Title:
Trussed joist
United States Patent 3925951


Abstract:
A trussed joist comprises: A. upper and lower chord members extending in generally the same longitudinal direction and in spaced apart relation, B. metallic tubular webs extending in zig-zag configuration in the space between the chord members, each web having opposite ends which are flat, one end of each web extending proximate the inner side of the upper chord member and the other flat end of each web extending proximate the inner side of the lower chord member, the ends of successive webs extending in overlapping relation, and C. fasteners attaching the ends of the webs to the chord members.



Inventors:
Jackson, Edgar D. (Alta Loma, CA)
Jackson, Thomas E. (Upland, CA)
Application Number:
05/494414
Publication Date:
12/16/1975
Filing Date:
08/05/1974
Assignee:
STEEL WEB CORPORATION
Primary Class:
Other Classes:
403/217
International Classes:
E04C3/292; (IPC1-7): E04C3/292
Field of Search:
52/693,694 403
View Patent Images:
US Patent References:
3748809TRUSSED JOIST STRUCTURE1973-07-31Jackson
3702050WOOD TRUSS ARRANGEMENT1972-11-07Price
3137899Composite truss1964-06-23Troutner
1839178Metal joist1931-12-29Rebman
0114039N/A1871-04-25



Primary Examiner:
Perham, Alfred C.
Attorney, Agent or Firm:
Haefliger, William W.
Claims:
We claim

1. In a trussed joist, the combination comprising

2. The joist of claim 1 wherein said tubular web ends are defined by flattened tubing.

3. The joist of claim 1 wherein said fasteners comprise lag screws.

4. The joist of claim 1 wherein the tension webs form sockets receiving edges of the compression web flat ends.

5. The joist of claim 1 wherein said tension web ends are of substantially equal length.

6. The joist of claim 1 wherein one end of each web is substantially longer than the other end of said web, the longer end of each web extending adjacent a chord member inner side, and the shorter end of each web extending flatly adjacent the longer end of a successive web.

7. The joist of claim 1 wherein said fasteners comprise bolts extending through the chord members which have outer sides with recesses sunk therein to receive flanges on the bolts.

8. The joist of claim 7 wherein said flanges comprising bolt heads, there being nuts on bolt threaded terminals proximate said overlapping web ends.

Description:
BACKGROUND OF THE INVENTION

This invention relates generally to the construction of trussed joists adapted for use in mobile homes and similar environments. More specifically, the invention concerns simplication of the construction process and the formation of a superior product.

Prior to this invention, the process of trussed joist construction required preliminary cutting of wooden reinforcement webs to size to be placed between and connected to wooden chord members. No way was known to employ lightweight tubular members as reinforcement between chord members, in the advantageous manner contemplated by the invention, and to achieve unusually beneficial results that include: high strength, simple construction; and the provision of web flat ends or tabs which may be overlapped and rapidly connected to chord members at their inner sides.

SUMMARY OF THE INVENTION

It is a major object of the invention to provide structure and method meeting the above needs and greatly simplifying and speeding the construction of trussed joists. Basically, the joist involves the use of:

A. UPPER AND LOWER CHORD MEMBERS EXTENDING IN GENERALLY THE SAME LONGITUDINAL DIRECTION AND IN SPACED APART RELATION,

B. METALLIC TUBULAR WEBS EXTENDING IN ZIG-ZAG CONFIGURATION IN THE SPACE BETWEEN THE CHORD MEMBERS, EACH WEB HAVING OPPOSITE ENDS WHICH ARE FLAT, ONE END OF EACH WEB EXTENDING PROXIMATE THE INNER SIDE OF THE UPPER CHORD MEMBER AND THE OTHER FLAT END OF EACH WEB EXTENDING PROXIMATE THE INNER SIDE OF THE LOWER CHORD MEMBER, THE ENDS OF SUCCESSIVE WEBS EXTENDING IN OVERLAPPING RELATION, AND

C. FASTENERS ATTACHING THE ENDS OF THE WEBS TO THE CHORD MEMBERS.

As will be seen, the tubular web ends or tabs may be formed or defined by flattened tubing susceptable to close overlapping and extending integrally with the main extents of the webs; the webs typically include tension webs extending diagonally upwardly and longitudinally toward an end of the joist, and compression webs extending diagonally downwardly and longitudinally toward an end of the joist, the tension web ends extending flatly against the inner sides of the chord members; the tension web ends typically include first portions overlapped by compression web ends, and second portions extending longitudinally substantially beyond the compression web ends for additional attachment to the chord members.

These and other object and advantages of the invention, as well as the details of an illustrative embodiment, will be more fully understood from the following description and drawings, in which:

DRAWING DESCRIPTION

FIGS. 1a and 1b are side elevations of joists incorporating the invention;

FIG. 2 is an enlarged perspective showing of a correspondingly designated portion of the FIG. 1 joist;

FIG. 3 is an enlarged perspective showing of a correspondingly designated portion of the FIG. 1 joist;

FIG. 4 is an enlarged side elevation of a correspondingly designated portion of FIG. 1;

FIG. 5 is an enlarged side elevation of a correspondingly designated portion of FIG. 1;

FIGS. 6 and 7 show optional flat end shapes;

FIG. 8 is side elevation of a modified joist; and

FIG. 9 is a side view of a further modified joist.

DETAILED DESCRIPTION

FIG. 1 shows upper and lower longitudinally elongated chord members 10 and 11 extending in the same generally horizontal direction, and spaced apart vertically. Such members typically consist of wood, and they have inner sides at 10a and 11a and opposite lateral faces 10b and 11b.

Metallic tubular webs 12 and 13 extend in zig-zag configuration in the space between the chord members, webs 12 being tension members, and webs 13 being compression members. Note the symmetry of the webs 12 and 13 at opposite sides of, and with respect to, the vertical center line 14 in FIG. 1. Webs 12 extend diagonally upwardly and longitudinally toward an end of the hoist, and webs 13 extend diagonally downwardly and longitudinally toward an end of the joist.

The opposite tab ends of each web are flattened, as by flattening the tubular material at such ends. Thus webs 12 have flattened ends 12a and 12b, and webs 13 have flattened ends 13a and 13b. Further, one flattened end of each web (i.e. ends 12a and 13a) extends proximate the inner side 10a of the upper chord member, and the other flattened end of each web (i.e. ends 12b and 13b extends proximate the inner side 11a of the lower chord member. In addition, the flattened ends of successive webs extend in overlapping relation. For example, the flattened ends of the compression webs overlap the flattened ends of the tension webs, as shown, the compression web ends 13a typically overlying the tension web ends 12a at the inner sides of the latter (the outer sides of ends 12a extending flatly against the upper chord member inner side 10a); and the compression web ends 13b typically overly the tension web ends 12b at the inner sides of the latter (the outer sides of ends 12b extending flatly against the lower chord member inner side 11a).

In addition, the tension web ends include first portions 12a1 and 12b1 overlapped by compression web ends 13a and 13b respectively, and second portions 12a2 and 12b2 extending longitudinally substantially beyond such respectively compression web ends, as is clear from FIG. 4. Fasteners are provided to attach the ends of the webs to the chord members, as shown; certain fasteners in the form of lag screws project through the compression web ends and the tension web end first portions into the chord members, and other fasteners project through the tension web end second portions and into the chord members in offset relation to the certain fasteners. For example, certain fasteners 16 are associated with tension web end first portions 12a1 and compression web ends 13a proximate chord 10; other fasteners 17 are associated with tension web end second portions 12a2 proximate chord 10; certain fastener 18 are associated with tension web end first portions 12b1 and compression web ends 13b proximate chord 11; and other fasteners 19 associated with tension web end second portions 12b2 proximate chord 11. As a result, an extremely simple and strong joist is provided.

Near the center line 14, the flat ends 120b of two successive tubular tension webs 120 overlap to receive a lag screw fastener 121 connected to lower chord 11, and the opposite flat ends 120a of webs 120 overlap with the flat ends 13a of the next in succession compression webs 13, as shown, to receive lag screws 122 connected with upper chord member 10. Flat ends 120a and 120b need not be elongated in the manner of ends 12a and 12b.

For increased strength, the compression tubular webs 13 may typically be of heavier material (i.e. greater wall thickness) than the tension webs; also, the tension webs will have additional body to resist shear.

It should be noted, as in FIG. 4, that the tension webs form sockets 30 between the flat ends 12b and the convex extents 31 converging toward these flat ends. The outer edges of the flat ends 13b of the compression webs may fit into these sockets to be retained and to transmit some loading to the flat ends 12b. This construction also exists at the flat ends 13a of the compression webs.

FIGS. 6 and 7 show optional rounded and squared shapes of the flat ends 13a and 13b, at 140 and 150.

The tubular webs for best results may consist of steel and have outer diameter of about 0.925 inch and wall thickness of about 0.046 inch, as used with wooden chord members of 2 inch × 4 inch cross section. Also, the lag screw holes may be pre-drilled in the chord members. The x and y dimensions in FIG. 1b typically may be "16" and "32", respectively.

Finally, in FIG. 8, the webs 50 are alike, and include tubular mid sections 51, and flat ends 52 and 53. Ends 52 are relatively larger and extend flatly adjacent the inner sides of the chord members, and ends 53 are relatively shorter and extend flatly adjacent the inner sides of the ends 52 of successive webs. Bolts 54 pass through both ends 52 and 53, and bolts 55 may be used if desired, i.e. passing through the long ends only. Such a construction may be employed at the middle two thirds of a joist which carries less load than the ends of the joist.

In the FIG. 9 truss, the chord member 60 contains a drilled opening passing the shank of a bolt type fastener 61 extending completely through the chord member. The outer side 62 of the chord member is recessed at 63 to receive a flange on the bolt, and such flange may comprise the convex bolt head 61a. The top of the latter is nearly flush with the outer side 62 of the chord member, that outer side therefore being free of outwardly protruding structure. The bolt also passes through the flattened overlapping ends 64a and 65 a of the tubular metallic web members 64 and 65, respectively. A nut 66 is tightened on the bolt threaded terminal 61b to compress the flattened ends 64a and 65a toward the inner side 69 of the chord. Similar structural connections are employed along each of the upper and lower chords at the loci of the tubular member flattened and overlapping ends, which contain aligned openings to pass the bolts.