US630809A - Bridge. - Google Patents

Description

No. 630,809. Patented Aug. s, |899.

w. A. Gunn.

BRIDGE.

{Nu Model.) (Application med Feb. 13 1899.) 2 Sheets-Sheet l.,

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Aim l SIMM/Wto@ @5W- @maren m No. 630,809. Patented Aug. a, |899.

w. A. GUNN.

BRIDGE.

(Application filed Feb. 13, 1899.) LNo Model.) 2 Sheets-Sheet Z.-

UNITED STATES PATENT OFFICE.

lVILLIAM ADAMS GUNN, OF LEXINGTON, KENTUCKY, ASSIGNOR OF ONE- HALF TO VILLIAM EDIVARD GUNN, OF COVINGTON, KENTUCKY.

BRIDGE.

SPECIFICATION forming part of Letters Patent N o. 630,809, dated August 8, 1899.

Application iilell February 13, 1899. Serial No. 705,404. (No model.)

T0 ctZZ wiz/0m t may concern..-

Be it known that I, WILLIAM ADAMS GUNN, residing at Lexington, in the county of Fayette and State of Kentucky, have invented certain new and useful Improvements in Bridges, of which the following is a specication.

My invention relates to an improvementin bridges which are composed of wire or other cables passing over towers, with floor system suspended from said cables.

The object of my invention is to secure a greater amount of strength and stiness in a bridge with a given amount of cables and anchorage, or to reduce the amount of material in the cables, Suspenders, anchorages, `and towers necessary to obtain a required degree of strength and stiffness and it is also an object of my invention to reduce the amount of material in the oor system which must be suspended from the cables both on the main span between the towers and on the opposite side of the towers away from the center of the bridge and toward the ends of the bridge, commonly called the land-spans.

the manner illustrated in the accompanying drawings,forming a part of this specification, in which- Figure 1 is a vertical section of the bridge in the direction of its length. Fig. 2 is an enlarged view of the tower in the same direction. Fig. 3 is a vertical elevation of the tower transverse to the line of travel.

The bridge consists of double towers A and A, resting on masonry F F, and cables O O, passing over the towers and fastened in the anchorage masonry or in any other suitable manner to the ground at B B.

D D represent Suspenders, and E E stilening-trusses carrying the floor. There is also a truss fastened to the inside of each tower and projecting past the sides of the same, as

shown at II I-I. Over-floor cables or stays, as

where steel towers are used the posts which are shown in outline on the drawings will be built according to customary designs for steel I obtain these objects by constructing said bridge inl columns-as, for instance, two channels fastened together by riveted la'ttices-and so as to details of all the members of both towers and trusses, the uselof customary forms of chords, posts, struts, ties, floor-beams, rbc., is contemplated.

Each toweris quadruple, preferably, being y composed of two sets of 'towers which diverge from the base to the top, so that each tower forms, in fact, a double, diverging tower, the divergence being in the direction of the length of the bridge. In the drawings a single-span bridge is shown for convenience of illustration, and, as will be seen, the outer tower members of the towers lean toward each other or toward the middle span of the bridge R R and the inner tower'members lean toward the land-spans, thus reducing the spans in each direction. For wide bridges more leaning towers may be combined to form a tower, as three or more diverging members upon each side, and I speak of these diverg ing members as constituting a double tower. The divergin g members are tied to each other and braced from each other, as shown at KK. This connection must act as a tie to hold the weight of the towers that diverge yfrom each other and Inust also act as a brace .when the cables are cradled-namely, drawn in the middle ot' the center span nearer together than at the towers. This helps to resist the wind-pressure. The diverging tower members must be held to each other by ties, as M M, or by trusses N N, or by both. The trusses N N may be constructed of Vertical posts and horizontal eyebars and inclined tierods connected by pins at the top and bottom of the posts, or may consist of two horizontal cables trussed by vertical posts and inclined tie-rods. In this case it will be necessary to hold the ends of the parts at fixed distances horizontally. The purpose of this truss is to hold the diverging tower members at 'x'ed distances horizontally from each other and lessen the deflection of the bridge caused by a heavy load compared to' a light ,load from reduced sag in cables M M. This objectcan also be further secured by holding the cables down between the leaning arms of the towers and between the towers and anchorages, as shown at V V. The inclined tower members ICO may be held apartrfrom each other at their base by struts X X, that will take up the horizontal thrust, so that the weight of the whole tower and its load shall descend vertically on the masonry or other support, or the towers may be brought to a common center at their base and turn on a single pin. This base may consist of masonry pedestals or any other suitable anchorage.

In large bridges the cables should rest on saddles of steel or iron on top of the towers, and the saddles4 should be mounted on rollers, and the base of each saddle should be inclined in the direction that its tower leans one-half as far from a horizontal line as the cable slopes below a horizontal line immediately outside of the tower. On small bridges the cables may pass over fixed bearings on top of the towers. The land-spans maybe partly or entirely supported by Suspenders from the cables, or may, especiallyin large bridges, be a truss carryingits own weight. The form of the truss is not an essentialv feature. The cables can best besecured by masonryat the ends of bridges by passing the wires of which it is composed around pins held by eyebars which pass into the masonry, linked to other eyebars by pin connections, and, finally, to a large plate at or near the base ot the anchorage masonry. In large bridges and bridges of medium size the Suspenders nearest to the towers had best be omitted to a distance from the center of the tower equal to the distance from the center of the tower to the center of the land-span. The object of this is to allow this part of the stiffening-truss to balance against the half of the land-span and actas a separate span. This portion of the stiiening-truss may be made upon a distinct span. Expansion can best be provided for at the center of the middle span and at the anchorages, but may be arranged at the ends of spans fastened in the towers. The towers are made to act in conjunction with the truss-span which they carry to secure the advantage ofa cantaliver principle both toward the middle span and toward the ends of the bridge and are also intended by the divergence to secure the advantage of the arch form from the base of the tower to the truss. They should therefore be much stronger below the trussvthan above. The trusses H H within the tower may be constructed as a component part of the towers instead of a separate structure attached to the towers.

The arms of the tower should lean toward the middle of the bridge about twenty-six and one-half degrees from a vertical line, its diverging tower members leaning a like number of degrees in the opposite direction. The

cables should descend from the tops of the towers toward the land at about the same` slope they have on the side toward the middle of the bridge.

-In light bridges the swaying resulting from wind-pressure may be'lessened by the use of supported by the cables.

By the use of towers with diverging arms the points of support of the cables are brought nearer together and the depth of the cable below the plane of the supports is increased compared to the distance between the supports, decreasing the tension resulting 'from a given load. The diverging form of these arms, combined with the cantaliver span, also decreases the length of the floor system to be The stieningtrusses may be divided into a larger number ot spans, or they may be converted into a continuous truss the length of the bridge.

In this case the truss may be connected with the towers so as to move horizontally but not vertically, the chords sliding in grooves, and

the expansion will then occur at the ends of the bridge. Over-Hoor cables or stays may be used or they may be omitted. The best application of a stay or stays is to leave the main cables unloaded at the part upheld byv the stay or stays.

While my principle of diverging towers is primarily adapted to be applied to suspensionbridges having a -single span, it is obvious that it can be applied with equal advantage to bridges employing a multiple of spans, and I do not wish to limit myself to the particular form shown. v

Having described myA invention, I claim-V 1. The combination in a bridge 0f double towers divergin g in the direction of the length of the bridge,with cables, Suspenders, trusses and anchorages, substantially as specified.

2.` The combination in a suspension-bridge, of two or more supports consisting of tower members diverging from a base in the direc-` tion of the length of the bridge, cables passing over the diverged tops, and a bridge struc ture suspended from said cables, substantially as described.

3. In a suspension-bridge the combination of two or more double towers diverging in the direction of the length of the bridge, each supported upon a suitable base, the said diverging tower members being braced together, cables passing over the tops of said towers, a bridge structure suspended from said cables above the line of tower-bases and supported by said cables and by the diverging towers at their points of intersection with said bridge structure, substantially as specified.

4. In combination with a bridge,tower members diverging in the direction of the length of the bridge, a cantaliver bridge-span intersectin g and supported bythe diverging tower members above the base, substantially as specified.

In testimony whereof I have hereunto set IOO IOS

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