US35251A - Alpiionse ornry - Google Patents

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" lwel PATENT* @FFI-CE. f

lmenov EMENT nil BRIDGES.

perial Corps of f-P'ontsandChaussesff lin `the Construction of `Suspension-Bridges;

4 l"aflldldohereloy declare thenature of my'said invention and in what manner the same is to "be` perform ed to heparticularly described and l 'ascertained in andby-the 'following statement ,the1'eof,1efc1e'11ce being had to the dra-wings `sulriecttxl to aigrezlter burden tlianfotherfpor# `tifinsft docs not become distorted orfput out fof shape, neither is the structure itself liable `:to cfscillate. ".lheplattorms of 'suspensionl ln'idges` asjnsnally madveareconnected to one veral tl Xiblclor'jointed cables or chains hole` llcin g` equallyhalanc'ed under the glitfo'f the s tll'ucture, and' being 4iiexible are apalilei'ptbeing put outof shape. The [action of an \oierloa-dA `applied` to Yone lparticulai; pai-tj of le platform alters'the equilibrium tortion, and consequently `j`a.\i'1esl1`equ1 brium has to be found. The

` ldistrtion isincieased in proportionas the ',"over ad is lllhlied to the p'latiorlnotv the 'na conniredI space.: lt is, however,

infproportion Athe overload is apo a latrgcriliortion ofthe length `of the plie .l 1plattei'm,"so" that" if this overloading is spread eier*tliexwhole length of the` platform the primi( iveeq'ui librifuln w ill be practically mainp tained. a suspension #bridge although inad'efuiilh"flexible chains, would become ay rioid bridgelfnorided the platform was sufy. ly rigid to overcome any 'citent ot' parllialorundueoverloading.. v l

` .BlyiriventioiV rther consists in prevent-v ing" i ur-cllairlsfro'nl losing their {Altllough stillZfiexible, they w l nothe'derangcd byaln excessive or partial loading ot'` the platform. l obtain this result"`lby `forming a means ol" suspension withV two parabolic chains or cables, A B C DE and "lreayirtg `lletwe "1" them the spaces A B CB' "and"4 DflQDjlalrge enough to comprise' all Variatims ot the curves that each sin glechain Specificationforningpart of `Letterslatent No. 35,251, dated lllay 13,1862.

l would take if unduly loaded on one-"particular` partofl the. platform. These spaces are -lilled up by connecting-rods, which maintain the chains in their relative-positions. lVhen, -therefore,the bridgeis loaded upon agiven point of the platform, the effort of the tension will be to become closer'V 'to thelower chain,`which is immediately over the loaded part, ,and to become closer to the upper chain in the corresponding-pointin the otherhalf. By the introduction'of other diagonal rods, in conjunction with `the hereinbeforementioned connecting-rods, the surplus strain on either 'cable' or chain ,will be communicated to the other, by which means the strain will be :equjalized K The plane of suspension Awhich contains the suspension-rods `which connect the platform yWith-the chainsv ma.r be'placed vertically, and to pre'entllateralmotion to the platform they mayloe placed at lan angle with the' plane of the plat-form; Inlake use of inclined suspension-frbds onthe planeof the platform, which Willlead to the employment of rollers or sectors placed on planes'perpendicular to the plane of suspension, S, Fig. 52, being the crosssection, and A B' in Fig. being ,the plan 'perpendicular to the plane of suspension. To

platform and the twisting or shaking of the suspension-rods, the platform must be as rigid as possible. To obtainthis rigidity, I prefer -to employ a platform constructed on the sys tem shown in drawings, Fig. 2, A, in which the rigidityof the lattice will allow the suspension rods te be farther apart, sor that it will not he necessary to employ zmore than Aone suspension-rod to every two or three cross- -tie pieces, as shown in Fig. 5.

, When the span or opening of the bridge' is of extraordinaryWidth, Iiind it convenient same plane ofsilspensiombut some projecting vertically and others placed obliquely, con! necting them together, forming akind of lattice or rigid whole, (ensemble) .If the suspension-rods all projelct vertiealbf, Iiind` it corr- Venient to place diagonal-tie-pieces up to .a

vgidity. lf four double chains are connected togetherfly straight rigid bars or rods', main- `of suspensiomas seen at Fig. l0, the actionl of the wind coming'inthe direction of the arf row F' cannot put the chains out (gt-their poe ,prevent the swinging lor oscillation ot' 'the to use suspension-rods `all contained in the certain height, which addgreatly to the ri taining the chains inl their respective planes sitionA of equilibri um as long as the momentum of F with regardto @"b' c d is infer1or to the sum of the momentum of Vweight of each of the groups of the system of suspension, the

first with regard ,to a', the second with regard to C. Y

' When the platform requires to be attached close to the chains, the cross-tie pieces-above mentioned cannctbe employed in the middle of the span, as they would interfere with the traffic.V In this case thetwo' double chains on the sideof the platform should Abe connected together, leaving the middle space free. Then each of the tie-pieces, in a lat-tice or other form, is firmly connected with the rigid plat-V form. This is not shown inthe drawings, but is a necessity. of position. i

In giving a convenient inclination to the' planes of suspension, and in rendering them rigid by inserting cross-tie pieces, AI may always destroy the tendency to distortion induced by a horizontal `force acting laterally on the four double chains, the'line a blo d in' Fig. 1.0 being Iixedvinfspace, and the platform being sustained on one-side bythe oblique .rods a m and him, and on the other side by the oblique rods c n and d fn.. The action of the wind in the d'irection of the arrow G upon the platform cannot forcethe platform on "one side as long :as the momentum of G with; regard toa b c (lis inferior tothe momentum of weight. of the platforml suspendedin m with regard to a., and suspended in n with regard to c. By conveniently inclining the suSpenSiOn-rOds-that is to say, the plane of suspension-and ballast#v ing ,the plat-form properly I can always 'ren'- derthe platform immovable undervthe action of thel wind.

' In the first part of this specification I have shown the means by which4 AI can,-with the aid of cables or chains, construct a suspension-bridge which cannot be put out of form.

` I have said that to arrive at this result it was necessary that the two cables, A B C D and A'B O D E, (see Fig. 14, which shows the position lof the chains with the rods in zigzag, A and E being the points of'suspension,)being.disposed in a manner -to cornprise -allthe curves of distortion r deformity ,which a flexible cable can take, I maintain themin' their position by vertical rods. I have also before observed 'that to transport to the portion of thecable on whichthere is the least tension the excess of t .nsion which I -preferthe use of steel or 4alloys of steel cast,

tempered, hardened, or otherwise, in erecting these suspension-bridges, and cables of steel wire either tempered or hardened, or otherwse,maybeused. Fig. I is adiagrain of the parabolic cables; Fig. 2 sh'ows the new system of suspension in longitudinal elevation and in section; Y Figs. 3 and 4 show the assemblage or junction of the'lower links of a chain cable withthe sus=.. pension-'rods and the diieren't tie-piecesfor.` a bridge of moderate'V span, Fig. 3 being theside.view, and Fig. 4 being theplan, of such assemblage. .Figd 5 is a portion of the longi-` tudinal'elevation of a bridge of Wide span,"

showing the diagonal tie-pieces. Fi'gs andv` 7 show the same assemblage as Figs.` 3 and 4,.'

r but vfor a bridge ofextraordinary.spanfin which the links are -made of circular section;

Figs. Sand 9', the same assemblage, but the bars are fiat. Fig'. 10-is a transverse 'section of a'bridge in which four double' chains of suspension.A are employed, andgalso shows the position and disposition of the suspension- -rods placed obliquely to theplaneof the platform, two inclining outward `and two inward, withA cross-ties in lattice con-n ecting to.-V gether the four double chains. Fig. 1l shows Athe assemblage 'of the. chains with* the `con-f necting-rods in zigz,l g. Fig.{l2 lis the section'. of Fig. l1 at the `line 1'2. Fig. 13 is theviexit-l of the zigzag rods seen from above. These -zigzag rodsmaybe replaced by vertical' and diagonal rods used vbetween two chains, asl shown in Fig. 2. Fig. 14 is` the'chain with zigzag tie-pieces.' Fig. 15 shows the ,seQiong of a tie-piece which might lbe conveniently, used in the zigzags I Having now described the nature of Ilmy said invention and in-What-manner th saine is tobe performed, I declare that I' claim' as my improvements in the construction of sus-fl pension-bridges- V1. The employment -of double parabolic, cables or chains, as hereinbefore described," and shown in the accompanying drawings.

The employment of two series of rods` s et 4obliquely to the plane off the platform,` substantially'as hereinbefore described, and

shown at '-Fig. 10 of the' accompanyingdrawings.

overcome the effect of a horizontal lforce act-A ing laterally upon the four double chains or v systems of suspension which'hvvouldl otherwise tend todeform, distort, `or alter their l form, together with the means, described to` replace such tie-pieces in the middle of a bridge or viaduct, so as not to impede the circulation, allas hereinbcfore described and illustrated with .reference to the accompanying-drawings. l In testlmon y whereof I have signed my name to this speciiication before two subscribing witnesses.

Mivar-lessee' -Atriirmsn oitDR-Y.

. GEO'. HUT'roN,

L. EPLAEZ.

3. The 4employmentof rigid tie-pieces to

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