US114039A

US114039A - Improvement in truss-bridges

Info

Publication number: US114039A
Authority: US
Publication date: 1871-04-25
Anticipated expiration: 1888-04-25

Description

T W. PRATT.

improvement in Truss-Bridges.

Patented April 25.1871.

ddltiitll Stairs jfitttnt (tffitr.

T. WILLIS PRATT, OF BOSTON, MASSACHUSETTS.

Letters Patent No. 114,039, dated April 25, 1871.

lMPROVElVlEN'I'- IN TR USS-BRIDGES,

The Schedule referred to in these Letters Patent and making part of the same.

To all whom it may concern V Be it known that I, T. WILLIs PRATT, of Boston, in the county of Suffolk and State of Massachusetts,

have invented certain Improvements in the Gonstruo Figures 4,5, 6, and 7 detail and modifications to bereferred to.

My invention consists, first, in a peculiar connection of the strut and'tensiou-braces with each other and the upper and lowe chords of a bridge, in which the iron employer of channel form and My invention consists *lx-boudly, in the application of one or more plates to .ach joint or point of connection of the 'st'rg't and tension-braces with the upper and lower'chords, for the purpose ofaddiug strength at the points where the said braces are connected with the chords.

To enable others skilled inthe art to understand and use my invention, I will proceed to describe the manner inwhich I have carried it out.

In the said drawing-- A represents the upper chord of a bridge, the chord being formed of iron, either cast or wrought, of channel form, well known to be that shown in'fig. 4, in which the iron is so shaped that a flange, 'a is produced below and at right angles to each side of the horizontal portion 1), the flanges a being parallel, or nearly so, to each other.

This channel iron may be made in one piece, fig. 4, or be composed of two pieces of angle-iron riveted directly together, (fig. 5 or of two pieces of angleiron connected by a plate, fig. 6.

B represents the lower chord, of a form similar to that A.

The upper and lower lower chords A B are connected and fastened, by rivets c or otherwise, to strutbraces G and tension-braces D, likewise made of iron, of channel form-the strut-braces (I being those which incline from the upper chord downward and away from the center of the bridge, and the tension-braces D being those which incline from the upper chord downward and toward the centeroi the bridge. The strut-braces may, however, be formed of I-shaped iron, fig. 7.

The upper and lower ends (I e of the tension-braces are so bentin opposite directions as to fit snugly under and upon, and lie parallel to, the upper and lower chords AB, the upper and lower ends M of the strutbraces 0 being also bent in opposite directions, as shown in section, fig. 2.

The upper ends or portions 71. of the strut-braces G are made tofitsnugly under the upper ends or portions (1 of the tension-braces D, while the lower ends or portions '2 of the strut-braces O fit snugly upon the lower ends e of the tension-braces D, through which they are riveted to the upper and lower chords A B.

EEare flat metal plates, placed one at each side of the joints or points of connection of the tops of the braces G D with the upper chordB.

Each plate E is placed inside the flange a so as to shed water, and is riveted thereto at It, the plate being also riveted, at Z, to the flanges a of both the strut and tension-braces.

G G are plates similar to those (E) riveted, at m, to the outside of the flanges a of the lower chord B, the plates G being also riveted, at n, to the flanges a of both the strut and tension-braces, by which construction the bond between the braces and chords is still further increased and strengthened; the joints which otherwise would be somewhat flexible being thereby rendered rigid, as requiredwhere the bridge is to sup port a, weight in notion. T g

The beams supporting the floor of the bridge may be laid either upon the tops of the upper chords B, or upon the tops of the plates G, the space between these plates in either case being covered or filled up to prevent exposure to the Weather.

It will be seen, from the foregoing, that a tensile strain is exerted on the braces D, which, at their upper ends, (I, is converted into a horizontal thrust in the direction of or toward the center, as indicated by the arrow 10, while, at their lower ends, e, the horizontal strain is exerted in a direction from the center toward the ends of the bridge, as indicated by the arrow 11.

The upper and lower chords, as well as the braces, may be curved instead of straight, if desired; but I find it more econo'rnicaland convenient to make them straight, as shown.

I-shaped or double-channel iron, fig. 7, may be used in the construction of triangular trussbridges, instead of iron of single-channel form, fig. 4, if desired, without departing from the spirit of my invention.

Claims.

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

' described and shown, strut and tension-braces G D,

1. The peculiar method herein shown of connectand chords A B, the whole constructed and operating the strut and tension-braces G D'with the upper ing as and for the purpose set forth. and lower chords A B in the construction of triangu- Witness my hand this 8th day of February, A. D. lar truss-bridges, substantially in the manner and for 1871. the purpose described. I Witnesses:

2. The combination of the plates E G, formed as N. W. STEARNS,

W. J. CAMBRIDGE.

T. WILLIS PRATT.