Note: Descriptions are shown in the official language in which they were submitted.
2195616
TRUSS-TYPE FLOOR JOIST
BACKGROUND OF THE INVENTION
This invention relates generally to improvements in truss-type joists
5 used in building construction.
The prior art has provided a variety of metal webbed wood trusses
typically used as floor joists and comprising top and bottom wood chords with
metal webs interconnecting these chords. A floor truss or joist of this nature is
described in C~n~ n Patent 1,035,534 issued August 1, 1978 n~min~ James
Knowles as inventor and in the U.S. counterpart No. 4,078,352 issued March
14, 1978 (RE 31807). Wood-webbed trusses are also well known wherein the
various components are secured together by the well-known toothed connector
plate. Traditionally these two kinds of trusses are custom m~nllf~ct~lred in
various lengths, depending upon the job requirements. Typically, little or no
15 provision was made for on-site adjustments.
Wood-I beam joists m~nl~f~ctured with wood chords and oriented strand
board or plywood webs are well known and one example is described in
C~n~ n Patent 1,042,621 issued November 21, 1978 and in the U.S.
counterpart No. 3,991,535 issued November 16, 1976. These types of wood-I
20 beam joists are fabricated in certified plants under controlled conditions so that
the structural characteristics can be carefully established to ensure that
specifications are met. These I-beam joists are typically fabricated in long
lengths and utilize a unique tongue and groove joint detail to provide a secure
connection between the chords and the web.
25 SUMMARY OF THE INVENTION
It is a basic object ofthe present invention to combine the above two
basic types of structures to provide a composite truss-type metal or wood-
webbed floor joist with a variable or adjustable end arrangement based on the
wood-I beam joists briefly described above.
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Accordingly, the invention in one aspect provides a composite truss-type
joist comprising a pair of elong~te-l, parallel spaced apart wood chord members
which are interconnected together by metal or wood webs and having fasteners
associated therewith to secure said web to said wood chord members, end
5 portions of said wood chord members extending outwardly beyond said webs
at at least one of the opposing ends of said joist, and a fabricated wood
structural beam insert located between and interconnected to said outwardly
extending end portions of said wood chord members at said at least one of the
opposing ends of the joist whereby to enable said at least one end of the joist to
10 be cut and shaped at a job site to a desired ~imen~ion.
In a pr~r~lred embodiment, the above described beam insert is a wood-I
beam section made so that it can be inserted between the top and bottom
outwardly extending end portions of the chord members of the webbed joist,
with suitable connectors such as truss plates being suitably placed and then
15 pressed in to firmly connect the outwardly extending top and bottom chords ofthe joist with the top and bottom chords of the wood-I beam insert. The
resulting composite joist structure has the ability to resist high shear forces on
the ends of the joist due to the style of the I-beam. Since the engineered I-beam
insert is fully certified from the outset, i.e. the certification has already been
20 built into the wood-I beam, truss or joist fabricators can build trusses
incorporating the adjustable ends on existing equipment without getting special
certification from regulatory officials.
Further features and advantages of the invention will be more readily
apparent from the following description of preferred embodiments with
25 reference being had to the accompanying drawings.
BRIEF DESCRIPTION OF THE VIEWS OF DRAWINGS
Fig. 1 is a side elevation view of a portion of a metal web truss-type joist
with extended top and bottom chords;
Fig. lA is an end elevation view thereof;
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.
Fig. 2 is a side elevation view of a fabricated wood I-beam insert;
Figs. 2A and 2B are end elevation views of one embodiment of I-beam
insert;
Fig. 3 is a side elevation of an end portion of the variable end truss-type
5 floor joist according to one embodiment of the invention;
Fig. 3A is an end elevation view thereof;
Fig. 4 is a side elevation view of the variable truss-type floor joist
according to one form of the invention;
Fig. 5 is a perspective view of an end portion of the variable end truss-
10 type floor joist according to one embodiment; and
Fig. 6 is a perspective view of a portion of a variable end wood-webbed
truss-type joist according to another embodiment of the invention.
DESCRIPTION OF PREFERRED EMBODIMENTS
In the description which follows, like parts are marked throughout the
15 specification and drawings with the same respective reference numbers. The
drawings are not necessarily to scale and in some instances proportions may
have been exaggerated in order to more clearly depict certain features of the
invention.
A metal webbed wood floor truss-type joist 10 (see Fig. 1) is typically
20 used to support a floor in a building. The joist is typically composed of spaced
parallel top and bottom wooden chords 12, 14 with metal webs 16
interconnecting both chords. These top and bottom chords 12, 14 are
preferably 2 x 4 or 2 x 3 inch lumber with the respective major surfaces facing
w~rds and dowllw~dly as best seen in Fig.l. The chords 12, 14 are
25 interconnected by the diagonally arranged struts or webs 16 formed of sheet
metal. Such metal webs 16 are made in a chevron or V-shape to provide web
legs 18, an apex connector plate portion 20 and enlarged leg connector portions
22. The connector portions 20, 22 are provided with a multiplicity of struck-
out spikes 24 or teeth for embedding into the chord members 12, 14.
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The edges of the web leg 18 are bent to form a continuous inner flange
26 which extends subst~nti~lly the full length of each leg 18 and continues
around the arc forming the apex between the legs and an outer flange. A
channel or groove 28 is formed along the length of each leg by bending or
5 impressing for rigidifying the legs in conjunction with the flanges.
The metal web connectors 16 are applied in pairs, one on each vertical
face of the aligned chords and their teeth are embedded only into the laterally
facing minor side faces of the chords 12, 14. This permits forming the joist by
laying the web-connector down upon a horizontal surface with its teeth
10 upwardly, laying the chords 12, 14 above it and then placing the second or
opposing web-connector upon the exposed upper minor surfaces of the chords,
teeth down, so that a single compression or clamping operation at each
overlapped connector portion can cause the teeth thereof to penetrate the wood
from opposite sides. For further details of construction reference may be had toC~n~ n Patent 1,035,534 issued August 1, 1978 n~ming James Knowles as
inventor.
Referring also to Figs. 3-5, the top and bottom wood chord members 12,
14 ofthe joist have end portions which extend outwardly beyond the metal
webs 16 at the opposing end portions ofthe joist. A fabricated wooden
20 structural I-beam insert 30 is located between and is interconnected to and co-
extensive with the outwardly extending portions of the wood chord members
12, 14 at each of the opposing end portions of the composite joist whereby to
enable the ends of the composite joist 10 to be cut and shaped at a job site to
desired dimensions as noted previously. It should be re~li7e~ however that the
25 adjustable end structure need only be provided at one end of the joist in many
cases.
The fabricated wooden structural beam insert 30 l~,fel,~d to above can
assume different forms but it is ple~ d that these I beam-like inserts be
constructed subst~nti~lly as described in C~n~ n Patent 1,042,621 issued
2195~16
November 21, 1978 n~ming James R. Keller et al as inventor.
The wooden structural I-beam insert 30 described in C~n~ n Patent
1,042,621 (see Figs. 2A and 2B) essentially comprises a pair of elongated chord
members 40, 42 of wood material and a plywood web member 44
S interconnecting the chord members by means of glued tongue and groove
joints. The plywood or oriented strand board web member 44 has at least two
layers of veneer 46 in which the grain of the wood runs approximately
perpendicular to the length of the chord members 40, 42 and has at least one
intervening layer of veneer 48 in which the grain of the wood runs
10 approximately parallel with the length of the chord members. These two layers46 of veneer project beyond the intervening layer 48 on two opposite edges of
the web member 44 to form a pair of parallel spaced apart bendable tongues 50
on each of said opposite edges. A pair of longitudinal grooves 52 in each of thechord members 40, 42 are spaced apart so as to receive the tongues 50. These
15 grooves 52 in each chord member are inclined from top to bottom relative to
each other to bend the tongues 50 out of parallelism with each other and to
form a self-locking dove-tail joint when the chord members are pressed onto
the web member. These joints hold the members 40, 42 together in assembled
relation without external clamps while the glue is setting. Further details of
20 construction and the manner in which assembly is achieved may of course be
had from a more detailed review of the above-noted C~n~ n Patent
1,042,621.
Regardless of the precise type of I-beam insert 30, 30' used, the top and
bottom chords are preferably 2 x 4s or 2 x 3s with the respective major surfaces25 facing ~w~ds and downw~dly as best seen in Figs. 3-5. A typical insert 30,
30' can be up to about 18 inches long (or even longer if desired) and these
inserts are trimmed from stock lengths which are prefabricated in a certified
manufacturing plant.
The assembly of the composite joist is as follows. Each insert 30, 30' is
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cut and trimmed from a stock length of wood-I beam. They are inserted
between the extended end portions ofthe top and bottom wood chords 12, 14
of the truss at each end, a typical length of which can be 18". Toothed
connector plates 80 are embedded into the laterally facing minor surfaces of theend portions of the top and bottom chords 12, 14 and into the laterally facing
minor surfaces ofthe top and bottom chords ofthe wood-I beam inserts 30, 30'.
These plates firmly interconnect these components. A typical truss plate may
be a 6 x 3 inch connector plate. The connector plates 80 are placed at both
sides ofthe proximal ends ofthe inserts 30, 30 ' to connect the top and bottom
chords ofthe inserts to the respective top and bottom chords of the joist. The
sizes and gauge of plates 80 can best be determined by the strength required by
the specific size and span of the joist. Intermediate vertical posts 32, 34 are
placed between the chords 12, 14 in the middle of the span. The distance
between the two wood-I beam inserts 30, 30' defines the primary section of the
joist whereas the intermediate vertical posts 32, 34 define the size ofthe chaseopening in the middle. In greater detail, the two vertical posts 32, 34 extend
between the top and bottom chords 12, 14 (see Fig. 4), and are connected
thereto by metal connector plates 36, 38. Vertical posts 32, 34 (which are
preferably 2 x 4 or 2 x 3 inch size,) thus extend between the downwardly facing
major surface of top chord 12 and u~w~rdly facing major surface of bottom
chord 14. The teeth of the connector plates 36, 38 are embedded into the
laterally facing minor surfaces oftop and bottom chords 12, 14 and into the
laterally facing minor surfaces of posts 32, 34 to firmly interconnect the postswith the chords. Each plate 36, 38 is preferably a 1.5 x 3 inch size.
Each composite joist end section can thus be trimmed at the job site as
required. For example, if the overall length of the composite joist, including
end sections, is 20 feet, the joist can be configured for any length between 18
and 20 feet simply by trimming one or both end sections.
Fig. 6 illustrates that the invention is not limited to use with metal-
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webbed truss-type joists. Here, joist 10' comprises spaced parallel top and
bottom wood chords 12', 14' as previoiusly described, which chords are
interconnected by the wooden struts 16' arranged in a repeating combination
of vertical and diagonal shaped pattern with int~rmediate posts 17 extending
5 transversely between wood chords 12', 14', with spaced apart toothed connectorplates 19, 21, 23 serving to interconnect the struts and posts to the wood chords
in a manner well known as such in the art. The end portions of wood chords
12', 14' extend outwardly beyond the wooden web members 16', 17 and
between them and co-extensive thercwilh is situated the fabricated wood
10 structural I-beam 30" exactly as described above. Insert 30' is secured in place
by toothed connector plates 80' as described above which are embedded into the
laterally facing minor surfaces ofthe top and bottom chords 12', 14' as well as
the top and bottom chords ofthe wood I-beam insert 30".
The great advantage of the invention is that it allows for ease of
15 adjustability on the job site~ i.e. the composite joist can be custom fitted to suit
the length requirements on the site. In addition it will allow all truss/joist
fabricators to build adjustable end detail with existing equipment. Furthermore,the invention allows for the fabrication of standard stock lengths for inventorypurposes. The inventory can be stocked in a warehouse or yard for future sales.
20 This can be produced during a slow construction season to build up inventory
for sale in a busy building period. Furthermore, the engineered wood I-beam
insert is fully certified from the outset, i.e. the certification has already been
built into the wood-I beam and hence truss/joist fabricators can build adjustable
ends on existing equipment without getting special certification from regulatory25 officials.
Although the term "floor joist" or "joist" has been used throughout this
specification, those skilled in this art will appreciate that the present invention
may find application in other areas where structural load-carrying beams are
required. Additionally, the term "wood" as used herein is not limite~ to natural
2195616
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woods but encomp~ses man-made materials such as strand board and similar
materials having strand or fibre reinforcement therein.
Preferred embodim~n~ of the invention have been described and
illustrated by way of example. Those skilled in the art will realize that various
S modifications and changes may be made while still rem~ining within the spirit
and scope of the invention. Hence the invention is not to be limited to the
embodiments as described but, rather, the invention encompasses the full range
of equivalencies as defined by the appended claims.
