US2062399A - Joist - Google Patents

Description

Patented Dec. 1, 1936 UNITE-D STATES 2,062,399 PATENT OFFICE JOIST Edwin n. nodding-ton, Milwaukee, wis.,

to Reynolds Corporation,

assignor New York, N. Y., a

corporation of Delaware Application November 1, 1935, serial No. 47,867

9 claims.- (c1. '1a-s1) cessfully marketed in competition with lumber.'

In addition it possesses advantages over lumber, such as resistance to fire and proof against attack by destructive insects. The joist furthermore is adapted to receive nails in the attachment thereto ofthe floor boards of buildings, and may be sawed to length somewhat similarly to lumber.

More especially the invention has for an vobject-the provision of a joist comprising a pairof parallel longitudinally-extending chords each composed of a sheet metal casing enclosing a.

Y nailable cementitious core, these chords being supported in spaced relation by a web composed of a continuous channel member passing diagonally back-and-forth between the chords, A characteristic' feature of the invention resides in forming the return bends of the web 4with short straight sections, or ats, attheir points'of junction with the chords.' In the preferred form of my invention the sides of the channel arefolded inwardly against its b ottom with their edges lying in substantial contact with each other and thereby providing an additional thickness of metal at the ilats. These flats-may be disposed within -recesses extending externally along the opposed faces of the chords andbonded, as by welding, to the side walls thereof so as to form a rigid unitary structure.

Other objects and advantages will become apparent from the following detailed description of a preferred form of joist embodying the features -of my invention, reference being had to the annexed sheet of drawings in which:

Figure 1 is a perspective view of one end of a joist exemplifying the invention;

Figure 2 is a side view of the-web alone;

Figure 3 is a detail view showing the manner in which the web is attached to one chord of ,theA joists;

Figure 4 is a detail view illustrating the manner in which the web is attached to the companion chord; and

Figure 5 is a detail sectional view disclosing an alternative mode of attaching the web to a chord. A

The j oist shown in Fig. 1 comprises an upper.

chord I, a lower chord 2 and an intermediate web 3 extending back and'forth between the two chords and supporting them in parallel spaced relation.

The upper chord I comprises a sheet metal trough-shaped member 4 having a bottom 5 and outwardly-flaring sides 6. 'I'he sides are extended beyond '.the bottom 5 and folded back upon themselves to form the sidewalls 'l .of a

recess 8 extending longitudinally and externally of the bottom of the chord. lThe sides 6 ter-- minate in horizontal flanges 9, and a cover plate II) of sheet metal extends between the anges and closes the top of the trough, thelateral edges of the cover plate being bent around the anges and secured thereto by crimps, indicated at'I I, or alternately, by' puncturing or4 welding.

The cover platev thus forms with the trough a.

tubular casing of generally trapezoidal crosssection.

The interior of the trough is lled with a cementitious core I2, which for example may be 20 composed of a mixture of gypsum, Portland cement and sawdust represented in the approximate proportions, by weight, :20:9, respectively. This material may be packed into the casing in a dry state,l and moisture then being introduced thereinto through perforations I3 in the cover plate. Upon drying, the material sets into a hard mass into which nails may be driven A without causing it to crack or crumble, and which offers great frictional resistance totheir withdrawal. This mode of fabricating `composite structural members is more fullyA described in my copending application Serial No. 39,022, led September 3, 1935. l

The cover plate I Il is of relatively light sheet metal so as to permit the use of nails Il in the attachment of oor slabs or boards I5 (indicated by dotted linesin Fig. 1) to the joist. To prevent the nails fromV passing out of the joist when ldriven into the edge of a chord, the trough 4 is made of heavy sheet metal which causes the ends ofthe nails to be deflected by its inclined sides and clenched withinthe core.

'I'he lower chord 2 is of identical construction to the upper chord I and for convenience'corresponling4 parts' thereof are designated by the primes of the same reference numerals.

The upper and lower chords are associated in reverse relation with their bottoms opposed to each other and-joined by the web'S.. As illustrated in Fig. 2 the web is constituted of a continuous channel member bent back and -foith and having its apices flattened as at IB- so as to atly contact the chords. 'I'hese ilats are further characterized by thedeformation of the sides l3a of` the channel inwardly against its bottom with their edges in substantially meeting engagement and together providing an additional thickness of metal overlying the bottom of the channel.

The width of the channel is such that its flattened areas I6 are snugly received within and substantially contact the bottom of the recesses 8 and 8 extending along the chords I and 2. As shown in lFig. 3, the folded over sides 3a of the channel underlie its bottom Where the channel joins the lower chord 2; while, as illustrated in Fig. 4, these sides overlie the channel bottom wherethe channel joins the upper chord I. In

both cases, however, the side edges of the flats are bonded to the side walls of the recesses as by welding I1.

The joist may be closed at its ends by struts I8 which extend pcrpendicularly between the chords I and 2 and foot within the recesses 8 and l8'. These struts may comprise straight sections of a channel member similar to that which constitutes the web 3. One end of each strut overlies the flattened terminal of the channel 3, and both struts are welded to the side walls of the recesses so as to form a rigid connection with the joist.

Instead of joining the web 3 to the chords in the manner just described, this may be accomplished by the process known as smash welding as exemplified in Fig. 5. As illustrated in this figure, the side walls 'I of the recess 8 extending along the chord 2 are swaged into tight engagement with the edges of the flats I6 contemporaneously with the welding of these parts as designated ati 9. This operation` also acts to bend over the tops of the side Walls 'I against the fiats I6 to securely anchor the web in place. It will be obvious that this type of bond can be employed at the junction of the web with either the upper or the lower chord. Various other changes in structure and design in the form of joist described above may be made without departing from the spirit of my invention.

I claim:

4l. Ajoist comprising a pair of chords, a web supporting the chords in parallel spaced relation, said chords each being composed of a sheet metal casing enclosing a nailable core and said web comprising a continuous channel bent so as to extend back and forth between the chords and the sides of said channel being folded inwardly upon itself to provide a double thickness of metal at the points of junction of said channel with the,

chords. l

2. A joist comprising a pair of chords, a web supporting the chords in parallel spaced relation, said chords each being composed of a sheet metal casing enclosing a nailable core, and said web comprising a continuous channel bent so as to extend back and forth between the chords, said channel being flattened at its points of junction with the chords and having its sides folded inwardly upon said flattened portions.

3. A joist comprising a pair-of chords each being composed of a sheet metal casing enclosing a nailable cementitious core, a web supporting the chords in parallel spaced relation and comprising a continuous channel bent so as to extend back and forth between the chords, a. recess extending longitudinally of each chord and said channel having its sides folded inwardly upon itself to provide a double thickness of metal at its reverse bends and disposed within the recesses.

4. A joist comprising a pair of chords each being composed of a sheet metal casing enclosing a nailable cementitious core, a web supporting the chords in parallel spaced relation and comprising a continuous channel bent so as to extend back and forth between the chords, said channel being flattened at its reverse bends, and a recess tion with the chords.

5. A joist comprising a pair of chords each being composed of a sheet metal casing enclosing a nailable cementitious core, a web supporting the chords in parallel spaced relation and comprising a continuous channel bent so as to extend back and forth between the chords, said channel being attened at its points of junction with the chords and having its sides folded inwardly upon said flattened portion to provide a double thickness of metal, and upright struts extending between the chords and closing the two ends of the joist.

6. A joist comprising a pair of chords each being composed of a sheet metal casing enclosing a nailable cementitious core, a web supporting the chords in parallel spaced relation and comprising a continuous channel bent so as to extend back and forth between the chords, each of said chords having a longitudinal recess extending along its bottom and said channel being fiattened at its return bends and having its flanges folded inwardly and bonded to the side walls of the recesses, and upright channel sections extending between the chords and closing the ends of the joist.

7. A joist comprising a pair of chords each being composed of a sheet metal casing of generally trapezoidal cross-section enclosing a nailable cementitious core, a web supporting the chords in parallel spaced relation and comprising a continuous channel bent so as to extend back and forth between the chords, each chord having a recess extending along its external bottom face and said channel being flattened and having its sides folded inwardly at its reverse bends to provide ardouble thickness of metal and bonded to the side walls of the recesses.

8. A joist comprising a pair of chords each being composed of a sheet metal casing of generally trapezoidal cross-section enclosing a nailable cementitious core, a web supporting the chords in parallel spaced relation and comprising a continuous channel bent so as to extend back and forth between the chords, each chord having a recess extending along its external bottom face and said channel being flattened and having its sides folded inwardly at its reverse bends to provide a double thickness of metal and bonded t9 the side walls of the recess, and upright channel sections extending between the chords and closing the ends of the joist, said channel sections having their ends projecting'within the recesses and bonded to the side walls of the recesses.

9. A joist comprising a pair of chords, a web supporting the chords in parallel spaced relation, said web being constituted of a continuous channel bent so as to extend back and forth between the chords and having its sides folded inwardly at its points of junction with the chords, and each of said chords comprising a trough-shaped 'member having outwardly flaring walls of relatively thick sheet metal enclosing a nailable core, and a cover plate of relatively thin sheet vmetal rigidly connected thereto, whereby nails may be driven through the cover plate and clenched against the outwardly flaring walls of the trough-shapedy

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