Improvements in or relating to the Construction of Bridges and the like.
Year: 1898

page_text: PROVISIONAL SPECIFICATION.
Improvements in or relating to the Construction of Bridges and
the like.
I, JOHN SHIELDS, c/o John Shields & Co., Wallace Works, Perth, N.B.,
Gentleman, do hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in the construction of bridges and the
like structures in which it is desired to secure a considerable span clear of any
obstruction.
By my invention I am enabled to construct such works with a clear span very
greatly exceeding that obtainable by the constructions hitherto employed inas-
much as my device attains the maximum possible amount of rigidity, and
freedom from flexion or tremor with the minimum weight of material employed,
its power of resistance to the strain being especially arranged in the ease of a
railway bridge, for instance, to resist the weight of the train as well as the weight
of its own mass.
My invention may be carried out in very various forms according to the precise
purpose to which it is applied and the dimensions of the structure. Thus for
instance, it would find especial application in the case of railway bridges of
suitable strength and span; also in the case of ordinary bridges, and even for
bridges of comparatively small dimensions as hereinafter explained. In addition
to its applicability for bridge work, my invention is applicable to the construction
of girders and other supports resting upon pillars or the like, placed near their
ends or at definite points along their length, and supporting weights over open
spaces in a similar manner to the span of a bridge. Other applications of the
principle of my invention are also within the scope of my application for Letters
Patent.
The principle of my invention consists essentially in the construction of the
bridge girder or other supporting device, in such a manner that it will be of
triangular preferably equilateral section transversely across its width. In other
words it consists in having the sides of the girder put together making one long
triangular tube, not requiring other support than the two ends where suitable
supports would be built on which the girder would rest at either end. In bridges
of large span the 3 sides of the triangle must be wide in proportion to the length
of the span, thus in a railway bridge for instance, the apex of the triangle
whether the same be entirely closed or more or less open, may be placed either
upwards, in which case the rails are preferably laid so that the train will run
within the triangle, or the apex may be turned downwards and the rails laid
The cross
upon the upper surface of the triangle formed by the structure.
section of the girder must be of the same width from one end to the other. In
large spans
will also be necessary to provide means whereby a certain amount
of sliding can take place at the points of support, in order to allow of the slight
vielding of the bridge when weights are placed upon the same. In bridges and
the like of small dimensions the construction may suitably be effected by bending

page_text: a flat plate of mild steel or the like into a triangular tube and joining the edges
thereof at the apex as aforesaid; such a form of girder or bridge will be extremely
strong and rigid.
In bridges of large dimensions this method of construction is not applicable,
both on account of the size of the plate required, as also on account of the weight
of the material. In such a case I may build up the sides of the girder or bridge
of cross pieces, preferably of triangular tubes, bolted to one another and united
at the angles by suitable angle plates in the well known manner..
My invention may be carried out in any suitable material, but the material
which I have at present found preferable for the purpose is steel plate of good
quality, such as is usually employed for bridge building purposes; the principle
of the invention is however applicable to structures carried out in any continuous
rigid material.
Improvements in or relating to the Construction of Bridges and
the like.
I, JOHN SHIELDS, c/o John Shields & Co., Wallace Works, Perth, N.B.,
Gentleman, do hereby declare the nature of this invention and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
My invention consists of a girder or beam or other strengthening bar formed
in the shape of a triangular sided tube, which may be of one solid piece of metal,
or may be built up of pieces of metal like a girder, a cross section of which forms
a triangle preferably an equilateral triangle.
By my invention, namely the triangular sided beam or girder a bridge may
be built with a longer span than what has been hitherto attained by other
inventions.
Referring to the accompanying drawings:-
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Figure 1 is a perspective view of the three-sided tube,
Figure 2 a view of a railway bridge.
Figures 3 and 4 sections of bridges.
A indicates the apex, B and C the basal angles respectively. My invention
may be constructed in various forms according to the precise purpose for which
it is intended and the dimensions of the structure. Thus for instance, it would
find special application in the case of railway bridges of great span as well as
of bridges of smaller dimensions. In addition to its applicability for bridges,
my invention is applicable for the construction of girders, beams, ribs and such
like supports required for spanning a space, or strengthening a wall, or support-
ing a flooring, roofing, decks of vessels etc., whether the same are placed or formed
in a level shape or curved like the deck of a ship, or bent in other forms such as
the ribs of vessels or curved beams for roofs of buildings or for strengthening any
structure where great rigidity and strength are required.
The principle of my invention consists essentially in the three long sides of
the girder or beam or tube being braced or fastened together so that it becomes a
rigid triangular sided tube or girder. A girder so formed that a cross section
of it would form a triangle preferably an equilateral triangle and with large

page_text: sides in proportion to the length of the span required (that is wide as well as long
and high) would be capable of spanning a very broad river and would require no
other support than a foundation on each bank for its ends to rest on and keep
it in its place. Such a girder would rely for its strength on the rigidity of its
sides and the fastenings by which these three sides are braced together. Such a
girder might be built up of V or T or Ụ shaped beams or any of the other
different kinds of bars in use at present or of triangular sided tubes or bars which
triangular sided tubes are preferable for the purpose, so long as the girder so
built up be of a triangular sided shape, and a beam of triangular section whether
used in the construction of this girder or for other purposes is also covered by
this patent.
In the case of a large bridge the girder would be placed across the river with
the apex uppermost and the base be low so that trains would run through the
inside of the girder on the base, but for a small bridge the apex of the girder
would be on the lower side and the base above with the trains running over it.
The cross section of the girder may be of the same width and height from one
end to the other or may vary in width and height. In large spans it will be
necessary to provide means whereby a certain amount of sliding may take place
at either end where the girder rests on built foundations in order to allow of
expansion or contraction also to allow of a yielding of the bridge when a weight
is on it.
My invention may be carried out or constructed of any suitable material and
may be of one solid piece or built up of different or various pieces. It may
consist of one big girder or tube, or of more than one placed side by side across
a river or other space on which a roadway may be formed. The metal preferred
for its construction is mild steel. Tubes of triangular section are preferably
built up in the form of a triangular section girder.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed. I declare that what
I claim is:
-
1. In bridges, girders and the like, constructing the weight supporting frame
three-sided, and of practically triangular cross section, substantially as and for
the purposes described.
2. A span girder bridge composed of three suitably inter-connected girders,
preferably of lattice or frame work; said girders so arranged as to form a bridge
triangular in transverse section, having its apex uppermost and a free road-way
through its interior, substantially as described.
3. A span girder bridge of triangular cross section, having its apex downwards
and a roadway upon its flat upper surface, constructed substantially as described.
Aviation 1000
W. P. THOMPSON & Co.,
322, High Holborn, London, W.C., Patent Agents for the Applicant.