US843167A - Bridge structure. - Google Patents

Description

m. 843,167. PATENTED FEB. 5, 190"]. J. P.. NIKONOW.

BRIDGE STRUCTURE APPLICATION mam MAB 24, 1906'. V

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No. 843,167: PATENTED FEB. 5, 1907. J. P. NIKONOW- BRIDGE STRUCTURE. APPLIOATION FILED 111111.24. 1906.

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No. 843,167 PATENTED FEB. 5, 1907.

' vJ. P, NIKONOW. BRIDGE'STRUGTURE.

5 PLIOATION FILED MAR. 24, 1906.

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' third of the .Fi bri d e, showing .the positionof the reactions UNITED wags PATENT orrroa.

JOHN P. NLKoNoW, or PITTSBURG, PENNSYLVANIA BRIDGE STRUCTURE.

To all whom it may concern:

. Be it known that 1, JOHN P.--NIKoNow, a subject of {the Czar' of Russia, residing at Pittsburg,

State of iennsylvania, have invented certain tively light superstructure to be employed.

To this end the invention comprises a bridge structure'in which the principles of the cantaliver and arch are combined, so that the horizontal, and vertical components of the reactions of the arch have opposite 'momen'ts about the bases of the piers and tend to counteract each other. e

The structurealso has the advantage of enabling the piers to be built with a comparatively small base, since the accepted condition of safety that the resultant of all the forces acting shall pass through themiddle base of the pier can be very satisfied.

readily full description of the inventn.

- For a knowledge of the details of construction of the means for effecting the result, reference is to be had to the following description and accompanying drawings, in which- Figure 1 is a diagrammatic view of a bridgeconstructed in accordance with the invention. ,2 is a similar view of one span of the etermined :by the graphical method.

Fig. 3 is a diagrammatic view of one span,

' showing a modification in which the end postof the cantaliver is inclined inwardly and the arch provided with an overhanging endportion. Fig. 4 is a similar view of a modifica tion in which'the end post of the cantahver is inclined outwardly. Fig. 5 shows the sections of the archdesigned so as to be lifted.

Fig. 6 shows a portion of the arch and a hydraulic cylinder lifting the .same. .Fig. 7 is a plan view of ar end portion of one of the arch-sections. Fig. 8 is a side elevation of a portion of one of. the arches, and-Fig. 9 is an Specification of Letters Patent. implicationfiled March 24, 1906. Serial No 307,850.

-in the county of- Allegheny and shown.

and the merits thereof, and also to .acqune a- Patented Feb. 5,1907.

enlarged sectional view showing the method of attaching the counterweight to the archsections. I

- Corresponding and like parts are referred to in the following, descr ption and indicated in all the views of the drawings by the same reference characters.

The numerals 1 deslgnate'the piers, which are of the usual construction, 2 the cantaliver structuresresting upon the piers, and 3 the arches connecting the cantalivers, said arches preferably being of the three-hinged type, as In their specific construction both the cantaliver and the arch may comprise may be given a trussconstruction with upper and lower chords connected by suitably-d e signed web members. The arch 3 and thecantalivers 2 are so disposed withregard to each other that the horizontal and vertical components of the arch reactions have opposite moments about the bases of the piers and tend to counteract each other. This construct-ion. where the vertical component -of the reaction hasno moment about the base of the abutment and theZen-tire horizontal thrust has to-be resisted by either reinforcing or enlarging the abutment. This feature can best be shown by determining the reactionswhieh would occur when the arch is loaded and observingthe effect of the reactions upon the structure For the present purpose this result can'best' be accom lished by the graphical method. 'The dead load or weight of the arch-sections will beams having solid webs and flanges or has obvious advantages over the true arch first be considered," and for the purpose of determining the reactions the dead-loads can be considered as acting upon the centers of gravity of the two halves of the arch.

In Fig. 2 the force p, acting at A, represents the weight of the left-hand section of the arch, and the force p, acting at B, rep resents the weight of the right-hand section of the arch. Considering these foreesse aratelythe components of. the reactions ue to these forcescanbe determined Theseare'determined by the usual method of solv-' ing ,the three-hinged arch. In considering the force p the line of action thereof is extended upwardly to C, where. it meets the line DE, passing through the center hinge D and the right hinge 'E. The line CF is then drawn through the left hinge F, and

' to the eft reaction is represented in magni-' this line gives the line of action of the component of the left reaction, due to the force This solution is based upon the principle that three non-parallel forces must be concurrent in order to be in equilibrium and the fact that the line of action of the component of the rightreaction, due to the force p,mus7t pass through the two hinges DE. By laying on the force p from the point C and com-. pleting the parallelogram of forces the magnitude .of the components can be determined. In the resent instance the force transmitted tude and direction by the line CG, and the component transmitted to the right reaction by the line CH. In a similar manner the force 1) can be considered by extending the line of action thereof upwardly to J, where it intersects the line FD, and then drawing the line JE. The parallelogram of forces 'can then be drawn in the same manner as for the force p, the line JK representing the magnitude and directionof the componenttransmitted to the left reaction, while the line JL gives the similar properties of the force tsansmitted to the right reaction. Byv setting off the distance FM equal to CG' and EN equal to JKand completing the parallelogram of forces the left reaction F0 may be determined for the-deaddoad. In

' a similar manner the right reaction may also be determined. In considering the live or moving load P it may be stated that the horizontal thrust of the arch will be greater when the live load is concentrated at the crown D and" that this position'will therefore be the most trying upon the resent structure. Considering the force as acting at D the magnitude and direction of the comonents may be determined by drawing the horizontal line RS through the point T, the latter point being so taken that the' line DT represents the magnitude of one half the force P. The arch reactions due to the combined dead and live loads can now be found by laying 03 the line FU equal to line 'DR- and completing the parallelogram of forces.

I: .reaction may be resolved into' its vertical component FW and its horizontal component-IX. The horizontal component repre-.

through the pier and has no moment. Withthe vertical. and the condition t The line FV then reresents both the magnitude and direction 0 the left reaction of the arch, due to the dead load and'the mosttrying condition of live load, and this this constructionit will be apparent that the pier may accordingly have a lighter construction than would-otherwise be the case.

The fact that the critical osition of the resultant moment tending to overturn the pier willbe comparatively small and that the 1 force P is when acting at the iinge D maybe readily proven by moving the force to either side of the point D and observing the effect upon the reactions.

ystudying the diagram it will be apparcut that any movement of the force P will increase the vertical component of the react1 ons and decrease the horizontal component,

and since the. vertical com onent tends to overcome the moment of t e thrust of the arch it will be apparent that the critical condition will exist when the vertical component has the smallestvalue. v

In order to vdetermine the resultant of the reaction FV, the line FV'is prolonged to the point Y, where it intersects the vertical line passing through the center of gravity of the force Q, representing the combined Wei ht of the pier 1 and cantaliver i '2 and the are weight of the pier, and'the force g, repre i senting the weight of the cantaliver structure. The distance YZ is thenset ofi equal.

to Q+q, and Ya equal to FV. The resultant Yb of all the forces acting can then be found in the usual wa and this resultant may be considered as aving the horizontal component Y0 and the vertical component Yd. Since the weight of the pier 1- and-cantaliver 2 can have. no horizontal component, it will be apparent that the horizontal component Ye is exactly equal to the thrust FX of the arch. Owing. to this fact, the resultant Yb' forms a comparatively small angle [3 Y with at the resultant of all the forces shallpass through the ICO middle third of the piercan be easilyfulfilled. The horizontal thrust of-the arch is the I -most trying force which the structure has to resist, and it may be shown that this thrust depends upon the loading and dimensions of the arch. For present 'urposes the deadloa'dwill be, ignored and the live load considered alone. In the triangle DRT the line RT represents the thrust of the arch, or the horizontal'component of triangle is similar to the triangle DFe, and the following ratio may be deduced.

in n

TD DE 2 is equal to g '2 I h This latter. ratio is obtained by substituting equals the thrust due to.

the reaction due to the live load P. This v I one-half P for DT, for Fe, where L I equals the span of the arch and h theiri seof RT equals the arch] From the latter ratio we can ob; tam the following eguatiou:

Where RT represents the thrust of the arch dueto the. force I. \Vit-h a given force P the 1 I value of the ratio will depend entirely to L upon the variable quantity In the practical ripnstruction of bridges the value of the I 5 ratio -must not exceed 20 when the horizontal component of the force would be equal to five times the force, as can be seen by substi-' ';tut1ng values in the equation. In the pres-- chat construction L, or the span of the arch, represents only afraction of the distance be tween the adjacent piersor the total span of the bridge, which may be designated by L Therefore, since the ratio is used for the a entire span L the value of the ratio is diminished. can be readily seen from the following equation, in which the quantity h 18 constant;

-LI/L2 707. In other words, for the same rise of arch I am enabled to employ a greater total span than with the-pure-arch construction. This feature has avery. great advantage in actual construction, since it enables the piers to be spaced farther apart, or with fixed piers the superstructure may be constructed of lighter steel.

A modification is shown in Fig. 5, in which the two halves of the three-hinged arch are to give a free channel. \Vith'this construction the hinge D at the crown of the arch is formed by giving one of the arch members a tongue, which rests loosely within a depression upon the opposite arch member. *The hingeoints F and E are formed in a some what similar manner bysharp rojections f1,

- which bear against the bases 0 recesses 5 1n the cantaliver structure. The upper portion of the ends of the arch-sections 1s hinged arch throu the latter members are so mounted so 'to bec 5 drawn to one end of the slots 8 by means of so constructed as to be readily lifted in orderv have a suflicient play when the arch is in nor- 1 to the counterweights.

. increasing apparent that t the threaded stems 9 and cooperating nuts 20 when lifting the arch.

. In order to provide for'the simultaneous operation of the nuts 20 on each section of the arch, 'the said nuts maybe formed with wormgearing, which engages with the worms21 upon the shafts 22. Q

With the lift construction the arch-sections are each provided with a counterweight 10 andmeans whereby the counterweights can be forced downwardly in order to lift the arch. For the latter purpose hydraulic cylinders may be employed, as shown at 11, or

the counterweights 10 may be provided with segmental racks 12, which cooperate with pinions 13, the latter being operated by any suitable source ofpower. I

In Fig. 7 aplan view is iven, which shows a method ofconnecting t 1e counterweights 10 to the various beams 13 which compose the arch. In connecting the beams 13 and counterweights 10 it will be observed thata pair ofapproximately U-shaped members 14 are employed, which have their arms. joined to thebeams, while their heads are connected A diagonal brace 15 may also be employed to insure a rigid con struction. members 14 the counterweights 10 are pro- ,vided with the inwardly-projecting flanges 16, which have the racks 12 formed thereon.

Another modification is shown in Fig. 3, in which the end osts of the 'cantaliver construction 2 are inclined inwardly at 17 and the arch-sections are provided with the over On each side of the U-shaped too hanging portions '18. With this construction the horizontal component of the reaction due to dead load is somewhat diminished. At 19 inFig. 4 the end osts of the cantaliver construction 2 are inc ine'd in the opposite direction, this has the result-of ponent of the resultant of all the forces acting, and when this vertical component is increased it will beapparentthat the angle [J' which the total reaction bears to the vertical will be decreased. p

. From the fore oing explanation it will be e principal advantages of the present constructionreside in the fact that the'cost of building a bridge of a iven len 'th and. designed to resist given oads wil be greatly diminished, owin to the fact that the piers can be given a ighter construction or spaced farther apart, or that. where the piers are fixed a lighter superstructure can be employed.

Having thus described the invention, what is claimed as new is I 1. In a bridge, the combination of iers, cantalivers resting upon the piers, and t ee-. hingearchcs connecting the cantalivers, the

' the weight of the cantaliver and correspondingly increasing the vertical comsections ofthe arches being so formed as to be lifted-when'desired and for this purpose being lceael y connected to the. cantalivers 5c interfere with the actions ef the three hinges, 10 as not to.ii1terfere with the action cf the and means for tighteningithe joint.

three hinges. In testimony whereof aifix'my signature 2. abridge, the ccmhlll atio i 9f iers, in presence of two witnesses, March 22, 1906. 5 cent" e rest ng u 91; h piers, t ehingearcheg connecti g the cantalivers, the JOHN W sections of the arches being connected to the witne ssesi canta ivers by a loose jpii t which enables 1 BIRNEY HINES, them to-be lifted when desired and does not IDA W. REINEGKE. I

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