US2369525A - Roof truss - Google Patents

Description

Feb. 13, 1945. 1 F BLA$K| l 2,369525 ROOF TRUss Filed July 8, 1942 l 2 Sheets-Sheet 1 l Feb. .13, 1945. I- l 1 BLASK] 2,369,525

ROOF TRUSs Filed July 8, 1942 2 Sheets-Sheet 2 IHIIII Patented Feb. 13, 1945 UNlTED STATES PATENT OFFICE ROOF TRUSS John F. Blaski, Chicago, Ill. Application July 8, 1942, Serial No. 450,205

(Cl. S-23) 4 Claims.

My invention relates to a roof truss and method of making the same and is particularly although notvexclusively pertinent to an arched truss construction such as may be used in erecting hangars, garages and other buildings requiring large floor areas free of roof support.

An object of my invention is to provide a novel method of making a roof truss so that the tendency of a lower chord to buckle when iny compression is resisted solely by the strut means between upper and lower chords.

Another object of my invention is to provide a roof truss constructionA with maximum strength and rigidity and with minimum material.

Another object of my invention is to provide a roof truss construction using one more upper chord than lowerl chord and connecting strut means so that the same perform double y. duty, namely, take care of they tension and compression forces between the upper and lower chords and effectively prevent the tendency ofthe lower chords to buckle.

and partially in' elevation, showing socket means for securing struts to a lower chord;

Fig. 5 is a fragmental enlarged side View of a portion of a lower chord and showing side elevational appearance of the sockets -ior'securing the struts to the chord; y

Fig. 6 isI a fragmental view, partially irrelevation and partially in section, showing the bolt and wedge arrangement for securing a strut in a socket;

Fig. '7 is a bottom plan view, with parts in section, of Fig. 5;

Fig. 8 is a plan view of one of the bridge members used in connecting abutting ends of' the planks of a lamination of a chord;

Fig. 9 isv an enlarged Vertical sectional View taken in the plane of line 9 9 of Fig. 8;

Fig. 10 is a fragmental plan view of adjacent roof boards'showing the novel clip arrangement of my invention for maintaining these boards in surface alignment; y

Fig. 11 is an enlarged elevational view of the clip as it appears when applied to an edgeof one of the boards and p Fig. 12 is a fragmental sectional View through two adjacent roof boards showing the side eleva- 'means for maintaining the ends of boards in A the laminations of the chords in connected relation to prevent endwise separation of such boards. A still further object of my invention is to pro; vide means for maintaining the surface alignment of the roof boards Where there are no tongue and groove connections between the boards.

My invention has for a further object the provision of bolts and wedges for securing the struts in the sockets to Aenable the use of socket material of light weight. i

A still further object of my invention is to improve generally the construction of arched roof trusses for hangars and likebuildings.

The above, other and further objects` of my invention willV be Lapparent from the following description and the accompanying drawings,the

tional apparatus of the clip.

The drawings will now be explained.

Referring to Fig. 3fit will be observed that a truss of my invention includes two upper chords A and B and one lower chord C. These chords f are preferably laminated by tiers of boards arranged in end to end relation suitably glued and nailed together.

The lower chord C is disposed below and between the two upper chords and lies in' a vertical plane which is midway'between the upper chords.

A number of laminations in the upper and lower chords depends on the length of the span load tov be carried by the arch and other condi- :tions present in the construction of archedv trussed roofs..

Struts `I and 2 are connected between the upper and lower chords. As shown, the strutsv I are connected between the upper chord A and the lower chord C while thevstruts 2 are connected betweenl the upper chord B and the lower chord C.- As will be observed from Figs. 2, 3 and 5 these struts are inclined to the vertical as well .as tothe horizontal. While these struts might .be bolted directly to the'chords, I prefer to utilize adapted to be bolted to the sides of the chords. The plate 3 has a marginal portion 1 offset with respect to the plane of the plate so as to overlie an adjacent margin 8 of the plate 4, as is illustrated in Figs. 5 and 7. Welded to the plate 3 is a socket 9, and Welded to the plate 4 is a socket I0. These sockets are illustrated as rectangular in cross section although it is to be understood that they might be circular or polygonal as desired.

` The sockets are so welded to their plates as to incline the struts in the desired angular relation to secure maximum strength between theV chords. IIhe sockets for the plates used with the lower chord are closed at their bottoms and thev` sockets for the plate `used with the upper. chords are closed at their tops. I have found that it is feasible to securely attach thestruts withinithev sockets by a singlebolt per socket when using.

wedge-shaped washers.

Fig. 6 shows azfragmentalportiongofa socket and a sectional .portionof an. inserted strut. The socket is apertured totreceivea bolt. lil and two opposite faces of thestrut'are. cut out as. at l2 and l3'tcA receive wedge-shaped washers I4` and Vredt'lcing the tendency of wear in the bolt aper- When the sockets are made of relatively ture. thin material, increased bearing engagement for the bolt is Aachieved by application of collars I1 and I8 to the outerV surfacey of. a socket and in register withv the bolt apertures, which collars are welded in place. There isv accordingly provided ample bearing surface between thebolt and socket to resist shear stresses.

The. socket plate 3 is provided withanaperture to receive a securing bolt I9,.while the'plate 4 is. apertured to receive a securing bolt 20. The overlapping portions 'I and. 8 of the face are apertured to receive securing bolts. 2| and 22.. In applying-the plates to achord. washers I4 are applied over the bolts against the side surfaces of the chord and asy thebolts are` tightened the washers are` pressedy into` engagement with the chords, indenting the chords toprovide cooperating seats for the washers. I .have foundthatthis manner of attaching the plates isfsatisfactory and isonewhich preventsloosening ofthe plates. g f

In order to=prevent endwise separation of the planks in the laminations of the chords Ihave provided novel bridge` means. Such means are illustrated in Figs. 8 and 9 andincludetwo simila'r bridge plates 23 and 24vmade of a su-itable thicknessof sheetI metal. Prongs or teeth 25and 26 are struck out of the plates. Whentheadja-` centends of plan-ks suchas 21 and. 28 aretobe connected, the-bridge plate. 23y is-placedovex; the side surfaces of adjacent..endsof-theplanksand another. plate.. 24 on thebottom.. The` ends of theplanks. are brought togetherand. then the` two plates are hammeredso `that the prongs orteeth 25y and 2liV enter the plankssthus securinglthe. ends together against separation.

My invention'contemplates the application of roofllbo-ardss 29 directly toitheupper. chords ofthe trusses so that the roof boards thus. become integral."` lpartsV of. thev trusses and:` brace` the upper chords, holding them in place'.-

Because of present restrictions in the manufacture of lumber, it is impossible to obtain tongued and grooved material. To maintain surface alignment of the roof boards 2!) I therefore provide novel clips, one of which is illustrated in Figs. 10, 11 and 12. A clip is fashioned from metal of suitable thickness and comprises a central body 30 having upper and lower ears 3| and 32 projecting at right angles to the body on one side of the same and another pair of ears 33 and 3'4 bent in the` opposite direction. Struck out of the body between its ends and extending in opposite directions therefrom are teeth 35 and 36. When used to maintain surface alignment of the 1 boards these clips are placed between the adjacent side margins of the boards and the boards forced together. The clips 3|, 32, 33 and 34 engageA the. outer surfaces of the boards while the teeth.35.v and 36 enter the boards through their side'rnargins, thus maintaining the surface alignment ofztheboards.. The lengths oftheclips and teeth' are. such. i as to maintain surfacewalignment of the. boards vunder expansion.. and contraction due Ato weather. conditions..

It will be observed that the trussA construction of my inventionA provides a. truss which is rigid and strong and made up from a'minimum amount of material, by reason of the fact that one lower chord is so connected to two upper chords as to bracethe lower chordagainst anyl tendency to buckle should the lower chord-be in compression. Such construction. eliminates thelateral braces heretofore` employed between i the lowerv chords of trusses constructedwith the-lower chordsin vertical alignment. with the upper chords.

It will be observed also that the struts of. my truss constructionfunction to take care of. cornpression and tension. stresses between the upper and lower. chordsfand also constitute the sole means for resisting buckling ofthe lower chords.

Instead. of. usingwood struts as described, pipe might be substituted'. Such pipe struts might be used with the sockets. described, or` the sockets might be eliminated andthe. pipe bolted directly to the chords.

It willbe notedthat the number of .plies in the lower chord C of Fig. 3 is greater than the number of plies in the` lower chord illustrated `in Figs. 4 and 5. V Figs. 4. and .5.. are illustrativeof the manner. ofsecuring the socket plates to the chords, the number of plies in a chordmakingno diierence as to the manner of applying the plates to the chord. In Fig. 3 it will be observed that the socket plates extend only part way down the lower chord C. The extent of. such platesv depends, of course, onthe depthof theA chord'.

The method of my invention. contemplates making a roof truss so that the tendency of the lower4 chord to buckle when incompression is resisted solely by the struts between the upper and lower chordsv and so. disposing the upper and lower chords. withalower chord below and between two upper chords. and. connecting each of the upper chords withxthelower. chords by strutswhich. areainclined.. toa vertical. planefincludingthe lower chord.,

WhileA my. invention` has. been illustrated. in connection with an arched truss, the sameconstruction could be'employedinmaking a straight truss.

Prior to the application ofthe struts. to the sockets the strutsA are. suitably waterproofed by paint.. or chemical. substanciasl to.v prevent undue expansion and contraction of the struts incidentaltoweather varations.- Such waterproofing of the struts prevents loosening of the struts with v respect to the chords, thus maintaining the rigidity and strength of the trusses.` K

I do not intend to limit the invention to the details of construction shown and described except only in so far as certain of the appended claims may be specifically so limited, as it' will be obvious that modifications may be made without departing from the principles of the invention. f

I claim:

1. A truss roof comprising a plurality of spaced l pairs of upper chord members, a lower chord member disposed `intermediate the upper chord members of each pair in such lateral offsetv rela-l tion that no upper and lower chord members lie in the same vertical plane, struts connecting the upper and the lower lchord members and being inclined to the length of the chords and also to the vertical whereby the same struts that are subjected to compression and tension forces of the upper and lower chords function to prevent buckling of a lower chord when the same is in compression, and roof boards attached to said upper chord members spanning the spaces bef tween adjacent trusses and the spaces between the upper chord members of each truss to provide an unbroken roof surface, said roof boards effect-l ing lateral bracing of said upper chord members.

2. A truss roof construction in which lateral bracing of the-lower chords is effected solely by the truss struts, each truss comprising two upper chords and one lower chord disposed between and below said two upper chords, and struts connecting each upper chord with'said lower chord,

` necting each of theupper chords with the lower' v said struts being inclinedto the vertical and hori-- zontal in such manner that the horizontal components of forces act to prevent buckling of the lower chord` when the latter is in compression, said trusses being disposed in laterally spaced relation, and roo-f boards attached to said upper chords spanning the spaces between adjacent trusses and the spaces between the upper chords of each truss to effect lateral bracing of said upper chords.

3. A roof truss comprising two parallel and laterally spaced upper chords, one lower chord disposed in a vertical plane midway between the two upper chords, and struts connecting each of the upper chords with the lower chord wherebythe same struts function in compression and tension between the upper and lower chords and also prevent buckling of the lower chord when it is in compression.

4. In a roof truss comprising two parallel andy laterally spaced upper chords, one lower chordV disposed ina vertical plane midway between said two upper chords; a pluralityA of struts for conchord, means for connecting the struts tothe lower chord comprising plates attached to the side surfaces of said lower chord, sockets secured to said plates with the lengths thereof inclined -to the horizontal andvertical, a bolt passing ythrough a socket and its strut, and means for relieving forces of compression and tension on the bolt by a strut Icomprising wedge Washers acting against opposite faces of a strut.

JOHN F. BLASKI.

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