US1392882A - Trussed-roof structure - Google Patents

Description

W. J. SUMMERBELL.

TRUSSED' ROOF STRUCTURE.

APPLICATION FILED NOV. 21. 1919.

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TRUSSED-ROOF STRUCTURE.

treatise.

Application filed November 21, 1919. Serial No.

. oof Structures; and I do hereby declare that the following is a full, clear, and exact descriptlon thereof, reference being had to the accompanying drawings, and to the characters of reference marked thereon, which form a part of this specification.

This invention relates to improvements in roof trusses, particularly adapted to arched roofs of large spans and constructed to support the roof without the necessity of posts within the building. The invention relates to the component parts of the truss and also to the manner of connecting the joists of a roof structure to the upper or top chord of the truss and to improvements of the roof as a whole embodying said truss.

Among the objects of the invention is to produce a 'truss in which the load stresses are readily determinable, and a truss that may be made of few and simply fabricated parts, thereby materially saving in installation and to produce a truss of relatively light weight as compared to its loading capacity.

A further object of the invention is to produce a roof truss that is so constructed as to enable the finished roof structure to be lowered relatively to the top chord of the truss as compared to trussed roof structures in common use, and thereby effect a material saving in the cost of the masonry work of fire walls which are usually required by fire ordinances to extend around and above the roof at the skew-back of the arched member of the truss, and which also reduces radiation from the space inclosed by the roof, that is to say, radiation required to heat the inclosure, and which also reduces heat conducted to the inclosure from sun rays which strike the roof.

A further object of the invention is to so connect the top or upper chord or member of the truss with the joists as to afford a firm support for the joists at the upper Specification of Letters Patent.

chord of the truss without the necessity of overlapping the joist lumber, thereby effectmg a material saving of the joist lumber.

A further object of the invention is to afford better lateral bracing of the trussed roof structure due to the fact that the joists abut laterally against the top or upper chord of the truss and are firmly supported on said upper chord of the truss.

A further object of the invention is to provide in an upper truss chord, laterally projecting members at the bottom of said chord to directly support the trusses in the general plane of said chord.

A further object of the invention is to provide a novel tension member for connecting the upper and lower chords which is designed to be firmly connected to the upper and lower chords of the truss, so as to thereby greatly strengthen the truss as a whole, and so, also. to make the stress on said connecting tension members readily determinable.

Another object of the invention is to provide a novel member for connection between the upper and lower chords of the truss, together with means for rigidly fastening said tension member to the upper and lower truss chords. v

Other objects of the invention are to further improve, simplify, and reduce the cost of roof trusses for the purpose set forth and roof structures embodying said trusses, and the invention consists in the combination and arrangement of -the elements shown in the drawings and described in the specification, and is set forth in the appended claims.

In the drawings.-

Figure 1 is a fragmentary cross section through a building equipped with a roof truss embodying my invention.

Fig. 2 is a vertical section on the line 22 of Fig. 3.

Fig. 3 is an enlarged View, showing the truss elements in elevation and the joists in section.

Figs. 4 and 5 are sections on the respective lines 4- l and 55 of 3.

Fig. 6 is a. perspective view of one of the reinforcing straps of a vertical tension member connecting the upper and lower truss chords.

l i.3.- I

is shown in said drawings, 10, 10 desig nate two of the vertical. inclo'sing walls of the buildingand 11' atruss embodying my.

' said joists abuttingagainst the lateral sides of said upper chords. 13. designates the sheathing supported by said joists and which in turn support the roof cover or facing. I

Each roof truss .comprising an upper curved compression member or chord 14, shown as composed of a number'of laminations 15 (Figs. 2, 3, and 5),.a lower tension member or chord 16, likewise composed of a plurality of laminations 17, and a plurality of interconnecting tension and compression members 18, 19, respectively. The lower chord or member of the truss is supported at its ends on shoulders orledges of the walls 10 and the upper chord is supported at its ends on the lower chord and fixed thereto by the steel strap 20 shown in Fig. 1.

The laminations of the lower chord are disposed vertically as shown in Figs. 2 and 7 and are spaced at the transverse center of the chord to receive the lower. ends of the tension and compression connecting members 18 and 19. The laminations 15 of the upper chord are laid superposed on each other in arched formation, as shown in Figs. 2 and 5, being made narrower than the full width of the upper chord to provide longitudinal spaces to receive the upper ends of the tension and compression members 18 and 19. The upper chord comprises, in addition to the laminations 15, topmost strips or laminations 22 against which the upper ends of the tension and compression members 18 and 19 abut, the strips being slightly spaced at their inner edges for a purpose hereinafter described, and lying with their upper faces flush with the upper edges of the joists 12 to partly support the sheathing 13. Said upper chord comprises also lower strips or laminations 23. which extend at their outer edges beyond the lateral faces of I the upper chords to constitute ledges 24: to

support the joist, as best shown in Figs. 2 and 5. The laminations or strips of the upper chord are fixed together by through bolts 25.

The lower chord comprises, in addition to the laminations 17, lower horizontal strips 26 that extend across the lower edges of the laminations 17 and extend at their outer edges flush with the side faces of said lower jchord, being slightly spacedat their inner edges for-1 a purpose hereinafter described.

Theen'd'sl-of the tension and compression laminations -17 and strips 26 being such as to members abut against and ,are'supported on' said lower s'trips26, the arrangement ofthe,

afford a longitudinal groove to {-receive the;

lower endsof said tension and compression v members 18 and 19. The connecting members 18 and 19 of the truss preferably. comprise wood strips- Each of the compression members extends diagonally between adja cent tension members 18, but do not cross the latter. The upper and lower ends of said oblique compression members 19 are obliquely cut to fit at. their lower ends againstv the lower strips or laminations 26 of the lower chord and against'the edge faces of the lower ends of the tension members, and

to fit at their upper ends against the upper strips or laminations 22 of theupper chord and againstthe edges faces, of the upper I ends of said tension members.

The vertical tension members 18 are ofv composite construction, each comprising two parallel sidestrips 28 of wood that abut at their ends against thestrips 22 and 26 of the upper and lower chords, and intermediate, parallel metalstraps 29 that lie against each other and the strips 28 throughoutthe lengths of the tension-members and extend beyond the strips 28 through the spaces be- 1 tween the respective strips 22 and 26, as best shown in Fig. 2.

The reinforcing straps their lowerends with outturned hooks, com- 29 are formed at ioe prising lower members 30 that extend across i the lower strips 26 of the lower chord and upturned terminals 31 that lie along the side faces of the outer laminations of the chord, the whole being secured together by through bolts 32. The upper ends "of said reinforcing, metal straps 29. are turned, laterally outwardly at 34 and lie transversely across between the uppermost strip 22 and the next adjacent laminations 15 of the upper chord and aretwisted to form members 35 that lie flat against the sidefaces of the f joists 12 and'are nailed thereto in theman ner shown in Fig. 2, and are formed with terminal inturned hooks 36 that extend inwardly beneath and partially embrace the ledge laminations 23.. The through bolts 25 extend through said outturned members 34 and also through the terminals 36 to firmly bind the parts together.

The construction described provides an exceedingly rigid connection between the tension members 18 and the upper and lower chords, and a connection that is economical to make and is readily fabricated. Moreover, the construction described provides at the lower ends of the tension members 18 a chord elements.

truss bracing connection between the compression and tension members 19 and 18, in

upper laminations 15 and strips 22 (Fig.-

5) and are nailed or otherwise fixed to said blocks; and said stripsare twisted to form members 40' that lie flat against the side faces of adjacent joists and-are nailed thereto, and are formed with terminal inturned hooks 41 that partially embrace the upper chord. The lower reinforcing or filler blocks 39 are fixed to the lower chord by metal stirrups 42, as bestshown in Figs. 1, 3 and 7.

It will be observed that the respective vertical tension and oblique compression members connecting the chords are so arranged that they do not cross each other, and, furthermore, that their arrangement in connection with the upper and lower chords is such as to enable normal stresses readily to be determined.

It will be furthermore noted that the joists 12 lie in the general planes of the upper chords of the trusses and abut the side faces of said chords and are supported by the lateral extensions orledges of the chords with their top faces of the upper edges flush with the upper members 22 of the upper chord, so that thereby, in addition to a better bracing of the structure, the roof itself is lowered as compared to trusses wherein the joists extend above the level of the upper chordsof the trusses. A further advantage to be noted is that the chord extensions 23 and other laminations therebeneath, if desired, are unitary or integral parts of said chords or parts which are in predetermined stress under expected loading. Therefore, the joists are fixed in a most substantial and'advantageous way to the It strengthens the chord laterally and resists the compression load. An important advantage of this construction, to'be observed from an inspection of Fig. 1, is that the roof itself is lower so that the fire walls that extend above the level of the lower chords of the trusses need not be so high as in the type of truss roof referred to, thereby saving materially in the initial installation of masonry. In other words, the fire walls need not rise so high, above the ledges which support thetrusses. Another advantage arising from bringing the roof to this lower level is that the radiation required to heat the building isreduced, and also the surface of the roof subjected to the direct action of the sun is lessened and thus the conduction of heat of the sun through the roof is correspondingly lessened.

Another advantage of the construction which has been hereinbefore set forth is that the constituents of the structure are readily fabricated and assembled, which goes toward reducing the cost of installation, and, inasmuch as the trussed roof structure is thoroughly braced, the maintenace of the roof is thereby lessened.

It will be understood that the illustrative embodiment of the invention shown in the drawings is capable of some variation within the spirit and scope of the claims hereto appended, and that the invention is not limited to the particular details shown, except as to claims wherein the details are specifically setforth, and as imposed by the prior art. For instance, lattice tension and compression members may sometimes be employed between the upper and lower chords, and .said chords need not necessarily be laminated, although such laminated structure is desirable. The interconnecting means between the top and bottom chords may also be varied in respect to the manner of constructing the top chord and also with respect to the manner of carrying the metallic connections between the web members and the top or bottom chord, or both.

I claim asmy invention,-

- 1. A roof truss comprising top and bottom chords and interconnecting compression and tension means, the top chord being upwardly curved and of built up construction and embracing at its lower side a unitary joist supporting ledge, that extends longitudinally of the chord and is connected. thereto to constitute a compression element of said top chord.

2. A roof truss comprising an upwardly curved top chord and a bottom chord and interconnecting compression and tension means, the top chord having at its lower side a unitary, longitudinally disposed continuous joist supporting ledge.

3. A roof truss comprising top and bottom chords, interconnecting compression and tension members, the top chord having at its lower side a unitary joist supporting ledge that extends longitudinally of the chord and is connected thereto to constitute a compression element of said upper chord, and metallic reinforcin'gmembers for some of said interconnecting members extending to and secured to said top chord and reinforcing said ledge.

4. A roof truss comprising top and bottom chords, interconnecting compression and its lower side a unitary joist supporting r top and bottom chords, and interconnecting bers together.

ledge that 'extends longitudinally of the chord and is connected thereto to constitute a compression element of said top chord, and straps extendin along some of said interconnecting mem ers and fixedly attached at their upper and lower ends to the top and bottom chords and reinforcing said ledge.

5. The combination with a roof truss comprising a curved top chord and a bottom chord and interconnecting compression and tension means, the top chord being built up and having at its lower side a unitary built in joist supporting ledge that extends longitudinally along, and is connected to, said top chord and constituting a compression element thereof, of a joist abutting said top chord and supported on said ledge.

6. The combination with a roof truss comprising top and bottom chords and interconnecting compression and tension members, the top chord having at its lower side a unitary joist supporting ledge that extends 1ongitudinally along, and is connected to, said top chord and constituting a compression element thereof, of a joist abutting said top chord and supported on said ledge, and reinforcing members for some of said interconnecting members having terminal portions, exterior to said top chord, with means to fasten each of said terminals to said top chordand to a neighboring joist to bind the said chord joist and interconnecting mem- 7 A truss for a roof structure comprising top and bottom chords and interconnecting compression and tension means, said chords being of laminated structure and recessed to receive the. ends of said tension and 'compression means, and the top chord being upwardly curved provided at its; lower side with. unitar longitudinally disposed joist supporting I edges.

' 8. A truss for a roof structurecomprising compression and tension members having reinforcements embracing the top and bottom chords, the upper chord being provided at its'lower side with unitary,- laterallyand oppositely extending joist supporting ledges that are disposed longitudinally of said top chord. 1 i

9. A truss for a roof structure comprising top and bottom chords and interconnecting compression and tension means, the top chord being laminated and connected to the ends of. the tension and compression means,

and a lower'lamination of said chord ex tending laterally from the side face of the chord to constitute a joist .supporting ledge. 10. A truss for a roof structure comprising top and bottom chords and interconnecting compression and tension means, said top chord being laminated and irecessed to reare formed at their upper ends with laterally. extending membersprovided with terminal parts to fit flat against and to be at tached to joists supported on said ledges.

12. A truss for a roof structure comprising top and bottom chords and interconnecting compression and tension members, the said chords, being laminated and recessed to receive the ends of the tension and compression members, the top chord being provided at its lower side with joist supporting ledges, and said tension members being reinforced by metal straps which are formed at their upper ends with laterally extending members provided with terminal parts to fit fiat against and to be attached to joists supported on said ledges and extendingbeyond said joists to partially embrace said ledges and fixed thereto.

13. A truss for a roof structure comprising top and bottom chords and interconnecting compression and tension means, the top chord being laminated and the lower laminated member being. wider than the-- other laminated member to form at the sides of said chord joist supporting ledges.

14. A- truss for a roof structure comprising top and bottom chords and interconnecting compression and tension members,

the top chord being laminated and grooved to receive the endsof the tension and com- Y pression members, the upper chord being provided at its lower side with joist supporting ledges, certain of said interconnect ing members being reinforced by metal straps which are attached at their upper ends Y to joists supported on said ledges, said top chord being laminated and the laminae members thereof being connected together by means which attach thereto members on which are formed the joist supporting ledges;

15. A truss for a roof structure comprising top and bottom chords and interconnecting compression and tension members, the chords being laminated and grooved to receive the ends of the tension and compression'members, the top chord being provided at its lower side with joist supporting ledges, said tension members being rein- 65 ceive the ends ofthe'tensio'n and-compresforced by metal straps which are attached at their upper ends to joists supported on said ledges, said top chord being laminated and connected together by through bolts wh ch attach thereto members on which are formed the joist supporting ledges, the bottOlHx chord being of laminated structure with the principal laminations thereof vertical and spaced to receive the lower ends of the tension and compression members, and bolts 10 extending through said laminations and the tension members.

In testimony, that I claim the foregoing as my invention I affix my signature this 19th day of November, A. D. 1919.

WILLIAM J. SUMMER-BELL.

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