US8713A - Bridge - Google Patents

Description

1. W222. as 2612mm 51703712.

".PETERS. PHOTO-LXTHOGRAPHER. WASHINGYON. D. C

Pal/21:15:? 1 M 3, A952.

UNITED STATES PATENT oFFroE.

AMMI W'HITE, OF BOSTON, MASSACHUSETTS.

BRIDGE.

Specification'of Letters Patent No. 8,713, dated February 3, 1852.

tion of lVooden Suspension-Bridges, and l do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part of this specification, in which Sheet 1, F igure 1, is a longitudinal elevation of a bridge of my improved construction. One half of the bridge is represented as finished, but in the other half the frame only is shown. Sheet 1, Fig. 2. is a plan of the bridgeone half being finished, but the other half showing only the frame. Sheet 1, Fig. 8, is a cross section through m m in Fig. 1. Sheet 2, Fig. 4, is a longitudinal vertical section of part of one of the stringers or suspension chains, and Sheet 2, Fig. 5, is a plan of the same.

Similar lettersof reference indicate corresponding partsin each of the several figures.

7 My invention relates to a wooden tubular suspension bridge and the nature of it consits in such a combination and application of certain methods of constructing and uniting the several details as to admit of a long span, combine strength with lightness and obviate or reduce lateral motion, together with other beneficial results which will be hereinafter set forth and which, in the following preliminary description of the bridge may partly be seen. a Wooden suspension stringers of catenary form are extended or hung between suitable piers so. as to support the roadway stringers of the bridge by means of'wooden suspension rods, the lateral distance between the suspension and roadway stringers being greater at the-ends or closer 'at the center, and so held by the transverse roadway and roof timbers. The roof of the bridge consists of stringers of catenary form which support rafters to which a double covering of diagonal planking is secured, the planks of the two layers crossing one another. The sides of the bridge are covered with similar double diagonal planking which is secured to the suspension rods and towers or piers.

The floor or roadway is also composed of double diagonal planking. Side guards to increase the stiffness of the bridge laterally and to afio-rd covered accommodation for foot passengers and other purposes are added, which guards consist of a continuous fender rave fitted and secured to the ends of the transverse floor timbers which project beyond the stringers, and rafters inclining upward and downward from the rave to the suspension rods or sides of the bridge, the whole being covered with the double diagonal planking. These guards like the bridge itself are wider at the ends. The bridge when complete forms a tube which is smallest at the center, suspended as clescribed and at the same time, if desired, is in part supported by a direct arch or arches.

To enable those skilled in the art to put my invention in practice I will proceed to describe more fully its construction.

A, A, represent the abutments upon which the bridge is erected.

B, B, are the towers, which are made of suitable strength and well secured by backstays O, C.

D, D, are the suspension stringers constructed in the following manner which will be best understood by refernce to Fig. 4 in Sheet 2 of the drawings: A tree E, is selected of a suitable size for the end of the stringer, and is squared down and slightly tapered from within a certain distance of its base indicated by a. The part from a to the base I is cut of any suitable form to lock into the endsof the backstays C, C, and the other part is cut to receive a number of boards, (Z, d, which are spliced to it. These boards are of a proper width to form the stringer and are laid togetheruin su' llicient number to make the stringer of the required thickness and are continued to the required length in acatenary curve whose deflection is about forty (40). feet. in five hundred (500) and then united to another timber E,

similar to the one upon which they were commenced. The boards are spliced by bolting them together with bolts 6,5, and

letting dowels c, 0, of ironor woodhalf into one board and half into the next one to suspension stringers, thus constructed are raised to the towers by any convenient means and locked to the back stays.

H, H, are stringers of catenary form but with a less deflection than D D. They are secured at each end on the top of the stringers D D and form the supports for the sides of the roof.

' I, is a stringer of catenary form which is attached at each end to strong braces J, J, which are placed across the back-stays, or is otherwise attached to the towers. It forms the support for the center of the roof.

K, K, are the roof rafters resting on the stringers H, H, and I.

F, F, are the suspension rods which support the roadway stringers G, G. They are suspended from the stringers D, D, and H, H.

M, is a direct arch springing from each of the abutments, and bearing under the roadway or floor stringers G. It is connected to the suspension rods F, F, or to other suspension rods F, F hanging from the floor stringers. Both these modes of suspension are shown in Fig. 1.

N, is another direct arch springing from each of the abutments just above M. and

- bearing under the upper stringers D D. It

may be cut away where it comes in contact with the suspension stringers D, D, and roadway stringers G, or may be double and pass on each side of the stringers. drawing the arch is supposed to be cut away but still the stringers themselves form a continuation of it.

' O, O, are the transverse floor timbers or roadway bearers, which rest on the roadway stringers G, and overhang them a considerable distance. (See Figs. 2 and 3 in Sheet 1 of the drawings.) The distance which they overhang increases toward the ends of the bridge.

P,"P, are the fender raves, which are fitted to each end of the transverse timbers O, O.

Q, Q, (see Fig. 3 in Sheet 1 of the drawings) are the inclined rafters, which are fitted to the fender raves and to the suspension rods or other parts of the sides of the bridge, forming in conjunction with the fender rave the forming of the side guards or braces.

When the parts above described are all erected the double diagonal planking is bolted to the roof and the bridge is then load-ed down with a weight equal to about double the weight it is designed to bear in ordinary traffic. The double diagonal planking is then bolted on the sides and if it is a railroad bridge under the transverse timbers O, O, which serve as the sleepers, but if a turnpike or common road bridge above the said timbers. The side guards or braces are also covered with similar planking.

In the stringers, while by the double diagonal bracing, the increased width of the, bridge at the ends and the addition of the side guards or braces both the vertical and lateralvibration which is incidental to suspension bridges is prevented or greatly reduced. The bridge being entirely constructed of small timbe'ras all the arches and stringers are intended to be built in the same manner as the suspension stringers D D-may be more cheaply and expeditiously put up than if made of large'heavy timber, and will be much more durable in consequence of the fact thatsmall timber can be so much more perfectly seasoned than large. Theroof instead of being a dead weight is not only self-supporting but will support a large portion of the rest of the structure. By the diagonal boarding in addition to being braced all the main parts of the structure are effectually pro tected from the weather and on any part of it being decayed or injured it can be re moved and replaced without detriment to the main structure.

Bridges constructed on this plan may be constructed of great length. I believe by experiments tried on a small scale that the span may be extended to fifteen hundred (1500) feet with the most perfect safety.

The side guards constructed as described not only strengthen the bridge and reduce lateral motion, but, by their angular shape and continuity, break or glance the'efl'ect of wind upon the structure. They likewise form a covered foot walk for passengers, planking being placed on and over the projecting extensions of the transverse roadway timbers.

Having thus described the whole construction of the bridge I wish it to be understood that I do not claim separately as new the mode of constructing the stringers by splicing and securing planks in the manner set forth and shown, nor yet do I claim separately the use of diagonal planking crossed in layers as described, nor yet again do I claim by itself increasing the width of the roadway and other parts of the bridge at the ends, neither the mere employment of side guards or braces, as all these or similar devices or applications belong to common carpentry or ordinary bridge-building. They however are necessary details or contain principles essential to the construction of my bridge involving a combination having the effects and advantages specified. But

What I do claim as my invention and desire to secure by Letters Patent is 1. The combination of parts constructed and arranged as described in formation of a wooden tubular suspension bridge, that is, the several suspension stringers D D of catena r'y form and constructed and united in pieces as explained, the outer ends of the extreme stringers being locked, as represented, in the back stays) the stringers H H and I for construction thereto or thereon of the inclined roof made of diagonal planking;the roadway stringers G G connected by suspension rods to D D and H H;the

direct arch M united by suspension rods and further direct arch N bearing under the upper stringers together with the transverse floor timbers and roadway; the bridge, thus constituted, being formed-that is, its stringers, arches and coverings,-of short pieces of wood united and having their fibers running in appropriate directions as shown, and the bridge being, in form, wider at itsextreinities, gradually narrowing toward the center;by which combination and arrangement of parts, the tensile strength of the wood in the suspension stringers is fully employed, vertical and lateral vibration are reduced, the roof more than assists toward the support of its own weight, and the bridge may be extended over a considerable span.

2. The continuous angular side guards, formed by fender raves P P, inclined rafters Q, Q, diagonal plank covering R, R, and extensions of the transverse roadway timbers O O: the said side guards projecting most and being of greatest extent at the eXtremities of the bridge, gradually diminishing toward the center; and the specified side guards serving not only as braces to reducelateral motion, but as a covered roadway, and to break the effect of wind upon the structure.

AMMIE WHITE. l/Vitnesses:

A. K. P. JOY, J. D. TAYLOR.

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