US 14584 A
Description (OCR text may contain errors)
UNITED 'STATES PATENT OFFICE. r
GEO. W. O. HUYGENS, OF ST. LOUIS, MISSOURI, ASSIGNOR T0 HIMSELF, CHAS. BNDER,
AND D. F. TIEDEMAN.
Sbecificatiori of Letters Patent No. 14,584, dated April 1, 1856.
T0 all whom z't may concem:
Be it knowvn that I, GEORGE W. O. HUY- GENS, of St. Louis, in the State of Missouri, have invented a new and Improved Mode of Constructing a Bridge, with the Object of Preventing Vibration.v
In order to explain fully the principle and the character by which it is distinguished from other inventions, do I proceed to state that my invention is based on the principle, of compensating the result of the elastic action in the material, by compensating the result of compression in the material by its own action, using for that purpose the compensated effect of compression only; which compression is originated from the pressure caused by the loads on the floor of the bridge; said compression is forced to divide itself in two compressive forces, the final results of which are caused to be in two directions, which.are directly opposed to eaoh other, while in the same time, said final results are cased to be perfectly equal in intensity; the mechanical result of such forces, when tied together is rest; they annihilate each other; in this way the effect of compression is compensated by its ovvn effort, Whi0h explains fully the meaning of that which is here designated by the terms, of the principle of compensating the result of the elastic actions in the material. by using the compensated effect of compression only.
This prinoiple as here explained, constituting the base of my invention, above mentioned, distingnishes its character from other inventions aiming at the same object; like such is claimed for certain improved suspension bridges, or like is claimed for certain improved bridges, which are constructed with the aroh-principle and suspension principle combined in one; or like is claimed for certain improved bridges, which are constructed, with the arch principle and girder principle combinedin one; all the mentioned improved bridge principles, use tension alone or partially, and claim a neutralizing eflect, conseqnent on their combined chamoter, but their object is always to neutralize the. compression of material by the tension of material, or the resistance of material against compression by the resistance of material against tension, and they claim that as their invention, without mentioning bowever the principle of compensation of the results of elasticity, or contemplating any measures to make said compressive and tensive forces act by their final results in opposed directions, or to make the results of said forces equal in intensity while opposed in direction, in order to efiect a mutual compensation, and without mentioning any object of such anature as preventing vibration, it being a general feature of the said improved bridge systems, to limit their object to nentralization like above mentioned, in order to produce more stiflness with less material, quite different from preventing vibration, and specially difierent by the mechanical character of the principles brought in application, which diflerence is significai1tly represented by the word tension; and by the absence of the terms equality of intensity.
In order to explain fully, the mode in which I have contemplated the application of the principle, which constitutes the base of my invention, do I proceed to state that:
I originate said two compressive forces, which this pr1nciple calls for, by means or arches; 1, which arches are constructed following a determined special proportion, in regard to the respective amount of their material; 2, which arches are arrangedin parallel vertical planes, with their curve reversed on each other; 3, which arches are provided vvith resting points ofiering their resistance or leverage in different directions,v
in such a manner, that those arches, *having their curve pointing upward, receive their leverage in one direction, and those having their curve pointing downward, receive their leverage in another direction; 4, which arches are not connected or conjoined by means whatever in their crossing points;
the object of my invention to be obtained,
viz: preventing vibration, by the application of the above mentioned principle by using the compensated eifect of compression only; in consideration of which I call this bridge a compensating bridge.
The compensating bridge consequent on the peculiar mode in which vibration is prevented in it, offers the advantage of not being subject to alteration of its shape nor of the level of its fioor, when under pressure, which will allow cars and locomotives to pass over its fioor uncler full speed, without incurring the risk of being thrown off the rails, by undulatory motions in the fioor; the compensating bridge offers the advantage of less wear and tear of the material of its construction, incident to the distortions of uncompensated results of elastic act-ions in the material and consequent vibration of the bridges; the absence of vibration in the compensating bridge, Will allow to save a great amount of material, which is used in other bridge systems, above the demand of tenacity,avith a view to oppose and combat by the thickness of the parts, the uncompensated result of elasticity and consquent Vibrafion of the whole; which insures to the compensating bridge the advantage of superior lightness, and the consequent facility of building much larger spans than is possible to reach with heavier bridges; all of which combined insures to the compensating bridge the advantage of economy, and makes it the cheapest of all known bridges, by from forty to sixty per cent.
I do hereby declare that the following is a full and exact description of my invention, reference being had to the accompanying drawings and to the letters of reference marked thereon.
1. The nature of my invention consists in providing a bridge instead of Which an upper chord, with a certain number of arches, in no case less than six, but more in proportion. The span exceeds (200) two hundred feet; in the latter case the total number of arches becomes'a matter of individual judgment, only the said number should always belong to that class, Which are divisionable by the number three, withont any rest remaining; the reason for this lies in the necessity to have always one third ofthe total number of arches, with their curve pointing upward, like those marked A and B, the 'remaining two thirds with their curve reversed on the former pointed downward like those marked a, b, c, d, al. The proportion Which should exist, between the amount and their material, is found by using the formula in which V represents the ziggregate amount of the material contained in the upper arches, 'v that amount in the lower arches, P the strain which would happen in the loWer arches if they were alone unaided by the upper ones, p the actual strain which happens in the upper arches. The reason for this special proportion lies in the neCes sity called for by the principle to make the result of the compressive forces in the upper and lower arches equal in its intensity, which could never happen if the momentums of the elastic compression, consequently the elastic power, of the upper and lower arches, were not made to be equal, and this is done by the said proportion, by Which the amounts are brought in inverted ratio to the elastic efforts on the fiber of the materal. The lower arches are to be constructed with an increased cross section toward the middle, the increase to be in direct ratio to the decrease in distance to the fioor, in order to oifer the required resistance against the compressing force.
2. The arches are arranged in parallel and vertical planes with their curve reversed on each other. The object of this arrange ment is to prevent the arches whose curve is reversed on each other, to intersect or meet each other bodily in any point, and to enable them to cross each other without conjoining, (et) it being required that there should exist no connection whatever between the upper and lower arches in their crossing points; the reason for this lies in the prin ciple which requires tWo compressive forces; now it is evident that if the upper and lower arches had a point common to them, the consequence would be, that the lateral pressure of the upper arches would plant itself over in the lower arches and cause their immediate tension; besides by having a point in common would cause the upper and lower arches to intermix their respective actions, and make it therefore' impossible to obtain from them results, Which are equal in intensity, like is called for by the principle. The reason why the lower arches have their curves reversed to the upper ones lies in necessity imposed by the principle to create two forces in those arches the results of which are to act in directions directly opposed to each other, that'is the created tendency to curve apart or asunder, which never could exist if the arches were placed with their curve running parallel.
3. The arches are provided with resting points, ofi'ering their resistance or leverage in diferent directions, in such a manner that those arches, having their curve pointing upward, receive their leverage in one direction, andthose having their curve pointing downward, receive their leverage in another direction; the reason for this lies again in the necessity to create tW0 results in direc tions linear opposed to each other, called for by the principle; it Will be evident that never such opposition can be obtained, When the arches were not provided with leverage in difieremt directions. This difierence in leverage forms or constitutes another reason why the upper and lower arches cannot have points in which their material bodily wOuld be conjoined, for such a point would cause a new leverage to spring forth, which would be a cause for the destruction of their individual original independent leverage. In fact a single bolt driven through their crossing points, would totally destroy the com pensating qualities of the bridge; this Will be evident by the remarks oflered upon this subject; Which is strikingly illustrative of the great difierence in the character of this compensating principle from other bridge principles, all of which without exception conjoin and secure by all available means, those points where parts of their materiil cross each other. The tension rods do not constitute pomts, in which the arches are bodily conjoined.
5. The arches are connected with the fioor in a special manner; this special manner consists in the lower arches alone be directly tied and braced to the fioor, which is only connected indirectly with the upper arches through the medium of the lower; in such a manner that the lower arches a, b, c and (Z, are tied and braced to the fioor as shown in the drawings, it being necessary to take special care not to bolt, brace, tie or 7 strap the 1qaperzwches A and B to the fioor,
in order that there be no direct connection, 1n no manner whatever, hetween the floor and said upper arches; the lower arches u, k
7), c and d, to be tied and braced to the upper arches A and B, as shown in the drawings, taking speoial care not to bolt, brace,
tie or strap or key them together in their crossing points. and not to allow any ten sion rod or brace between them, which would be farther out of the perpendicular position,than one inch in ten; such places between the arches, where said slope would be more out of the perpendicular lime, ought to remain without. The tension rods between the arches, to be normals on the curve of the upper arches A and B, also the braocs betwe'en the arches outside their crossing points, to be normals on the same curve. The position of the braces between the arches inside their crossing points is immaterial to the compensating principle, and
-said braces may be removed after the process of securing the tension rods (L) equally tight by their aid, is gone through. The object of this special manner of connecting arches With arches, and arches with a fioor, is to carry out and bring in applica tion those parts of the principle, which are described in the following terms see page 1 of this specificaon, While in the same time, said final results are caused to be perfectly equal in intensity the mechanical result of such forces, when tied together, is
' rest; they annihilate each other. The reason why the fioor is not tied directly to the upper and lower arches at the same .time, lies in the principle which rcquires that the strain should be divided in the upper and lower arches in order to create two compressed forces; it Will be evident that if the floor was tied directly to the upper and lower arches at the same time, the necessary consequence would be, that either the upper or the lower arches alone would take all the strain; owing to the practical impossibility to tie both in such an equal manner that a division of strain between them would take place.
T0 enable others skilled in the art to make and use rny invention, I Will add to this description of its nature the following practical remarks.
The distance between the crossing points of the arches, in a longitudinal sense, should always be, between the limits, of not less than one third and not more than two thirds, of the span of the bridge.
In proportion that the curve used for the arches in the compensating bridge is nearer the pure parabola, of which the parametcr is equal to five times, half the span of the bridge, shall the result produced be more efiectual, taking care to use the same curvaturc in the construction of all the arches.
There should be alfiays as many floor chords as there are 1oWer arches.
The compensating qualities et the bridge would be made nearly useless if the fioor is not less given to deflection than those in common use in bridge building. In proportion that the floor of the compensacing bridge is less subject to defiection, in the same ratio Will the compensating qualitics of the bridge offer a more satisfactory practical result. Therefore the fioor best adapted for the Compensacimg bridge Will be such a one likc is represented on the drawings, which is constructed on the Well known tubular principle, as used in the celebrated iron tubular bridge Britannia, constructed Over the Menai Straits by Robert Stephenson, Esqr., C. E.
The fioor of the compensating bridge shown in the drawing consiscs in a double range of.floor beams (Y), separated by the fioor chords, forming a hollow body, which is braced diagonally inside, by horizontal pieces, bolted togethcr vertically where they form crossing points with the beams and witheach other. The ends of the floor should become longer as ten feet, in whidrcase counter braces may be used to intersect their iength.
The braces in the compensating bridge need not be so strong as those in other bridges, because they play only a secondary part in the compensating bridge; that such is a fact becomes strikingly illustrated in observing that, by removing the braces in the compensating bridge, the bridge remains notwithstanding able to sustain a considerable load, however losing its compensating qualities; while removing the braces in other bridges actuafly destroys them as a bridge, s0 effectuaily chat withont them they are not able to sustain their own weight of material.
' What I daim as my invention and desire to secure by Letters Patent is:
1. Thac combination of and between chose mechanical agencies and technical parts Which constitutes the herein described mode, to prevent vibration in a bridge, by using the compensated effect of compression oniy; as carried out and brought in appication, in the herein described compensating bridge. The term compensated eiect, as used here, does not mean the combined result of the forces, which are opposed and neutralized by each other; but is to be understood in the definitive sense of the following Words of our specification the medmnical result of two forces, which are opposed t0 each other in direction, and equa1 in intensity; when tied together.
2. I daim: The combination of and between: the mode in which the arches are arranged and cross each other; and the mode in which they are connected with the fio01; and fina11y the mode in which they receive their leverage; as herein described; tire mechanical efiect of which said combination is, to originate The tendencies in the upper and lower arches to curve apart or asunder.
3. I daim: The combination of and be tween: the mode in which the arches cross each other; and the mode in which they are connected with the fioor; and the mode fina1ly'in which they are constructed in regard t0 amount of material; as herein described; the mechanical effect of which said combination is, to originate the equai in* tensity of the said tendencies.
4. I daim: The employ, in bridge construction, of the herein described arches, arranged and connected as described, as a practical snbstitnte for npper chords, and generally for all such parts in bridges, which serve to uphold the fioor.
5. I daim: The special mode, in the herein described arches, are connected with the floor.
G. W. O. IIUYGENS. VVitnesses:
J AS. A. CONWAY, JOHN FLYNN.