Improvements in Girders and the like Structural Work, in which Struts and Tie Bars are Employed in Combination with other Parts, for the Construction of Bridges, Roofs, Piers, and the like.
Year: 1895

page_text: Date of Application. 24th May, 1895
Complete Specification Left, 24th Mar., 1896-Accepted, 9th May, 1896
PROVISIONAL SPECIFICATION.
Improvements in Girders and the like Structural Work, in
which Struts and Tie Bars are Employed in Combination
with other Parts, for the Construction of Bridges, Roofs,
Piers, and the like.
1, HENRY CLARK, of the Teesdale Ironworks, Thornaby-on-Tees, in the
County of York, Draughtsman, do hereby declare the nature of this invention
to be as follows:-
This invention relates to girders of the lattice or bowstring type and to the like
structural work such as is used in bridges, roofs, or piers and other structures in
which struts and tie bars are used in combination with other parts to take
the strains which the structure in question is intended to bear.
The means usually employed for providing girders and structural work of the
kind to which my invention is applicable consist of bars in the form of flats, angles
and tees secured in their respective positions by means of rivets by which they are
rivetted to the web plates or specially provided plates such as gusset plates secured
to the webs, flanges or booms of the girder or other structure; a mode of
construction which involves much labour and machine power, both in the first
construction and at the site of erection, such as punching the rivet holes iu
the several parts, and closing up the rivets therein, and further in consequence of
the loss of sectional area due to the rivet holes, much extra material is required
especially in tensile members in the webs and Hanges, and a larger section of bar
throughout its length in the tie bars and struts.
The object of my invention is to wholly or largely dispense with the use of rivets
to form the connection between the tie bars and struts of girders and the like
structural work and the webs, flanges or other parts to which they require to be
secured in their several positions with a view not only of saving labour and material
I am aware that
but also to facilitate and simplify the erection of such structures.
pin connections have been used for this purpose and with great economy of material
and also of labour at the site of erection; but such connections are costly to the
manufacturer requiring great accuracy and are otherwise unsatisfactory.
I provide as means for connecting the tie bars and struts to the webs, flanges or
other parts of the structure what may be termed union blocks such as in the form
of a malleable or steel casting having high tensile or pressure resisting properties.
These union blocks are secured at the required positions to the webs or flanges or
to both web and flange of the girder or other structure by means of bolts or their
equivalents and being of the requisite tensile strength and rigidity can generally
be attached thereto to serve as connections at the joints of the booms. These
union blocks are furnished with sockets or lugs for the reception of the tie bars and
struts which extend therefrom at various angles to their connections with other
union blocks. In the case of bars which are always in compression the means of
securing them to the union blocks is immaterial providing the requisite end wise
abutment is afforded to the bars within a socket or recess and where the bars are
always in tension, ordinary round bars may be used screwed into their respective
sockets, or secured by means of keys, bolts, pins or their equivalents the said tie
bars having their ends up ended or thickened to make up for loss of section due to
the mode of attachment; and further where the bars are subjected to tensile

page_text: strains at one time and compressive strains at another, I use tubes or their
equivalent forms which are screwed or otherwise secured in the sockets or lugs of
the union blocks having their ends preferably thickened or swelled up to compensate
for loss of sectional area due to the mode of attachment.
COMPLETE SPECIFICATION.
Improvements in Girders and the like Structural Work, in
which Struts and Tie Bars are Employed in Combination
with other Parts, for the Construction of Bridges, Roofs,
Piers, and the like.
1, HENRY CLARK, of the Teesdale Ironworks, Thornaby-on-Tees, in the
County of York, Draughtsman, 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 girders of the lattice or bowstring type and to the like
structural work such as is used in bridges, roofs or piers and other structures
in which struts and tie bars are used in combination with other parts to take
the strains which the structure in question is intended to bear.
I shall describe my invention as applied to bridge work and from such description
it will be understood in what way and to what extent it can be usefully applied to
other structural work and in order that my said invention may be more readily
understood and clearly distinguished from the existing modes of construction to
which it applies and is intended to supercede, I will first refer to such existing
modes of construction and then describe the essential features of my improved con-
struction and for that purpose shall refer to the several figures of the accompanying
drawings, throughout which the same reference letters denote similar or corre-
sponding parts.
The method usually employed in the construction of girders and structural work
of the kind to which my invention is applicable is illustrated in Fig. 1 and consists
of bars in the form of Hats, angles and tees secured in their respective positions by
rivets by which they are rivetted to the web plates or specially provided extensions
therefrom known as gusset plates secured to the webs, flanges, or booms of the
girder.
In Fig. 1a a are tie bars and b struts rivetted in the manner shown to the gusset
plates c. The tie bars a a are flat bars the available strength of which is to be
found in the sectional area left after the rivet holes are allowed for, for the rivets
by which the bars are secured to the gusset plates, and in the case of the struts,
which may consist of tees, angles, channel bars, or are otherwise made up to
suitable sections, it will be seen that the connection by rivets is essential to such
struts to sustain them in position to receive the compression allotted to them in the
distribution of strains. This is therefore a mode of construction which involves
much labour and machine power both in the first construction and at the site of
erection such as punching the rivet holes in the several parts and closing up the
rivets therein, and further in consequence of the loss of sectional area due to the
rivet holes much extra material is required in the tensile member, such as
the bars a a and the bottom main members in which a larger section of bar is
required throughout its length.
The object of my invention is to wholly or largely dispense with the use of rivets

page_text: to form the connection between the tie bars and struts of girders and the like
structural work, and the webs, flanges or other parts to which they require to be
secured in their several positions with a view not only of saving labour in the
rivetting and material by the use of sections of bars giving the highest resistance,
but also to facilitate and simplify the erection of such structures.
I am aware that pin connections have been used for this purpose in the manner
illustrated in Fig. 2 in which the tie bars a a a a and the strut bare all secured in
position by means of a pin d which takes the place of the gusset plate c in Fig. 1
and this mode of construction has resulted in great economy of material and also of
labour at the site of erection, but such connections are costly to the manufacturer
and require great accuracy of workmanship, and owing to the heavy duty imposed
on the pin d, are liable to get out of order under heavy traffic through the tendency
of the pins to slogger and get loose.
By my invention I provide as means for connecting the tie bars, and struts to
the webs, flanges, or other parts of the structure what may be termed union blocks
such as malleable or steel castings having high tensile or compression resisting
properties and adapted to be used in combination with sections of iron and steel of
the tubular form as illustrated in Figs. 3 to 7 inclusive and including round bars or
other sections as hereinafter described.
Union blocks of the kind adapted for the purposes of my invention are illustrated
in several useful modifications in Figs. 8 to 14 inclusive. These union blocks are
secured at the required positions to the webs or flanges or to both web and flange
of the girder or to a tubular boom. In Figs. 8 to 14 inclusive e is the union block
which is secured to a tubular boom in Figs. 8, 9 and 10 and rivetted to the web
or flange of the boom in Figs. 11, 12 and 13 or abuts against the coupling ferrule f¹
in Fig. 14. Referring to Figs. 8, 9 and 10, of which Fig. 8 illustrates the union
block e and its connection in sectional view, it will be observed that the tie bars a
are round bars in Fig. 8 secured to lugs e on the union block by means of bolts
and single or double eyes, and the strut bis received into a socket e so as to abut
end wise against a seat therein. The union block e may also serve as a coupling
ferrule to the tubular boom f. In Fig. 9 the tie bars a have enlarged ends a¹
which are screwed into sockets e³ on the union block, the strut being accomodated
as in Fig. 8; in Fig. 10 provision for an intermediate or vertical strut is omitted.
In Figs. 11, 12 and 13 the tie bars a are secured to the union block e as in Fig. 8, and
the strut in the form of a tee bar is rivetted in position in Fig. 11, but accomodated
with a socket in Figs. 12 and 13.
These Figs. 8 to 14 inclusive are to be taken as representing how readily and to
what extent my improved connections can be varied to adjust them to any particular
requirement, as for instance, in providing connections for bars which are always in
tension, or always in compression, or are sometimes in tension and sometimes in
compression, and for utilizing the union blocks as couplings to the booms or
as couplings and cover plates combined as for instance by casting the union block
with a flange e as in Fig. 13 which is a transverse sectional view of Fig. 12, or a
detached coupling ferrule may be used as in Fig. 14 in which case the union block e
simply slips along the boom until it abuts against the coupling ferrule by the
resultant tendency of the strains sustained by it. But it is not essential to my
invention that either the union block itself or the ferrule against which it abuts
should be used as couplings for joints in the boom which may be otherwise
provided for.
Figs. 3 to 7 inclusive are intended to show tubular sections which give the
greatest resistance in compression for the material used to facilitate the use of
which is an object of my invention. Fig. 4 is a sectional view of Fig. 5 which shows
how hoops can be shrunk on a slotted or open tube to close it and impart to it the
strength of a tube. Fig. 6 is a transverse sectional view of Fig. 7 showing the tube
furnished with longitudinal ribs or stiffeners but other sections can be employed
both as tensile and compressive members with more or less advantage without
departing from the essential features of my invention.

page_text: It will be observed that these improved connections are not only adapted as
substitutes for existing connections in bridges and the like structural work, but that
they admit of great freedom of design in this class of work such for instance as the
novel types of bridge shown in Figs. 15, 16, 17 and 18 in which tubular sections
and round bars are the prevailing elements of construction throughout, Fig. 15
being a side elevation, Fig. 16 an end elevation, and Fig. 17 a plan view corre-
sponding to each other showing a portion of a deck bridge. Fig. 18 is a transverse
sectional view showing this construction duplicated in the form of a double triangle,
and in this way produces a deep girder with short struts adapted to carry a load
midway between the top and bottom booms in the manner shown.
Having thus described in detail the leading features of my invention as applied
to bridge work, I would have it understood that whilst this is a very important use
of the same, my invention is not confined to this use exclusively, but is obviously
applicable with suitable modification almost to any extent to roofs, piers and
structures generally, as her einbefore mentioned in which struts and tie bars are used
in combination with other parts.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. The improved combination of parts in which the tie bars and struts of girders
and the like structural work are retained in their several positions by means of
union blocks, the said tie bars, struts and union blocks being constructed, arranged
and connected together as parts of the girder or the like structural work, sub-
stantially in the manner and for the purpose as herein before described with
reference to the accompanying drawings.
2. The use in combination with tubular booms or their equivalents, of union
blocks adapted as herein before described to fit onto each tubular boom whether in
the form of a ferrule as illustrated in detail in Fig. 8, or as abutting against a
ferrule as illustrated in detail in Fig. 14 and applied in either case to the general
construction of girder work as illustrated in Figs. 15 to 18 inclusive of the
accompanying drawings.
Dated this 23rd day of March 1896.