or the free flow of the water under the bridge.

Having in mind the above mentioned and other well known problems, my invention is concerned with the solution of these problems and .provides several novel features in the method of constructing hinged bridges and in the functioning of the completed bridges. I

One of theobject's of the invention is to provide a hinge construction better adapted for sustaining heavy loads, while permitting freedom of movement.

Another object of the invention is to provide a hinge construction for bridges which will not deteriorate through exposure to the elements.

Another object of this invention is to provide a new mode of constructing a hinged bridge in which the need for temporary supporting structure is eliminated.

Another object of the invention is to provide a mode of constructing poured concrete bridges whereby important savings in time may be accomplished.

Another object of the invention is to provide a mode of constructing reinforced concrete bridges in which the danger of destruction of green concrete by settling of the forms and false work is eliminated.

Other objects and advantages of this invention will become apparent in the specification which follows.

In the drawings, two embodiments of the invention are shown, one being a foot bridge and 50 the other a highway bridge. Of course, bridges having other uses may be constructed in accordance with this invention.

Fig. 1 is a perspective of a completed hinged foot bridge;

Fig. 2 is a sectional view showing one abutment and a portion of an arch ring of the same bridge;

Fig. 3 is a partial bottom plan view with portions in section showing an assembly of two arch rings;

Fig. 4 is a detail view illustrating the provision for preforming of the arch rings;

Fig. 5 is an elevation showing the manner in which a pre-cast arch ring is lifted into position between the abutments of a bridge for a highway;

Fig. 6 is a plan view showing the operation of lifting and carrying such an arch ring; and

Fig. '7 is a sectional view of a highway bridge made in accordance with this invention.

Referring furtherto the drawings, abutments, generally indicated as I and 2, are first provided and anchored in accordance with good practice at the margins of the space to be bridged. Any suitable form of construction, monolithic or otherwise, may be used for the essential portions of the abutment, the dress or finish being not a part of this invention. However, in each abutment there will be provided a poured concrete hinge saddle having a lower section 3 and a subsequently poured upper locking section 4. The lower section is first poured or pre-cast and internally finished, and the upper locking section poured after the arch ring is in place. The cylindrical surface of the saddle should be carefully and smoothly shaped and before use is preferably coated with one or more coats of a liquid cement paint to protect the concrete from detrimental action by the lubricant, followed by an application of a lubricant of the character of Superla (6X) as at present manufactured by the Standard Oil Company of Indiana. This lubricant is preferable to ordinary lubricant because of its stability under exceptionally high pressures. However, some other lubricant may be used. In each abutment there will be provided an especially formed saddle for the end of each arch ring, the number of arch rings, of course, varying in accordance with the width of the bridge and the load it is designed to carry. 1

In accordance with the preferred procedure, while the abutments are being built and the saddles provided thereon, the arch rings will be poured at a location adjoining or convenient to the bridge site. If the number of arch rings to be made for one job or a series of jobs warrants it, these arch rings might be preformed at some place remote from the bridge, but, in any event, they are not to be poured in concrete forms supported between the bridge abutments as has been the usual practice heretofore. Where they are poured adjacent to the bridge, it is a simple matter to build a platform 5, such as is shown in Fig. 4, supported above the ground on base members which may be two-by-fours or other available material. While the finished arch rings, when in use, are arched in a vertical plane, it is my prac tice when pouring them to so construct the form that the arc of each ring will lie in a horizontal plane. The bottom of each form may consist of a plurality of planks I, while the sides 8 and 9 may be constructed for easy removal.

In order that the hinge or knuckle on each end of each arch ring may be accurately and snugly shaped to fit the cylindrical saddle, it is preferred that a mold, made of plaster of Paris or other suitable material, having a very smooth interior surface be positioned in the form with its cylindrical axis extending vertically to shape the hinge. The necessary steel reinforcing rods will, of course, be supported in the form and the concrete then poured. Usually it will be good practice to allow each poured arch ring to cure for about three weeks before it is removed from the form, although after the first twenty-four hours the side walls of the form may be removed to hasten the curing. Each arch ring I I pre-cast or poured for the foot bridge illustrated in Fig. 1 will have a hinge or knuckle l2 at each end. By the time the required number of arch rings have been poured and cured, the abutments and their saddles, also made usually of concrete, should be ready.

When the arch rings are made for a foot bridge such as is shown in Fig. 1, they are lifted into position with their knuckles l2 resting in the lower saddle sections 3. Thereafter locking keys 4 are poured in place, the newly poured concrete conforming perfectly to the contour of the hinge, lying snugly on the pa nted and lubricated surface of the hinge or knuckle l2.

Thereafter if cross brace members are desired for establishing lateral connections between two or more arch rings, the forms for them may be suspended upon the arch rings and concrete then poured in place. To accommodate the connection with such cross braces, there may be provided, as shown in Fig. 4-, a plurality of dowels l3 extending laterally from the surfaces of the arch rings at the proper positions, after which cross beams or braces I 4 and I5 may be poured in forms reinforced in any desirable manner. I have shown in Fig. 3 diagonal tie rods such as l6 and I! for establishing a further bracing of the structure, although such rods may be omitted. Where they are employed, it is well to provide in the cross beams, when they are being poured, pipes such as l8 into which the rods may after- Ward be inserted.

As the bridge now being described is intended as a foot bridge, a plurality of planks I9 may be secured directly on top of the arch rings in any suitable manner. Where ornamental wooden posts such as 2| are provided to support a guard rail 22, one may provide recesses such as 23 in the arch rings to receive these posts. Various suitable methods of finishing the bridge for foot trafiic may be resorted to and do not form a part of this invention.

Not only is the invention useful in constructing ornamental foot bridges having an arched traffic surface, but it is also useful in the constructing of high way bridges which are required to have a flat and usually horizontal traffic surface. Such a bridge is shown in Fig. '7 and for the construc-' tion of it the same principles apply as to the precasting of the arch rings and saddles for them, the positioning of each arch ring in its saddle followed by subsequent pouring of a locking key for each saddle.

Highway trafiic conditions at the present time require either two-lane, four-lane or six-lane bridges and as arch rings made in accordance with this invention will be spaced rather closely for example, not over three feet apart, a large number of them would be required on any bridge. It is accordingly advantageous, in connection with the pre-casting and curing of these arch rings before they are set in place, to provide some apparatus which will facilitate their ready and accurate placement. I have shown such an apparatus consisting of four masts 24, 25, 26 and 21 provided with the necessary sheaves, blocks and cables, each mast having a winch such as 28 to facilitate picking up each arch ring as it lies on the ground adjoining the bridge abutments, raising it, moving it outwardly to a position where it may be lowered vertically into the saddles which are ready to receive it. This movement,

of course, will be accomplished by winding up certain of the winches and unwinding others, as required. To facilitate handling of the arch rings, protruding eye-bolts such as 30 may be positioned on their surfaces when they are being poured. Of course, any other suitable means may be employed for securing the hoisting apparatus to the arch ring.

Referring to Fig. 7 showing an arch ring 29 resting in a saddle 3!, it will be observed that before the locking key 32 has been poured it would have been possible to lower the arch ring vertically until it comes to rest in the saddle, and thisis one of the convenient features of the invention. Each saddle is located at the bottom of a vertically extending pocket such as 33 which serves to guide the ends of the rings into place and aids in maintaining them in proper alignment before, during and after the pouring of the locking keys 32.

After all of the arch rings are in position and the locking keys are poured, lateral bracing such as is shown in Fig. 3, that is, reinforced concrete beams, may then be poured between the arch rings in forms supported solely on the arch rings. The horizontal concrete slab which receives the traffic wear or at least supports such a wearing surface may then next be poured, utilizing forms that are supported wholly upon the arch rings and cross beams. To support the horizontal slab 34, reinforced concrete beams such as 35 may be poured simultaneously with the slab, each of these beams extending the full width of the bridge and being supported preferably upon horizontal shoulders or steps such as 36 formed on the arch rings, there being, however, no union between the beams and the shoulders. Preferably the beams have notches such as 31 to fit over the shoulders to prevent slippage of the slab and beams laterally relatively to the arch rings, or tilting of any arch ring. It is also preferred that the surface of each shoulder be painted and lubricated, as are the hinge saddles, so that during expansion and contraction or other movements of the roadway slab relatively to the arch rings, a slight but necessary amount of slippage may readily occur between beams and the shoulders. This will avoid unnecessary breakage and strains and will make available to the fullest the advantages inherent in a hinged bridge.

Referring to Figs. 2, and 7, it should be noted that the upper sections of the saddles when poured fit into appropriate recesses such as 38 in the abutments proper to make certain that there will be no upward movement of a hinge out of its saddle.

It will be now observed that temporary supports extending froma river bed for carrying concrete pouring forms are not necessary for the construction of any portion of the bridges described above. The arch rings are pre-cast on solid ground, usually adjacent the abutments and preferably while the abutments are being poured. When both the abutments and rings are properly cured, the arch rings may be placed in their saddles by means of the hoisting system described, or by some other equivalent means, and such other concrete as must be poured thereafter can be poured in forms that are supported on the arch rings.

The ends of the arch rings-cooperate with their supporting saddles to constitute hinges, these hinges being new in the bridge building art. A large amount of surface to receive the thrusts imposed during use is provided in the cylindrical saddle supporting each hinge. The thrust being distributed over a large area, grinding action of a destructive nature will not occur. The mutually contacting surfaces of the saddle and knuckles are concrete covered with paint and lubricant. No corrosion can take place and consequently freezing or rusting of one part to another is impossible. As the thrust surfaces of the lower saddle section and the knuckle are preferably cast against a surface of plaster of Paris, or other material suitable for the purpose, of the greatest possible smoothness, these two surfaces should facilitate rotation of the hinge without grinding. Both the saddle and knuckle should be painted and lubricated similarly. Hence, when the upper saddle section or looking key is poured in place against the knuckle, the cylindrically shaped surfaces of the entire saddle and knuckle mutually contacting will be parallel, equally smooth, disposed about a common horizontal axis, and will facilitate rotation of the hinge without grinding.

Ample clearance is provided, as shown, between the upper and lower socket margins of each saddle and that portion of the arch ring which protrudes from the saddle, whereby upward and downward oscillation of the ring will not be impeded. A bridge made in accordance with this invention will require no lubrication after its erection and will not require maintenance service nor deteriorate in its hinge portions, as commonly happens with other previously known hinged bridges.

It should be understood that the details of construction and the methods of practicing the invention are subject to considerable variation without departing from the spirit and scope of the invention.

Having shown and described my invention, I claim:

1. In a hinged bridge, opposing abutments having a plurality of saddles formed integrally therewith, arch rings having cylindrically shaped knuckles shaped to snugly fit said saddles, each saddle having an upwardly facing socket of cylindrical curvature for receiving a correspondingly shaped knuckle of an arch ring, said socket being open to receive said knuckle when the latter is lowered thereon in a vertical path, and a locking section for each saddle having a surface forming a continuation of the cylindrical surface of the saddle to snugly fit said knuckle and extending forwardly toward the bridge center a substantial distance beyond a vertical plane tangent to the surface of said knuckle.

2. In a hinged bridge, opposing abutments, each abutment having a plurality of arch ring saddles therein, each saddle being formed of concrete and having a concrete surface of cylindrical contour, arch rings having cylindrically shaped knuckles at their opposite ends fitted snugly in said saddles and free to rotate therein, a trafiic supporting reinforced concrete slab, and reinforced concrete beams integral therewith supporting the slab and resting on but structurally free from said arch rings so as to be capable of sliding movement relatively thereto lengthwise of the rings.

3. In a hinged bridge, opposing abutments, each abutment having a plurality of arch ring saddles therein, each saddle being formed of concrete and having a concrete surface of cylindrical contour, arch rings having cylindrically shaped knuckles at their opposite ends fitted snugly in said saddles and free to rotate therein, a traffic supporting reinforced concrete slab and reinforced concrete beams integral therewith supporting the slab and resting on said arch rings but free to slide relatively thereto lengthwise of the rings, said beams being notched to embrace the sides of the rings to prevent substantial lateral relative movement.

4. In a bridge construction, the combination of a pair of opposed abutments each provided with a plurality of semi-cylindrical concrete saddles, a vertically disposed guide pocket extending upwardly from each saddle to guide the complemental end of an arch ring into position in said saddle, and a plurality of arch rings provided at the ends thereof with semi-cylindrical concrete knuckles seated in said saddles.

JOHN A. TAGGAR-T.

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