US2337994A

US2337994A - Skew bascule bridge

Info

Publication number: US2337994A
Application number: US485505A
Authority: US
Inventors: Jr Clinton D Hanover
Original assignee: Individual
Current assignee: Individual
Priority date: 1943-05-03
Filing date: 1943-05-03
Publication date: 1943-12-28
Anticipated expiration: 1960-12-28

Description

I Dec. 28, I943.

SKEW BASCULE BRIDGE Filed May s, 1945 5' Shets-Sheet 1 IN VEN TOR.

" /mfm Q fianorm/r 'c. D. HANdVER, R 2,337,994

Dec. 28, 1943. Q D HANOVER JR I 2,337,994

SKEW BASCULE BRIDGE Filed Mays. 1943 5 Sheets-Sheet 2 INVENTOR.

1943- c. D. HANOVER, JR 2, 7,

SKEW BASCULE BRIDGE Filed May 3, 1945 5 Sheets-Sheet 3 Dec. 28, 1943.

c. D HANOVER, JR 2,337,994

SKEW BASCIULE BRIDGE Filed May 3, 1943 5 Sheets-Sheet 4 Dec. 28, 1943. c. D HANOVER, JR

' SKEW- BASCULE BRIDGE Filed May :5, 1943 s Sheets-Sheet 5 I N V EN TOR. 6///7/0/7 Q flmawn/n Patented Dec. 28, W43

' UNITED STATES PATENT OFFiCE I SKEW BASOULE BRIDGE Clinton 1). Hanover, J12, Little Neck, N. Y. Application May 3, 1943, Serial No. 485,505

Claims.

The invention relates to a new type of skew bascule bridge, and is especially suitable where the bridge crossing 'isat a considerable skew with the center-line of the channel crossed.

Various types of skew bascule bridges have heretofore been used for skew crossings, and bridges without skew have" been used at skew crossings where previously known types of skew bridges were deemed structurally unsatisfactory, thus increasing the length of the bridge and, accordingly, its cost. Skew bascules heretofore have had their main supporting girders or trusses wholly at right angles to the axis of rotation, the main girders being not at any part parallel with the roadway and so necessitating that these girdersbe set close together, reducing the space available for counterweight and operating machinery and requiring large triangular shaped sections of the bridge roadway and framing to be cantilevered outside the main girders, with resultant lack of rigidity in theentire structure. Such skew bridges frequently have much heavier loads on one main girder or truss than on the other, as well as much heavier loads on one trunnion or rolling segment than on the other and require that the counterweight be made much heavier at one end than at the other.

It is the object of the present invention to provide a skew bascule bridge with the shortest feasible span for a given skewed crossing, having simple and rigid framing, with both the forward and rear portions of the main girders or trusses spaced as far apart as may be desired, providing maximum room between rear portions of the main girders for the counterweight and operating machinery, with the center of gravity of the counterweight near the center-line between the rear portions of the main girders and with the loads on the trunnions or rolling segments equal or nearly equal.

Another object is to provide a skew bascule bridge such that a satisfactory single-leaf skew bascule bridge can be used where otherwise a much more expensive double-leaf bascule bridge without skew, swing bridge, or retractible drawbridge, would be necessary. Another object is to provide a skew bascule bridge such that a satisfactory double-leaf skew bascule bridge can be used where otherwise a much more expensive lift span or high-level bridge would be necessary.

In the skew bascule bridge of the present iners are at right angles, or nearly at right angles,

to the channel line. The two knee-joints of the main girders or trusses are strongly and rigidly the rear portions of the main girders.

to suit particular circumstances.

connected by a girder or truss, whichds approximately parallel to the center-line of the channel. Each floorbeam of the forward or span section of the bridge is framed into the main supporting girders or trusses farther from the knee-joint of one girder than from the knee-joint of the other girder. This novel arrangement of main girders. J

or trusses, cross girder or truss at knee-joints and floorbeam framing allows the forward leaf to be balanced by a counterweight, th center of gravity of which is not on a line drawn through the center of gravity of the forward leaf. and at right angles to the axis of rotation of the bridge, but is at or near the center-line between This is a very important feature of the invention, because a substantially uniform counterweight can be used and because the load is about equal on the two trunnions or rolling segments.

The invention can be used for skew bascule bridges for highways or for railways. It can bev used as a single-leaf bascule with the toe end resting on a pier or other support when in the closed position. It can be used in a double-leaf bridge where the width of the channel crossing requires along span. It can be used on a bridge supported and rotating on trunnions or on rolling segments or on rollers. Th materials of construction and their arrangement can be varied The cross-section of the forward leaf of the bascule may be symmetrical or non-symmetrical with respect to the center-line between the forward parts of the main supporting girders; that is to say, the center-line of the roadway need not coincide with the center-line between the forward portions of the main girders.

Further advantages of structure and operation of the invention will be described in connection with the accompanying drawings, in which:

Fig. 1 is a plan view of a single-leaf bascule of the present invention, in closed position;

Fig. 2 is a vertical section, taken on the line 2-2 ofFigJi vention, the main supporting girders or trusses Fig. 3 is a horizontal section, taken on the line 3-3 of Fig. 2;

Fig. 4 is a front elevation, partly in section,- looking from the right of Figs. 1 or 2, with the bridge raised, the section being taken on the line 4-4 of Fig. 3;

Fig. 5 is a diagrammatic plan view of the bridge shown in Figs. 1 and 2, showing th main merndashed lines, the bridge rotating on trunnions;

Fig. 7 is a fragmentary vertical section of the structure shown in Fig. 5, taken on the broken line 6-6, similar to Fig. 6, but showing a bridge rotating on rolling segments;

Fig. 8 is a plan view in diagrammatic form of a modification, showing one single-leaf span where the floorbeams are framed into the main girders at an angle other than ninety degrees;

Fig. 9 is a plan view in diagrammatic form of another modification, showing one single-leaf span where the floorbeams are framed into the main girders at such an angle that the center of gravity of the counterweight is located nearer to the outer girder than to the inner girder;

Fig. 10 is a diagrammatic plan view of a singleleaf span where the floorbeams are framed into the main girders at such an angle that the center of gravity of the counterweight is still further toward the outer girder;

Fig. 11 is a plan view showing the present invention as a double-leaf bascule bridge; this bridge has a roadway and two sidewalks, the

,cross section of each forward leaf being symmetrical with respect to the center-line between the forward parts of the main supporting girders;

Fig. 12 is a plan view of a modification, showing a single-leaf bascule, in which the span or forward sections of the main girders are not parallel to each other, the forward section of the inner main girder being parallel to the centerline of the roadway, while the forward section of the outer main girder is at an angle intermediate between that of the center-line of roadway and of an extension of the line of the rear portion of the girder;

Figs. 13, 14 and 15 are diagrammatic plan views of three modifications in which the span or forward sections of the main girders are parallel to each other, but not parallel to the center-line of the roadway, these three forms involving different floorbeam framing.

Referring to the drawings, more particularly to Figs. 1, 3 and 5, line li-ll designates the center-line between the forward portions of the main supporting girders and 2 I. Line I la-l la designates the direction of bridge tramc, line l2-l2 the center-line of channel and the direction of marine traffic, l3-j3 the channel clearance lines, H a curb line, IS the forward leaf or span of the bascule bridge which rotates about the axis of rotation l6, and is balanced by the counterweight H.

The span as a whole is supported by the main pier I0, I9 being a toe pier used on some singleleaf applications. The forward portions of the main supporting girders, 20 and 2|, to the rear portions of the main supporting

girders

22 and 23 at knee-

joints

24 and 25. Girder 20-22, being on the convex side of the bascule leaf, may be referred to as the outer main girder and girder 2I-23 being on the concave side as the inner main girder. Girder 20 is a cross-girder or'knee-girder connecting the main are joined girders at the knee-joints. This girder is preferably made the same depth as the main girders at the knee-joint connections and may vary in depth between connections. Girder 26 carries the torque required to hold the top and bottom chords or flanges of the main girders at the knee-ioints in equilibrium and may also be used as the heel floorbeam of the forward leaf. 21 is a toe floorbeam and 28 are a number of floorbeams framed between the main girders, while 29 are floorbeams framed between a main girder and either the toe floorbea-m 21 or the cross-girder 26. Line 30 is the center-line between the rear portions of the main girders and intersects line II-ll at the cross-girder 26. Point 3i indicates the location of the center of gravity of the forward leaf or the leaf except the counterweight, while point 32 is the location of the center of gravity of the counterweight and point 33 is the location of the center of gravity of the entire leaf.

Each of the main girders 20-22 and 21-23 being rigidly jointed at the knee-

joints

24 and 25, both in the same general direction, allows the forward portions of the

girders

20 and 2| to be parallel or nearly parallelto the center-line of roadway or the direction of bridge trafilc Ila-l la. For extreme skews, it may be advisable to have forward portions of the main girders at an angle to the center-line of the roadway, as in Figs. 13, 14 and 15. The rear portions of the

main girders

22 and 23 are at right angles or nearly atright angles to the center-line of the channel or direction of marine traflic l2-I2. This arrangement materially increases the distance between the rear portions of the

girders

22 and 23, thus giving sufiicient room for the counterweight I1 and for locating the operating machinery between the girders. This arrangement allows the axis of rotation to be placed parallelor nearly parallel to the channel, thus providing the shortest leaf for any particular skew crossing.

The analysis of the forces in the members of the structure may be understood by referring in particular to Fig. 5, and considering the bascule leaf to be slightly raised. The cross-girder 26 carries moments induced in it by the tension and compression forces in the flanges of the main girders at the knee-

joints

24 and 25. The angular relation of the forward and rear portions of the main girders at the knee-joints being in thesame general sense or direction, these induced moments are of the same sign and are therefore additive. moments is equal to the moment of the forward leaf about the center-line 30. To maintain equilibrium in cross girder 26, it therefore follows that girder 21-23 exerts a force upwardly and girder 20-22 exerts a force downwardly, which forces produce a moment balancing the moments induced by the tension and compression in the main girders. The effect of this cross-girder 26 is, therefore, to exert a'force downwardly upon girder 2l-23 and upwardly upon girder 20-22, which forces tend to require that the center of gravity of the counterweight be on the line 34 which is a, line passing through the center of gravity of the forward leaf and perpendicular to the axis of rotation, in order that the moments in each main girder are balanced at It by counterweight II. Such location of the center of gravity of the counterweight is considerably off center and is therefore preferably to be avoided.

The sum of these induced line 34 can be counteracted at will by varying the method of framing the

floorbeams

28 and 29 into the

main girders

20 and 2|. This control of the location of the center of gravity by the use of different floorbeam framing is an important feature of the present invention. By framing each of these floorbeams into the outer forward girder 20- farther from knee-joint 24 than they away from line 34 toward the outer rear girder 22, thus allowing the center of gravity of the counterweight to be placed at 32, and allowing the counterweight to be built with as nearly a uniform weight per unit of its length as may be desired. This fact in turn makes it readily possible to construct a counterweight heavy enough to balance the span since it is not necessary to concentrate its entire weight near one of its ends.

True balance of the bridge isobtained in all arrangements shown. For true balance of the bridge it is necessary only that the location of the center of gravity of the entire moving structure be located somewhere on the axis of rotation It. It is not necessary that the total weight of the entire movable structure fall centrally between the trunnions. The structure is stable if the entire weight is somewhere on IS, between the main girders. Y

In fact, each of Figs. 5, 8, 9 and 10 may be regarded as a compromise in view of the conditions that must be met in bridges of this type. In Fig. 5, the load on the trunnions is not quite the same; the counterweight is nearly uniform, being a little heavier toward beam 23, to 'put its center of gravity at 32. In Fig. 8, the'load on the trunnions is not quite the same, While the counterweight I! is uniform, with its center of gravity at its middle. In Fig. 9, theload on the trunnions is nearly the same, while the counterweight is a little heavier on the' side toward irder 22. In Fig. 10, the load on the trunnions is uniform, while the counterweight is heavier on the side toward girder 22, the displacement being greater than in Fig. 9. p

The framing of the forward leaf i5 is com.- pleted by supplemental beams 36 and diagonal bracing members '38. and other conventional members.

In practice. the pivotal axis ortrunnions IS, a short distance below the highway level, as in Fig. 2, is supported on frames 40, positioned in the counterweight chamber 42 in pier l8, in which chamber the counterweight I 1 moves. Conventional operating machinery, indicated generally at 44. positioned on platform 46, drives the usual gears 48 for raising and lowering the bridge. The forward leaf in Figs. 1-4 is provided with a sidewalk 49 along one side.

In Fig, 7, the bridge is shown as movable on a conventional rolling segment 50 rolling on sup port 5|, as is well understood in the art of bascule bridges. 4

Inthe modifications shown in Figs. 8, 9 and 10, in which corresponding parts are numbered as in Figs. 1-6, the floorbeams indicated at 28' and 29' are shown as set at different angles, other than 90, with respect to the forward

main girders

20 and 2|. The change in the position of the center of gravity 33, with the changing angular setting of the floorbeams, is evident from' these three figures. -As the angle of the floor beams is successively increased, as in Figs. 8, 9 and 10, the center of gravity 33 of the bridge is displaced toward the

outer girders

20, 22.

Fig. 11 is a plan view showing the bridge of the present invention built as a double-leaf bascule, for bridging a wide channel. The parts shown are the same as those described in connection with Figs. l-4 and corresponding parts are similarly numbered. Conventional means for locking the toe beams 21 together, when the bridge is down, are used.

Fig. 12 is a plan view of a modification where only one of the main girders is parallel to the In this form, the forward portion 2| of the inner main center-line of the highway ||a-||a.

girder is connected at the knee-joint 25 to the rear portion 23 of this main girder. The forward portion 20a of. the other main girder, is at an acute angle with the center-lineof the highway, and is connected at the knee-joint 24a to the rear portion 22a of this main girder.

Kneejoints

24a and 25 are connected by knee-girder 26a. Floorbeams 54 are secured to the

forward portions

20a and 2| of themain girders, these floorbeams being-preferably but not necessarily perpendicular to girder 2|. Certain of these floorbeams 54 are extended beyond main girder 20a and support. a fascia girder. 56, the ends of which are respectively secured to an extension of knee-girder 26a, and to a short extension of toe fioorbeam 21a. The fascia girder and the extensions of. the knee-girder support a bridge section 58 necessitated-by the sharp angle of intersection between the center-lines of the highway and channel. In this form, the main pier It does not necessarily extend entirely across the roadway, but may be located more or less centrally with the rear portion of the bascule leaf.

In installations where the bascule pier. I8 is not extended entirely across the roadway a supplementary and conventional pier or abutment He may be used in conjunction with the bascule pier to support the approachto the bascule span. This shortening of the main pier results" in a large reduction in the cost .of a bridge project.

In the modification shown in Fig. 13, the forward portionZOb of the outer main girder is connected at knee-joint 24b to the rear portion 22b of the main girder. The forward portion 21b of the inner main girder is connected at kneejoint 25b to the rear portion 23b of the main girder. The knee-joints are connected by kneegirder 26b. The forward portions 20b and 2| b of the main girders are parallel to each other, but at an acute angle with center-line ||a-| Ia of the roadway. Knee-girder 26b is continued in one direction, and supports one end of fascia girder 60, at 6|. The other end of girder is supported at 62 by main girder 20b and toe beam '2'"). .Toe beam 21b is continued in the other direction and supports fascia girder 64 at 65. The other end of girder 64 is supported by the main girder at or near knee-joint 25b.

Floorbeams 66 are provided as shown, interconnecting the forward portions of themain girders with knee-girder 26b and toe beam 21b. Smaller floor-beams 88, secured to the main girders and preferably, to fioorbeams 65 also, further support the fascia girders and.

In the modification shown in Fig. 14, the main girders are substantially the same as in Fig. 13,

the only difference being in the framing of floorbeams 10, which interconnect the fascia girders 60 and 64, forward portions 20b and 21b of the main girders, knee-girder 26b and toe beam 21b.

In the modification shown in Fig. 15, the ends of fascia girders 12 are secured. at 13 and II to opposite ends of fioorbeam 16. Additional floorbeams 18 interconnect the main girders 20b and Nb, the fascia girders, knee-girder 26b and toe beam 21b.

From the foregolngdescription, it will be seen that the forward leaf of the bridge is simple in outline, with the main. girders as near the outer limits of the bridge as may be desired, and placed in such a position that the entireleaf can be rigidly braced with bracing members wholly within the limits of the main girders and the toe and heel floorbeams. Also, the floorbeams may beframed into the main girders at right angles foreasy framing, the number of skew connections thus being kept low. It will also be seen that ample room is obtained for the counterweight and incidentally for operating machinery located between the rear portions of the main girders. 'As shown particularly in Figs. 12 to 15, the basic design of the bridge may be var ed considerably, especially for crossings of extreme skew. The fioorbeams may be used to support fascia girders, where the angle of skew requires the use of such beams. In the several forms of the invention, the moments in the main girders at the axis of rotation tend to become equal, the construction serving to shift the moment from the inner girder to the outer girder, and this shift of moment having the effect of counteracting the moment forcesintroduced into the main girders by the cross girder 26. The load on the two trunnions or rolling segments is about the same, and the center of gravity of the counterweight is about at its mid-point, results difficult of achievement in skew bascule bridges.

Many variations can be made in the form,

\ arrangement and construction of the elements included! in the invention, such as the use of .trusses instead of girders, double-web girders or single-web girders, girders of uniform or varying depths, counterweights rigidly fastened to main girders or hung on main girders by means of trunnions. Two leaves may be built side-by-side, in close proximity, the inner girder of one being attached to the outer girder of the other, in order to form one leaf of greater width. Although I have shown and described only certain forms and embodiments of the invention, I do not limit myself to any specific form or embcdiment.

I claim as my invention:

1. A skew bascule bridge, the forward portions of the main supporting girders of which are connected to their rear portions at obtuse angles of the same general sense at rigid kneejoints located in front of the axis of rotation of the span.

2. A skew bascule bridge, comprising main supporting girders wherein the forward, spancarrying portions of the main girders are rigidly connected to the rear, counter-weight-carrying portions of the girders at obtuse angles of the same general direction by rigid knee-joints, a counter-weight carried by the rear portions of the main girders, and means forming a pivotal axis for the bridge between the knee-joints and the counterweight.

3. In a skew bascule bridge the combination of main supporting girders, the forward portions of which are connected totheir rear portions at obtuse angles of the same general sense at rigid knee-joints located in front of the axis of rotation of the span, and another girder connecting the main girders at their knee-joints.

4. A skew bascule bridge, comprising main supporting girders, knee-joints rigidly and angularly connecting the forward, span-carrying por-. tions of the main girders with their respective rear, counterweight-carrying portions, said kneejoints forming obtuse angles in the same general direction, a counterweight carried by the rear portions of the main girders, a. knee girder connecting the main girders at said knee-joints, and means providing a pivotal axis of rotation, between said knee girder and the counterweight.

5. A skew bascule bridge, comprising main supporting girders, knee-joints rigidly and angularly connecting the forward, span-carrying por tions of the main girders with their respective rear, counterweight-carrying portions, said kneejoints forming obtuse angles in the same general direction, a counterweight of generally uniform cross-section, carried by the rear portions of the main girders, said counterwe ght having its center of gravity at substantially the middle thereof, a knee girder connecting the main girders at said knee-joints, and means providing a pivotal axis of rotation, between said knee girder and the counterweight.

6. In a skew bascule bridge the combination of main supporting girders, the forward portions of which are connected to their rear portions at obtuse angles of the same general sense at rigid knee-joints located in front of the axis of rotation of the span, another girder connecting the main girders at their knee-joints and floorbearns connected to the main girders so that each'floorbeam is attached farther from the knee-joint of one main girder than from the knee-joint of the other main girder.

7. A skew bascule bridge, comprising main supporting girders, knee-joints rigidly and angularly connecting the forward, span-carrying portions of the main girders with their respective rear, counterweight-carrying portions, said knee joints forming obtuse angles in the same general direction, a counterweight carried by the rear portions of the main girders, a knee girder connecting the main girders at said knee-joints, fioorbeams connecting the main girders, one point of intersection of each floorbeam with one main girder being farther from the knee-joint of that girder than the other point of intersection is from the other knee-joint, and means providing a pivotal axis of rotation, between said knee girder and the counterweight.

-8. A skew bascule bridge, comprising main supporting girders, knee-jointsrigidly and angularly connecting the forward, span-carrying portions of the main girders with their respective rear, counterweight-carryingportions, said knee-joints forming obtuse angles in the same general direction, a counterweight carried by the rear portions of the main girders, a knee girder connecting the main girders at said knee-joints, floorbeams connecting the main girders, said floorbeams forming an acute angle with the longiknee-joints looated in front of the axis of rotation of the span, a main bascule pier supporting the bascule bridge, said main bascule' pier extending only partialli across the roadway, a smaller bridge pier supplementing said main bascule pier, extending under and supporting the approach to the bascule for the remaining width of the roadway.

10. In a skew bascule bridge, the combination of main supporting girders, the forward portions of which are connected to their rear por- 10 of the roadway.

CLINTON 11 HANOVER, JR.