CA1130078A - I-beam truss structure - Google Patents

Abstract

Abstract of the Disclosure A wooden truss structure comprises upper and lower chords, each of which is grooved on the side facing the opposite chord. A web member formed of sheet material, such as plywood, interconnects the chords and fits within the chord grooves. At the web/groove interface, the webs are scalloped to provide alternating alignment guide areas and glue vent areas which extend above the interface and allow the escape of excess glue from the groove. The scalloping, in addition to venting the glue line, forms individual, pressurized glue pockets which assure even glue distribution.
The scalloping is preferably provided by pressing the wood web material to compress it at the glue vent areas and thus permit the web member, due to its memory, to expand after contact with the glue. This expansion pressurizes the glue pockets and forces glue from the joint area into the wood further enhancing the expansion process. The web is rigidly bonded to the chord members, all while being aligned by the alignment guide portion. This scalloping is effected along the lateral walls of the web at right angles to the longitudinal dimension of the web and consists of compressing the wood so that the impressions are deeper at their bottom than at their top.

Description

l~L3(~ 8 3821--CIP I--BE~I TP~USS STE~UCTUR~
Background of the Invention This invention relates to 700den-type truss s-~ructures ~7hich include upper and 10~7er wooden chords interconnecte~
by webs formed of wooden sheets. Both the chord members 5 and the we~s may either be solid wood members or composite -or laminated wooden members, as desired. Such truss structures have been constructed extensively in the prior art and are typically characterized by a pair of beams running parallel to one another or angled relative one 10 another to form a roof incline, with the webs spanning these chords in a plane intersecting both chord axes. As has been recognized by the prior art, the greatest difficulty encountered in the construction of such truss structures is the web/chord joint formed at the chord groove. Enough 15 of the ~Jeb cross-section must remain at the joint to prohibit sheer forces from rupturing the web member adjacent the chord. At the same time, howevex, the joint must provide substantial surface interface for gluing purposes~
In addition, it is preerabIe that these desirable objects 20 be accomplished without a requirement for long duration ~¦ clamping devices to maintain alignment of the structures ~ during curing of the adhesive used for their interconnection_ ;l In the prior art, it has been sho~n that it is possible to increase the surface area oE glue contact 2S by grooving the web member to provide mul-tiple grooved i¦ interconnections between the web member and each of the chords Such an attempted solution is sho~m, for example~
in U.S Patent ~rO7~/498t in U.S. Patent 3,991,535, and in U.S. Patent 3r960,637. Unfortunately, these attempted 30 solutions ~ubstantially increase the cost of fabrica~ion, since additional grooving and additional fittin~ of grooves, ~` all re~uiring close tolerance mill wor~, are required Of even more importance is the fact that increased surface area at the glue joint is provided only at the 35 expense of a lack of sheer strenyth at the web/chord interface, since the cross-section of the web is typically substdntially reduced by internal grooves near the p ~ ~3~78 interface, so that the structural integrity o the web itself is degraded.
Other solutions to the problem have suggested a S compression of the web at its edges and the placement of the compressed or tapered edges into tapered grooves to provide self-pressurizing joints as the wood, which has been previously compressed, expands in response to the glue's moisture. Unfortunately, this solution, as presented in U.S. Patent 3,490,188, for example, does not provide adequate venting for glue. Thus, if the ; groove in the chord is partially filled with glue, the web will often not compl~tely enter the groove, even under ! pressure, since the glue cannot be vented from the groove ! 15 during assembly. Furthermore, even if all of the glue is vented, it is unlikely, using the system of that patent, that the glue will be evenly vented to assure coating of all of the interface surfaces. Rather, the t~ glue tends to vent from portions having softer wood ~ 20 surfaces or indentations, finding a single path of least `~ resistance, so that much o~ the surface area may remain :`~2 uncoated and therefore not contribute to the structural ~ integrit~ of the joint.
- In the prior art, the edges of the web in above configurations, whether they were tapered edges or multiple grooved interconne~tions, have always been machined or compressed along the longitudinal dimension of the web. This was done because;such forming of the wood of the web was easier and it facilitated the handling of the workpiece.
In the prior art it has been thought necessary to use configurations, such as those described above, in order to pressurize and align the joint interface without external clamps. ~hus, it has been thought necessary to either risk the loss of sheer strength`at the joint or to risk poor adhesive coverage at the joint in order .

~,13~,,t~78 2a to bond the structure without clamps which remain in place during the assembly and curing processes~
Summa~ of the_Inven'tion The present invention, on the other hand, provides a web/chord inter~ace.for wooden composite beams which permits the entire web cross-section to remain intact at the joints in order to maintain the structural integrity of the web, while provi.ding adequate, distributed glue venting along the joint so that glue placed in the chord - groove will be uniformly vented and distributed, during assembly and thereby coat substantially the entire web/chord interface joint surface. At the same time, the venting apertures are preferably provided by pressing, rather than cutting the wood, so that, in response to the absorbed moisture of the adhesive used to provide the joint, the vents are slowly closed after assembly and automatically provide a pressure bond with the chord member.
Unlike the prior art, the venting apertures are formed at right angles to the longitudinal dimension of the web. The impressions are preferably deeper near their bottom than their top in order to provide, in cooperation with the tapered sides of the chord groove, even glue distribution over the entire web/chord interface. Furthermore, these vent areas extend above the top o~ the yroove to allow excess glue to escape the pressurized pockets formed when glue at the top of the vents dries, causing them to become sealed.
The expansion of the compressed wood causes pressure build-up in the vents driving even more glue into the wood.
Alternating with'the vent areas are'ali~nment surfaces which'are'formed at a different cross-sectional configuration than are'the vent areas~ These alignment surfaces provide'alignment and temporary attachment of the members during curing of the adhesive so that no long ~;3~(~7~3 durati~on clamps are required in manufacturIng the trusses.
Thus, clamping is required for initial assembly, but not during the longer duration glue setting time.
In accordance with a broad aspect, the invention relates to a we~-type wooden truss comprising:
a pair of spaced wooden chords each including a straight groove facing and in registration with the groove of the other chord, said grooves containing glue; and a web member having opposite edges fitting within said chord grooves, said edges ha~ing undulating cross-sections in a direction parallel to the length of said grooves to provide, in cooperation with said grooves, individual glue dispersion pockets which evenly distribute the glue in the web/chord interface, said edge cross-sections undulating between a more acutel~ tapered edge ha~ing a more acute taper than the taper of said grooves and a less acutely tapered edge having a less acute taper than the taper of said grooves.
In accordance with another broad aspect, the invention relates to a we~ type wooden truss, comprising:
a pair of spaced chords each having a groove which faces the groove of the other chord; and a web having opposite edges fitting within said grooves, each said edge having opposite scalloped sides which ~`~ are parallel to said grooves, and further having an undulating bottom, said sides and said bottom pro~iding, in cooperation with sa~d grooves, glue dispersion poc~ets.
In accordance with a further broad aspect, the invention relates to a web-type wooden truss, comprising:

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~13(~(~78 upper and lower chords, e.ach having a groove wh.ich faces and is aligned with the groove of the other chord;
a web having oppos~te edges fitting withln said grooves; and a laminated sheet member attached to the upper surface of said upper chord in a location separated from said groove, said sheet mem~er receiving roofing panels, said laminated sheet member distributing shear ~orces applied to said truss by said panels to prevent the splitting of said upper cAord.
In accordance ~ith a further broad aspect, the invention relates to a method of manufacturing a wooden truss, comprising the steps of:
grooving a chord member;
forming glue dispersion pockets on the sides of a web member near one edge thereof;
applying glue to the groove of said chord member;
inserting said edge into said groove to capture and evenly distribute said glue in said pockets;
venting excess glue from the web/chord interface;
and sealing said pockets.
In accordance with a further broad aspect, the invention relates to a web-type wooden truss comprising:
a pair of chords spaced apart from one another, each chord having a tapered groove facing and aligned with the groove of the other chord, said grooves containing glue;
a web extending between said ch.ords and having opposite`edges inserted into said groo~es;

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~13~ 78 pockets compressed on each side of said edges for distributing said glue over the edge~groove interface, said pockets increasing in depth toward said edges of said web and toward the pocket center to uniformly distri~ute said glue in said interface, said pockets providing a tapered edge which is more acute than the taper of said grooves.
These and other advantages of the present invention are. best understood through a reference to the drawings, in which:
Figure 1 is a perspecti~e view of a wooden composite trus~ which is constructed in accordance with the present invention;
Figure 2 is a perspective view., similar to Figure 1, showing a truss with discontinuous web members;
Figure 3 is a perspective view of the end portion of the web of the truss of Figure l;
Figure 4 is a broken-away perspecti~e view showing an enlarged portion along the edge of the web of Figure 3;
Figure 5 is a sectional view taken through ~he chord/web interface of Figure 1 at a vent location, the section location identified at line 5-5 in Figure 4, to show : the interrelationship of the memhers at this cross-section;
Figure 6 is a partial sectional view show~ng the ~dge of the web member of Figure 1 and the chord at an ali~nment surface ~ection, this section location identified at line 6-6 in ~igure 4, just prior to insertion of the web into the. sroove;
Figure 7 $s a view similar to that of Figure 5 ~ut sho~ing the reIations~ip at this point during assembly - 3b -of the vent section, line 7-7 of Figure 4, of the web edge;
Figure 8 is a schematic representation illustrating a first method and apparatus for scalloping the edge of t~e web member of Figure l;
Figure 9 is a schematic view sh.owing a second method and apparatus for scalloping the edge of the web member of Figure l;
Figure 10 is a schematic view sho~ing a third method and apparatus for scalloping the edge of the web member of Figure l;

11:3~078 Figure 11 is a broken-away perspective view, similar to Figure 4, showing an enlarged portion along the edge of a web wherein the vented areas overlap slightly;
Figure 12 is a perspective view, similar to Figure 11, showing an edge of a web that has vented areas on both its sides and bottom;
Figure 13 is a perspective view of an edge of a web which has horizontal and ver~ical corrugations for the venting and distribution of glue;
Figure 14 is a perspective view of an edge of a web having triangular impressions;
Figure 15 also illustrates in perspective a web with intersecting triangular impressions;
Figure 16 is a perspective view illustrating a web edge having triangu}ar impressions which intersect at least two other such impressions;
Figure 17 illustrates the edge of a web having interlocking, circular pockets at variable depths for glue ventilation and distribution; and Figure 18 illustrates in perspective a completed I-beam truss with a panel attached to the upper surface of the upper chord.
Detailed-Description of the:Preferred Embodiment : 25 Referring initially to Figure 1, a truss 11, constructed in accordance with the present invention, is shown to comprise an upper chord member 13 and a lower chord membor 15. In the form of the truss shown in Figure 1, the chords 13 and 15 extend in a parallel relationship to form the upper and lower flanges of an I-beam~ It will be understood by those ski~led in the art that if the truss 11 is to be used as a combination ceiling joist ana roof raftsr, the chord 13 may not extend parallel to the chord 15, so that a roof slope may be provided by the combined structure 11.

-1~3(~078 4a In the embodiment shown in Figure 1, each of the chords 13 and lS is formed of a solid piece of wood. In an illustrative example, these chords 13, lS may be formed of two-by-fours, with.the one and five-eights ~ .inch dimension extending in the combined plane of the chords 13, 15 and the three and five-eights inch dimension extending normal to that combined plane. The chords 13, 15 include grooves 17 and 19, respectively, which grooves are, in the preferred embodiment, centrally located on the wide face of the chords 13, 15 which face one another.
Thus, these grooves 17 and 19 are aligned to receive the opposite edges of a web member 21.

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~3~'078 Those skilled in the art ~7ill recogni~e the fact that the web member 21, sho~7n in Figure 1, may, if desired, compriSe a single length oE wooden shee-t so that no voids are left between the chords 13 and 15. AlternatiVely, the construction shown in Figure 2, in which webs 21 alternate with spaces 23 may be used. The configuration most practical I fox a yiven application ~Jill depend upon the sheer strength I necessary in the web portion of the composite beam. Except for the form o the web member 21, the truss structures of 10 Figures 1 and 2, as well as the design at the chord/web interace, to be described below, is identical.
The web members 21 are conveniently fabricated from p-ywood. Other thin wooden boards, of course, or fabricated wooaen sheets, may be subs~ituted, }ust as a laminated 15 structure may be substituted for the solid chord members 13 and 15.
The grooves 17 and 19 are slightly tapered, as will be described in more detail below. The grooves 17 and 19 receive opposing edges 25 and 27 o the ~Jeb mem~ers 21, 20 which edges 25,27 are scalloped. Those skilled in the art will recognize the fact that the overall structure of the i composite I-beam 11 is typical of those used in the prior ¦ art The invention, in this instance, is the manner of ! attaching the edges 2S,27 of the webs 21 withln the grooves i 25 17,19, respectivel~.
¦ . In many instances, it is pre~erable to block the ends of the truss 11 with vertical posts 28 ~7hich span bet~7een the chords 13,15. The posts 28 permit the ends of the truss 11 to be supported on a wall benea:th the chord 15, 30 with the posts 28 distributing a portion of the end shear load to the chord 13.
Referring to Figures 3 and 4, it can be seen that . both the upper and lower edges 25,27 of the t~7ebs 21 comprise a series of alternating scallops 29 and 35 interveniny planar areas 31. The scallops 29 are typically fonned by compressing the edges 25,27 bet~een rollers so that opposite sides of the web 21 at each ll3ao7s edge 25,27 are identically compressed. ~hus, as is best seen in Figure ~, the scallops 29A on one side of the edge 27 conform with opposing scallops 29B on the opposite face o~ the eage 27. As will be more completely described below, the opposing scallops 29A,29B form glue channels during assembly of the truss of Figure 1 which vent glue from the gxooves 17,19, ~` and spread glue uniforml~ to assure an adec~uate glue coverage of the entire joint area. In addition, these 10 opposing scallops 29A,29B provide an expanding surface when they react with the liquid in glues. This expansion is due to the wood's memory ~Jhich responds to moisture~
q'he expansion clamps the edges 25 and 27 within the grooves 17,19 of the chords 13 and 15 during the curing of the 15 glue 50 that the entire glue line is pressurized during curing o the glue.
, During assembly of the truss of Figure 1, and prior to expansion of the scalloped areas 29, the planar unscalloped areas 31 serve to align the edges 25,27 within the ;~ 20 grooves 17,19 o~ the chords 13,15, respectively, ana at the same ~time form outer perimeters for the individual glue pockets or channels formed by inclividual scallops 29 Thus, as the edge 27 of the web 21 is inserted into the groove 19, glue within the groove 19 will be foxced 25 under pressure away from the edge 27, channeled by the scallops 29A. Each scallop 29A will capture a small amount of glue and channel it to cover the sur~ace area of the scallop,~ with the unscalloped areas 31 acting as barriers to permit individual glue pressuriza~ion and 30 spreading within each of the scallops 29A.
This interrelationship bet~reen the scalloped eages 25,27 and the groo~7es 17,19 is best shown in PicJures 5, 6, and 7, ~7hich illustrate schematically the assembl~
process. Figure 5 is a section taken at the middle of 35 a scallop 29A,29B, alony line 5-5 of PicJure ~, after the edge 2;7 has been ful~y inserted into the ~roove 19. It ~
be seen that, prior to expansion of the wood fibers at t~e -- scallops 29, in reaction to the liquid in the glue, the , 1~3(~078 scallops 29 have a more acute taper than does the groove 19. Thus, the scallops 29A and 29B, in cooparation with the groove l~, form a plurality of thin glue channels, each of which distributes and vents a small amount of glue to provide an even distribution of glue on both sides of the edge 27. Furthermore, the taper of the scallops 29A and 29B can extend above the groove 19 so as to allow the escape of excess glue completely out of the web/chord interface. Figure 4 illustrates these scallops 29A
which extend above the top of the chord, indicated at line 77.
Figures 6 and 7 show sections through the planar areas 31 (line 6-6 of Figure 4) and scalloped areas 29 : 15 (line 7-7 of Figure 4), respectively, just prior to insertion of these sections into the groove 19. It will be seen that in a typical application, glue 33 is applied to the bottom of the groove 19. This glue 33 will be spread over the surfaces of the joint by pressure, which ; 20 ~ is generated;as the edge 27 is inserted into the groove 19. The planar area 31 will be a tight fit within tha tapered groove 19. Its width, however, is small enough, that is, the area~between adjoining scallops 29 is sufficiently narrow, that it will deform under the pressure usea to assemble the webs 21 with the chords 13 and 15.
~his compression will temporarily lock the members together and serve to accurately align the web 21 with the chords ~ 13 and 15. At the same time, glue cannot pass from one : scallop 29 to the next because of the tight fit between : 30 the planar area 31 and groove 19 of the joining members.
It will be seen, on the other hand, that, as illustrated in the section of Figures 5 and 7, there is space between the joining scallop portion 29 and the groove 19. ~his space is formed by the more acute taper of the scalloped portion 29; thus, it is widest at the bottom of the groove where the scalloped portion is compressed : ~ . : : .

ll3ao7s the most and therefore ultimately will accomodate the most glue thereby enhancing the expansion qualties of the wood at that location.
The taper of the scalloped portion 29 cooperates with groove 19 to form individual pockets in which ; the glue 33 is distributed. Distribution is caused by the pressure created by the advance of the edge 27 of the web 21 in the groove during insertion. The uniformity and symmetry of the pockets insures that the glue will be distributed evenly along the web/chord interface.
Referring to Figure 4, it will be noted that scallop~d portions 29 extend just above the top of the groove 19, indicated at 77, to allow excess glue to be forced out of the web/chord inter~ace by insertion pressure.
Venting of excess glue insures complete contact between the mating surfaces of the web and chord and further provides easy and efficient inspection of assembled trusses. That is, the completeness of the glue distribution 20~ in the web/chord interface, and ultimately the quality of the bond, can be easily determined by notiny whether beads o~ excess glue appear at the top portion of the scallop areas 29, above the groove 19.
As previously stated, the scallops 29 are formed by compressing the fiber o~ the edges 25, rather than by cutting away these edges. The glue 33 typically contains moisture which will react with the compressed fiber to activate the wood's memory, so that the wood in the scalloped areas 29 will expand and securely hold edges 25 and 27 within the grooves 29~ This expansion further assists in holding the assembled pieces 21, 13 and 15 together as the glue 33 sets, so that, once these members have been clamped together, they may be removed from the clamps and allowed to dry or cure. This ability to assemble the devices without clamping during the curing stage reduces substantially the amount of-equipment required to fabricate the truss of Figure 1. The initial ~ : ' ~13~078 self-clamping of the structure, even prior to expansion of the scalloped areas 29, is accomplished by the tight, compressed fit between the planar areas 3I and grooves 17, 19. This fit holds the parts together as the scalloped areas 29 expand to pressurize the glue joint. The same advantages apply to areas 31 of Figure ll wherein scalloped areas 29 overlap slightly. Although the planar area is fore-shortened, it nonetheless accomplishes ~ 10 its holding and alignment functions, whi~e further ¦ facilitating insertion of the web.
~ Thus, it can be seen that the scal~}oped areas 29 '~ cooperate with other members of the web and chord to perform several important functions. First, the compression of the wood of the edge 27 of the web at right angles to the longitudinal dimension of the web forms an accute taper which, in cooperation with the sides of the groove 19, allows distribution of the glue in a generally vertical direction to insure that the complete web/chord interface is coated with glue.
Secondly, the scalloped areas 29 define individual glue dispersion pockets, which are uniform and symmetrical, and which capture equal amounts of glue in order to evenly distribute~it along the length of the web. Similar}y, excess glue is vented from the web~chord inter~ace to insure complete contact between the mating surfaces of the web and chord. Furthermore, thè planer areas 31 between the scalloped areas 29 provide alignment and holding of the web in its proper position in the groove of the chord without the need for clamps, nails or other holding devices during the curing stage.
Finally, the scallops 29 also become individual pressurized pockets causing the compressed wood of the scallops to absorb even more`glue than under vented conditions. This condition oçcurs very simply in the assembly process. During assembly of the web to the chord, the pressure in the interface builds up only at the final stages of insertion when the bottom of the , ~
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~l3~l()78 web begins to displace the glue in the bottom of the groove and the planar areas 31 of Figure 11 Pnter the groove. The glue is then spread in a generally vertical direction over the face of th~ scallop portion 29, the taper of the scallop allowing the glue to rise to cover the complete face of the scallop. As the web reaches i the bottom of the groove, excess glue is vented out of the groove at the top of the scallop, however, no more 10 than an excess amount of glue is able to escape ~1 because the depth of the impression of the scallop 29 at its top is very narrow. Here at the top of the ~¦ scallop, wh~re the glue line is thinnest and exposed to air, the glue drys, sealing the scallop pocket. Glue l 15 in the pockets is absorbed into the compressed wood ¦ thereby stimulating the expansion of the impressions which J aauses pressure buildup in the pocket, driving still more glue into the wood. This extra glue driven into the wood of the scalloped areas 29 ènhances the expansion 20 of the same, forming a very tight bond in the interface I and insuring the complete mating of interface surfaces.
Therefore, this expansion characteristic of the mpressed areas of the scalloped portions 29, and the ,~ enhancement caused by individually pressurized pockets 25 ~ just described, provides a secure bond between the web and chord members.
Figure 8 shows schematically a method for scalloping the edge 27 of the web 21. In this case, a pair of forming rollers 37/ 39 are rotatably mounted on eccentric 30 axles 41 and 43, respectively, which axles are inclinea relative one another. This alignment o~ the axles 41, 43 forms the general taper of the scallops 29, while the eccentric placement of the axles 41, 43 pro~ides the scalloping action. ThuS, when the web 21 is in position 35 for scalloping and the rollers 37, 39 are in a first orientation, they do not touch the edge 27. In this ~ ... .. .

~13(.?078 orientation the planar areas 31 are provided. As the web 21 is moved in the'direction of the arrow 45, and the rollers 37 and 3g are rolled in the direction of the arrows 47 and 49, respectiveIy, the wider portions of the rollers 37 and 39 contact the edge 27 t~ form the scalloped indentations 29.
An alternative'forming tool is shown in Figure 9.
In this instance,' a pair of scalloped inclined rollers 51 and 53 are mounted on axles 55 and 57, respectively. The axles 55 and 57 are parallel to one another and are each concentric with their respective rollers 51, 53. In this instance, scalloping is formed by the shape of the outer periphery 5g and 61 of the rollers 51 and 53 respectively, as the web 21 is moved in the direction of the arrow 63.
A third alternative forming tool is shown in Figure 10.
In this case, four large gears 63, 65, 67 and 69 are mounted on inclined axles, so that the gear pair 63, 65 is inclined relative the gear pair 67, 69. These gears 63-69 are standard items, but'are used in pairs so that the gear 69, for example, forms interleaved scallops with ' ~ ~ those formed by the gear 67. This interleaving is necessary because of the spacing of the teeth on standard gears. The embodiment of Figure 10 permits a relatively inexpensive web scalloping fixture using of~-the-shelf components.
It will be seen that with any o~ the devices of Figures 8, 9, or lO, either the web 21 may be driven past the rollers or the rollers may be driven to draw the web 21 through the device. In either case, guides align the web 21 with the rollers to assure'that the'scallops 29 are formed at the proper depth. It should be noted that these devices compress the wood generally at right angles to the longitudinal dimension of the web, which is very different from the forming techniques of the prior art.

~.13(~078 After using these'forming devices, the webs 21 are pressed into the grooves 17, 19 in another fixture (not shown~ and then removed. After removal, and until the glue 33 sets, the interference fit of the planar areas 31 and grooves 17, 19 aligns and holds the assembled parts.
Using any of the'devices shown in Figures 8, 9 or 10, it wi}1 be apparent that the edge 27 of the web 21 is alternately compressed to form the scalloped areas 29 and ~ 10 left uncompressed to form the planar areas 31. The taper ¦ angle, in either case, is preferably adjusted so that, ¦ at the center of the scallops 29, the scallops have a more acute angle than the taper of the grooves 17 and 19, while at the planar portions 31, any taper angle is more obtuse than is the taper angle of the grooves 17 and 19. Thus, the advantages of this invention exist also in the case where the scallops 29 slightly overlap, as shown in Figure 11. In this case, the planar area is foreshortened, but still accomplishes its holding function.
Figure 12 depicts a web 21 having scalloped areas 29 along both the sides of lower edge 27, indicated at 29A and 29B,~ as~well as along the bottom, indicated at 29C. The scalloped areas 29C provide the same advantages as those along the lateral walls of the web by venting glue in the bottom of groove 19 along the bottom of the web. ~t the same time, they provide for the even ;~ distribution of glue along the bottom by acting as glue ~ ~ pockets. The uppermost portions of the scallops 29A and :
29B aan extend above the top of the chord, shown at 77, to allow venting of glue outside the web/chord interface.
Furthermore, if the scalloped areas 29C are formed by compressive techniques, the moisture of the glue will ~' stimulate the'expansion of these areas and securely bond the bottom of the'web to the'bottom of thè'groove. These areas may be formed utilizing methods similar to those illustrated in Figures 8 and 9, except that only a single roller device would'be're~uired instead of the opposed ~13G07B

pair as shown in thbse'drawings. It should be understood that the scalloped areas 29C can ~e used separately from or in conjunction with the areas 29A and 29B. If used in conjunction, however, alignment of areas 29C with areas 29A and 29B heIps to vent the glue from the bottom to the sides of the web 21. ' Those skilled in the art will recognize that the iembodiment shown in the figures is illustrative and that ¦lO the invention can be practiced, for example, by tapering, ¦to some extent, the portions shown as planar 31 is the drawings, so long as an undulating edge is formed to provide individual glue pockets which can separate and spread the glue at the glue line. Such undulation, ¦15 as previously described, also provides intervening areas ¦which orm barriers for the glue pockets and which serve ito align and hold together the assembled pieces during their initial assembly. All of this is accomplished while still providing a system which uses the natural ¦~20 memory of the compressed edge 27 to permit the scalloped areas 29 to expand in reaction to the glue and further t ~grip the grooves 17 and 19 to hold the assembled members together during curing of the glue.
As shown in Figure 13, the ventilation of glue along the sides of èdge 27 can be enhanc~d through the use of horizontal corrugations 71~ As with the embodiments of the present invention desaribed abave, these horizontal imPressions aid in the spreading of glue along the sides of the edge 27 of the web and result in a secure connection between the web and the chord. The embodiment shown in Figure 13 can be combined with vertical corrugations 73 ~^which serve to supply the longitudinal corrugations 71 with glue'from the'groove l9, and to vent glue from 'both grooves 71 and 73. As in previous embodiments -35 utilizing scallops,- the'vertical corrugation 73 can extend above'the'top of the chord, shown at 77, to vent glue from the web/chord interface.

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Figures 14, 15 and 16 illustrate three more embodiments of the present invention in which impressions in the side of the web are utilized to vent and evenly distribute glue from the groove'l9 to form a secure'and uniform bond along the entire'web/chord joint surface. Figure 14 ; illustrates sharply pointed impressions 75 in the lower edge 27 of the web which have the shape of longitudinal cross-sections taken through the'mid-point o a cone;
that is, they become deeper as they approach the zottom surface of the web.
Figure 15 shows similar cone shaped impressions 78 which overlap so that the portions of the web between them do not extend to the bottom surface. Like impressions 75, the impressions 78 are deeper as the bottom of the web is approached. This variation in the depth of impressions 75 and 78 allows the glue in the groove 19 to be distributed evenly withîn the web/chord interface. The portions of ' the web between both types of impressions are alignment areas 76 which allow the web to be properly positioned within the groove l9 of the chord so that the need for clamps or other fastening devices is elimQnated. As shown in Figures 14 and 15, the impres~sions 75 and 78 are sufficiently long to enable excess glue to be vented above the top of the web/chord interface, illustrated by line 77.
Figure 16 depicts a web in which imp~ession9 79 are angled with respect to one another 90 that they intersect two other such impressions along the side of the edge 27 of the web. The impressions 79 can either be conical, such as-those of Figures 14, 15 and 16, and therefore having a greater depth at the bottom of the web than at their tops or they can be uniform in depth (not shown). In either case, the impressions extend above ,~ the'we~/chord interface line 77 to allow venting of the glue'outside of the'groove 19.

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113(~(~78 Figure 17 illustrates an embodiment of the present invention in which circular pockets 83 are impressed into the side of the edge of the web to allow venting and distribution of the glue. These pockets interlock to allow distribution of glue from one to another and vary in depth, growing deeper as the bottom of the web is approached The uppermost impressions 85 extend above the web/chord interface line 77 to allow venting of the glue above the member into which the web is inserted.
The impressions of Figures 14, 15, 16 and 17 can all be formed in the edge 27 of the web utilizing the devices of Figures 8, 9 or 10 by simply changing the shape of I the faces of such devices.
! 15 Figure 18 shows a com leted I-beam truss structure in which the web 21 is inserted into grooves 17,19 in the upper and lower chords 13 and 15 according to one of the above-described web embodiments. Attached to the upper surface of the upper chord 17 is a panel 87. Where I-beams, , 20 such as the one shown in Figure 18, are used in roof systems having plural panels, such as plywood, fonming a flat deck, the nails which are used to attach the roof ; to the truss must be on very close centers, such as two inches, often causing the truss to split. In addition, 25 ~roof panels may join above the axis of the upper chord, so that the upper chord must transfer 9Uoh shear forces from one panel to another, and to the truss structure.
The thic~ness of the strips 87 lessens penetration of the nails into the chord of the truss and tends to reduce the possibility of splitting. In addition, the shear strength of the plywood 87 distributes the shear load from panel to panel, whether the panels are attached by nails or other means. These strips 87 can be attached to the upper chord 13 by any suitable means, such as gluing. The strips 87 themselves resist splitting because of the cross grains of the various layers of wood comprising the plywood.
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Claims (12)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A web-type wooden truss comprising:
a pair of spaced wooden chords each including a straight groove facing and in registration with the groove of the other chord, said grooves containing glue; and a web member having opposite edges fitting within said chord grooves, said edges having undulating cross-sections in a direction parallel to the length of said grooves to provide, in cooperation with said grooves, individual glue dispersion pockets which evenly distribute the glue in the web/chord interface, said edge cross-sections undu-lating between a more acutely tapered edge having a more acute taper than the taper of said grooves and a less acutely tapered edge having a less acute taper than the taper of said grooves.

2. A web-type wooden truss, as defined in claim 1, wherein said pockets are deeper adjacent the bottom of said groove than at the top of said groove, said pockets above said grooves to allow excess glue to escape to a location not under interface pressure.

3. A web-type wooden truss comprising:
a pair of chords spaced apart from one another, each chord having a tapered groove facing and aligned with the groove of the other chord, said grooves containing glue;
a web extending between said chords and having opposite edges inserted into said grooves;
pockets compressed on each side of said edges for distributing said glue over the edge/groove interface, said pockets increasing in depth toward said edges of said web and toward the pocket center to uniformly distribute said glue in said interface, said pockets providing a tapered edge which is more acute than the taper of said grooves.

4. A web type wooden truss according to claim 3 wherein the pockets on said sides comprise plural, interlocking dimples which are deeper as they approach said bottom.

5. The wooden truss of claim 4 wherein said pockets are wider adjacent said web edge than at the top of said groove.

6. The wooden truss of claim 4 wherein said pockets are separated by less-compressed areas.

7. The wooden truss of claim 6 wherein said pockets overlap.

8. A web-type wooden truss comprising:
a pair of chords spaced apart from one another, each chord having a tapered groove facing and aligned with the groove of the other chord, said grooves containing glue;
a web extending between said chords and having opposite edges inserted into said grooves; and pockets compressed on the sides of said edges for dis-tributing said glue, said pockets being compressed more at said web edges than at the top of said grooves to form a taper which is more acute than the taper of said grooves to provide means for confining glue for interaction with the web edge.

9. A web-type wooden truss comprising:
a pair of chords spaced apart from one another, each chord having a groove facing and aligned with the groove of the other chord, said grooves containing glue;
a web extending between said chords and having opposite edges inserted into said grooves to form an inter-face between the sides of said edges and the sides of said grooves; and compressions in said interface forming glue dispersion pockets, said pockets being compressed more adjacent the bottom of said grooves than at the top of said grooves to form a tapered pocket which is more acute than the taper of said interface.

10. A web-type wooden truss as defined in claim 9, additionally:
said pockets overlap at the bottom of said groove to permit the distribution of glue in a direction parallel to the length of said grooves, said pockets separated at the top of said groove by non-compressed areas to hold said web in said groove while said glue dries.

11. The wooden truss of claim 9 wherein said pockets extend above the top of said grooves to provide means for venting excess glue from said interface.

12. The wooden truss of claim 11 wherein said venting means is sealed by said excess glue when dried to permit pressurization of said pocket.