US3286429A - Composite wood-metal structural member - Google Patents

Description

Nov. 22, 1966 D. RATLIFF, JR 3,286,429

COMPOSITE WOOD-METAL STRUCTURAL MEMBER Filed Sept. 9, 1963 INVENTOR. GEORGE D. RATL/FF, JR.

@ Attorney United States Patent ce 3286429 Patented Nov. 22, 1966 3 286 429 attachment. After clinching, the spurs retain a degree of 9 flexibility so that panel 13 is not rigidly attached to the COMPOSITE STRUCTURAL top chord but with slight limited freedom to come and George D. Ratlifi, Jr., Churchill Borough, Allegheny County, Pa., assignor to United States Steel Corporation, a corporation of Delaware Filed Sept. 9, 1963, Ser. No. 307,403 1 Claim. (Cl. 52-727) This invention relates to a composite beam and, in particular, to a composite beam having connections between its top chord member and web which are slightly flexible so as to allow full stressing of the web material under load.

Composite beams of various types are known. All those with which I am familiar utilize rigid connections between the several members. Thus, where the members are of different materials, certain of them are not fully stressed under load. That is to say, the load is carried largely by stress principally in one member and the use of material is not very eflicient.

I have found that, by using connections between the members of a composite beam which are somewhat flexible the web is stressed more fully than would be the case were the connections rigid. In a typical example, to be described in detail, a beam web of wood incorporating my invention is stressed, under a given load, to almost double the value at which it would be stressed under the same load, using conventional rigid connections.

A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawings illustrating the present preferred embodiment. In the drawings:

FIGURE 1 is an elevation of my beam with a part broken away; and

FIGURE 2 is an enlarged partial perspective similarly broken away.

Referring now in detail to the drawings, beam 10 there shown as an example of my invention comprises a top chord 11, a bottom chord 12 spaced therefrom and a web panel 13 extending between the chords and secured thereto. One or more struts 14 may be incorporated, connecting the chords 11 and 12. The beam is supported in any suitable manner, as by studs 15.

As shown in FIGURE 2, top chord 11 is a structural member such as a Z formed from sheet steel. Studs are similar. Bottom chord 12 is a wood stringer and panel 13 is of plywood. Strut 14 is also of wood. The panel fits flush against the flanges of chord 11 and studs 15 and the side of chord 12. The flanges of the top chord and studs in contact with the panel have spurs 16 struck out therefrom, adapted to be self-clinching as the panel is pressed against the chord and studs for permanent go relative thereto. This characteristic imparts the better stress distribution between the chord and panel previously referred to.

Panel 13 may be secured to bottom chord 12 by nails or screws and, additionally or solely by adhesive, if desired.

In using my beam, stress in the web 13 increases as loads are applied. The stress is only partially transferred to the flange of chord 11, however, because of the flexibility of connecting spurs 16. In a specific example where the web 13 is plywood and the chord 11 steel, a conventional rigid connection therebetween would result in a stress of 1080 p.s.i. (strain 0.00067" per inch) in the web when the stress in the chord is 20,000 p.s.i. (strain 0.00067" per inch). With a proper degree of flexibility in the connecting spurs 16, however, stress in the web can be increased to the safe working value of the material which is 1875 p.s.i. (strain 0.00117" per inch) while the stress in the chord remains 20,000 p.s.i. (strain 0.00067" per inch).

It will be apparent that my invention permits the attainment of greater efliciency in the use of material in composite beams than the rigid connections ordinarily employed in such structures.

Although I have disclosed herein the preferred embodiment of my invention, I intend to cover as well any change or modification therein which may be made without departing from the spirit and scope of the invention.

I claim:

A composite beam comprising a top chord member, a bottom chord member spaced therefrom and a panel extending between and secured to said members, said top chord member being a flanged metal member disposed with its flange parallel to said panel and in abutting relation therewith, said flange having flexible spurs extending therefrom and said panel being impaled on said spurs, whereby on initial loading of the beam, the resulting stress in the panel is only partially transferred to the top chord member.

References Cited by the Examiner UNITED STATES PATENTS 1,075,845 10/1913 Mills 52731 1,328,201 1/1920 Rendano.

2,076,728 4/1937 Keller 52483 2,286,158 6/1942 Remmel et al 52-483 2,339,841 1/ 1944 Deuchler et a1.

2,844,233 7/1958 Westman 287-189.36

FRANK L. ABBOTT, Primary Examiner.

R. A. STENZEL, Assistant Examiner.

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