US3490188A

US3490188A - Web-type wooden truss with pressurized,adhesive joints

Info

Publication number: US3490188A
Application number: US693524A
Authority: US
Inventors: Arthur L Troutner
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-12-26
Filing date: 1967-12-26
Publication date: 1970-01-20
Anticipated expiration: 1987-01-20

Description

Jan. 20, 1970 A. L. TROUTNER 3,490,188

WEB'TYPE WOODEN TRUSS WITH PRESSURIZED, ADHESIVE JOINTS Filed Dec. 26, 1967 A0 INVENTOR.

ARTHUR L. TROUTNER BY e4? ATTY.

United States Patent 3,490,188 WEB-TYPE WOODEN TRUSS WITH PRESSURIZED,

ADHESIVE JOINTS Arthur L. Troutner, 9777 Chinden Blvd., Boise, Idaho 83700 Filed Dec. 26, 1967, Ser. No. 693,524 Int. Cl. E04c 3/42; E04b 1/54 U.S. Cl. 52-644 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to web-type wooden trusses and to a no clamp method for their fabrication.

Web-type wooden structural trusses comprising upper and lower chords and an interconnecting web member may be provided in two configurations, each of which has important applications. In one, which may be termed a panel beam, the web member is formed in a plurality of sections or interconnecting members which are separated at spaced intervals by transverse struts. In the other, known as a :bowstring truss, the upper chord is bowed and the web member comprises a plurality of sections or interconnecting members arranged at spaced intervals and provided in sufficient size, number and contour to carry the design load and impart to the truss the desired design appearance. In both cases the conventional construction technique requires gluing the components together, using nails or clamps to hold pressure on the glue lines of the components while the glue sets.

It is the general purpose of the present invention to provide a method for fabricating web-type wooden trusses of the classes described above which method may be effectuated rapidly, efficiently and without the use of nails or clamps to hold pressure on the glue lines during the gluing operation.

It is another object of this invention to provide a method for fabricating web-type wooden trusses which leads to the production of trusses of exceptional stability against shear, web-crippling and lateral chord rotation.

Still a further object of the invention is the provision of a method of fabricating web-type wooden trusses which may-be applied to the manufacture of trusses having a variety of structural applications and diverse design configurations.

The manner in which the foregoing and other objects of this invention are accomplished will be apparent from the accompanying specification and claims considered together with the drawings, wherein:

FIG. 1 is a fragmentary view in section illustrating a web component employed in the fabrication of the herein described truss,

FIGS. 2 and 3 are exploded and assembled views, respectively, of the truss in one of its embodiments,

FIGS. 4 and 5 are transverse sectional views taken along lines 44 and 5-5 of FIG. 3,

FIG. 6 is a view in side elevation of the truss of the invention in a second embodiment,

FIG. 7 is an end view of the truss of FIG. 6,

3,490,188 Patented Jan. 20, 1970 FIG. 8 is a fragmentary view in side elevation of the end portion of the truss in still another embodiment; and

FIG. 9 is an end elevation of the truss of FIG. 8.

The method of fabricating the presently described wood trusses takes advantage of the fact that wood, when compressed, has a memory and seeks to return to its Origina configuration, particularly after having been moistened With water or a suitable solvent. Thus if the framing components of the truss are grooved with tapered grooves, and the margins of the web components of the trussare compressed to provide beveled tongues of conforming contour, upon applying liquid glue to the tongues or grooves and assembling the components by wedging the tongues into the grooves, the liquid present in the glue will cause the tongues to swell. This pressures the glue interfaces between the components sufiiciently to interlock them while the glue sets, thereby eliminating the necessity of employing extraneous clamping fasteners or clamps.

The foregoing principle may be employed in the fabrication of the paneled type trusses (panel beams) illustrated in FIGS. 1-5 inclusive.

Each of the trusses includes an upper chord 10, a lower chord 12 and an interconnecting web or interconnecting member 14. It also may include a plurality of struts 16 which span the transverse intervals between the chords. In the truss of FIGS. 2 and 3 there are a plurality of interconnecting members disposed longitudinally of said chords, that is, one member 14 is positioned after another member 14 along the longitudinal dimension of the chords. The interconnecting members 14 in these figures are also disposed longitudinally at spaced intervals and the struts 16 span said intervals,

Upper and lower chords, 10, 12 may comprise 2 x 4s or other suitable wooden structural members of the desired length. They are arranged opposite each other and are provided with registering, inwardly tapered grooves 18, 20 respectively. The grooves are formed in the opposed faces of the chords and preferably extend the entire length thereof.

Struts 16 likewise comprise 2 x 4s or other wooden structural components of suitable size and shape. They have a length equal to the distance separating the chords and preferably extend substantially at right angles thereto. Their opposite side faces are grooved to form tapered grooves 2.1, FIG. 5.

It is to be noted that struts 16 are multiple purpose members. They act as web splices and will transmit shear. They act as stiffeners against web crippling. Still further, they act as stabilizers of the chord members against rotation.

Webs or interconnecting members 14 comprise plywood, lumber or composition board panels characterized by the capacity for fiber compression along their various margins. Their size is such as to span the distance between the chords and the struts.

When manufactured, their side edges are square as indicated in broken outline in FIG. 1. However, to adapt them to the present purpose, selected margins are compressed by the application of dies of suitable contour and angle. This forms wedge-shaped tongues 22 having an angle conforming to the angle of bevel of grooves 18, 20 in the chords and grooves 21 in the struts. The angle of taper of the compressed tongues is somewhat variable, depending upon the particular application, the identity of the wood, the type of glue to be applied, the manufacturing procedure to be applied. etc.

Since the side edges were square before compression, it will be apparent that the tongues have been compressed more at their outer extremities (narrow portions) than inwardly thereof (wider portions). Therefore, when the tongues have been placed into the grooves and the tongues have been swelled by the liquid in the glue, there will be a greater wedging pressure at the outer extremities of the tongues than inwardly therefrom.

In general, however, the taper should provide a sufii cient degree of wood compression so that the desired degree of swelling will occur upon application of the liquid glue. However, too great a taper should be avoided since this would result in overcompression with resultant crushing of the wood fibers. It also would result in providing a tongue so blunt as to be unsuitable for use in assembling the trusses.

' As shown in FIG. 1, a satisfactory angle a of taper for the compressed tongues, as well as for the grooves in the chords and struts, lies within the range of from 2-30, preferably 5-15 with reference to the plane of the webs.

-The glues which may be employed in the practice of the present method comprise any liquid glues containing Water or a solvent which will activate the memory of compressed wood. Particularly contemplated are the aqueoils phenolic, urea, resorcinol, epoxy and casein glues employed in the woodworking industry.

' The glue is applied to either the compressed tongues or to the grooves in amount sufiicient to form glue interfaces 24, 25 between the webs and chords and glue interfaces between the webs and struts.

gThe construction of the bowstring type truss illustrated in FIGS. 6-9 is similar.

1 The truss comprises an upper chord 30 which is bowed and a lower chord 32 which is straight. The opposed faces of the chords are provided with tapered grooves in the manner previously described.

A plurality of Webs or interconnecting

members

36, 38, 4t) interconnect the chords at longitudinally spaced intervals. The upper and lower margins of the webs are tapered by] compression to an angle of from 2-30, preferably from 5-15", with reference to the plane of the webs, confogning in this angle to the angle of the grooves. Their upper margins are sloped to conform to the contour of upper chord 30.

lieu of end web members 36, the uncompressed blocks 44 of FIGS. 8 and 9 optionally may be employed.

'The webs are spaced non-continuously in sufficient size and number to carry the design loads, thus facilitating construction and reducing the amount of material normally required.

The manner of assembly of either type of truss is shown schematically in FIG. 2. After the adhesive or glue has been applied, the components are placed in proper relation to each other and pressed together in a suitable assembly jig. Immediately after it has been assembled, the truss is removed from the jig and allowed to cure without the ,application of additional pressure from clamps or mechanical fasteners such as nails. The swelling of the compressed wooden tongues, induced by the application of the liquid component of the glue, pressures the glue interfaces sufficiently to maintain pressure on the glue lines} pending setting of the glue. In this manner there is provided a truss of simple construction which may be manufactured rapidly and inexpensively using a minimum of equipment and personnel. In addition, in its application the truss has superior stability against shear, Web crippling and lateral chord rotation.

Itis to be understood that the forms of my invention herein shown and described are to be taken as illustrative examples of the same and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of my invention or the scope of the subjoined claims.

Having thus described my invention, I claim:

1. A web-type wooden truss comprising a pair of spaced oppositely arranged wooden chords having registering tapered straight grooves in the opposed faces thereof,

(a) at least one straight wooden interconnecting member having compressed tongues on opposite margins, said tongues having a taper substantially conforming to the taper of the grooves in the chords, whereby a higher degree of compression occurs along the outer extremities than inwardly thereof,

(b) the tongues being wedgedly disposed into the grooves of the chords and adhesively united thereto,

(c) the compressed tapered tongues, the wood memory and the adhesive-induced swelling imparting a wedging pressure between the tongues and the chords greater at the outer extremities of said tongues than inwardly therefrom.

2. A web-type wooden truss according to claim 1, wherein there are a plurality of interconnecting members disposed longitudinally of said chords.

3. A web-type wooden truss according to claim 2, wherein said interconnecting members are disposed at longitudinally spaced intervals.

4. A web-type wooden truss according to claim 3, including a plurality of struts interposed transversely between the chords in said longitudinally spaced intervals, said struts having straight tapered grooves in their opposite faces, the edges of said interconnecting members facing said struts having compressed tongues having a taper substantially conforming to the taper of the grooves in the struts, said tongues being wedgedly disposed into the grooves of said struts and adhesively united thereto, the wedging pressure between said tongues and said struts being greater at the outer extremities of said tongues than inwardly therefrom.

5. The truss of claim 1 wherein the taper of the compressed tongues is from 230 with reference to the plane of the webs.

6. The truss of claim I wherein the taper of the compressed tongues is from 5-15 with reference to the plane of the webs.

References Cited UNITED STATES PATENTS 2,825,099 3/ 8- Simmons 52627 917,433 4/ 1909 Hofheimer 1443 14 1,377,891 5/ 1921 Knight 52729 1,759,057 5/1930 Meem 52-729 2,263,198 11/1941 Valiton 144327 3,079,649 3/ 1963 Willatts 52727 3,324,908 6/1967 Blanco 144-3 l3 FOREIGN PATENTS 691,335 1964 Canada.

397,513 1933 Great Britain.

140,019 1953 Switzerland.

HENRY C. SUTHERLAND, Primary Examiner US. Cl. X,R,