US1951810A - Joist structure - Google Patents

Description

' 9 amount of shrinkage.

' Patent-ed Man ,20,1934

uNiTEosT-ATES I JoIs'r STRUCTURE Adolf n. schaffen, Youngstown, ohio, signor to Truscon Steel Comp any, Youngstown, Ohio,

a corporation of Michigan y Application April 20, 1931` Serial No.l 531,525 4 Claims. (Cl. 189-37) This invention relates to a metal beam of the type having a nailing strip as a part thereof.

VA seriousobjectionto previously used devices of this type has been the development of squeaks I in the iioor supported by such joists, after the :door has been laid. These squeaks are very objectionable, and it is usually necessary that thev oo'r be taken up in order to eliminate them after they have developed.- This often involves great expense. 1

A series ofexperiments and investigations have shown that these squeaks are usually caused by the shrinking o f the nailing strip in the channel member of the rafter, which shrinkage causes 1| the nailing strip to become slightly loose and movable .in the channel member. The slight i movement of the floor, which this looseness allows when a weight passes over it, causes the squeak,

and it may occur between the floor and sub oor,

the sub oor and nailing strip, or the nailing strip and rafter member. Y

Attempts have been made to overcome this diiculty by kiln-drying the nailing'strfip and paintin g 'it before insertion into the channel member of the joist, the object being to preserve an even moisture content which will prevent shrinkage. 'I'his method has, however, proved unsatisfactory.

. At the place of utilization, the joists are often leftv inthe open and it has been found that the nailing strips absorb a. certain amount of moisture in spite of the coating of paint. Likewise under the conditionsY of a heated building orA 'in any manufacturing plant where the iioor is subjected to heat,`moisture will be driven olf with a consequent shrinkage. Y f

The object of the present invention is to provide such a juist. structure in which the. nailing strip is more permanently secured against movement with relation. to the :after regardless of the A further object is to provide such joist structure in which the nailing strip is substantially waterproof and is) thus 'not subject to expansion 5 and shrinking due to absorption and elimination ofmoisture.

` Another object is to provide an advantageous structure of the above type which will not materially increase the expense of manufacturing it.

In the accompanying drawingsz' Figure 1 is a perspective view of the joist. Figure 2 is a sectional view on lines 2-2 of Figure l. v

Figures 3 and 4 are cross lsectional views show- 6l ing two stages in the assembling of the joist.

Figure 5. is a cross sectional view of plet'ed jOist. Figure 6 is a perspective view ofamodication. lFigure 'T is a sectional view on' the line '7-7 of Figure 6.

Figure 8 is a view similar to Figure 7 of another modiation. f

Figure 9 is aperspe'ctive view of `the modied top chord member 4shown in Figure 8. y

In the preferred embodiment shown in Figures 1-5 an upper chord member 1 is supported by a lower chord member 2, and-an intermediate lattice member .3. The upper chord member 1 is channel-shaped having a bottom portion 4 and upstanding side walls 5 between which a. nailing 70 the coinstrip 6 is engagedl The upper chord member 1 is preferably rolled from plate steel. At spaced intervals inthe side walls 5 are inset portions '7. As shown-in Figure 2 these inset portions are alternately? disposed 'on' the two side 75 The inset portions '7 are formed at .the time of forming the member 1, the addition of one set of rolls to the machine usedfor that purpose'beingsulcient to form them. v f Figure 3 shows in cross section a chord member 1 as it is completed by the rolling mill, welded to the lattice 3 and ready to receive the nailing strip. After -the upper chord member is welded to the lattice member, as shownin-Figure 3, a nailing B6 strip 6 is positioned between the side wal1s\5 thereof and resting on the bottom portion 4, as

shown in Figure 4. Thelside walls 5 of the upper 1 chord'member are then pressed towards each other, preferably by means of rollers, intoclose UP engagement with nailing strip 6 lying between them. The result of this vperation is that the inset portions 'l are embedded in the nailing strip Gyas shown in Figures 2 and 5. The inset portions 'z hold the nailing strip s against. au move- 95 ment, and any shrinkage of the nailing strip will rather cause it to contract more tightly against -the inset portions, thus-more securely holding the parts against relative pla-y as the shrinkage` progresses. This being for the reason that shrinkage or contractionof'the material of the nailing strip which lies interiorly adjacent the emheddedprojections causes the upper and lower wallsot thepocket -or channel in which the projection lies to approach, eachother, thus bearing more tightly aga-inst the corresponding edges of the projection. 'More broadly, the rshrinkage' of the entire strip causes its top edge to approach its bottom edge. Any two points on the surface or in the uo los" As it is, however, advisable to prevent changes in the moisture content of the nailing strip, it is made substantially waterproof. preferably accomplished by saturating the strip with a mixture by volume made up of the following ingredients:

Per cent Linseed oil 40 Spar varnish 20 Dryer 10 Naptha 28 Parafn 2 It has been found that if the nailing strips are dried to a moisture content of approximately 8% and immersed in the above mixture for a period of one-half hour, the mixture will penetrate practically a'll the way through the nailing strip, and after such treatment there will be no appreciable swelling from absorbing moisture. After waterproofing the nailing strips they are placed in the upper chord members as above described.

In the modification shown in Figures 6 and '1, the inset portions 'I are replaced by inturned lip or flange portions 7a, which are formed and embedded in the nailing strip in substantially vthe same manner as in the embodiment first described. In this form longitudinally extending channels 8 are preferably cut in the sides of the nailing strip to receive the lip portions 7a. This is done to prevent the danger of splitting of the nailing strip which might occur if the lip portions were Asimplyiorced into the nailing strip as are the insets in the other form.

In the modification shown in Figures 'I and 8, spaced portions of the side walls are bent inward- 1y to form lip or flange members '7b. 'I'he mem;

' bers 'lb are alternately disposed on the side walls so that those borne by one side wall are not opposite those borne by the other side wall. This form of chord member is also formed by rolling,

after which the waterproofed strip is inserted between 'the walls, and the walls are then rolled towards each other into close engagement with the nailing strip, embedding the lip portions 7b in the adjacent sides of the nailing strip.

From the foregoing, it is thought that the construction, operation and many advantages of the herein described invention will be apparent to those skilled in the art without further description, and it will be understood that various changes in the size, shape, proportion and minor details of construction may be resorted to without departing from the spirit or sacrificing any of the advantages of the invention.

What I claim, is: Y

1. A joist structure including an upper. chord member having upstanding side walls, and a substantially water proof nailing strip positioned between the side walls, portions of the side walls being embedded in the sides of the nailing strip and gripped by the material thereof upon contraction of the said nailing strip.

2. A joist structure comprising a channeled chord member, and a nailing strip engaged in the channel of the chord member and' immovably carried by the chord member and portions of the chord member being embedded in the nailing strip for holding the latter against play irrespective of the .expansion and contraction of the nailing strip, and being more tightly gripped by the nailing strip when it contracts.

3. A joist Vstructure comprising a channeled chord member having upstanding side walls, a nailing strip positioned between and engaged by the side walls and extending above the side walls,

' portions of the side walls being embedded i-n the sides of the nailing strip at points substantially below the top surface of the nailing strip and l enclosed above and below by the material of the nailing strip and tightly gripped thereby when the nailing strip contracts.

4. A joist structure' comprising a channeled chord member having opstanding side walls, a nailing strip positioned between and engaged by the side walls, spaced portions of each of the side walls being inset and embedded in the sides of the nailing strip and enclosed and engaged above and below by the material of the nailing strip, the said portionsbeing tightly engaged by the said material upon contraction of the nailing strip. ADOLF H. SCHAFFEBT.

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