US1846682A - Composite supporting structure - Google Patents

Description

, 1930 3 SheetsSheet l Filed OCT. 1'7

INVENTOR V/'c'for F//mmel BY 63W t D a""/ ATTORNEYS Feb. 23, 1932. A v. F, HAMMEL 1,846,682

COMPOSITE SUPPORTING STRUCTURE Filed Oct. 1.7, 1930 B SheeS-Sheet 2 if z ATTORNEYS Feb. 23, 1932. v F HAMMEL 1,846,682

COMPOSITE SUPPORTING STRUCTURE Filed Oct. 17, 1930 3 Sheets-Sheet 5 ATTORNEYS Patented Feb. 23, 1932 PATENT OFFICE VICTOR F. HAMMEL, OF NEW YORK, N. Y.

COMPOSITE SUPPORTING STRUCTURE Application filed October 17, 1930.

systems or of telephone and telegraph lines and the like.

An object of the invention is to provide a composite supporting structure bf the above type having a lower section of metal, preferably iron or steel, and an upper section of wood.

A further object is to provide an electrically welded latticed or woven metal pole for use in said composite structure which combines the elements of maximum strength in bending, in torsion and in columnar action consistent with lightness in weight and facility and economy of construction* A feature of the latticed pole constructed in accordance with this invention is that when implanted directly in the ground for vertical support thereby it adords maximum resistance against earth movements as compared to existing poles when similarly supported.

The composite supporting structure of this invention is adapted to provide the most economical support for overhead electric power, light and communication conductors and cables, as well as grounding wires.

This application is a continuation in part of my copending application Serial No. 310,889, filed oct. 6,1928.

A composite supporting structure of the type specified when utilized as a. support for overhead power or communication lines possesses many unique advantages as compared to the commonly used pole structures consisting entirely of metal such as steel or entirely of Wood.

The all-steel pole in addition to being more expensive than the composite structure is necessarily more massive and heavy than the steel portion of the composite structure and hence is more diicult to transport to the many wild, mountainous and otherwise inaccessible regions where the poles are frequently required.

The all-wood pole is not always available in the lengths required for pole line construc- Serial No. 489,455.

tion. Unless especially treated, as by creosoting, it is quickly attacked by vermin such as boring insects which enter the wood at or near the ground, the resultant decay soon causing collapse of the structure. Brush fires frequently destroy miles of wood pole line, while lightning in its transit to earth often shatters a wood pole.

The composite structure obviously overcomes the above objectionable features inherent in the all-metal or all-wood pole. The metal lower portion protects the pole against destruction by fire or attack by vermin. The metal portion, being relatively light as compared to the all-steel pole may be easily transported to the regions where required and where almost any local timber supply will prove adequate to complete the structure.

A pole having its upper section of wood of definitely established longitudinal dimension together with a metal lower section gives great protection against destruction by lightning, lVith a definite gap between the steel section and the conductors the lightning will readily jump from the conductors across the wood and seek ground through the steel without burning the conductors or shattering the wood.

Since the top wood section in the composite structure is so much smaller than the timber required for an entire wood pile, a great amount of reasonably cheap timber not heretofore satisfactory will become useful for pole line construction. In many foreign countries and in some regions of the United States this factor is of prime importance since quantities of short slender timber constitute the only available local supply. Likewise, other woods having characteristic propertics more suitable from the electrical point of view, but previously unavailable because of the acceleration of decay when in contact with the earth will become applicable.

"he latticed or woven steel pole which is preferred for the lower section of the composite structure comprises rods wound in left and right hand intersecting helices having substantially equal pitch, together with flanged longitudinal bars of angle section eX- tcnding in alignment with the intersections of th-e rods and electrically welded thereto at such intersections. The angle bars are positioned outside of the helically wound rods with their vertices pointing outwardly. One advantage of this particular construction is that with the pole implanted directly in the ground for purposes of support, great resistance is obtained against ground movement of the implanted portion. Thus any transversely applied force such as that dueto wind pressure will in tending to shift the pole sideways, cause the earth to pack or wedge more tightly between adjacent angle inembers thereby automatically increasing the resistance to movement in proportion to theapplied force.

In the drawings:

Fig. l shows a composite pole or column in accordance with this invention comprising a latticed steel lower section and a wood upper section;

Fig. 2 shows an H frame comprising two composite poles in accordance with Fig. l trussed together by cross member supporting high tension power lines; the wood poles being utilized to cari', ground wires as a protection against lightning. n

Figs. 3, 4 and 5 disclose the structural details of the latticed metal pole of the Fig. l composite structure. Fig. 3 is a side elevation of the metal pole supported directly in the ground. Fig. 4 is a sectional view along the line 4 4 of Fig. 5; while Fig. 5 is an enlarged perspective view ofa portion of th-e structure.

Fig. 6 is a graphical disclosure of the man-- ner in which the pole of Fig. 3 is resistive of ground movements of the implanted portion due to transverselyT applied forces.

Referring to l, there is shown a columnar structure comprisng a steel lower section A of electrically welded latticed construction, the lower end whereof is implanted directly in the earth at B for supporting the structure in a vertical position. Inserted in the upper end of the steel pole A is a wooden pole or post C to the upper end of which are attached the cross-arms D having affixed thereto pins and insulators E for supporting the conductors F of an electrical transmission system, the conductors being preferably supported on the wood pole C over man-height from the metal section A, as indicated by the proportionate dimensions of the cross arms D and the length of the wood pole C, Fig. l. An aerial cable G is shown below the cross-arms, its supporting steel cable I-I being ailixed directly to pole C.

The wood top section provides an excellent construction of high electrical resistance for insulating a ground wire from the conductors. To this end the cross-arms D and aerial cable G may be attached at the top `original setting by the simple operation of attaching a wood top of any required length for future additional conductors as development requires. To this end a wood top of given length may readily be replaced by a longer one without interruption to service. Due to the inherent sag in conductors F between poles, this change can easily be accomplished by loosening the connecting means between the steel section A and the wood top C, raising the wood top, holding it to one side and inserting a new wood top section. This flexibility of construction further provides a structure easily adjustable inV height to suit the topography by using a standard length of steel base and varying length of wood upper section.

The latticed steel pole A is constructed as set forth in my copending application above referred to and comprises, as shown more clearly in Figs. 3 to 5 inclusive, rods l, preferably square or circular in cross-section, wound in left and right hand tapering helices of eoual pitch, together with trussed or flanged longitudinal bars 2, specifically of angle section, extending in alignment with the intersections of rods 2, being electrically welded thereto at the contact points 3 (see Fig. 4) adjacent the intersections.

It can be demonstrated that a pole constructed in this manner is of strength greater than a tubular pole of the same external dimensions and containing the same material, and thus constitutes a great improvement over such poles in that it achieves the same objectives at a marked saving in material and reduction in dead weight.

The latticed pole of Figs. 3 to 5 inclusive is ideally braced against every sort of bending, twisting or compressive force and is thus strong when acting as a beam or as a column or when subject to torsional stresses. l

The latticed construction reduces the resistance to windpressure while the cylindrical configuration renders the pole of equal strengtn for forces applied thereto from any transverse direction. By distributing all of the metal a maximum distance from the axis of the pole, a large section 'modulus is attained whereby the structure operates with maximum elliciency when acting as a beam or as a column.

The flanged longitudinal members have inherent stii'nessagainst bending and being bound together by helical rods which follow the naturally occurring lines of compressive stress in a solid or tubular pole sustaining a load, render the pole of maximum strength as a colunm.

By extending the helical members in accordance with both right and left hand spirals a set of tension members are provided to take up the load under torsion regardless of the direction of twist. Thus the torsional strength is increased since the rods 1 are able to withstand without failure much greater loads under tension than under compression.

By electrically welding the longitudinal and helical members at the points of contact, the strength of the pole is not only increased as compared to the employment of riveted or clamped joints, but the construction thereof may be accomplished with much greater facil ity and economy. lVhere bolted joints are employed the necessity for punching and aligning the rivets holes, and inserting and capping the rivets is inherently a slower and more expensive procedure than electric welding.

The specific construction for the latticed pole disclosed herein provides great resistance against shifting or movement of the pole w en implanted directly in the ground for purposes of support. This action will be understood by referring to Fig. 6.

It a transverse force is applied in the direction F1 it obviousl causes the earth to become more densely pacged or wedged between the angles A1 to A5 inclusive and this automatically increases the resistance of the pole against movement in proportion to the magnitude of the applied force. In any movement of the structure in the earth there is a circular shell of earth 5 which moves in conjunction with the pole, causing a resistive action by virtue of the greater frictional resistance between the shell 5 of earth and the surrounding earth. I the material included within the annulus 5 were composed entirely of steel or wood, the pole would out thru the earth much more readily than with the construction shown, because the coefiicient of friction between earth and wood, or between earth and steel is considerably less than that between earth and earth.

In addition to the resistance against earth movement thus provided by the present structure, attention need only be called to the great saving resulting from being able to set the pole directly in the ground omitting the usual concrete base.

It is of course not essential that the helically wound rods 1 of the latticed pole be continuously curved thereby producing a circular configuration when viewed in elevation as shown in Fig. 4. It sometimes becomes of advantage to have the rods 1 follow straight line paths between adjacent angle bars 2 such as to produce a pole of polygonal shape when viewed in elevation.

The modification of Fig. 2 comprises an H frame consisting of a pair of composite poles N, each similar to that of Fig. 1, trussed together by means of a cross member K to which are affixed insulators L supporting high tension lines M. The wood tops of poles N carry ground wires P which serve to protect the system from lightning. The structure may be suitably braced by means of guys R.

An adaptation in accordance with Fig. 2 may of course be applied to the usual forms p il' framed steel transmission towers and the I claim:

1. A pole or column for supporting overhead electrical transmission lines and the like comprising, a metal lower section adapted to be set directly in earth, and a wood pole upper section of the order of one-third to onehalf the length of said entire pole, and electrical conductors insulatedly supported upon said wood pole over man-height from said metal section.

2. A pole or column for supporting overhead electrical transmission lines and the like comprising, a latticed metal lower section adapted to be set directly in earth, consisting of flanged longitudinal bars integrated by diagonal latticing rods coextensive with said bars, and a wood pole upper section inserted in said metal section, said wood pole being of the order of one-third to one-half the length of said entire pole, and electrical conductors supported on the latter and located in the upper half thereof.

In testimony whereof I afiiX my si nature.

VICTOR F. HAM EL.

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