US2117567A - Flanged plate timber connecter - Google Patents

Description

May 17, 1938. J. E. MYER ET A1.r 2,117,567

FLANGED PLATE TIMBER CNNECTER May 1,7,4 1938. J. E. MYER ET AL FLANGED PLATE TIMBER CONNECTER Filed Deo. 23, 1936 2 Sheets-Sheet 2 Patented May 17, 1938 UNITED STATES FLANGED PLATE TIMBER CONNECTER James E. Mun-Washington, D. C., and Arthur C. Horner, San Francisco, Calif., assignors to `Timber Engineering Company, Washington,

' D. C., a corporation of Delaware Application December 23, 1936, Serial No. 117,380

claims. Y(ci. zo--zi 'I'his invention `relates to timber connectersof the bolt and plate type and embodies a particular form of plate. 1

n The installation and use of the present types 5 of timber connecters present difficulties in the prefabrication and assembly of timber joints. It has been found impractical to insert connecters in grooves or embed them partially into the Wood at the time of fabrication of the timber members lo due to the fact that such connecters project above the surface of the timber interfering with piling and storing of the prefabricated parts and the possibility of loss of the connecters. `Where timbers are prepared in advance to receive connecters by grooving or the like changes in the moisture content of the wood will cause alteration of the grooves so that at the time of assembly the grooves must berecut before the connecters can be inserted.

It is an object of this invention to avoid these diiculties by the construction of a timber connecter which will lle ush with the surfaces of the timber and be attached to said timber 'at the time of fabrication whereby to simplify the'installation of connecters and to facilitate direction of the fabricated parts.

A further object of this invention is to decrease the slip at the joint under load and to increase the loadcarrying capacity of the bolt by a reduction of bolt deformation under load.

Referring to the accompanying drawings in which similar reference numerals indicate similar I parts wherever used.

`Figure 1 is a sectional view. showing timbers connected by use of the device.

Figure 2 is a section on line 2--2 of Figure 1.

Figure 3 is a plan view of a different form of the invention.

Figure 4 is a' section on line 4--4 of Figure 3, partly broken away.

Figure 5 is a plan view of still another form of the invention.

Figure 6 is a sectional view showing timbers Figure 7 is a perspective view of the bushing II for ar purpose hereinafter explained. These seats and the recess may be formed .by an `expension bit and a grooving tool and a timber thus prepared is `ready for the installation of the device as illustrated in Figures 1 and 2.

The connecter comprises identical halves, each half being a circular plate I3 of suitable metal having a central bolt hole I4, a circumferential flange I5 and, in the constructions' shown ln Figures 3 to 6 a central hub and ange I6 surrounding the bolt hole. The plate I2 is formed with two or more nail holes I1, recesses I8 being provided for the reception of nail heads which seat therein.

In the form shown in Figures 5 and 6 the bore of the hub I6 tapers inwardly as at- I9 to receive a metal bushing which tapers from a center r of largest diameter 2I to form faces 22, 22, forming a double tapered bushing which is bored to form a central bolt hole 23.

In the manufacture of any of the forms of the connecter plates in larger sizes the plate I3 may be made with openings as 24, Fig. 3 in desired number, reducing the weight of the connecter with resultant saving of metal.

`Referringto Figure 8 the stress in the wood under the bolt in a simple bolted joint in which no connecter is present is concentrated at the edges of the timbers as shown by the shaded areas in said figure (Wood Handbook, 4September, 1935, United States Department of Agriculture, page 130).

In assembling a joint using the present form of connecters, the timbers to be joined are prepared as above described and the connecters seated with, in the case of the construction shown in Figures 1 and 2, the flange `I5 entering the groove I2 andthe plate I3 entering the recess prepared for it so that the outer face of the connecter lies flush with the surface of the timber. While in this position nails are inserted through the hole I1 and driven home so that the nail heads seat within the'recesses I8. In this way the connecter is attached to the timber without danger of loss and the connecter presents no interfering surfaces above the surface of the timber.

The installation of the connecter plates for the construction shown in Figures 3 to 6 is the same except that the timber has been additionally preprepared for reception of the hub ange I6.

To complete the joint `for the construction shown in Figures 1 and 2 the timbers are juxtaposed so that the bolt holes I I are aligned and a bolt 26 having anupper washer-21 is inserted seat formed in one of the plates by the inner wallof the hub IB as shown in Figure 6 which leaves that portion of the bushing 2li) above the median line 2l exposed. The other prepared timber is now placed in juxtaposition so that the bushing will be received by the other plate and seated within the hub I6. The usual bolt assembly described for the previous installation is now used and the joint tightened.

When it is desired to secure a timber to a metallic member the timber to be secured is fitted with one of the connecter plates as described and bolted to the metallic member in the usual manner.

By reference to Figure 8 it will be seen that in a simple bolted construction the stress in the wood members joined together is concentrated at the edges of the timbers as shown. 'By the use of the present device this concentration of stress is distributed by the plates to a much larger area of the wood than by using the bolt alone. Shear stress upon the bolt when used with the present timber connecter is distributed by the flanges l5 over the Wood in the case of the construction shown in Figures 1 and 2 and in the constructions shown in Figures 5 to 'l is taken up not only by the fianges l5 but by the hub i6 and by the bushing retained within said hub.l 'I'his distribution of stress increases the load carrying capacity of the bolt by preventing the walls of the bolt hole from crushing at the points where the shear stress is most-concentrated as illustrated by Fig. 8 thereby reducing its deformation under load and in the form of Figs. 5-7, due to the action of the connecter plates and bushing 20, transmits to the bolt a distributed and lessened shear stress solely.

As is well understood, bolted joints in timbers, without connecters. yield rst by crushing of the bers against the bolts. The bolts are thus deformed to a shape comprising laterally offset ends with parallel axes connected by a diagonal portion. The latter portion is subjected to a combined shear, tension and tearing action, most destructive upon the fibers of the metal.

In the forms of the present invention of Figs. 1 4, the bolt cannot crush the fibers of the wood, at least up to the limit of resistance against flanges l5. 'Ihe stress upon the bolt is therefore pure tension and pure shear at least until the washers 21, 28 sink into the wood and the flanges l5 crush the fibers. The bolt opening Il is shown as rounded or chamfered where it meets the surface to be engaged by the remaining plate so as to dull the shearing edges. It is obvious that this shear stress divorced from deformation of the bolt will be much less destructive of the bolt. The bolt hole i4 should t the bolt rather closely.

In the form of Figs. 5-7 is no shear upon the bolt until the flanges l5 crush the fibers of the wood and after this a shear will develop distributed between the points at the two engs ofthe bushing 20.

Minor changes may be made in the physical embodiments of the invention within the scope ol' the appended claims without departing from the spirit of the invention.

What I claim as new and desire to secure by United States Letters Patent, is:

1. A timber bond comprising juxtaposed timbers having coaxial grooves and recesses in the contacting faces thereof, a anged plate seated in each timber and fitting said groove and recess, whereby said plates lie flush with the surfaces of the contacting faces of said timbers.

2. A timber connecter comprising identical plates, each of said plates having a central bolt aperture, a flanged hub surrounding said aperture, a circumferential flange on said plate and a bushing engaging each of said flanged hubs when said plates are in connected relation.

3. A timber connecter comprising a plate having a plane surface to lie ush with the surface of a timber and a central bolt opening', said plate formed with a peripheral ange projecting from its remaining surface, and extending completely thereabout.

4. A timber connecter comprising a plate having a plane surface to lie flush with the surface of a timber, a central bolt opening dimensioned to closely fit a bolt to be used therewith, and hav ing nail holes between said bolt opening and the periphery of the plate; the angle between said plane surface and said bolt opening cut away to delocalize the shearing stress upon a bolt in said opening; and an annular peripheral flange projecting from the remaining surface of the plate.

5. A timber connecter comprising a pair of plates having plane surfaces in contact at the meeting plane of timbers to be connected, and having central 'registering apertures formed on frusto conical surfaces with opposed bases at said plane surfaces, each plate formed with an annular flange about said aperture and a peripheral annular ange projecting from its side opposite said plane surface, and a bushing having an axial bolt opening with its periphery formed complementary to the combined registering apertures in L said plates. l

JAMES MYER.

ARTHUR C. HORNER.

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