Tension and Compression Rods for Structural Purposes.
Year: 1890

page_text: Date of Application, 13th Mar., 1890-Accepted, 26th Apr., 1890
COMPLETE SPECIFICATION.
Tension and Compression Rods for Structural Purposes.
I, WILHELM LÜBBECKE, Engineer of Potsdamer Strasse 88* Berlin, Germany 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:-
This invention relates to the manufacture of structural parts consisting of tension
and compression rods, which are formed as uniformly as possible, similarly to the flat
rods hitherto used, and which may be employed in a similar manner. Structures
of any kind consisting of such rods acting on joint bolts may be made so as to
be readily put together and taken to pieces, like constructions composed of flat rods.
The rods in question are of
a
a
a
or of
a
shaped cross section having obtuse angles
at a in order to be capable of being placed closely upon. each other.
The following arrangements for instance of such rods are advantageous:
1. To arrange tension and compression rods like chains consisting of flat links
(see figs. 1, 2 and 3 of the accompanying drawing).
2. Compression rods bearing up against joint bolts (see figs. 4, 5 and 6 of the
accompanying drawing).
In the two cases the intermediate space left between the stems of the rods placed
against each other, may he reduced to zero if desired, according to the size of the
angle a. It is advantageous to leave on the rod Fig.1 an intermediate space equal to
the thickness of a stem, in the case Fig. 2 this space may be reduced to zero, so
that the stems may be placed closely against each other.
The flanges may be suitably shaped to a line of equal resistance to compressional
strain in order to save weight.
The two kinds of rods, with or without eyes, are of great value for homogenous
constructions and for a rapid building up of railway bridges, street bridges, foot
bridges, military bridges, piers of bridges, scaffolds and the like.
All such constructions may be made in their compression parts as decomposable as
was formerly the case when using flat rods in the portions under tension. As the
structure can be strengthened at will by joining on additional rods, it is possible to
construct with the same rod-elements, railway bridges, military bridges, piers of
bridges, scaffolds by joining as many rods as may be required for the tensile and
compression strain. For the most part, and in particular in American bridges, the
tensile element of girder and suspension bridges is usually made of flat rods arranged
the one close against the other; my above described rods are suitable for the same
purpose for the elements under compression of girder and arched bridges.
It has been attempted to construct bridges of flat iron rods only, but in this case it
was necessary to strut afterwards the upper parts. The resistance to be opposed by
the joint-bolt against bending strain has generally been increased because, owing to
the strutting, the forces could not act so favorably on the joint-bolt as was the case
with the flat rods placed one against the other, of the tensile elements.
But my above described rods require exactly the same width on the joint bolt in all
parts of the bridge as in pure chain elements and they do not need any supplemental
strutting.
By this means the building up of bridges and the like is essentially simplified. A
bridge may, for instance, be constructed according to Neville's system consisting of
equilateral triangles, for which purpose generally only the rod shewn in Fig. 1 may
be used, the span being of 30 metres and the bridge having a weight of only 5 tons,
when as few rods as possible are applied-in the upper arch, under arch, and-diagonals.

page_text: ABEL & IMRAY,
Agents for the Applicant.