US1441387A - Long-span bridge - Google Patents

Description

Jan. 9 1923.

' 1,441,387; 0. A. P. TURNER.

LONG SPAN BRIDGE.

ORIGINAL FILED Jun/10. 1913.

3 SHEET$-SHEET l.

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0. A. P. TURNER.

LONG SPAN BRIDGE. ORIGINAL FILED JULYIO, HH-

3 SHEEIS-SHEETZ 1N VEN TOR.

WITNESSES:

@ I mflm g B Jan. 9, 1923. 1,441,387.

0. A. P. TURNER.

LONG SPAN BRIDGE.

ORIGINAL FILED wuno, 1913. 3 SHEETS-SHEET 3.

INVENTOR.

WA TTORNEY.

CLAUDE a. rf'rnnnna; oriyunnnaroms, MINNESOTA, nssieivos or OLUMBUS, ,OI-IIO. I

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I LONG-SPAN 'BRID GE.

Application filed July 10, 1 913,Seria1 No..'77 3,278. Renewed January 21, 1921. Serial No. 439,058;

To all whomz't may concern;

Be it known that I, CLAUDE- A. P. TUnNnn, of Minneapolis, in the county of Hennepin and in the State of Minnesota, have in? vented a certainnew and useful Improvement in Long-Span Bridges, and do here.-.

by declare that the following is a full, clear, and exact description thereof.

My invention relates to'bridge trusses, and generally stated has for its object economy of material, and the production of a structure of great stiffness. This application is filed as a renewal of application No. 778,218, filed July 10, 1913, allowed Dec. 8, 1919,

and also to embrace a different embodiment.

the left and the top chord plan and bracing at the right; y i

Fig. 8 is a detail view in side elevation, showing the members of the cantilever frame extending between the top chord and the webbing- 1 Fig. 4: is a view like Fig. 1 of. another embodiment of my invention.

Referring to the drawings, the truss shown comprises a top chord 10 and a bottom chord 11, and lVarren type webbing consisting of thediagonal members 12 and the sub-verticals 13 the panel points of the twochords being located so that the bottom chord panels 1.2; 23; etc, are half as long as the top chord panels AB; B C; etc. In the truss shown in the drawings, which as I have stated is for a span of480 feet, the top chord panels are feet and the bot tom chord panels are 4:0'feet', from which dimensions an idea of the magnitude of the structure can be obtained.

At each side, of each topchord panel. point, a strut 14; extends between the top chord and a diagonal member 12, inclining upward and outward from the latter and between the lower ends of the two struts 1 1 a horizontal strut 15 extends, these various parts being riveted together, as shown, so that it will be seen a frame work is provided that extends aroundthe top chord panel. point, or the 3139);,33 a center,.bywhich the length of the top chore section inclined struts 14: at a point 20 feet from the panel point. The frame work formed by the struts 1' 1 and 15 is indicated diagrammatically in Fig. 1 by the lines (Z, c, 7 and 'g.

It will be observed that each of the struts 14c and 15 acts in compression, the struts 14L being in sense cantilever arms and the intermediate strut 15 sustaining the thrust of the arms.

It will be seen that as the struts 14 (corresponding to the members cl, 6 and and g of Fig. 1) are comparativelyshort, secondary stresses in the top chord sections due to stress in the diagonal members 13 of the webbing stretching or elongating said diagonal members, are largely eliminated. I

To stiffen the diagonal web members 12 I connect them above each lower chord panel point by a horizontal brace, or tie 16 which opposes the tendency of said diagonal mem-' bers to bow outwards under load. I The braces 16, it will. be noted, alternate with the struts 15 of the cantilever frame and each, it will be noted, is joined to the web member at a point that is a fraction of their height or the distance from chord to chord, which preferably is about a quarter thereof- The floor plan, as shown at the left of Fig. 2, includes floorbeams 17 laterals 18 and stringers 19, and the top chord bracing,

loads, that is taken up by 'fiexure in all the members meeting at the apex. I

Referring to what is shown in Fi 4: which illustrates a design'for a span til feet centers, the struts, 140, corresponding with the inclined struts, 14: of Fig. 1 ex tend from a point on the top chord, 100 midway between the panel points-and to the diagonal, 120, of the webbing at ampoint to alternate panels. The arrangement illustrated in Fig, 4 works out very economically of material in practice.

Bymy invention a truss as provided that uses a minium of material it has great stiffness and it eliminates, or greatly reduces secondary stresses.

Having thus described my invention what I claim is 1. In a bridge tr es, the combination of top and bottom chords webbing connecting the two chords that comprises diagonal members that meet in an apex at the top chord and a frame comprising struts constituting compression members which eX-' tend from points on the top chord on opposite sides of said apex downward'to said. diagonal members and supporting respectively the portions of the top chord to which they extend which lies between the supported extremities of said portions of the top chord, said frame including a compression member extending between said diagr nal members at the points where the lower ends olt said top chord engaging members oin said. diagonal members.

2. In. abridge truss, the combination of top and bottom chords, webbing connecting the two chords that comprises diagonal members that meet in anapex at the top chord and a frame at alternate panels comprising struts constituting compression members which'extend from points on the top chord on opposite sides of said apex downward to said diagonal members and supporting respectively the portion of the top chord to which they extend which lies between the supported extremities of said portion of the top chord, said framevincluding a compression member extending between said diagonal members at the points where the lower ends of said top chord engaging members join said diagonalmembers.

In testimony that I claim the foregoing I have hereunto set my hand.

' CLAUDE A. P. TURNER.

Vitnesses o CHAS. J. WVILLIAMsoN, A; T. IilAYES.

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