U.S. patent number 3,849,961 [Application Number 05/344,720] was granted by the patent office on 1974-11-26 for t-clip truss and rafter system of roof construction.
Invention is credited to Jacob M. Gwynne.
United States Patent |
3,849,961 |
Gwynne |
November 26, 1974 |
T-CLIP TRUSS AND RAFTER SYSTEM OF ROOF CONSTRUCTION
Abstract
A metal framed roof truss or rafter and joist system of
construction for the support and attachment of roof, ceiling and
floor covering materials and applied live and dead loads for homes
and other light constructions.
Inventors: |
Gwynne; Jacob M. (Willingboro,
NJ) |
Family
ID: |
23351721 |
Appl.
No.: |
05/344,720 |
Filed: |
March 26, 1973 |
Current U.S.
Class: |
52/639; 52/655.1;
52/714 |
Current CPC
Class: |
E04C
3/09 (20130101); E04C 3/11 (20130101); E04C
2003/0452 (20130101); E04B 2001/2448 (20130101); E04B
2001/249 (20130101); E04C 2003/0434 (20130101); E04B
2001/2424 (20130101); E04C 2003/0421 (20130101); E04B
2001/2457 (20130101); E04B 2001/5868 (20130101); E04C
2003/0491 (20130101); E04B 2001/243 (20130101) |
Current International
Class: |
E04C
3/04 (20060101); E04C 3/11 (20060101); E04C
3/09 (20060101); E04B 1/24 (20060101); E04B
1/58 (20060101); E04c 003/09 (); E04c 003/11 () |
Field of
Search: |
;52/634,635,636,639,645,641,646,655,640,643,714,760,758C,758G |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
|
|
|
|
|
|
|
368,132 |
|
May 1932 |
|
GB |
|
539,356 |
|
Sep 1941 |
|
GB |
|
Primary Examiner: Sutherland; Henry C.
Assistant Examiner: Braun; Leslie A.
Attorney, Agent or Firm: Strickland; Elroy
Claims
Having thus described my invention and certain embodiments thereof,
I claim:
1. A truss structure for a building construction comprising
elongated upper and lower structural chords each having
longitudinally extending web and flange portions, with said flange
portions having means for centering clips on said chords, and
longitudinally extending raised portions located on each side of
the flange portions and projecting beyond the general plane of the
flange portions, at least one elongated bracing strut extending
between said upper and lower chords, clips connecting the strut to
said chords, and having flanges provided with opposed extensions,
said flanges and extensions engaging the flange portions of said
chords, a leg depending from the flange of each clip fastened to
the ends of said strut, and centering means cooperating with the
centering means of said chords placing the webs of the chords in
alignment with each other and with the axis of said strut, means
fastening the depending legs of said clips to ends of said strut,
and, the flanges and extensions of said clips being clinched on the
flange portions of said chords by forcing the ends of said
extensions around and behind the raised portions on the flanges of
said chords, and crimped on the flange portions of said chords by
displacing material of the chord flange portions and the clip
flanges and extensions in directions normal to the planes thereof
at multiple locations therealong to prevent relative, longitudinal
movement of said clips and chords.
2. The structure of claim 1 including at least two inwardly facing,
longitudinally extending ledges provided on the flanges of the
chords on the web side thereof, and located on opposite sides of
the web thereof, and projections provided at the ends of the flange
extensions of said clips for seating behind the ledges of said
chords when the clips are clinched and crimped on the flange
portions of the chords.
3. The structure of claim 1 in which the web of the lower chord has
openings spaced apart along the length thereof, a solid eave and
piece located at each end of the lower chord, said end pieces each
having flanges and a solid end web portion, and clip means
respectively splicing said eave end pieces to the ends of the lower
chord by being clinched and crimped on the flanges of the lower
chord and eave end pieces.
4. The structure of claim 1 in which the strut is a tubular member
having flattened end portions provided with strengthening
longitudinally extending ribs.
5. The structure of claim 4 in which the flattened end portions of
the strut are radiused for bearing contact with the flanges of the
clips and for folding adjacent the chords in a sub-assembled truss
structure for storage and shipment, and offset from the
longitudinal axis of the strut to permit alignment of the strut
axis with the plane of the webs of the chords.
6. The structure of claim 1 including two additional clips for
connecting together the upper and lower chords adjacent eave ends
thereof, said additional clips each having a flange with opposed
extensions, and a leg depending from said flange, said leg being
offset to provide alignment of the web portions of said chords, and
a surface for bearing on one of said chords when the chords are
connected together by said additional clips, means fastening the
depending legs of said additional clips to the web portion of one
of the chords while the flange and extensions of said clips are
crimped and clinched to the flange portions of the other chord.
7. The structure of claim 1 in which the upper chord member
comprises a structure in which two elongated, separate chords are
located in aligned, end-to-end, abutting relationship, said two
chords having longitudinally extending flanges, and clip means
having flanges and flange extensions centered on and mechanically
engaging and securing together the flanges of said two chords at
their abutting ends by being clinched and crimped on the flanges of
said two chords.
8. The structure of claim 7 in which two clips are respectively
clinched and crimped on the flanges of the two upper chords, with
each of said two clips having a depending leg laterally offset from
the center of the clip, said legs being located in lapping
relationship beneath the two chords.
9. A roof rafter and joist assembly comprising elongated rafter and
joist members each having longitudinally extending web and flange
portions, with said flange portions having means for centering
clips on said rafter and joist members, and longitudinally
extending raised portions located on each side of said web
portions, and projecting beyond the general plane of the flange
portions, clips for joining together the rafters and joist members
at intersections thereof, each of said clips having a flange
provided with opposed extensions, said flange and extensions
engaging the flange portions of one of said rafter or joist
members, a leg depending from the flange of said clip fastened to
the web portion of another of said rafter or joist members,
centering means on said clips cooperating with the centering means
of said rafter and joist members aligning the webs of said rafter
and joist members, and, the flanges and extensions of said clips
being clinched on the flange portions of said members by forcing
the ends of said extensions around and behind the raised portions
on said rafter or joist members, and crimped on said rafter or
joist members by displacing material of the member flange portions
and the clip flanges and extensions in directions normal to the
planes thereof and at multiple locations therealong to prevent
relative longitudinal movement of said clip and members.
Description
BACKGROUND OF THE INVENTION
The invention relates to a competitive, lightweight metal roof
framing system of construction for building homes and other light
commercial, institutional, industrial, military, mobile and
vacation types of structures that may, for example, be constructed
with the framing members shown in U.S. Pat. Nos. 2,664,179,
2,736,403 and 3,129,792 issued in the name of J. M. Gwynne, the
present inventor.
Light rolled steel channel structural sections welded to form I
beam shapes for prefabricated trusses have been available for many
years. Such structures, however, are too costly to compete with
wood trusses, rafters and joists, and are now used primarily for
commercial buildings. Steel has also presented difficulties in
attaching covering materials, and steel sections are heavy so that
the handling thereof is difficult. New, somewhat lighter single "C"
channels may now be used, with self-drilling screws, but as yet are
not cost competitive with wood construction.
Wood trusses for houses and other light constructions are generally
fabricated and assembled in a truss factory specially equipped with
heavy and expensive jigs, tables and presses to provide a quality
truss assembly and reduce labor costs when sufficient volume of
each size and type of assembly permit the use of repetitive
production techniques. In the manufacture of most present day
wooden trusses, the component members thereof are first placed in a
single plane and then held in firm, tight, abutting relationship
with each other at the intersections thereof by jigging devices.
Mechanical joining is then effected by pressing multiple nailing
plates into each side of each intersection of the member
components, such pressing requiring the use of a large press or
eight or more lighter presses, (one for each joint), or a more
laborious use of a movable, single light press. From the factory,
the assembled trusses are shipped to a job site, or to a warehouse
for future shipping to a job site. Each assembled truss has a large
bulk which usually limits shipment to a maximum number of 60
assembled trusses per truckload.
Thus, the costs of fabrication, handling, setup and jigging make
the manufacture of small quantities of wood trusses of any one size
in a factory very expensive and not competitive with on-site, hand
fabricated rafters and joists. For this reason, factory made
trusses are not used except for factory produced homes or modules
and for other large projects where repetitive quantities of
standard size trusses can be utilized. In addition, the weight of
wooden trusses requires a substantial number of workers or costly
crane equipment (used generally on the larger projects only) to
erect.
Consequently, with the bulk of the homes in the United States and
elsewhere being built by small builders, and the variety of their
construction being extensive, wood trusses are not generally
employed in home construction. Rather, rafter constructions are
used since they can be hand nailed to ridge rafters, beams and
other supporting wall frames. They cannot generally be preassembled
because they are larger than trusses and they need the central
support of the construction below. Except for large projects,
rafter structures are not generally mass produced, thus requiring
substantial time and labor for job site fabrication.
BRIEF SUMMARY OF THE INVENTION
The present invention is directed to structural assemblies, made of
a lightweight metal such as aluminum, for use in building
constructions comprising structural metal members generally of "I"
beam configuration having flange and web portions, and generally
joined together in triangular or other roof form shapes. The
members are joined together by specially designed T shaped metal
clips (hereinafter called T-clips), crimped to the flanges of the
structural members, and riveted, bolted, and/or welded or otherwise
mechanically attached to (1) the web of another structural member,
(2) to metal struts or other bracing members extending between the
structural members, and (3) to each other as required to complete
the assembly. Such a metal construction has the advantages of being
incombustible, inasmuch as the material will not provide fuel to
feed a fire once started in other materials, and it can be shipped
either assembled or as knockdowned components for onsite, final
assembly. As explained in detail hereinafter, it requires less
labor to fabricate, assemble, handle and erect and less cost to
transport. When the webs are prepunched or expanded, the
constructions of the invention require less bracing material as the
constructions present less area for wind resistance. In proper
conjunction with the use of other non-flammable or firesafe
materials, the entire structure of the invention and its supporting
structure can provide lower insurance costs than for similar wood
framed structures.
With the T-clip system of joinery, the components of a truss or
rafter assembly can be assembled in the factory or on the job site,
the assembly process requiring only bolts and wrenches, thereby
eliminating the costly equipment needed for constructing wood
trusses, since the geometrical shape of the final assembly of the
invention, along with accurately fabricated struts and the factory
assembled T-clips, provide for accurate final assembly. In
addition, a truck that can carry only 60 assembled wood trusses, or
a few more partially nestable assembled metal trusses of the
present invention, can carry an amount of disassembled truss chord
components of the present invention sufficient to assemble a
thousand trusses. Further, the metal truss components of the
invention may be shipped in a knockdown manner with as many as 8 to
10 complete home framing packages on one truck when the components
for such framing packages are those shown in the above mentioned
U.S. Pat. Nos. 2,664,179, 2,736,403 and 3,129,792.
As explained earlier, wood rafters and joists generally require
fabrication near the location of final assembly. The lightness of
the metal roof frame of the invention may be finally assembled
wherever most convenient, handed up from the ground or the upper
floor of a building and placed into the erected position with
minimum erection personnel and without the need of cranes.
A typical 4 inch in 12 inch sloped roof truss with a 28 foot span
and 30 foot flat projection will weight approximately 30 pounds in
aluminum, 120 pounds in wood and up to 180 pounds in steel. The
non-lightened webs of the wood and steel members of the assemblies
will then require more time and workers to erect and more wind
bracing to hold into place until covered. A typical wood truss will
require 16 nailing plates, and the steel truss will require
riveting, bolting or welding. The aluminum truss of the present
invention will require only eight T-clips, as explained in detail
hereinafter.
THE DRAWINGS
The invention, with its advantages and objectives, will best be
understood from the consideration of the following detail
description when read in connection with the accompanying drawings
in which:
FIGS. 1 and 2 are, respectively, schematic views of typical truss
and rafter-joist assemblies in which the principles of the
invention are employed;
FIG. 3 is an end view of a structural chord or beam suitable for
constructing the truss or rafter-joist assemblies of FIGS. 1 and 2
in accordance with the principles of the invention;
FIGS. 4a through c are partial end views of other chord or beam
configurations suitable for the structures of FIGS. 1 and 2;
FIG. 5 is a side elevation view of the peak assembly area of the
truss structure of FIG. 1 in which (1) the top flanges of two top
chords are mechanically connected together with a peak splice clip,
(2) the bottom flanges of the two top chords are mechanically
attached to two bypassing peak T-clips, and (3) two tension struts
are fastened to the depending legs of the T-clips to consolidate
the total peak assembly of chords, struts and clips together with a
single fastening means;
FIG. 6 is a side elevation view of a lower truss chord assembly
area in which a lower chord-clip and lower ends of both tension and
compression struts are fastened together with a single fastening
means;
FIG. 7 is a side elevation view of an upper truss chord assembly
area having an upper chord T-clip, with the upper end of a
compression strut fastened thereto, the lower end of the strut
being shown in FIG. 6;
FIG. 8 is a side elevation view of one of the eave assembly areas
of the truss with an eave T-clip mechanically attached to the
bottom flange of the top chord and bolted to the solid pieces
attached to the bottom chords with splice clips;
FIGS. 9, 10 and 11 are end elevation views of the peak, chord and
eave T-clips of FIGS. 5, 6 and 8, respectively; FIG. 12 is a cross
sectional view of the splice clips of FIGS. 5 and 8; and
FIG. 13 is an end view of the struts of FIGS. 5, 6 and 7.
PREFERRED EMBODIMENTS
Referring now to FIG. 1 of the drawings, one building type truss 10
is shown schematically, the truss comprising two upper chords or
beam members 12 and 14, a lower chord 16, and four bracing struts
18, 19, 20 and 21 mechanically connecting the upper and lower
chords together. FIG. 2 is a schematic representation of a ceiling
rafter and floor joist assembly 10A in which the rafters and joist
have the same numerical designations as the chords of FIG. 1. With
the exception of knee walls 22 in FIG. 2, and ceiling rafter 23,
rafter assemblies generally do not employ bracing struts in the
manner of a truss so that in FIG. 2 only three rafters 12, 14 and
23, one joist 16 and the knee walls 22 are shown.
The truss and rafter-joist constructions of FIGS. 1 and 2, as thus
far described, are typical of roof framing structures generally
used in the light building industry.
The present invention is directed to truss and rafter-joist
structures, as schematically shown in FIGS. 1 and 2, or to other
truss and roof frame configurations suitable for building purposes,
using metal chords or other structural members having generally
flange and web portions 24 and 25, as shown in FIGS. 3 and 4,
though the invention is not limited to the particular
configurations shown. As shown, the chord of FIG. 3 is provided
with inwardly facing and longitudinally extending integral ledges
26 located on the inside surfaces of the flange portions 24, one on
each side of the web 25. Substantially opposite the ledges 26 are
provided integral, raised ribs 27 provided on the outside faces of
the flanges. A centrally located recess 28 is also provided in the
outside flanges of the chords and centered on the web 25. The ends
of each flange 24 are shown provided with a rounded enlargement or
stiffening rib 29, the ribs 29 having diameters greater than the
general thickness of the flanges. In addition, the diameters of the
ribs 29 are such that they present an outer surface located in the
same plane as that of the ribs 27. One of the purposes of the ribs
27 and 29 is to minimize the contact that covering materials make
with the metal chords to thereby minimize heat transfer to the
chords, though the invention (again) is not limited to such a chord
configuration. For example, in the chord embodiment of FIGS. 4a and
b, the edges of the chord flanges are shown provided with rounded,
longitudinally extending C-slots 29A, which slots can serve the
purposes of the ribs 29 in FIG. 3, as well as clip clinching
purposes described hereinafter, and the screw fastening purposes
described in the above-mentioned U.S. Pat. No. 2,736,403.
For purposes of brevity, hereinafter the term "truss" will include
rafter and joist assemblies, while the word "chord" is intended to
designate the structural members of trusses and rafter and joist
assemblies to which covering materials are attached.
The configuration of the chords of FIGS. 3 and 4a through c with
the ledges, recesses and ribs, as shown, can be inexpensively
extruded in a continuous extrusion process, and then cut into
appropriate lengths for the structures of FIGS. 1 and 2, such a
procedure providing a supply of long, continuous chord components
in a rapid, low cost manner.
The webs of the chords 12, 14 and 16 are preferably provided with
spaced openings 31, as best seen in FIGS. 5 to 8, which openings
may be provided by a punching operation, or by a web cutting or
slitting and transverse expanding process, the expanding process
developing the slits into openings somewhat similar to the spaces
31. Such spaces and openings provide a savings of metal, and
provide a visual measuring aid, such as 4 or 8 inch modules of
normal structural member assemblies on 16 or 24 inch centers. In
addition, the openings reduce the area of the web, which, in
conjunction with the ribs 27 and 29 on the faces of the flanges,
and the added length of the web material remaining in place,
provide additional resistance to heat and sound transfer through
the ceiling and roof.
Further, the openings 31 reduce the weight of the chord and truss
substantially below that of wood trusses of similar dimensions
particularly if the chord is a lightweight metal such as aluminum,
and reduce the wind resistance of the truss thereby facilitating
handling and erection by workmen during windy conditions.
FIGS. 5, 6 and 7 show the chords of the truss 10 mechanically
connected together by a system of clips and struts in a manner to
provide the advantages and savings described earlier. More
particularly, beginning with the structure of FIG. 5, the peak of
the truss 10 is shown as being comprised of two aligned but
angularly disposed chords 12 and 14 secured together by a peak
splice slip 33 crimped and clinched (in a manner explained in
detail hereinafter) on the upper adjacent flanges 24 of the chords,
and two angularly disposed and partially overlying clips 35 (for
bracing struts) respectively attached to the two chords by being
crimped and clinched to their lower adjacent flanges. It can be
appreciated, at this juncture, that the splice clip 33 is not
necessary if the top flange of the upper chord is a single,
continuous structure, or if the two chords 12 and 14 are connected
together at the peak by welding, for example. In a roof rafter and
joist system a second splice clip 33 can be used to join the lower
flanges of 12 and 14 together since bracing struts, with clips 35,
would generally not be required at that location.
The peak clips 35 have a T-configuration in cross section, as best
seen in FIG. 9, in which the opposed edges of the upper, planar or
flange portion 36 of the T have integral extensions 37 generally
folded over the upper portion. Each peak clip includes further a
lower or depending leg portion 38, shown in FIG. 5, fastened to the
flattened end portions 39A of a tubular strut 39 by a single nut
and bolt, indicated generally by numeral 40. The bolt extends
through aligned openings (not visible in FIG. 5) provided in the
peak clips and in the two strut ends. In FIG. 9 the opening in the
peak clip leg is indicated by numeral 41. As seen in outline in
FIG. 5, the depending leg of each peak clip 35 extends somewhat
beyond one edge of the flange portion 36 (in the plane of the leg),
to locate the holes 41 directly beneath the peak of the truss when
the clips 35 are disposed on the chord ends. Further, as seen in
FIG. 9, the clip leg is slightly off lateral center so that when
the two chords 12 and 14 are located at the peak the clips 35
overlap and bypass each other, and are in contact to each other
along mutually engaging planar surfaces. The top chords and peak
clips for all truss assemblies regardless of roof slopes, revolve
around the centers of the holes 41 in the legs of the clips, the
centers being directly below the roof peak.
From the depending legs of the clips 35, the struts 39 extend
downwardly to lower chord 16 for attachment to a second set of
T-clip 42 (i.e., chord clips), one for each strut 39, only one
chord clip 42 being shown in FIG. 6. Like the clips 35, clips 42
have extensions 37 folded over an upper portion of T flange 36
thereof, and a dependent leg 38 to which the struts 39 are
attached. However, the depending leg of clip 42, and its fastening
hole 41, is centered on the T flange. Further, the depending leg
preferably has serrated surfaces provided on both faces thereof
(FIG. 10) to provide greater friction between the clips and struts,
and thus add bearing strength to the assembly 10 when the struts
are firmly attached to the clips by a rivet (not shown) or by the
nut and bolt 43 depicted in FIG. 6. The two struts 39 in FIG. 5
correspond to the struts 19 and 20 schematically shown in FIG.
1.
The upper and lower chords are further mechanically braced and
connected together by yet a third set of chord clips 45 and bracing
struts 46, when using a single W strut configuration or other
design requiring upper chord struts, only one clip and strut being
shown in FIG. 7. The second set of tubular struts 46 corresponds to
the struts 18 and 21 of FIG. 1, and thus completes the W thereof.
The clips 45, as indicated in FIG. 7, can be identical in structure
to the clips 42 of FIG. 6 since their position and function are
essentially the same, i.e., clips 42 and 45 function to attach
struts to the flanges of chords at positions intermediate the ends
thereof. The upper ends of struts 46 may be respectively fastened
to the depending legs of the clips 45 by a single rivet (not
shown), or by a single nut and bolt 47, as shown in FIG. 7.
In the drawings, the struts are depicted as round, tubular members
having flattened end portions 39A for attachment to the depending
legs of the T clips. The struts, however, may be angular and/or
solid (in cross section), and may not need to be flattened at their
ends for the purposes of the present invention, though flattened
ends of tubular structures facilitate the assembly process, and
provide double wall thickness for a bearing and shear strength
greater than any non-tubular section of similar weight and
material.
Further, each flattened end of the tubular struts in the present
invention is preferably provided with reinforcing ribs 39B (FIG.
13), and, when in compression and fastened to the depending leg of
an associated clip, the flattened end is dimensioned and radiused
to engage the flange 36 of the clip, as seen in FIGS. 3 to 7. In
this manner, the end of each strut serves as a bearing surface to
receive loads imposed upon the roof frame, and thereby strengthens
the connection of the strut, chord and T-clip assembly allowing the
use of fewer and/or smaller diameter bolts or rivets.
In addition, in the end view of FIG. 13, it will be noted that the
flattened portion 39A of the strut is offset from the center
thereof. This provides symmetry of connected members by allowing
the strut axes to align with the planes of the chord webs 25 when
the struts are secured to the T clips 35, 42 and 45. Such symmetry
increases the strength of the roof structure over that of a
non-symmetrical design.
As suggested in the schematic assemblies of FIGS. 1 and 2, and as
shown in FIG. 8 of the drawings, the upper and lower chords
adjacent the eave ends of the assemblies must also be structurally
connected together to complete the assembly 10. This is
accomplished by a fourth set of T-clips 48, hereinafter called eave
clips, with one eave clip employed at each eave end of the
assembly. Only one such clip is shown in FIG. 8, the clip securing
the lower end of the upper chord 12 to one end of the lower chord
16. The cross section of eave clip 48 may have the configuration
shown in FIG. 11, in which case a portion of the depending leg 38
of the clip is offset at 49 to provide a bearing surface 50 for
seating on a sloped surface 51 of the web of the lower chord 16,
and to vertically align the webs 25 of the upper and lower chords,
such alignment maintaining the symmetry of the assembly at the eave
intersection. The clips 48 may be bolted to the web of the lower
chords (as at 52) for job site assembly, or riveted thereto for
factory assembly, though other fastening means may be employed at
either of the sites.
As seen in FIG. 8, the eave ends (or end pieces 54 presently to be
described) of the lower chord 16 are cut (at 51) to the slope of
the roof to accommodate the angular slope of the eave clips
attached to the upper chords 12 and 14 (only 12 being shown in FIG.
8, with an attached eave clip 48). Such a structure provides
bearing between the upper and lower chords via the cut edge 51
engaging the surface 50 of clip 48 when loading closes the
clearance in bolt receiving holes 41 provided in the eave clips. In
this manner, the shear forces on fasteners 52 are substantially
reduced to permit the use of fewer fasteners with smaller
diameters.
Preferably, both lower and upper chords are prepunched or
pre-expanded to reduce cost, weight, wind resistance and heat and
sound transfer through the chords, although solid chords generally
of less thickness and approximately equal strength and deflection
characteristics may be used. When continuously punched or expanded
members are used for the bottom chord, a separate eave end piece
54, mentioned above, having the bevelled edge 51 and a solid web
25, can be spliced to the end of the lower chord 16 by splice clips
55, as shown in FIG. 8, the clips being essentially identical to
the clip 33 employed to splice the peak of the truss, as described
earlier, except of course, that clips 55 would not have the angular
configuration of clip 33. The web of the eave piece 54 is provided
with holes (not visible in FIG. 8) for receiving the fasteners 52,
and may, as shown in FIG. 8, have weight reducing openings similar
to those provided in the chords.
The configuration of the clips 33 and 55, in cross section, is
shown in FIG. 12, such clips having extensions 37 located over a
planar base portion 36, and integral with the longitudinal edges of
the base portion. Further, the flange portions of the clips are
shown provided with pointed raised portions 56 facing inwardly to
engage locating recess 28 (FIG. 3) provided in the chords.
In addition, the folded over extensions 37 of the clips in the
present invention preferably have a length dimension sufficient to
reach, and integral, inwardly facing projections 57 sufficient to
seat behind the ledges 26 provided on the flanges of the chord
shown in FIG. 3, when the clips are crimped to the chord flanges in
the manner presently to be explained.
With the chords and struts cut to proper lengths and provided with
such necessary means as fastening holes, and prior to final
assembly of the truss 10 (or rafter system 10A), the T clips are
disposed on the flanges 24 of the chords and properly positioned
along the lengths thereof to be crimped and clinched into place
with a suitable crimping tool. Similarly, the eave end pieces 54,
if used, are attached to the ends of chord 16 by splice clips 55
crimped and clinched to the chord flanges. The clips may be
initially disposed on the chords by sliding them onto the ends
thereof if the clips are made with their extensions 37 folded in
the manner shown in FIGS. 7 to 10 and 12. However, if one or both
of the clips extensions 37 are initially formed to extend at say
right angles to the T flange 36, as indicated in dash outline in
FIG. 10, the clips can be directly disposed on the chords at
locations intermediate the ends thereof. The clips are centered on
the chords by the pointed projections 56, provided on the clips,
extending into the longitudinal recess 28 (FIG. 3) provided in the
flanges of the chords.
In crimping the clips on the flanges of the chords, the flanges 36
and the extension 37 of the clip are forced toward and against the
flanges of the chords to locate the integral projections 57 of the
extensions behind the integral ledges 26 on the chord flanges, as
shown in dash outline in the embodiment of FIG. 3, to clinch each
clip and chord together. This type of clinching provides a high
strength, balanced connection between the clip and chord since the
clip flanges engage the chord flanges near the web 25 of the chord
to thereby provide a considerable amount of reinforcement on the
chord and clip flanges when tension forces are imposed thereon.
This type of clinching is preferred over the clinching shown in the
embodiment of FIG. 4a in which extensions 37A of the clip (in dash
outline), when crimped to the chord flange, engages the chord
flange nearer the edges thereof (though inwardly of the C-slots
29A) than the embodiment of FIG. 3. Under tension, the crimped
connection of FIG. 4a is not as strong as that of FIG. 3 since
gripping near the edges of the chord flange creates substantial
leverage for bending the flange. In the clinching of FIG. 3, such
leverage is not provided.
In addition to the clinching of the clips to the chords, as
described above, the crimping of the clips and chords together
deforms the metal of the outer edges of chord and clip flanges in
planes normal thereto (as indicated at 58 in FIGS. 5 to 8)
sufficient to prevent relative longitudinal movement between the
chord and clips. With crimping of C-slots 29A in FIG. 4, the metal
of the slots also collapses to prevent any relative longitudinal
movement between the clip and chord. Preferably, the deformation of
metal out of the plane of the flange edges of chords and clips is
inwardly, i.e., toward the opposed flange of the chord, so that the
face of the chord with the clip is left free of outwardly directed
protrusions to facilitate finishing operations, such as the placing
of ceiling or flooring materials on the chord faces.
The truss construction of the invention, as thus far described, can
be completely assembled at a factory location and shipped assembled
to a job site or to warehouses for storage until needed at the job
site.
In addition, the components of the truss assembly of this invention
can be partially assembled together in a factory, and then shipped
in a knockdown, compact arrangement for final bolt assembly at
another location, such as the job site. Further, the truss or
rafter-joist assembly of the invention may be shipped completely
disassembled, or sub-assembled as components, and then wholly
assembled at the job site, before erection.
If the truss of the invention is to be only partially assembled at
a particular location, and then forwarded, in a folded and compact
manner, to another location for final assembly, the process of
making the partial assembly would include attaching the clips 35,
42, 45 and 48 to the individual chords by the crimping and
clinching method described above. One end of the struts 39 and 46
could then be fastened to the legs 38 of the clips 42, i.e., the
clips attached to lower chord 16, with the other ends of the struts
left free. The struts would then fold down to a position
essentially parallel to the chords 16 for shipping. The upper
chords 12 and 14, with the clips 35, 45 and 48 attached, are
shipped separated from each other and from the lower chord and
attached struts.
In the partial assembly thus far described, the peak clips 33 are
shipped with the chords and struts for attachment to the upper
chords at the job site. Since a crimping tool may not be available
at the job site the peak clips may be fastened to chord flanges by
self-drilling and tapping screws extending through holes 59 (FIG.
12) provided in the base wall 36 of the clips.
When the partially assembled truss reaches the site of final
assembly, the splice clips 33 are attached to the upper chords to
splice the chords together, and the struts are rotated into place,
with the unconnected ends of the struts quickly bolted or otherwise
connected to the depending legs of their corresponding clips. The
depending legs of the eave clips 48 are fastened to the web of the
lower chord to complete the assembly.
The holes 41 provided in the depending legs of the T clips 48 may
be tapped to hold bolts threaded therein at the factory to save
handling time and labor at the job site.
The upper chords, which in cold climates will tend to be colder
than the lower chords, can be insulated from the lower chords by
insulating the T clips from the struts and from the webs of the
lower chords at the eaves. This can be accomplished by insulating
washers or gaskets (not shown) located between the depending legs
of the lower chord clips and the flattened ends of the struts. At
the eave ends, such washers, indicated by numeral 60 in FIG. 11,
may be elongated, unitary structures having a plurality of holes to
accommodate the plurality of fasteners 52, and may extend slightly
above the sloping edge 51 of the chord, as shown in FIG. 11, to
fold thereover, and thereby limit physical contact between the
bearing surface 50 of the clip 48 and the chord edge 51, when the
fasteners 52 are tightened on the clip and chord.
As mentioned earlier, wooden trusses of the type shown in FIG. 1
require sixteen connecting plates (two for each joint) to properly
join together the type of truss shown schematically in FIG. 1. In
the present invention, a metal truss is completed with as few as
eight T clips, i.e., two each of the clips 35, 42, 45 and 48. With
the use of separate upper chords, a ninth clip (33) may be required
to insure the integrity of the upper chord section of the truss.
The connections provided by these clips are simply and rapidly
effected without the use of expensive jigs and heavy presses, and
all of the components used herein can be made rapidly and
continuously by repetitive extrusion and fabricating processes to
provide a supply thereof that is essentially inexhaustible and
indestructible under normal use conditions. Further, the metal of
the members does not provide fuel to feed a fire once started in
other materials in or associated with a building structure.
In addition, the use of aluminum components provides for
exceedingly long life in comparison to wooden members, and when
scrapped has a value approximately equal to the basic cost of the
metal at the mill.
While the invention has been described in terms of preferred
embodiments, the claims appended hereto are intended to encompass
all embodiments which fall within the spirit of the invention.
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