USRE3073E - Improvement in suspension-bridges - Google Patents

Description

UNITED s rSrrATEs PATENT OFFICE.

CHARLES BENDER, or NEW roux, n. Y.

`IMPROVEMENT INSUSPENSION-BRIDGES.

Specification forming part of Letters Patent No. 71,955, dated December 19, 1867 ;Reiss'ue No. 3,073, dated t August 11, 1868.

To-all whom it may concern:

Be itknown that I,"OHARLEs BENDER, ot New York, in the l York, haveinvented anew and useful -Improvement in Suspension-Bridges; andI do hereby declare that the following is a full and exact description of the same, reference being had to the accompanying drawings, and to the letters of reference marked thereon. Y

My invention refers particularly' to the different species of suspension-bridges which by any arrangement of trussing vare stiEened.

The trusses may be parallel t'o the longitudinal 'axis of the door; or the st iieningmay consist in a combination of chains or cables, so as to forma stili' curved truss,`or may beobtained by a connection of the cables or chains with longitudinal-oorbeams by uprights and diagonals, or by diagonale only. All these di'er'- ent species of suspension-brit] ges may be called stitl'ened suspension-bridges.

The nature of my yinvention consists, first, in

v dividing Ier separating lthe beams or trussesV at one or more points and connecting them by yieldingy joints; the chains or cables `to the beams or trusses .of the bridge itself 'instead of fastening the' same to abutments; further, in the manner ot' securing the ends of the bridge to the end piers vertically, and in such manner aste allow for the expansion and contraction of the bridge and, lastly, in leaning the beams lor trusses against the piers to prevent sidewise Inovements at these places, and fastening them at thesame time at one pier lin such a manner as to preventany' horizontal Increment inthe direction of the longitudinal axis ofthe bridge.

Figure I represents a longitudinal elevation of oneof Iny improved bridges belonging vto the first class of stiiened suspension-bridges, or with longitudin rate parts 0n an enlarged scale, and.- will be morefparticnlarlyreieried to in the descrip In the accompanying drawings, Arepresents one of the end or shore piersj-and B B the central piers. f. v.

G are the longitudinal trusses, which areto' .annihilate the momentum of the forces and tov repart the weights over the Suspenders. These county 'and State of Newr`l further, in the attachment of al trusses U. The remain-I ing figures represent details showing the sepatrusses are constructed in theusual manner, subject to many variations, to correspond with the style'and nature of the bridge.

D in Fig. 1`represents theyielding joints at the points whe're the beams or trusses are separated. One of the many possible plans of strengthening and sti'ening these parts of the beams or trusses and joining the same together.

by means of strong bolts E is represented in Fig. 1I, Sheet I. By means of the connectingplates N N, the nuts L, and heads M, or by any other arran gement-as wed ges, &c. -I prevent horizontal movements as caused by wind of one or more of the piers of the trusses.4 a

-'lhe object of providing one or more fyield ing jointsvin the whole length of the beams or trusses is to prevent thereby any danger from the different compressions and expansions of said beams or trusses, as well -as of the cablesl or chains; further, -to facilitate' thereby the bending of the bridge by change of tempe'rature to equalize any irregularity at the points ot' support ,ot-"fthe structure on the piers; wise, to facilitate and rectify thereby consider- 'ably' the analytical calculation of the whole structure, and also to save material. bemanner of constructing this joint, as well 'as the i manner of strengthening the adjoiningends of the beams or trusses, is subjectto many variations'aud has to' correspond with the style and, nature of the bridge.V In Fig. I this joint is represented exactly in the center' between the central-piers, B and B g butthesame mayl be placed in di'erent positions, andmay even.

he` arranged at two or/more places, laccording tothe natu're'and to the number of the spans 'ot' the bridge, and may be' used for all descriptions of sti'ened vsuspension-bridges.

Between the shore-piena` and the first 'ccn-v tral pier, B,'strong diagonal trussesF F (shown at an enlarged scale in Fig. Ill, Sheet ll) are 'arranged` in the truss-work of the beams, having at their point ot' junction a strong bolt, Gr,

around which the'cables or chains H are fastened. These trusses F transfer the horizontal forces of 'the cables or chainsto the chords or to the beams of the structure, "whilestrong the vertical pressure acting uprigh ts I resist in the system o 'f the trusses F."

It is not essential bywhat arrangement of details thestrains of 'the cableslor chains are liketransferred to the chords of the trusses or to the beams. In the accompanying drawings, for-instance, the trusses F F are exerted by strains,but they could also ed position, so as to resist pressures.

The only task to be fulfilled is the right distribution ot said-forces, and this may be effected by various arrangements of the different parts in a suitable manner, and mathematical examination in each single case will determine the most economical arrangement.

The exact position of the point ot'attachment of the'chains or cables to the beams or trusses depends likewise on circumstances, and may be nearer to or farther away from the shore' pier A, and in some cases it may even be advisable to extend the beanis or trusses beyond said shore-pierA, and place the point of attachment beyond said shore-pier. Mathematical and mechanical examination in each single casel will determine the 'most profitable position of these points. By this arrangement of attaching the cables or chains to the beams or trusses 'a great saving in most cases is obtained, as I dispense thereby with a great part of the expensive mason ry at present necessary at each end 'of the bridge to secure the ends of the cables or chains. l

Where the trusses of my suspension-bridges rollers K are placed, X X, fitting over. the surfaces of the platesu and m to prevent any side motion ofthe bridge-at the ends. Instead of one roller, two or more rollers with or without journals, or, to save material, only parts of rollers, could be used.

Arising from any overloading in certain contingencies or in case of wind, it is possible that the trusses or beams on the piers at or near the ends of the bridge have a tendency of an upward movement. To prevent this movement I attach said beamspr trusses to the piers in such a manner as to use the weight of the pi rs as resisting vertical power, said attachment being able to allow the horizontal movement of the bridge in case of'changeof temperature. Atthe sa me time it is necessary to prevent sidel'wise movement, which might be possible by action of wind, a movement which, in other bridges, where always is an important pressnre on the piers, is already annihilated by the friction, great enough toprevent sidewise deviation. One of the many possible ways to fulll these conditionsis shown in Fig. IV in front view and cross-section. Herethe ends ot the bridge are fastened in the foundation ot' the piers by heavy bolts. These are provided with suitable joints, n, to allow for the horizontal motion, and the said flanges X X are fulfilling the third condition.

To diminish the side motion caused by wind, .as well as for other reasons hereinafter mentioned, I cause thelongitudinal beams or trusses to bear against the central piers, so as to prevent sldewise movements at these points. This can be done 1n many ways. One ofthem is shown Y 1n FigV.

be placed in invert- Projections L are outside of the beams or trusses() at the desired position,which enter into suitable guide-frames, N, fastened to the piers in to leali thereby the bridge against the pie-rs, sutiicient play being allowed in one or more ot' the same to allow for the expansion and contraction ot' the trusses orl beams lengthwise. In the frames N, fastened to thepiers, suitable plates, w, are arranged, against which the projectionsL, attached to the beams C, are made to bear, said plates being capable of being regulated by means of set-screws au. On that pier which is either in the middle of the bridge or on that next to its center I attach these beams in such a manner as not to allow for any longitudinal motion, whereby the differences of the length of the bridge caused by changes of temperature are regulated and brought to a certainty on either side ot this point of attachment.

By the manner ot'leaning the beams or trusses against the towers to prevent movement sidewise the pressure caused by the lwind is partly annihilated, and the side motion of the bridge,caused by wind, is considerably reduced, for my whole horizontal construction represents a truss made stili' against bending horizontal and vertical to the axis of the bridge.

The trusses C, Fig. I, represent the chords, and the horizontal cross-bearers and diagonals between'the trusses C, Fig. Lrepresent the uprights and diagonals of the said truss. Such a single truss bearing against the towers to prevent sidewise movements has already 'a great effect; but by leaning my continuous truss against the towers and against theend piers of th,e brd ge the whole horizontal trusswork is m/ade a powerful continuous truss against deviations, and it is known that the deformations' by continuous trusses are considerably reduced. Further, by my method of leaning the trusses or the beams against the towers to prevent. horizontal movements ver- .tcal to the axis of the bridge the towers themselves are strengthened, as the pressure resulting from wind, and which in other cases is all on the top of said piers, where the cables or chains are supported, is brought thereby lower down or nearer to its base.

What I claim as my invention, and desire to secure by Letters Patent, isl 1. The construction and arrangement ot' one or more yielding joints connecting the beams or trussesof sti'enedsuspension-bridges, substantially as and for the purpose described.

2. The plates N, titted together as shown in Fig. II, and combined with the fulcrum-bolt-s E of the yielding joints of the trusses, substantially as and for the purpose set forth.

3. The attachment of the ends of the cables or chains-at or near the first or shore piers to the longitudinal beams or to stiiened suspension-bridges, substantially as and for the purpose described.

4. The method employed to reduce the side motion of a stii'ened suspension-bridge by securely attached to the such a manner as the trusses of `causing the longitudinal beams or trusses to bear against the several piers by means of projections L, as shown in Fig. V, all constructed and arranged as herein described.

5. The arrangement ofa connection which is rigid in a horizontal direction between each truss and one pier, While the connections of said truss with thercmainng piers are free to accommodate themselves to expansion and contraction ofthe beams or trusses, substantially as und for the purposes set forth.

CHARLES BENDER.

Witnesses:

M. M. LIVINGSTON, OTTO WALLAT.

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