US2520333A

US2520333A - Truss end construction

Info

Publication number: US2520333A
Application number: US758757A
Authority: US
Inventors: Axel V Pedersen
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-07-03
Filing date: 1947-07-03
Publication date: 1950-08-29
Anticipated expiration: 1967-08-29

Description

Aug. 29, 1950* A. v. PEDERSEN TRUSS END CONSTRUCTION Filed July 3, 1947 .n we L mp m 4 4232b r-ney;

.terially wider than the lower chord. .ltruss designs the materials employed .are such Jthat the lower chord need not be as 'wide' or as thick as the upper chord and in order to most advantageously employ the material .used it is Patented Aug. 29, 1950 UNITED 'TRUSSEND CONSTRUCTION Axel VrPedersen, Los Angeles; .Calif.

IApplication'July'3; 19 .17; Serial No. 758,757

- zfllaims.

.'This invention relates to improvements -'in truss end "constructions. The conventional wooden truss used in'the construction-ofbuildings'has a curved'upper chordimwhich-compression stresses are'developed and a' 'horizontal lower chord in'which tension-stresses are developed. Heretofore metal shoes have frequently been employed toforma connectionbetween the ends of the upper chord and the'ends of the lower chord. 'These"shoes, 'while satisfactory, have the objection that they'are-sometimes'difiicult to fit in transmitting the compressive stresses from the upper chord to the lowerchord so that the lower chord'may' properly perform its function of resisting spreading-of the ends of the upper chord.

In the manufacturingoftrusses'of this type the upper chord is usually made up of *laminations and there frequently is a considerableamount of scrap material available in cutting andposition- .ing the laminations of the upper chord so that they have staggered joints.

4 An object of the present invention is to provide an improved truss end constructionwhich is highly advantageous in that it enables a proper transfer of stresses'from the upper chord to the-lower. chord and which will enable the utilization of a substantial portion of lamination scrap that would otherwise be wasted.

Another object .of the invention .is'to provide a truss end construction which will enablea I'satisfa'ctory 'connectionlto be made between the lcurved upper. chord and the horizontal lower chord even. though the upper chord maybe ma- In. many desirable to have the. lower chord of smaller dimensions than the upper chord. Particularly Lis .Qthis. true where weight of the entireztruss is'an .impor.tantfactor. The improved truss end construction enables .the use of such chords and pro- "accompanyingdrawings'for' an illustrative embodiment of the invention. wherein:

Figure 1 isra view-in side elevation of the end of a. truss embodying the present invention;

Figs. land 3 are partialviews in elevation ;.taken substantially upon thlines'l 2--2.-.and 3--3,

respectively, upon Figffin the direc'tiondndicated; and

Fig.4 is a view side elevation of a modi fied or alternate form of construction embodyingtthe present invention.

Referring -to --the '-accompanying drawings wherein similar reference characters designate similar parts throughout, -10= indicates wthe end of a curved upper chord of a wooden truss. H indicates-the-end ofthe: horizontal: chord of the truss. Inaccordancewith-common practice the curved upper chord-i0 is made-uplofi-a seriesi'of wooden laminations that are glued together and which collectively .are .bent to. thezzdesired cur-.ve of-the upper chord. .The .lower. chord. l.l;.may;be but ordinarily is notlaminated. In thezcourse of constructionofi the tnusstherexfrequently .develops a. inumberaof 1shortopieces:of.laminations which heretofore have either been wastedior employedl inaa m'annerdzhat'is notzzparticularly useful. In. accordance cwithathe present. invention these laminations are, utilizedto provide the-con- :nection between the :endrofi ithe iuppenchord til andzthe endof thellowerrchordwl i. 1.111 so. doing the laminations. aretrimmed 2- along their-iaees so as itoibe.taperedzasindicatedaat 12. These tapered laminations cthen. have their abutting faces glued together; so-that thepglue planesor planes oi" adhesionibetween adjacent laminations .in effect; radiate from a center located at the inner section of the axis ofttheiendofthelower chord lllandthe axismfithe end-.-of the-.=upper chord iii. .'I!he uppermost .laminations indicated at I3 and which are disposed in planes substantially parallel to. the, end of. the upper-chord l0 needwnot be tapered .and,.preferably..havethe glue planes or. adhesion planestherbtween arranged substantially: parallel-to. the. axis, of-the end of the upper. chord. In. a similarmanner the-lowermost laminations Mneed not be tapered and may be arranged parallel to the length bf the horizontal chord H Whentheblock of. glue laminations is thus-prepared. itisready for assembly with .theends of the .upper and. lower chords. Anyformnf rconnectionb'etween this block and the end of the upper chord that is suitable for transmitting compressive stresses from the upper chord. to the blobk-maybeemployed and'likewiseany' formof connection suitable for transmitting tensionstresses between the bottom of'the block of .laminations and the end of the lower chord"! I may be employed. "In the preferredform oftcon'struction, howeverf-I preferto employ a wood joint of 'the typedis closed in my :copending application Serial No. 516,067, filed .December 29 11943; *nowabandoned,

whereinthe end'of theupper chord-"iflhas oppositely shaped" scarfs I5 and lt 'formewthereon, one above the other. The slopes of these scaris 3 are preferably less than 1:6 and usually are in the neighborhood of 1:10 or 1:12. In a similar manner the upper portion of the triangular laminated block is equipped with complementary scarfs indicated at I! and I8. The end of the lower chord H is similarly scarfed as indicated at [9 and 20 and complementary scarfs 2i and 22 are formed on the laminated block. These opposed mutually engaging scarfed faces on the chords and on the block are glued to each other thus completing the connection between the upper chord and the lower chord. noted that by this construction the glue planes or planes of adhesion between the laminations of the block gradually and progressively change in position from the horizontal, which is parallel to the horizontal bottom chord II, to a position parallel to the end of the upper chord l0. These glue planes or planes of adhesion are thus most advantageously arranged to transmit the shear developed in the block between the compressive upper chord l9 and the horizontal lower chord II which is under tension. Usually the ability of the adhesive to carry shear stresses is greater than that of the wood laminations itself but as u the wood laminations are relatively thin they are capable of carrying this shear stress under ordinary truss design if the thickness of the block is made equal to the thickness of the upper chord. lamination scraps to advantage but, by the arrangement of the glue planes, I may nicely and in a distributed manner transmit compression from the upper chord to the tensile lower chord H.

In many forms of truss design it is desirable to utilize a thinner lower chord I I than the upper chord IE and to this end the lower chord II is shown as being considerably thinner than the block of laminations l2 in Fig. 3. With this arrangement, one side of the lower chord is disposed fiush with one side of the laminated block and the scarfs cut on the laminated block to complement the scarfs on the end of thelower chord. At the end of the innermost scarf 29 on the lower chord the block may merely be shouldered as indicated at 23.

' In Fig. i there is disclosed an alternate form of construction wherein the lamination scraps have been tapered glued together to form a block generally indicated at 24 wherein the glue planes approximately radiate from a center at the intersection of the upper chord as extended with the lower chord as extended. In this form of construction any type of connection may be employed to transmit compressive stresses from the upper chord to the block, but a double scarfed wood joint as above described has been illustrated. The lower chord 28 has its top surface positioned directly against the bottom of the laminated block and glued directly thereto. In this form of construction it is not essential to use untapered laminations corresponding to those illustrated t I3 and M on Fig. 1. The stress developed in the block is transmitted directly to the lower chord through the glued surfaces at 21 and immediately above the lower chord the laminations of the block may start tapering immediately. While there is a slight departure of the uppermost glue planes of the block from being exactly parallel with'the end of the upper chord 25, this slight departure is ordinarily not of any great consequence. In both It will be In this way I am able to not only use forms of construction as illustrated, the glue planes between the laminations of the block are approximately parallel to the direction of shear in their respective locations.

It will be appreciated. from the above described construction that the improved truss end connection is quite versatile in that it optionally enables the upper and lower chords to be either of equal thickness or of unequal thickness. Furthermore, accurate fitting of parts as in the case of a metal shoe is not required.

In the conventional wooden truss construction the laminations of the upper and lower chords are made from boards wherein the grain runs lengthwise thereof and as the laminations l2 and 24 are usually prepared from scraps from these boards they will likewise have their grains running lengthwise thereof. The trimming of these scraps or pieces to taper them does not alter or affect their grain arrangement with relation to the lengths of the laminations. Consequently when the tapered laminations are stacked together the grains of the laminations will be running lengthwise substantially parallel to the glue planes between adjacent laminations.

Various changes may be made in the details of construction without departing from the spirit and scope of the invention as defined by the appended claims.

I claim:

1. A wooden truss having a horizontal lower chord and a curved upper chord, the ends of the chords being adjacent each other and arranged so that their axes if projected would intersect each other at an angle, a stack of tapered wooden laminations between the chord ends glued to each other and to the chords, said laminations having their grains running lengthwise thereof, the tapers of the laminations being substantially uniform toward the apex of said angle whereby the glue planes between adjacent ymr laminations progressively change from substantially horizontal near the end of the lower chord to an inclined position near the upper chord substantially parallel to the end of the upper chord.

2. A wooden truss having a horizontal lower chord and a curved upper chord, the ends of the chords being adjacent each other and arranged so that their axes if projected would intersect each other at an angle, a stack of tapered wooden laminations between the chord ends glued to each other and to the chords, said laminations having their grains running lengthwise thereof, the tapers of the laminations being substantially uniform toward the apex of said angle whereby the glue planes between adjacent laminations progressively change from substantially horizontal near the end of the lower chord to an inclined position near the upper chord substantially parallel to the end of the upper chord, each chord having a scarfed joint with the stack of laminations in the form of opposed scarfs on each the chord and lamination stack, which extend across a vertical plane through the stack.

AXEL V. PEDERSEN.

REFERENCES CITED The following references are of record in the file of this patent:

FOREIGN PATENTS Number Country Date 77,435 Austria Aug. 15, 1918 488,463 France Oct. 15, 1918