US1453084A

US1453084A - Long-span bridge

Info

Publication number: US1453084A
Application number: US524832A
Authority: US
Inventors: Joseph B Strauss
Original assignee: Individual
Current assignee: Individual
Priority date: 1921-12-27
Filing date: 1921-12-27
Publication date: 1923-04-24
Anticipated expiration: 1940-04-24

Description

Apr. 24, 1923.

J. B. STRAUSS LONG SPAN BRIDGE Filed Dec. 27. 1921 5 Sheets-Sheet 2 Apr'. 24, 1923.

J. B. STRAUSS LONG SPAN BRIDGE 3 l J@ o f QN. c. ,SQ

Patented Apr. 24, l923.

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LONG-SPAN BRIDGE.

Application filed December 27, 1921. Serial No. 524,832.

T 0 all whom t may concern.'

Be it known that I, JoSEPH B. STRAUss, a citizen of the United States, residing at Chicago, in the county of Cook an'd State of Illinois, have invented a certain new and useful Improvement in Long-Span Bridges, of which the following is a specification.

This invention relates to long span bridges, and has for its object to provide a new and improved bridge of this description. One of the objects of the present invention is to provide means for practically and commercially erecting long span bridges. The distance between the piers which can be spanned by a rigid bridge structure is limited, and this is also true of a suspension bridge struc-ture. rl`here are some locations where the span of the bridge must be' of a greater length. than can be constructed with the present devices. The longest suspension bridge which has been erected is the East River lVilliamsburg bridge in New York city, which has a span between piers of 1,- G00 feet.

The present invention permits the construction in a commercial and practical way of a bridge having a span between piers of over `twice this length.

The invention is illustrated in the accompanying drawings, wherein Fig. 1 is a view showing one form of device embodying the invention;

Fig. 2 is an enlarged sectional view taken on line 2-2 of Fig. 1;

Fig. 3 is an enlarged view showing the expansion connection at'the center of the bridge;

Fig. 4 is a plan view showing a moditied form of expansion connection at the center of the bridge.

Fig. 5 is an enlarged view showing one form of connecting the. rigid sections with the piers;

Fig. 6 is a plan view showing a modified construction Fig. 7 is an enlarged plan sectional view showing 'one method of connecting the cable with the rigid sections;

Fig. 8 is a side view in part section of the construction shown in Fig. 7;

Fig. 9 is a plan view of the bridge shown in Fig. 1;

Fig. 1() is a cross section of the bridge shown in Fig. 6 taken at a point intermediate `the adjacent ends of the rigid sections.

parts.

Like numerals refer to like parts throughout the several figures.

Referring now to the drawings I have shown two sets of piers, inner piers 1 and outer piers l, Mounted on the piers 1 are rigid bridge sections which have the rearwardly extending or anchor members 3 which are connected with suitable supports at the ends of the bridge, such as the piers 1a. These rigid members also have forwardly projecting parts 2. The forwardly or outwardly projecting parts 'or arms 2 have a main upwardly projecting member 2a, and al main downwardly projecting member 2b which meet or join at a point 2, above the roadway. There are suitable cable holding devices at the point 2c. These rigid sections are provided with posts 2d which are over thepiers and which form a part of the rigid sections being preferably incorporated in them. These rigid end or flanking spans are mounted on the inner piers, and the parts 2 form outrigger or outbearing part-s or eX- tensions. It will be noted that these end sections form trussed quadrilateral members. In the construction shown in Fig. 1, there are at each end two of these rectangular trussed members, having the arms 2 and 3, one on each side of the roadway (see Fig. 9). vConnecting the ends 2 of these rigid members. is a flexible section 4, which may be a cable. In the construction shown in Fig. 1 there are two of these cables. one on each side of the roadway (sce Fig. 9). This forms a suspension bridge section between the rigid sections. There are stilening trusses 5 and (i supported by'this suspension section by means of supports 5 and (S. Some means is providedfor maintaining lateral stiffness and yet provide expansion joints. prefer to provide expansion joints intermediate the piers.

ln Figs 3 and 4 l have shown two forms of intermediateexpansion joints. ln Fig. 3 there is a horizontal pin 7 connecting the trusses so that they have relative=movement up and down, but are rigid laterally, while in Fig. 4f the ends of' the trusses are connected by the overlapping connecting device 8. which is preferably provided with rollers 9 to facilitate relative movement of the One form of this stitening truss is shown in Fig. 2. and it will be noted that it has bottom and side members and also a top member 10.

lOl)

There is a floor system 11 intermediate the top and bottom connected by truss members 1Q with the main body ot' the stitfening truss. I also prefer to provide foot passenger walks 11a at each side.

(.)ne form of expansion joint at the end or at the piers is shown in Fig. 5. In this construction there is a connecting member 14 between the pier and the rigid member of the bridge, and the rigid member is mov-ably,

mounted on the connecting member 1, and the connecting member is also movably mounted upontheI pier. .\s herein shown this is accomplished by means ot' the curved engaging vt'aces 14 which permit the rocking of the member 1,4 as much. as necessary to compensate for the expansion and contraction.

Too great a movement is prevented by the stops 15. In Fig. 6 I have shown a modiiied construction where the rigid members on opposite sides of the roadway have inclined members 2f which project inwardly and meet at a point. This permits a single cable or fiexible device 4 to be used to sustain the roadway and stitfening trusses between the rigid members.

In Figs. 7 and S l have shown one method of connecting the c: ble to the rigid members. As herein shown the able is made of a series of separate members 17. These separate members pass through rigid members 18 connected with the. rigid end sections. and are held in place by the enlarged parts 19 on the ends thereof. It will be noted that these cables are formed in a fan arrangement, and there are strengthening plates 2() by these points ot connection. The cables stop at the outer ends of the rigid sections. It will be noted that the cable or cables of the bridge extend over and support one-halt' or more of the total length ot' the span.

This construction greatly reduces the amount of metal. the weight and the cost. and yet permits a longer structure than has heretofore been possible.

The construction wbcrc the trnssed picr or end sections. that is the rigid sections at the ends have theI base part and the overhaneing part herein referred to. is ot great importance. and it is essential to the success of a long lspan bridge oi this description tor the suspension section to take its natural curve and to properly distribute the stresses in these trussed pier'sections and these results are produced in the present case by the construction and arrangement ot the pier sections and by having the cable connections to the overhanging parts at a distance above the roadway. This brings about an efficient distribution of the immense forces, causing the parts to function in a maximum way in taking care of these forces` so as to get the minimum weight of material to carry the given load. The great diiiiculty `have a plurality of functions.

in a long structure of this kind is to get the structure to carry its own Weight for the greatest forces and stresses are produced by this Weight. The construction herein shown secures this result and utilizes in an efficient manner, the material in the end sections, getting the maximum resisting eifect from it. It will be noted that the end sections are formed into trussed sections, each having a base resting on the piers, there being a post member vertical over the pier. nearest the central span and an overhanging part With cable terminals above the roadway. This construction serves to receive the loads from the cables in the most favorable manner, and carry them economically through the side spans and convert them into horizontal and vertical reactions on the piers. One of the vital elements of every suspension bridge is the stiffening truss. The size and weight of the stifl'ening truss increases very nearly as the square of the span. By having the Hoor systems on the trussed pier sections built into and forming an integral part thereof and the intermediate Hoor spans suspended from the cables` the stiitening truss for the cable is shortened, and this reduces the stresses not simply in a direct ratio to such shortening, but nearly as the square. and it also materially reduces the defiection. It also makes the determination of the s resses more exact and the stitening truss itself more economical` and the reduction is felt all through the structure. It will further be noted that the suspension section in this case is a true suspension bridge having the true suspension bridge action. The trussed pier or end sections because of their construction i wherein they have the portion on the two piers at the end and the overhanging portion to which the cables are connected to The portion between the piers acts as an anchor and also as a part ot' the span carrying load and also takes up the pull ot' the cables. lt is ot great importance to have the pier sections with the outer depressed ends and the elevated inner parts to which the cable is connected. It will be noted that the posts in the end sections are arranged over the piers nearest the central section and that portions of the trusscd end sections project in both directions from these posts. The horizontal distance trom the tower to the cable connection Yto the rigid end section should bear a certain relation to the height ot the tower and should not be greater than the height of the tower by more than one third the height ol'l the tower and taking the other view of the matter tlu` height ot the tower should not exceed the horizontal distance from the tower to the cable connection to the rigi( section by more than one third the height of the tower. It the claims I have used the expression that the height o1" tower and the horirenacer zontal distance between the tower and the cable connection to the rigid section are sub stantially equal and by that expresisond mean to include any structure coming within the foregoing description.

I claim:

l. A bridge comprising separated cantilever arms extending towards each other and over the space to be spanned and terminating above the door of the bridge, anchor cantilever arms extending from the supports of the first-named arms to the shore piers, and cables suspended between and secured to the extremities of said firstnamed arms, said cables supporting and extending over, at least one-halt the total length of the span.

2. A bridge comprising a main span of flexible members, two trussed pier sections with overhanging ends, said trussed pler sections having main posts over the piers and having top members meeting at the posts, the ovcrhan ing ends havin terminals for the tlexibe members, sai terminals being nearer vertically to the horizontal line through the meeting point of said top members than to the horizontal line through the bottom of the posts, said Flexible members supporting and extending over, at least one-.half of the total length of the span.

3. A bridge comprising a. pair of piers on each side of the space to be spanned, trussed pier sections mounted thereon, having base parts and overhanging parts, the base parts having bottom members between the piers on each side and connecting to them, a floor system connected with said bottom members and extending between the piers on each side, the overhanging parts having main bottom members inclining upward and outward from the piers and main top members intersecting the bottom members and forming cable terminals beyond the piers and above them, cables connected to said cable terminals and inclined downwardly, door trusses suspended from said cables and the inclined bottom members of the overhanging parts, a fioor connected to said door trusses and extending across the space to be spanned, said cables, overhanging parts and ioor system forming the main part of the bridge and connecting with the door system between the piers on each side to form a complete load carrying structure `trom end to end.

4. A bridge comprising a main span, two end bridge sections, an outer and inner pier at each side on which each of said bridge sections is mounted, each bridge section comprising trusses, a door system rigidly supported on said trusses, and extending from the outer to the inner pier, an entension on said trusses, elevated cable connectors at the ends ot said extensions, main span cables connected to said cable connectors, and terminating thereat, a suspended floor forming a part of the main span longitudinal trusses separate from the cables, upon which said suspended floor is mounted, said cables supporting and extending over, at least one-half of the total length of the span, said suspended door extending between the inner piers and connecting with the rigidly supported Hoor on the said bridge sections.

5. A bridge comprising two piers at each side. of the space to be spanned, two trussed pier sections, each having a long end and a short end, the long end connected to the piers at both its extremities, the short end extending beyond the piers, and terminat` ing in a cable terminal located at a point within the space to be spanned, a cable connected to said terminals and extending across the space to be spanned, doorl sections connected with said pier sections, door trusses suspended from said cable and below it, a floor carried by said door trusses and connecting with the two door sections on the pier sections, said cable supporting and extending over, at least one-halt of the total length of the span.

6. A bridge comprising piers at opposite sides of the space to be spanned, posts on said piers, trussed end sections in which said posts are incorporated, said trussed end sections having portions which project rearwardly from said posts and portions which project part way across the space to be spanned, a cable connected to said latter portions and spanning the space between them, the height of the post and the horizontal distance from the post to the point where the cable is connected to the trussed end sect-ion being substantially equal.

7 A bridge comprising two separated rigid end sections having adjacent ends separated by a space, a suspension section 'connected with said ends and spanning said space, a stitiening truss construction extending along said suspension section and supported thereby, 'said stiening truss be ing rectangular in cross section and having upper and lower chords connected by side connections to form transverse frames at intervals, a door intermediate said upper and lower chords and forming a part of said stiiening truss, and stid'ening connections from said door to said lower chord, the roadway passing through said transverse frames.

8. A bridge comprising two separated trussed end sections each projecting part way across the space to be spanned the adjacent ends of said trussed end sections forming cabie terminals, a cable extending between the adjacent ends ot said trussed end sections, said cable near its ends being divided into a series of separate members iared out, a connecting device on the end sections with which said separate flared out members are separately connected, whereby the stresses are properly distributed over and into the end sections.

9. A bridge comprising two separated cantilever trussed pier sections, each pier Section havingr a depressed outer end and an elevated inner part. a ca'ble spanning the space between said cantilever trussed pier sections, said'eable being connected to the adjacent portions of said elevated inner parts so as to transmit the stresses from the cable thereto, a ioor connected with the depressed end of each cantilever pier section and also connected With the cable, Said floor at its central portion being parallel to a line tangent to the cable at its center, said cable supporting and extending over, at least one-half of the total length of the span.

Signed at Chicago county of Cook and l State of Illinois, this 24th day of December,

JOSEPH B. STRAUSS.