US2024001A - Framed bridge or bridge-like structure - Google Patents

Description

Dec. 10, 1935. A. M. HAMILTON 2,024,001 FRAMED BRIDGE OR BRIDGE LIKE STRUCTURE Filed Jan. 14, 1955 4 Sheets-Sheet 1 Fig.5.

A. M. HAMILTON FRAMED BRIDGE OR BRIDGE LIKE STRUCTURE Filed Jm. 14, 1935 4 Sheets-Sheet 2 EE Er Ecw ATTOI/Vi 513.!liiiilnuindi. I IIii?IE III F EI l lliiillfl ufiifi law w mi M Dec. 10, 1935.

L P IUD P IF G I.

mg O O Dec. 10, 1935.

A. M. HAMILTON 2,024,001

FRAMED BRIDGE OR BRIDGE LIKE STRUCTURE Filed Jan. 14, 1935 4 Sheets-Sheet 5 Fig. 9. /2 Fig 12 1 fi J it m i. it 1' it if it w'L Dec. 10, 1935. A. M. HAMILTON 2,024,001 7 FRAMED BRIDGE OR BRIDGE LIKE STRUCTURE Filed Jan. 14, 1935 4 Sheets-Sheet 4 I l T \J h A E F I LL 5 6 I E iv v Patented Dec. 10, 1935 UNITED STATES PATENT OFFICE Archibald Milne Hamilton, London, England, as-

signcr to Oallenders Cable and Censtructicn Company Limited, London, England, a British company Application January 14, 1935, Serial No. 1,607

In Great Britain May 12, 1933 I 6 Claims.

This invention relates to means for improving the efficiency of connections in bridges and like structures by giving additional stiffness and strength and facilitating erection. It has special applicability to structures built of standardized parts but is also applicable to other forms of structures.

In the accepted practice in building bridges of the truss variety made of structural steel, all loads supported by the bridge are as far as possible carried at or vertically above or below the so-called panel points where the axes of members intersect.

The object of this practice is to lessen or eliminate the secondary stresses that may arise in members if the loads are not so applied. By the application of this rule, all truss members usually carry simple compression or tension stresses which can easily be calculated. To provide for this state of affairs, the main cross girders which 2() transfer deck loading tothe trusses are generally hung below the panel point or else are attached vertically above it.

On the other hand, in accordance with the present invention, a connection element in the form of a gusset plate is used and is such that a departure from the above practice results and small secondary stresses may be present. This disadvantage is however small and is accompanied by substantial advantages resulting from increased strength and rigidity, particularly lateral rigidity, so that there is an overall saving in weight or additional stiffness for a given weight especially in. bridges of the through type where lateral stiifness of trusses must be supplied by the crossv girders.

The form of the gusset plate is such that not only does it make direct attachment to the members lying in vertical longitudinal planes, such as the horizontal and diagonal and vertical members of the truss, but also to the cross members. The improved gusset plate is so formed that the group of longitudinal members can be attached to the face thereof in the usual way and, in addition, means are provided for connecting the cross members to the gusset plate at two ends of that plate.

The form of this plate and its method of use in bridge type structures and the advantages resulting from such use will be further dealt with by the aid of the accompanying drawings in which Figure 1 illustrates an elevation of a preferred form of the gusset plate with channel section cross members.

Figure 2 shows a side view of four gusset plates attached to two channel section cross members to form a box-like structure, possible positions of other gusset plates being shown dotted.

Figure 3 is a plan of this box-like arrangement. Figure 4 is a plan of a gusset plate indicating two arrangements of the flanges which are welded in place. Figures 5 and 6 show in plan other forms of gusset plates. In Figure 6 the halves are shown separated for clearness but are normally in contact to constitute a single element. 10 Figures 7 and 8 show an elevation and plan of a through Warren-truss road bridge built of standard parts and incorporating gusset plates and cross bearers. This type is referred to as a double-truss bridge. 1-5

Figure 9 is an alternative elevation applicable to the bridge shown in Figures '7 and 8.

Figure 10 shows an elevation of a double Warren-truss bridge of the through type built of standard parts but containing gusset plates of 20 the double-ended or invertable type where diagonals meet.

Figure 11 is a. cross-section of the bridge shown in Figure 10.

Figure 12 is a cross-section of a multi-truss deck 25 bridge.

By reference to Figures 7 and 9, it will be seen that the gusset plate i in the usual manner forms the connection between what have been referred to above as the longitudinal members. These 30 are the horizontal or chord members 2, the diagonal members 3 and (where these are used) the vertical members 4 (Figure 9). In addition, in accordance with the present invention, the gusset plate is also made to serve as a direct connection 3 between these members and the cross members 1. For this purpose, the gusset plate is formed of a flat plate 5 of usual form and a flange 6 at each end of the plate 5. These flanges do not extend the full depth of the plate. They have a depth 40 corresponding substantially with the height of the cross member I and terminate at an appropriate position topermit of the horizontal members 2 passing above or below the cross member I.

It is clear that there are many ways in which such gusset plates may be manufactured and typical forms are shown in Figures 4, 5 and 6. In Figure 4, the flanges 6 of suitable length are Welded to the plate 5 with or without a mortise and tenon joining. In Figure 5, angle pieces bolted or riveted in place may constitute the flanges 6. In Figure 6, .another arrangement is shown in which the main gusset plate is of bent, or rolled section, material in two halves; these form in effect a single plate when the 55 halves are drawn tightly together by the bolts or rivets which attach the truss members. Either of the parts shown in Figure 6 may be used separately if conditions do not necessitate the full strength of the two parts back'to back. In general, the flanges need not necessarily project to both sides of the gusset plate.

The form shown in Figure 4 might be made from a rolled section of common form in which the flanges are cut away to suit the required conditions; or the flanges may be rolled T sections attached to the gusset plate.

The flanges 5 are not necessarily always at right angles to the gusset plates but may be skew as shown in the alternative at the right of Figure e so that skew bridges and structures may be easily built therewith.

Gusset plates in accordance with this invention may also be of the double-ended form shown at 10 on Figure 10. These plates are provided with four instead of two flanges 6 and are normally in all respects similar to the plate I as above described, .except that the plate part 5 extends both above and below the line of the horizontal member 2.

Referring to Figure 1, it will be seen that, while. in the usual construction of gusset plate the upper part of the plate 5 is stiffened by the presence of the ends of the diagonal members 3 and, in some cases, of a vertical member (such .as 4, Figure 9) and the lower part of the plate 5 is stiiiened by connection to the horizontal members 2 which are connected together by the plate 9, there is a certain amount of lateral flexibility owing to the necessity for spacing apart these two sets of connections. When using a gusset plate in accordance with the present invention, this flexibility is reduced to a negligible value. This efiect is due to the connection to the cross members 1, which are placed at the ends of the plate tures of different dimensions and load capacities.

In this type of standardized construction, it is desirable to use as far as possible identical ele-' ments for the chords and the diagonal members of the trusses. This can be done provided that I the elements can be combined together appropriately to give members of the different strengths required in the different parts of structures within the range of construction aimed at. the example illustrated in Figures 7 to 12, an element of angle section is taken and is built up in groups of two, three orfour as required. This is shown by the sections inserted at the brakes in the horizontal and diagonal members in Figures 7. It will be realized that such a construction is particularly suitable for bridges and girders of the Warren type. Each element can in such a construction be made of such a size and weight that it can be readily handled and the connections can be made simply so that erection can be done with simple gear and comparatively unskilled labour. The present invention provides a gusset plate particularly suitable for such a typeof construction since a plate can be produced having comparatively small weight and dimensions which is, when arranged as previously indicated herein, capable of giving a satisfacto y connection between members of a large range of strength and stiffness.

When applied as shown in Figure 10 in the form of both single and double plates, the connection is seen to be applicable to a greater ex- 5 tended range ofstructures by adopting the double Warren type. It will be noted that two identical gusset plate combined with two cross members 1 can be built up to form an open box structure as indicated 10 in Figures 2 and 3. This preliminary assembly may be used with advantage when erecting a structure of the standardized type. For instance, a bridge which will when complete comprise a number of similar parallel trusses (such as four 15 and inner trusses built up thereon. This possi- 20 bility follows from the fact that the partial structure has suflicient inherent lateral rigidity to support satisfactorily the loads which come on it during the erection.

In addition to cross members which support i s the loads there may be subsidiary cross members,

usually shorter in length, connected between certain of the flanged gusset plates, so that trusses are formed into pairs or groups and held by means f v of these subsidiary cross members at as many 30 points as possible, thereby distributing stresses to the trusses as perfectly as possible. An example of this is shown in Figures 10 and 11, where flat plates H connect the double in adjacent trusses.

35 Figures 8, 11 and 12 indicate possibilities of the advantages conferred by the lateral stiffness due to the improved gusset plate and the use of it in the manner already indicated. The structures shown in those figures depend for their lat- 1o eral stability mainly on the lateral stiffness of the groups of trusses connected together by the main and subsidiary cross members. The rigidity of the connection between a pair of trusses, such as shown at each side of Figure 8, makes 45 that group of great lateral stability for a given weight. This stability may be further increased by interconnecting the two trusses at the middle points in theirheights. In Figure 8, this I2 which directly connects together the adjacent diagonals 32 and 33 of the two trusses. The connection is further extended by bolting together the diagonals 3i and 32 as at [3 and the diagonals 33 and 34 as at M. This makes each 85 side of the through bridge shown in Figure 11 60 consists in eifect of two double truss units superposed and stiiiiy connected together by the double gusset plates l0 (Figure 10) and the cross plates II and the side plates 22. These two units provide a very stiff side member. The two side 65 members connected together by the main cross members form a structure of great lateral stability which in general does not require sway bracing, although it may be used occasionally in the manner indicated by dotted lines in the upper 76 part of Figure 11.

What I claim as my invention and desire to secure by Letters Patent is:

'1. A bridge or bridge-like structure comprising vertical fiat gusset plates, members in a vergusset plates l0 is shown as affected by means of a batten plate 50 tical longitudinal plane connected to one face of said plates, and horizontal cross members attached to the ends of said plates, the connections of said cross members being at substantially the same level as the connections of the said members in the vertical plane.

2. A bridge or bridge-like structure comprising gusset plates having flanges on the ends thereof, diagonal members passing above said flanges and connected to a face of said plates, horizontal members passing below said flanges and attached to a face of said plate, and horizontal cross members passing between said diagonal and horizontal members and connected to the flanges of said plates.

3. A bridge or bridge-like structure comprising two trusses placed side by side each having gusset plates, members in a vertical longitudinal plane connected to one face of said plates, and horizontal cross members attached to the ends of said plates, the connections of said cross members being at substantially the same level as the connections of the said members in the vertical plane, said cross members connecting together the two trusses.

4. A bridge or bridge-like structure comprising two trusses placed side by side each having gusset plates, members in a vertical longitudinal plane connected to one face of said plates, and

horizontal cross members attached to the ends of said plates, the connections of said cross members being at substantially the same level as the connections of the said members in the vertical plane, said cross members connecting to- 5 gether the two trusses, and batten plates conmeeting together the two trusses at points between the gusset plates.

5. A flat gusset plate for use in a vertical 1ongitudinal plane in a bridge or bridge-like struc- 10 ture, having on one part of its face means for making connection with diagonal members of the structure and on another part of its face means for making connection with horizontal members and having on its two vertical ends means for 15 making connection with cross members which lie between the diagonal and horizontal members.

6. A flat gusset plate for use in a vertical or longitudinal plane in a bridge or bridge-like structure, having on its face means for making 20 connection with diagonal members of the structure and means for making connection with horizontal members, the two said means being spaced apart vertically, said plate also having on its two vertical ends flanges which extend across the 5 distance by which the two said means are spaced apart.

ARCHIBALD MILNE HAMILTON.

Images