US3103026A - Bridge structures - Google Patents

Description

Sept. 10, 1963 M, HAHN 3,103,026

BRIDGE STRUCTURES Filed. June 10. 1960 2 Shee ts-Sheet 1' H 30 I9 IZ Z l 2! l4 'I V v/ W m I i y 2 MARION Ki C O/m 4 d ATTORNEYS Sept. 10, 1963 M. HAHN 3,

BRIDGE STRUCTURES Filed June 10, 1960 2 Sheets-Sheet 2 INVENTOR.

5T MARION HAHN ATTORNEYS United States Patent 3,103,026 BRIDGE STRUCTURES Marion Hahn, 916 S. 38th St, Lincoln, Nebr. Filed June It), 1960, Ser. No. 35,269 3 Claims. (CI. 14-13) This invention concerns a bridge structure and more particularly is directed to a bridge truss member having a joint adapted to diffuse the pressure accumulating therein throughout the entire truss.

It is a primary object of my invention to provide a bridge truss in which pressure applied by weight to the upper joints of the truss will be diffused laterally in both directions from the joint to prevent a concentrated load at anyone point.

It is a further object of my invention to provide a device in which vertical load pressures will be redirected into a horizontal plane, the point of such redirection being adapted to permit limited shear movement.

It is yet another object of my invention to provide a device in which a plurality of truss members may be positioned adjacent each other over a wider span than an equivalent single truss member could be similarly positioned.

It is yet a further object of my invention to provide a device in which an eccentric joint may be employed to carry the vertical load. I

It is yet another object of my invention to provide a device in which the eccentric joints may be positioned either at the ceiling level or the floor level of the bridge.

Other and further features and objects of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawings and following specifications, wherein are disclosed several exemplary embodiments of the invention, with the understanding, however, that such changes may be made therein as fall within the scope of the appended claims, without departing from the spirit of the invention.

In said drawings:

FIGURE 1 is a view in side elevation of a bridge showing a plurality of frame members positioned adjacent each other to cover the span, the positions of eccentric joint suspension assemblies being indicated therethrough.

FIGURE 2 is a detailed side view of a single eccentric joint constructed according to my invention.

FIGURE 3 a is detailed view of the eccentric positioned relative to the tace on which it operates, and

FIGURE 4 is an enlarged detail of the lower portion of an eccentric suspension assembly at its lowermost point showing the manner in which the bridge frames are hinged.

FIGURE 5 is a view of an eccentric joint adapted to be positioned beneath the floor of a bridge, and

FIGURE 6 is an enlarged view of a modified eccentric joint in which several eccentrics are employed.

Referring now to the drawings:

Generally a bridge is constructed of one or more frame members in series, the outermost ends being supported by piers on either side of the river or other depression being spanned by the bridge.

In a device constructed according to my invention, a series of frame members or pairs of panels, indicated at FIGURE 1 generally at 11, 12, 13 and 14, are provided. These frames are joined together to make a complete structure, the outer ends 16 and 18 being supported on conventional piers.

In between each of these frame members are eccentric joint structures 19, 20 and 21. Extending downwardly from these eccentric members are hangers 24, and 26. These hangers are adapted to support the floor 29 of the bridge. Pass-over plates, such as 30 of eccentric 19, are provided for each of the eccentric joints. It is this general structure which I will now describe in greater detail.

The eccentric joints are comprised of a pair of eccentrics such as 31 and 32 of FIGURE 2.. These eccentrics are each mounted on a plate 33 which has a down wardly extending shank 34. This downwardly extending shank is attached to the hanger members, such as 24 of FIGURE 1, which in turn support a bridge floor, therefore the load on the bridge. It will be apparent that this load is transferred through the hanger to the shank 34 and the plate 33 and thence to the eccentrics 31 and 32. Adjacent the eccentrics and on the frame members on the inner side of the joint are pressure receiving surfaces 35 and 36. These are preferably of hardened alloy steel and have one fiat vertical plane which engages the surface of the eccentrics. These plates are mounted on the frame members such as 11 and 12.

It will be obvious that a :load on the hangers and plate 33 will tend to move the assembly downwardly. At the same time, the eccentric members will tend to rotate. Since they are off-center members, any rotation will result in an increase in the radius from the mounting pivot 37 and 38 which in turn will tend to push the two frame members 11 and 12 further apart. Of course as the top line of the truss is thereby lengthened, the bridge floor will tend to resist any actual downward movement, and of course it must be understood that the actual relative movement between the eccentrics and their adjacent pressure receiving surfaces will be extremely limited and any lengthening of the upper chord of the bridge will be measurable in only small fractions. It will be further apparent that the structure is more concerned with forces than with actual movement and that as the bridge load increases, the pressure between the face of the eccentric and the face of the receiving surface will increase proportionate to the load on the bridge floor. Since the relationship between these two surfaces is a pure compression relationship, the maximum load carrying efficiency of the metals or other materials used will be realized. A vertically downward pull of the load will, through the eccentrics, be transferred into a horizontal force emanating outwardly from the joint along with the upper chord of the bridge frame.

It will be understood that the redirection of these forces from the vertical to the horizontal direction results from the permissive movement between the eccentrics and their receiving surfaces in the form of a shearing action, which is ordinarily resisted in the conventional beam structure. In any conventional structure, downward force is applied, and if collapse occurs it is by reason of the localized stress on the material which causes it to bend in its weakest cross sectional area. In the applicants device, this downward force is through the eccentrics diffused in opposite directions along the horizontal chord of the frame structure and thus in compression and in the cross sectional area of the member offering the greatest strength.

To further reinforce this horizontal correctional application of load, I have provided a compression pass-over above the joints which comprises two horizontal plates, plate 111 being atlixed to frame 11 and plate 112 being afiixed to frame 12. These two plates abut together at their midpoints above the joint, which is indicated at 113.

In a joint structure such as has been described, it is also necessary that the main frame members 11 and 12 be jointed at their lower point in such a manner as to permit relative movement between them, and to permit such movement I have provided a hinge structure which is shown in detail in FIGURE 4. The lower extremities of the bridge frames are again identified as 11 and 12 and the shank member of the eccentric as 34. Fastened to this shank at its lower end is an I beam 40 which is positioned at right angles to the frame members and supports the bridge flooring 29. The frame members 11 and 12 have downwardly extending ears 41 and 42 which are mounted as a 'pin 43 at their lower ends. The ears are free to rotate on this pin 43, thus providing a hinge at that point. Outwardly extending truss members 44 and 45 are also connected to the hinge pin 43.

It will be appreciated that no great motion occurs at this hinge, but that the frame members 11 and 12 are free to rotate and therefore no binding action can occur at this point which will cause a deflection of the frame structure, and any forces present will be distributed throughout the adjacent steel work.

It will also be apparent that lighter bridge structures maybe formed in a similar manner without the frame members. Such a modification is shown in FIGURE 5. In this structure, the floor 46 is supported by an eccentric assembly 47. This assembly comprises two eccentries 48 and 49 which are mounted in the main plate of the assembly, identified separately as 4711. Also mounted in a slot 50 of this plate is a pivot pin 51. The horizontal bridge beams, indicated at 52 and 53, are adapted to receive the pin 51 to permit slight relative rotation between them. As the weight on the floor 46 depresses the eccentric assembly 47, the two eccentrics 48 and 49 rotate, their radius increasing to apply a horizontal force in each direction to stiffen the frame members 52 and 53 and thus apply a compression loading along the length of these structural members. The notch 50 is provided to prevent any of this downward pressure from being applied directly to the pin 51.

It also may be desirable to provide a structure in which a plurality of eccentrics are employed. Such a modification is shown in FIGURE 6. In this structure the two longitudinal frame members are indicated generally at 55 and 56. These structures are joined by a pivot pin 57 which in turn is received by a plate 58 which carries four eccentrics 59, 60, 61 and 62. These eccentrics are p ositioned in pairs one above the other, the pairs 59 and 60 being operatively adjacent the receiving surface 63 and the pair '61 and 62 being adjacent the receiving surface 64. The receiving surface 64 is rotatably mounted on the frame member 55 by means of a pin 65 and the receiving surface 63 is rotatably mounted on the frame member 66 by 67.

In operation, weight on the plate 58 will cause it to be moved downwardly, rotating the four eccentrics against the receiving surfaces which in turn are able to react by rotating upwardly to cause the pressure between the eccentrics and the receiving surfaces to increase. It should be understood that throughout this disclosure, the applicant has referred to a relative movement of the eccentrics in relation to the receiving surfaces and that while such movement will occur, it will be proportionately small, but will nevertheless result in the increase of pressures along the horizontal chord of the adjacent structure, which increased pressures are in resistance an opposition to the loading on the bridge floor.

The applicant has also shown in FIGURE 3 a modification in which the movement of the eccentric 70 is positively controlled in relation to the receiving surface 71. This action is achieved by a bolt member 72 which functions as a pin extending inwardly of the circumferential arc of the eccentric 70,this projecting portion of the bolt 72 being received by a notch 73 in the eccentric 70. The eccentric is mounted on a plate 74 and the receiving surface on a portion of the bridge frame, indicated generally at 73.

It will be understood that as the plate 74 moves down- 4 wardly, any slippage is prevented by the presence of the bolt 72 [in the notch 73. The eccentric then is forced to revolve on its mounting pin 76 to increase the radial distance between the pin and the receiving surface.

Although I have described several embodiments of my invention, it is apparent that modifications thereof may be made by those skilled in the art. Such modifications may be made without departing from the spirit and scope of my invention as set forth in the appended claims.

I claim as my invention:

1. In a bridge truss and joint therefor, a pair of vertically walled frame members in longitudinally end to end relation, the lower portions thereof being hinged together, a roadway suspended at the bottom of said pair of frame members, a plate member interposed between said frame members at the upper portion thereof, eccentrics pivotally mounted on and at each side of said plate and positioned to engage the vertical walls of said frames, a shank extending downwardly from said plate, and roadway supporting members affixed to the lower end of said shank in the same plane as the suspended roadway at the bottom of said frame members, whereby downward pressure on said roadway will cause said shank .and plate to move vertically downward to revolve said eccentrics to cause a radial increase adapted to direct pressures outwardly longitudinally of said frame members.

2. In a bridge structure including the roadway, a plurality of panel frame members disposed in spaced-apart adjacent end to end longitudinal relationship, the lowermost portions of said frame members being hinged one to the other, a shank member extending upwardly from the bridge roadway between said spaced-apart frame members, a plurality of eccentrics pivotally mounted on the opposed sides of the upper extremity of said shank portion extending outwardly thereof in longitudinal relationship in the same plane as said frame members, the outer periphery of said eccentrics being in contact with the upper vertical portion of said adjacent frame members, and

roadway support means attached to the lower portion of said shank member adapted to support a roadway, Whereby a downward pressure on said roadway support and shank member will cause the eccentrics to revolve and increase the longitudinal dimension of the upper chord formed by said adjacent frame members by rotation of the aforesaid eccentrics. a

3. In a bridge structure of the type described, a plurality of frame members disposed in adjacent longitudinal end to end relation in parallel pairs, a roadway between said longitudinally disposed pairs of frame members, said frame members being hinged longitudinally one to the other at their lowermost points, .a plate member having a plurality of eccentric members pivotally mounted thereon extending outwardly on opposed sides thereof, said plate members being freely disposed between the uppermost portions of said frame members immediately above the aforesaid hinged portions, and supporting means extending downwardly from said plate members and having cross members afiixed thereto adapted to support portions of said roadway, the pivot point of said eccentric members being so disposed in said plate that downward force on said cross members will cause said eccentrics to revolve outwardly to increase the radii thereof, whereby [the forces thus applied will be extended longitudinally of said frame members to cause a stiffening thereof as loads are passed over said roadway.

References Cited in the file of this patent FOREIGN PATENTS

Claims (1)

1. IN A BRIDGE TRUSS AND JOINT THEREFOR, A PAIR OF VERTICALLY WALLED FRAME MEMBERS IN LONGITUDINALLY END TO END RELATION, THE LOWER PORTIONS THEREOF BEING HINGED TOGETHER, A ROADWAY SUSPENDED AT THE BOTTOM OF SAID PAIR OF FRAME MEMBERS, A PLATE MEMBER INTERPOSED BETWEEN SAID FRAME MEMBERS AT THE UPPER PORTION THEREOF, ECCENTRICS PIVOTALLY MOUNTED ON AND AT EACH SIDE OF SAID PLATE AND POSITIONED TO ENGAGE THE VERTICAL WALLS OF SAID FRAMES, A SHANK EXTENDING DOWNWARDLY FROM SAID PLATE, AND ROADWAY SUPPORTING MEMBERS AFFIXED TO THE LOWER END OF SAID SHANK IN THE SAME PLANE AS THE SUSPENDED ROADWAY AT THE BOTTOM OF SAID FRAME MEMBERS, WHEREBY DOWNWARD PRESSURE ON SAID ROADWAY WILL CAUSE SAID SHANK AND PLATE TO MOVE VERTICALLY DOWNWARD TO REVOLVE SAID ECCENTRICS TO CAUSE A RADIAL INCREASE ADAPTED TO DIRECT PRESSURES OUTWARDLY LONGITUDINALLY OF SAID FRAME MEMBERS.

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