A NEW OR IMPROVED GIRDER AND FIREPROOF FLOOR
Year: 1884

page_text: I HENRY HEWITT BRIDGMAN of 42 Poultry in the City of London Architect
and Surveyor F.R.I.B.A. do hereby declare the nature of my said Invention for
"A NEW OR IMPROVED GIRDER AND FIREPROOF FLOOR" to be as follows :—
This invention relates to a new or improved construction of girder and fireproof
floor the object being to economize the construction of fireproof floors and at the
same time to give additional strength to the girders supporting the same.
The improved girder or joist whether of wrought or cast iron or steel is made
with an intermediate flange or flanges along the web between the top and bottom
flanges the advantage being that instead of the concrete of fireproof floors resting
on the bottom flange of the girder or joist (which is the weakest part of a girder)
and as is now the practice such weight can with this improved girder be carried at
a higher level and at a stronger part of the girder or joist, the intermediate flange
or flanges being formed at such height in the web as may be necessary for con-
structive purposes and according to the thickness of cross joists and concrete it may
be intended to use.
It may be mentioned that joists or girders of the ordinary depths for spans up to
say 20 feet will carry the weight of the concrete floor constructed on the intermediate
flanges with practically unimpaired sustaining power.
These improved joists are of considerably less weight than the so-called patent
girders (compounded of two rolled joists one above another) of the same depth
and the drilling and rivetting will be saved and they will bear greater loads.
In construction of floors with these girders or joists the intermediate flange
construction is employed upon which to receive the ends of cross joists and concrete
and great lateral strength is afforded which is very necessary in girders, the webs
of which exceed twice the width of the flanges, or when they are placed entirely
beneath the floor or when the web is not effectually embedded, but when embedded
in the concrete increased rigidity is given to the floor whilst only a small portion
of the girder appears below the ceiling level to be encased.
"Patent girders" of double construction before referred to are not made of joists
less than 6 inches in depth thus giving a 12 inch width of girder whilst these
improved intermediate flange girders can be made to any less or greater depth and
consequently girders of less depth can be used allowing at the same time also for
the use of smaller cross joists. For a span of 20 feet on bays of 10 feet a 12 inch
by 5 inch intermediate flange girder for ordinary floors will be found sufficient and
with cross joists of 4 inches by 24 inches 2 feet apart bedded in 6 inch concrete
will make a safe floor.
DL
1001
WALTER A. BARLOW,
6, St. Paul's Churchyard, E.C.

page_text: I HENRY HEWITT BRIDGMAN of 42 Poultry, in the city of London Architect
and Surveyor, F.R.I.B.A. do hereby declare the nature of my said invention for
"A NEW OR IMPROVED GIRDER AND FIRE PROOF FLOOR" 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 a new or improved construction of girder and fire proof
floor, the object being to economize the construction of fire proof floors and at the
same time to give additional strength to the girders supporting the same.
In order that my invention may be more fully understood I have hereunto
annexed a drawing showing in section a girder or joist constructed according to
this invention.
The improved girder or joist, whether of wrought or cast iron or steel or other
metal is made with an intermediate flange or flanges A. A running along the web
between the top and bottom flanges BC the advantage attained thereby being that
instead of the concrete of fire proof floors resting on the bottom flange of the girder
or joist (which is the weakest part of a girder) and as is now the practice; such
weight can with this improved girder be carried at a higher level and at a stronger
part of the girder or joist, the intermediate flange or flanges A, A being formed at
such height in the web as may be necessary for constructive purposes and according
to the thickness of cross joists and concrete it may be intended to use.
It may be mentioned that joists or girders of the ordinary depths for spans up
to say twenty feet, will carry the weight of the concrete floor constructed on the
intermediate flanges A, A, with practically unimpaired sustaining power.
These improved joists are of considerably less weight than the so-called patent
girders (compounded of two rolled joists one above another) of the same depth, and
the drilling and rivetting will be saved and they will bear greater loads.
In constructing floors with these improved girders or joists, the intermediate
flange construction A, A, is employed upon which to receive the ends of cross-
joists and concrete, and great lateral strength is afforded which is very necessary in
girders, the webs of which exceed in depth twice the width of the flanges; or again
when the girders are placed entirely beneath the floor; or when the web is not
effectually embedded.
When the girders are embedded in the concrete, increased rigidity is given to
the floor whilst only a small portion of the girder appears below the ceiling level
to be encased or not as desired.
"
Patent girders" of double construction before referred to, are not made of joists
less than six inches in depth thus giving a twelve inch depth of girder, whilst these
improved intermediate flauge girders can be made to any less or greater depth and
consequently girders of less depth can be used, allowing at the same time, also for
the use of smaller cross joists.
For a span of twenty feet in bays of ten feet, a twelve inch by five inch
intermediate flange girder for ordinary floors will be found sufficient and with cross
joists four inches by one and three quarter inches, or three inches by three inches,
two feet apart bedded in five inch concrete will carry two and a half hundred weight
to the foot superficial distributed; and make a safe floor.
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
L-
Firstly. The improved girder or joist constructed with the intermediate flange
or flanges A, A as and for the purpose herein set forth and illustrated by the
.

page_text: Secondly. The improved construction of fire proof flooring, with the girder
provided with the intermediate flange or flanges A, A, constructed and operating
together with the material employed as and for the purpose herein set forth.
Dated 1st October 1884.
WALTER A. BARLOW,
Agent for Henry Hewitt Bridgman, F.R.I.B.A.
WALTER A. BARLOW,
Agent for Henry Hewitt Bridgman, F.R.I.B.A.