US 3416283 A
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Dec. 17, 1968 A. c. SANFORD COMBINATION WOOD AND METAL TRUSSES 3 Sheets-Sheet 1 INVENTOR. ARTHUR CAROL SANFORD ATTORNEYS 1968 A. c. SANFORD COMBINATION WOOD AND METAL TRUSSES 3 Sheets-Sheet Filed Nov.
v INVENTOR- ARTH R CAROL SANFORD ATTORNEYS Dec. 17, 1968 A. c. SANFORD COMBINATION WOOD AND METAL TRUSSES 3 Sheets-Sheet 15 Filed NOV. 5, 1966 /26 F I 6. l4
INVENTOR. ARTHUR CAROL SANFORD fl/8A FIG. /3
ATTORNEYS United States Patent 3,416,283 COMBINATION WOOD AND METAL TRUSSES Arthur Carol Sanford, 400 S. Ocean Blvd, Palm Beach, Fla. 33430 Filed Nov. 3, 1966, Ser. No. 591,788 11 Claims. (Cl. 52--693) ABSTRACT OF THE DISCLOSURE A truss having wooden chord members and metallic web or strut members therebetween having apertured load transfer end flanges abutting the chord members, said end flanges being secured to the chord members by overlying toothed connector plates of larger area than the end flanges, all of the teeth of said connector plates being embedded in said chord members, and a plurality of said teeth extending through and abuttingly intermeshing with the apertures in said end flanges to maintain said flanges against lateral movement relative to said connector plates.
Back rolmd 0 the invention The present invention relates generally to trusses. More particularly, the present invention relates to a combination of wooden and metallic members conjoined as a truss. Specifically, the present invention relates to a novel truss of combined wooden chord members and improved metallic web connectors.
Trusses are used a great deal in building construction for the support of roofs providing long, clear spans and frequently for supporting floors. In early construction practices wooden trusses predominated over their metallic counterparts. This was understandable inasmuch as wood was extremely plentiful and modestly priced. Moreover, skilled carpenters were available to assemble the wooden trusses on the job at low cost. As the price of labor increased the use of prefabricated trusses found favor, but for a long time prefabricated metal trusses found more favor than prefabricated wooden trussesparticularly because they were more readily adapted to mechanical fabrication techniques and because they provide an excellent strength to weight ratio. With the advent of metallic truss connector plates, one example of which is shown in my United States Patent No. 3,104,429, prefabricated peaked wood roof trusses became economically, as well as structurally, feasible. Floor trusses and flat roof trtrses, however, remained primarily metallic because to substitute an all wooden truss would require increasing the height of the building to accommodate the increased depth of the truss required when using all wooden members. Metallic trusses of this type thus prevailed even though furring or other wooden nailing strips often had to be applied on both the top and bottom to allow flooring and ceiling materials to be attached.
It is therefore a primary object of the present invention to provide a truss of combined metallic and wooden structural members which provides excellent spanning support with an economically feasible effective beam depth.
It is a further object of the present invention to provide a combination truss, as above, in which the chord members are wooden so that no separate nailing strips need be applied and in which the web members are metallic.
It is a still further object of the present invention to provide a combination truss, as above, in which the number, placement, and orientation of the web members can be custom located for the particular design loading conditions.
It is an even further object of the present invention to provide a combination truss, as above, in which the wooden chord members can be doubled, if desired, to meet heavy load requirements.
Summary of the invention These and other objects are accomplished by providing a truss having upper and lower wooden chord members in one plane with metal strut portions extending between the chord members and having perforate flat transfer end flanges abutting the sides of the chord members, said flanges being connected to said chord members by toothed connector plates of larger area which overlie said flanges, all of the teeth being embedded in said chord members, and some of said teeth passing through said perforate transfer flanges.
It is yet another object of the present invention to pro vide a combination truss, as above, which is economical to produce and which can be easily and efliciently assembled with the same apparatus used to apply connector plates to prior known wooden trusses.
These and other objects which will become apparent from the following specification are accomplished by means hereinafter described and claimed.
Three variations of the preferred embodiment are shown by way of example in the accompanying drawings and described in detail without attempting to show all of the various forms and modifications in which the invention might be embodied; the invention being measured by the appended claims and not by the details of the specification.
In the drawings:
FIG. 1 is a side elevation of a Warren truss constructed of a combination of wooden and metallic members according to the concept of the present invention;
FIG. 2 is an enlarged cross section taken substantially on line 22 of FIG. 1;
FIG. 3 is a partial side elevation taken substantially on line 33 of FIG. 2;
FIG. 4 depicts that portion of the web connector shown in FIG. 3, but obversely;
FIG. 5 depicts an alternative form for the strut portion of a web connector according to the present invention;
FIG. 6 is a further enlarged area of FIG. 3;
FIG. 7 is an even further enlarged cross section taken substantially on line 7-7 of FIG. 6;
FIG. 8 is a cross section taken substantially on line 8-8 of FIG. 7;
FIG. 9 is a cross section taken substantially on line 99 of FIG. 7 depicting a connector plate tooth in elevation;
FIG. 10 is a cross section taken substantially on line 1010 of FIG. 7 depicting a tooth opposed to that shown in FIG. 9 but punched from the same opening;
FIG. 11 is a plan view' depicting the relationship of the two teeth to be punched from a single opening;
FIG. 12 depicts a variation of a truss constructed according to the concept of the present invention utilizing double wooden chord members with a variation in the construction of the web connector;
FIG. 13 is an enlarged cross section taken substantially On line 1313 of FIG. 12;
FIG. 14 is an enlarged area of FIG. 12 with the wooden chord members removed to show the interengagement of two metallic web members with a sandwich type con nector plate; and
FIG. 15 is a cross section taken substantially on line 1515 of FIG. 14.
The members which form the outline or perimeter of a truss are generally called the chord members, or simply chords. The interior members connecting between the chords are called the web members, or, commonly, the diagonals or verticals, depending upon their direction in the Web system.
In the art an exterior type connector plate is used to connect wooden structural members that are joined in abutting relation and a sandwich type connector plate is used to connect wooden structural members that are joined in overlapping relation. The concept of the present invention employs either type connector plate.
In general, a truss constructed according to the concept of the present invention utilizes wooden chord members and metallic web members. The metallic web members not only supply the normal function of resisting the tensile and compressive forces between chord members but also, as web connectors, impart the necessary unity to the truss.
Each web connector has a strut portion extending between the chord members and a load transfer flange at each end of the strut portion. The load transfer flanges are secured to the chord members by tooth means such as exterior connector plates. Preferably, the load transfer flange has a plurality of apertures through which at least a portion of the teeth on a connector plate are insertably received. The connector plate teeth abuttingly intermesh with the side walls of the apertures so that the load transfer flange not only lies snugly between the body portion of the connector plate and the wooden chord member in which the connector plate teeth are embedded but also is maintained against lateral movement with respect to both the body portion of the connector plate and the chord member.
Additionally a truss constructed according to the concept of the present invention may utilize chord members consisting of, parallel, adjacent wooden structural members. In this variation a sandwich connector plate is readily utilized.
Referring more particularly to the drawings, a combination truss according to the present invention is designated generally by the numeral in FIG. 1. The upper chord member 11 and lower chord member 12 are generally parallel and interconnected with diagonal web connectors 13A, 13B, 13C to present a general Warren truss arrangement supported between bearing walls 14 and 15. Although a Warren truss arrangement has been disclosed, it should be understood that those skilled in the art will be readily able to adapt the present concept to a host of truss configurations.
The chord members 11 and 12 are of wood, and the web connectors 13A, 13B are of metal. As best seen in FIGS. 2-6, the web connectors 13 each have a strut portion 16, each end of which terminates in a load transfer flange 18 and 19. Typical examples of suitable web connectors 13 are depicted in FIGS. 4 and 5. In FIG. 4 the strut portion 16 is depicted as being of channel-shaped across section with the load transfer flange 18 being, in part, an extension of the base 20 of the channel-shaped section. The legs 21 and 22 of strut portion 16 may be formed, through transitional contortions 23 and 24, respectively, to lie in the same plane as the base 20 at the ends of the web connector 13 and thereby complete the load transfer flange 18.
Another form of web connector 113, as disclosed in FIG. 5, also has a strut portion 116 but it is of tubular cross section, and the ends are simply flattened to form the load transfer flange 118.
While the channel-shaped and tubular cross sections for the strut portion of the web connect-or 13 have been found to be quite satisfactory, those skilled in the art who have acquired an understanding of the present invention will be able to design other satisfactory cross sections to satisfy their aesthetic and structural needs. However, irrespective of the particular cross section utilized in the strut portion 16 of the web connector 13, the load transfer flange will be provided with a plurality of perforations, or apertures, 25. The exact shape of the apertures 25 is not critical so long as they intermesh with the teeth means sufl'iciently to maintain the load transfer flange 18 fixed with respect to the chord member to which it is secured.
The tooth means is preferably a toothed exterior connector plate, such as is indicated generally by the numeral 26. The exact configuration of the connector plate 26 is not critical, but a construction which performs extremely Well has a plurality of teeth 28 which are struck, or punched, from the body portion 29 of the plate in opposed pairs. As can best be seen in FIG. 7, each tooth 28 has a thickness generally equal to the thickness of the plate because it was struck therefrom, and, as best seen in FIGS. 9 and 10, each tooth has a base portion 30 the edges 31 and 32 of which are generally parallel and extend generally perpendicularly outwardly from the body portion 29 of the plate 26. Each tooth also has a tip portion 33 of lesser width than the base portion 30 which is formed integrally outwardly thereof with one edge 31A being preferably a continuation of the edge 31 of base portion 30. The opposite edge 34 of the tip portion 33 is preferably parallel to edges 31 and 31A but is spaced more closely thereto than the corresponding edge 32 of the base portion 30. The edges 32 and 34 are joined by an inclined transitional shoulder 35.
The preferred proportions of this tooth can also best be seen in FIGS. 9 and 10. The width of the base portion 30 is approximatly one-third the length of the tooth 28,
with the length of the base portion 30 being approximately one-half the length of the tooth. The length of the base portion includes the length of the transitional shoulder 35 which is approximately one-sixth the length of the tooth, and the width of the tip portion 33 is approximately onehalf the width of the base portion 30.
Applying these preferred proportions to obtain the dimensions for a typical of an inch long tooth, the base portion 30 would be approximately of an inch wide and V of an inch long, of which the transitional shoulder 35 would extend approximately i of an inch. The width of the tip portion 33 would also be approximately of an inch.
These teeth are preferably punched in pairs from openings 36 which are longitudinally aligned and laterally staggered so that lateral alignment occurs between alternate rows. The die by which the teeth are punched causes the opposed teeth 28A and 28B in each pair to separate along a cleavage line 38 (FIG. 11) inclined to the axis 39 of the longitudinal alignment of the openings 36 so that the teeth present a point 40 at the outermost extent of the tip portion 33. And, as the teeth are punched the metal tends to draw as it separates along cleavage line 38, thus sharpening the tip of the tooth.
As the teeth are struck from the opening 36 the punching die also bends each tooth so that there is a slight rearward arching of each tooth about its base portion 30 so that the tip portion 33 is inclined away from the opening 36 from which the tooth was struck in the direction of their longitudinal alignment.
The punching die also crimps, or dishes, each tooth 28 so that the outer surface 41 of the base portion 30' is generally arcuate. The dishing is along a crimp line 42 which is slightly inclined with respect to the outwardly extending direction of the tooth so that the tooth is contorted into a gentle twist about the crimp line 42. It has been found desirable to incline the crimp line toward the side 31A of the tooth 28A on one side of opening 36 (FIG. 9) and toward the transitional shoulder 35 of the tooth 283 on the other side of opening 36 (FIG. 10) so that the teeth will be complementarily twisted as can be seen in FIG. 4.
Teeth having the particular configuration described above have been found to possess superb holding power and easy insertability and yet can be economically produced.
As pointed out above the exact shape of the apertures 25 is not critical so long as the position of the load transfer flange 18 is maintained with respect to the chord member and the connector plate 26. For example, the aperture could be constructed so that the abutment of the side walls of the apertures with the edges 31 and 32 of the base portion 30 of each tooth maintains the flange 18 against movement laterally of the longitudinal alignment of opening 36. Further, the outer arcuate surfaces 41 of the base portion 30 on opposed teeth 28A and 28B can abut the opposed end walls of the apertures so as to maintain the load transfer flange 18 against movement parallel to the longitudinal alignment of openings 31. With the teeth 28 maintaining the connector .plate 26 against movement with respect to the cord member into which the teeth are embedded, the flange 18 is also thereby maintained against movement relative to the chord member.
By using circular apertures 25 having a diameter substantially equal to the span of the base portion 30 of each tooth 28, the engagement of the edges 31 and 32 with diametrically opposed surfaces of apertures 25 thereby maintains the load transfer flange against both lateral and longitudinal movement with respect to the connector plate 26.
It should also be noted that it is not necessary for the load transfer flange 18 to be coextensive with the connector plate 26. For example, tests have been made using 20 gauge metal for both the load transfer flange 18 and the connector plate 26 and, with the exemplary teeth described above, the connector plate 26 was found to develop between 350 to 400 pounds of holding power per square inch of plate area. At the "same time, the load transfer flange 18 could be loaded as high as 1000 pounds per square inch of perforated area in contact with the connector plate without initiating premature failure in the holding power of the teeth 28 or destruction of the wooden member. Hence, the use of a load transfer flange 18 having approximately three-eighths the area of the connector plate 26 has been found to be quite satisfactory in distributing the stress in the web connector 13 to the chord members 11 or 12.
However, by using a connector plate 26' of relatively larger area, at least on the side portions of the wooden members which rest on the 'bearing walls 14 or 15, the wooden member is thereby armored both to provide greater resistance against crushing and to increase the horizontal shear strength thereof.
Incidentally, the holding power of the teeth 28 which intermeshingly engage the apertures 25 has been found to be increased over those which directly penetrate the wood-the flange 1'8 apparently reinforcing the teeth against bending and thereby increasing their holding power.
With the use of web connectors 13 embodying the concept of the present invention they may economically be placed as needed. For example, in a truss designed in accordance with that shown in FIG. 1 to support a uniform load it is well known that the diagonal web members adjacent the bearing walls 14 and 15 are subjected to the greatest stress, the stress on the diagonal web member successively toward the center of the truss span being less and less. Thus, the engineer computing the design for such a truss may require that two web connectors 13A and 13A be used for the first diagonal but one be used for the diagonals more remote from the support.
Similarly, space limitations and loading requirements may require that one or both chord members 11 and 12 be doublers rather than a single member of deeper cross section. Such a combination truss 110 is shown in FIGS. 12-15. The lower chord member 112 is comprised of two wooden members 112A and 112B positioned in parallel, side-by-side relation. The exemplary web connectors 113A and 113B depicted may both be anchored between the chord members 112A and 112B by a single sandwich type connector plate 126, best seen in FIGS. 14 and 15, with the flange 118A lying on one side of body portion 129 and the flange 118B lying on the other side.
While the pattern in which the teeth extend outwardly from one side or the other of the plate may be countlessly varied to produce a sandwich type connector plate, convenience suggests that the pattern be such that any web connector 113 be capable of being attached to either side of body portion 129 without the use of excessive apertures through the load transfer flange 118.
One very effective tooth pattern results by having the openings 136 from which the teeth 128 are punched aligned both longitudinally and laterally. The individual teeth 128 may be of exactly the same configuration as the teeth 28 on the exterior plate 26 and may also be punched as opposed pairs from a single opening. With such an arrangement the teeth may be punched from laterally adjacent rows to extend alternately from one or the other side of the body portion 129, the teeth punched from the openings in any longitudinal row extending from only one side of the body portion 129. Apertures 125 need, therefore, only to be provided for intermeshing with teeth 128 punched from every other longitudinal row of openings 136 and the web connector 113 may be secured by placing the load transfer flange 118 on either side of the body portion 129 with the strut portion 116 diagonally oriented either to the left or to the right of the location of the load transfer flange 118.
In order that the successive web connectors 113A, 113B, 113C need not be required to 'be translated along their own axes the distance necessary to accommodate the alternate positioning of teeth on opposite sides of the plate 126 additional alternate longitudinal rows of apertures 125 may be provided in flange 118, as shown. In that way one series of alternate rows will be used on one side of plate 126 and the second series of alternate rows of apertures 125 will be used on the other side without the necessity of translating the successive web connectors 113.
It should also be noted that when doubler chord members, such as 112, are used, it may be desirable to use additional sandwich plates 126 between the location of the load transfer flanges to assure further integrity of the members 112A and 112B into a single working member. And, particularly with a doubler top and bottom chord 111 and 112, respectively, it may also be advantageous to use one or more additional web connectors 13 mounted with exterior connector plates 26 in those locations where the web members are subjected to the greatest stress, as is shown in the variation depicted in FIGS. 1 and 2.
It should now be apparent that the use of metallic Web connectors in combination with wooden chord members is capable of providing an economically feasible truss in which the chord members are themselves nailing strips and the members may be arranged in standard or custom truss arrangements and assembled with the same apparatus heretofore used to apply metallic connector plates to wooden trusses. The objects of the invention have thus been accomplished.
What is claimed is:
1. A combination truss comprising wooden chord members and metallic web connectors, said web connectors each having a strut portion extending between said chord members and a load transfer flange at each end of said strut portion abutting the chord members, tooth means connecting said load transfer flange portions to said chord members, at least one of said chord members comprising parallel, side-by-side, wooden members, and the tooth means comprising a toothed sandwich connector plate between said chord members having a plurality of teeth extending outwardly in opposite directions into said side-by-side chord members, at least a portion of the teeth extending in one direction passing through the apertures in the load transfer flange.
2. A combination truss, as set forth in claim 1, in which at least two web connectors are secured to said parallel wooden members by one said sandwich connector plate.
3. A combination truss, as set forth in claim 2, in Which the apertures through the load transfer flange for one of said web connectors are abuttingly intermeshed with at least a portion of the teeth on one side of said sandwich connector plate and the apertures through the load transfer flange on the other web connector are abuttingly intermeshed with at least a portion of the teeth on the other side of said sandwich connector plate.
4. A combination truss, as set forth in claim 3, in which the apertures through the load transfer flange on each web connection and the teeth on each side of said sandwich connector plate are oriented in a pattern whereby said load transfer flanges can he secured by the teeth on either side of said connector plate body portion.
5. A combination truss, as set forth in claim 3, in which sandwich connector plates in addition to those securing web connectors are used to unify the parallel wooden chord members.
6. A combination truss comprising wooden chord members and web connectors, at least selected web members carrying tensile loads having a metallic strut portion and metallic load transfer flanges at the ends contacting the chord members and having a plurality of apertures, and toothed connector plates overlying said load transfer flanges and having a plurality of teeth extending through said apertures into said chord members, the toothed area of said connector plates being greater than the area of said load transfer flanges.
7. A combination truss as defined in claim 6, in which the teeth and the apertures abuttingly intermesh to main: tain the load transfer flanges against lateral movement with respect to the body portion of said connector plates.
8. A combination truss as defined in claim 6, in which; the metallic strut portions have a channel-shaped cross section.
9. A combination truss as defined in claim 6, in which the metallic strut portions have a tubular cross section.
10. A combination truss as defined in claim 6, in which connector plates are applied to both sides of a chord member in proximity to the bearing rest thereof to resist crushing of said chord member.
11. A combination truss comprising wooden chord members and web connectors, at least selected web memhers carrying tensile loads having a metallic strut portion and metallic load transfer flanges at the ends contacting the chord members and having a plurality of apertures, and toothed connector plates overlying said load transfer flanges and having a plurality of teeth embedded in said chord members, some of said teeth ex tending through said apertures into said chord members, the toothed area of said connector plates being greater than the area of said load transfer flanges.
References Cited UNITED STATES PATENTS 1,438,575 12/ 1922 Brown 85-13 3,025,577 3/1962 Jureit 85-13 X 3,172,171 3/1965 Knight 85-13 3,211,043 10/ 1965 Sanford 85-13 3,292,481 12/ 1966 Couch.
3,298,151 1/1967 Jureit 85-13 3,304,106 2/1967 McCormack 85-13 3,336,706 8/ 1967 Troutner 52-693 X FOREIGN PATENTS 1,199,914 6/1959 France.
FRANCIS K. ZUGEL, Primary Examiner.
US. Cl. X.R. 85-13