United States Patent 3849961

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.

Application Number:
Publication Date:
Filing Date:
Primary Class:
Other Classes:
52/655.1, 52/714
International Classes:
E04C3/09; E04C3/11; E04B1/24; E04B1/58; E04C3/04; (IPC1-7): E04C3/09
Field of Search:
View Patent Images:
US Patent References:
3352070Truss type panel structures1967-11-14Raynes
3061978Metallic building frame structure1962-11-06Elia et al.
2664179Nailable metal structural member1953-12-29Gwynne
2399785Metal hangar or similar building1946-05-07Blickenderfer
2177277Metal stud1939-10-24Burke
1763300Toy building construction1930-06-10Gilbert
1674211Clamping device1928-06-19Loucks
1535504Metal building and structural unit therefor1925-04-28Stephens
1532695Metal building1925-04-07Harting et al.

Foreign References:
Primary Examiner:
Sutherland, Henry C.
Assistant Examiner:
Braun, Leslie A.
Attorney, Agent or Firm:
Strickland, Elroy
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.


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.


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 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.


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.