US20020095905A1

US20020095905A1 - Composite reinforced wood structural members

Info

Publication number: US20020095905A1
Application number: US09/775,684
Authority: US
Inventors: Norman Fawley
Original assignee: Individual
Current assignee: Individual
Priority date: 2000-02-03
Filing date: 2001-02-05
Publication date: 2002-07-25

Abstract

A wood pole having a wood body defined by a stripped tree trunk is reinforced by strips of composite reinforcement wrapped helically around the wood body, wherein the reinforcement comprises parallel high strength filaments in a resin matrix. The thickness and/or number of layers of reinforcement can be varied along the length of the pole to best suit the loading to which the pole is to be subjected. The reinforcement also performs the functions of the prevention of rot, insect infestation and water absorption, which are conventionally performed by harmful materials such as creosote. An electrical conductor can extend the length of the pole, protected under the reinforcement, which is transparent to electromagnetic signals, to act as an antenna or as a ground wire. No-maintenance color, fire retardant and/or reflective elements can be mixed in with the resin during the reinforcing of the pole.

Description

CROSS REFERENCE TO RELATED APPLICATION

This application claims the priority of U.S. Provisional Patent Application No. 60/176,056, filed Feb. 3, 2000, which is incorporated herein by reference.[0001]

BACKGROUND OF THE INVENTION

The present invention relates to wood structural members and, more particularly, to elongate, composite reinforced wood structural members for uses such as utility poles, piles and beams.

In the United States alone, there are more than 100 million electric distribution poles and about 8 million to 10 million electric transmission poles. The distribution poles are typically 45 feet to 50 feet in length, whereas new transmission poles are usually from 85 feet to 100 feet in length and carry high voltage lines. Wood is, by far, the material of which most of these utility poles are made, although some are made of steel, concrete and composites. In order to make wood utility poles, trees are cut, delimbed and then peeled to the proper taper.

It is estimated that more than 250,000 transmission poles and 3 million to 4 million distribution poles need to be replaced every year. Rot that occurs at the ground line and woodpeckers destroy many wood poles or make them too weak for further service, and wind and ice storms can destroy all types of utility poles. In some places, the life of a wood utility pole can be as low as 10 to 15 years. The severe ice storms in the northeastern United States and in the Canadian provinces of Ontario and Quebec in January, 1998, destroyed or damaged many thousands of utility poles, including about 50,000 utility poles in Ontario and Quebec. In conditions like those of an ice storm, the weight of ice on lines and poles puts at least close to a maximum load on the poles. If one pole fails under such conditions, it very likely pulls down neighboring poles in a domino effect, thereby resulting in extensive damage.

Wood utility poles are less expensive than utility poles made of other materials. Composites are 5 to 10 times the cost of wood in distribution pole length sizes. As a result, many prime trees are cut down to satisfy the need for utility poles. Over the years, most wood utility poles have been made from trees of the following types: western red cedar, lodgepole pine, red pine, jack pine, Scots pine, southern yellow pine, Douglas fir and radiata pine. Softwood trees, such as southern yellow pine, have a quick growth rate but lack durability. Scrub trees and other trees are unsuitable because they are too weak. Species such as hemlock and spruce do not absorb the materials normally used to prevent infestation and rot. Therefore, they are not used as utility poles. The materials normally used to prevent infestation and rot include such hazardous materials as pentachlorophenol, chromate copper arsenate, ammoniacal copper arsenate, copper naphthenate and creosote wood preservatives. The carcinogenic aspect of creosoted utility poles has been widely discussed, and in many cases creosoted poles must be disposed of in separate land fills due to potential contamination from the creosote. Furthermore, because wood utility poles are made from trees, and trees have limbs, the bases of the limbs (commonly referred to as “knots”) become stress raisers in the poles. In the examination of many utility pole failures, it has been found that the failure originated at a knot area, usually about one third of the way up the pole. Wood utility poles are relatively inflexible and usually fail along a plane extending down at an angle from one side of the pole to the center, with the wood on one side of the plane pivoting away from the wood on the opposite side of the plane. In addition, in some conditions, wood utility poles become saturated with moisture and cause ground shorting, in which current flows from lines carried by the pole through the pole to the ground. Saturation also leads to rotting and failure.

SUMMARY OF THE INVENTION

By the present invention, elongate structural members made of wood, such as wood utility poles; can be reinforced with a composite material and thereby made stronger by a factor of from about 2 to about 4, depending on the specific arrangement of the composite material. Reinforced wood utility poles and other reinforced elongate wood structural members according to the present invention can comprise an elongate wood body defined solely by a core of a tree trunk. The composite reinforcement increases the flexural strength of wood structural members and gives them greater ductility. As a result, wood structural members reinforced according to the present invention bend farther without failing than bare wood structural members do. Furthermore, elongate wood structural members reinforced according to the present invention have sufficient strength to perform their intended functions, even though the wood bodies have insufficient strength in themselves to perform the functions. Wood utility poles or other wood members of a given cross sectional area can be made much stronger, or wood poles or other wood members of a smaller cross sectional area can be made strong enough to function as utility poles. Poles of lesser strength classes can be strengthened to the strengths of higher strength classes. The utility industry defines various classes of utility poles, with varying amounts of strength required for each class in accordance with the job that a pole must perform. Furthermore, poles from trees of inferior species, that is, species of soft woods and species otherwise too weak to be used as utility poles previously, can be reinforced to be suitable for utility poles, thereby saving the trees of more valuable species. It is even contemplated that palm trees reinforced according to the present invention can be used as utility poles, especially where other types of trees are not available.

The composite reinforcement according to the present invention performs the functions of the creosote and other treatment materials. As a result, the present invention makes possible the use of the non-absorbing woods as utility poles. By performing the functions, such as the prevention of rot and insect infestation and water absorption, previously provided by harmful materials such as pentachlorophenol and creosote, the composite reinforcement eliminates the use of the harmful materials and the associated contamination and disposal problems. Wood members reinforced according to the present invention can be totally wrapped by the reinforcement, including, in the case of utility poles, the areas where cross-arms are to be attached. In addition, a cap of composite material can be placed on the top of the wood member. As a result, moisture cannot get into the wood and cause the associated problems, such as rotting and ground shorting in the case of utility poles. Materials to discourage woodpeckers, such as cayenne pepper, can be added to the resin during or prior to making of the reinforced pole. Known fire retardant materials, such as cayenne pepper, can be added to the resin during the reinforcing of the poles so that the poles will be protected against fire from brush fires and the like. Moreover, the reinforced structural members can be made in any color by adding color to the resin component of the composite reinforcement as the structural members are being wrapped. As a result, there is no need for painting or maintenance. An outer winding of nylon, Reemay polyester or other polyester, or glass malts or veils, can be used to provide a significant long-term barrier to degradation of the underlying composite reinforcement from ultraviolet light and other weather-related elements. Especially where the poles are to be installed close to vehicular traffic, glass beads or other reflective elements can be mixed in with the resin to be used in all or a portion of the outer layer of reinforcement in order to provide greater visibility at night. As an alternative, reflective tape can be placed around the pole under an outer covering of resin. The resin can be transparent, so that the reflective tape shines through the resin, while the resin protects the reflective tape from degradation. Furthermore, the high strength filaments of the reinforcement, such as glass fibers, and the resin can be chosen to have the same index of refraction. As a result, the composite reinforcement is transparent, and the reflective tape can shine through one or more layers of the composite reinforcement. The composite material also prevents ground shorting by acting as a dielectric shell for wood utility poles. In this regard, E-type glass fibers, which are electrically non-conductive and transparent to radio and other electromagnetic signals, can be used as high tensile strength filaments in the composite reinforcement. Arrangements conventionally used for attaching steps and cross-arms to wood utility poles can be used with reinforced utility poles according to present invention due to the thinness of the composite reinforcement and the presence of the solid wood core. Such arrangements cannot be used with totally composite utility poles, which are typically hollow. Because the composite reinforcement provides so much strength, the present invention prevents, or at least greatly reduces, the failures of wood structural members due to stress concentrations at knots. Composite reinforced wood utility poles according to the present invention can be smaller in diameter and greater in height than unreinforced wood utility poles. Wood structural members reinforced according to the present invention have higher flexural strength and greater ductility and can carry greater loads than unreinforced wood structure members. Furthermore, by increasing or decreasing the amount of the high tensile strength filaments in the composite which are oriented generally in the longitudinal direction of the wood structural members, the members can be made with greater or lesser stiffness, whatever is desired for a particular application.

The reinforced utility poles according to the present invention are also well-suited to define the uprights and the horizontal member or members of towers for long distance energy transmission. H-towers constructed with composite reinforced wood horizontal members, or cross-arms, and with the reinforced utility poles as uprights are less costly than conventional wood H-towers and yet have greater wind resistance and ice load bearing ability.

The present invention can also be used for reinforced wood piles for piers and other marine applications. Unlike utility poles, the piles typically are not tapered. However, some marine piles are tapered from the top to the bottom, the smaller end being pounded into the earth.

In addition to providing the advantages described above in connection with composite reinforced utility poles, the composite reinforcement prevents the ends of the piles from splitting due to pounding. In addition to poles having circular transverse cross-sections, the present invention can be used with poles and uprights having non-circular transverse cross-sections, and with beams having non-circular or circular cross-sections. The wood structural elements to be reinforced, whether uprights or beams, experience an increase in shear modulus with the reinforcement according to the present invention.

In order to provide the above advantages, a wooden pole is covered with one or more layers of a composite reinforcing material comprising a large plurality of parallel, continuous, lightweight, high strength, electrically non-conductive nonmetallic fibers and a resinous material encapsulating the fibers. The pole can be tapered from bottom to top, like a conventional utility pole. The pole can be the same diameter as a conventional utility pole, or can be smaller in diameter than a conventional utility pole, since the composite reinforcing material will provide the necessary strength. Because loads on a pole are significantly less at the top than at the bottom, the number of layers of reinforcement can be decreased from the bottom to the top and/or the reinforcement can be otherwise arranged to provide the greatest reinforcement for the areas of the pole that will be subjected to the greatest stress. Because the utility poles are subject to side-to-side loads, as well as vertical compression, a large plurality of parallel longitudinal fibers, as well as a large plurality of parallel circumferential fibers, are in the composite reinforcement to provide an adequate side-to-side load reinforcement. The composite reinforcement applied in accordance with the present invention prevents the typical failure of the wood utility pole by hinged separation along a plane extending down at an angle from one side of the pole to the center. It also changes the mode of failure to end-to-end tension shear, the overall result of which is a horizontal break. This change in the mode of failure gives the reinforced wood utility poles greater flexibility and greater toughness, increases the loads the poles can bear, and eliminates from pole failures the domino effect by which neighboring utility poles fail as a result of the failure of a first utility pole.

The present invention is well adapted to the use of utility transmission poles as antennas for cellular phones and for other non-wired communications. By placing a conductor against a wood pole, running from the top to the bottom of the pole, a protected conductor can be provided. Such a conductor can also be used as a grounding device to prevent stray current from short arcing across the insulators and to take any stray currents at the ground. The conductor can be placed either in a groove cut longitudinally down the pole or simply on the surface of the pole, in either case, prior to applying the composite reinforcement. The conductor can be in a straight vertical line, in a spiral around the pole, or in other configurations.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects and advantages will be better understood from the following detailed description of a preferred embodiment of the invention with reference to the drawings, wherein: [0014]
FIG. 1 is a perspective view of an installed reinforced wood utility pole according to the present invention; [0015]
FIG. 2 is a front elevation of a reinforced wood utility pole according to the present invention before installation; [0016]
FIG. 3 shows a portion of a wooden core receiving first and second layers of composite reinforcing material and a conducting wire in the manufacture of a reinforced wood utility pole according to the present invention; [0017]
FIG. 4 is a transverse cross-section along the line [0018] 4-4 in FIG. 2;
FIG. 5 is a transverse cross-section of a reinforced utility pole according to the present invention having five layers of reinforcing material; [0019]
FIG. 6 is a schematic showing of a portion of a strip of composite material having randomly oriented filaments for use in a reinforced wood utility pole according to the present invention; [0020]
FIG. 7 is an enlarged portion of a strip of composite reinforcement for use in a reinforced wood utility pole according to the present invention, wherein all filaments are parallel to the length of the strip; [0021]
FIG. 8 is an enlarged portion of a strip of composite reinforcement having an arrangement of filaments in the longitudinal direction woven with filaments in the transverse direction; [0022]
FIG. 9 is an enlarged portion of a strip of composite reinforcement for use in a reinforced wood utility pole according to the present invention, wherein all of the filaments are transverse to the length of the strip; [0023]
FIG. 10 is a load versus position curve for a bare wood test sample; [0024]
FIG. 11 is a load versus position curve for a wood test sample reinforced according to the present invention with three specific layers of composite reinforcing material; [0025]
FIG. 12 is a load versus position curve for a wood test sample reinforced according to the present invention with three specific layers of composite reinforcing material; [0026]
FIG. 13 is a load versus position curve for a wood test sample reinforced according to the present invention with five other specific layers of composite reinforcing material; and [0027]
FIG. 14 is an H-tower in accordance with the present invention.[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As can be seen from FIG. 1, a utility pole reinforced according to the present invention which is designated generally by the [0029] reference numeral 10, comprises a wood core 11 wrapped with one or more layers of a composite reinforcement material 12. Cross-arms 14 are mounted on the pole 10, and insulators 16 are mounted on the cross-arms to support one or more lines 18 for the transmission or distribution of electrical power.
As can best be seen from FIG. 2, the [0030] pole 10 has different thicknesses of reinforcement at different sections along the length of the pole 10. The different thicknesses are due to differing numbers of layers of reinforcement. The pole 10 includes an elongate wood body 20 (FIGS. 3-5), which can be defined by a conventional, tapered wood utility pole. The thickest reinforcement on the pole, reinforcement 12 a, extends from the bottom of the pole to a point which is at least one-third of the height of the pole above the ground, when the pole is installed. The reason for this is that many utility pole failures occur at about one-third of their height above the ground. A middle section of the pole 10 is wrapped with composite reinforcement material 12 b having a total thickness less than the thickness of the material 12 a on the bottom section of the pole. The top section of the pole is wrapped with composite reinforcement material 12 c having a total thickness less than the thickness of the material 12 b of the middle section. In FIG. 2, the difference in the thickness of the reinforcement on the various sections of the pole is exaggerated for clarity of illustration. As an alternative to the thicknesses just described, the middle section can have a greater thickness of reinforcement than the other sections of the pole 10, if such an arrangement is called for by the loading on the pole. In addition, or as an alternative to the thickness arrangements described above, the individual layers can have different thicknesses from one another, and/or the directions in which the high tensile strength filaments extend in the reinforcement can vary from one layer to another. Still other configurations of reinforcement can be used to suit the loading to be imposed on the utility pole.
An [0031] end cap 22 made of composite material comprising high-strength filaments in a resin matrix is positioned at the top and bottom of the pole 10 to cover the top of the wood body 20. The cap 22 has a skirt extending for a short distance along the length of the pole 10, and the skirt is covered by the composite reinforcement material 12 covering the pole to help hold the cap on the pole.
As can be seen from FIGS. [0032] 2-4, the composite reinforcement material 12 on the pole 10 comprises one or more layers of strips 26 and 27 of the composite reinforcement material 12 wrapped helically around the wood body 20. Typically, the strips are wrapped at a small helical angle ‘a’ (FIG. 2) in the range of about 5° to about 30°, for which approximately 14.5° is typical. A first strip defining a first layer, such as strip 26, can be wrapped with the helical angle extending in one direction relative to the horizontal and a next strip defining a second layer, such as the strip 28, can be wrapped with the helical angle extending in the opposite direction with respect to the horizontal. A third strip 29 defining a third layer can be wrapped with a helical angle in the same direction as the first layer, and so on. The strip can comprise a large plurality of unidirectional parallel high tensile strength filaments brought together in a resin matrix prior to curing of the resin but otherwise unattached. As an alternative, the filaments can be stitched together. As another alternative, the strip can comprise two groups of parallel filaments, the filaments of one group lying at an angle with respect to the filaments of the other group. Additional groups of filaments lying at still other angles can be included. The groups of filaments can be unattached, or can be stitched together or woven together.
As can be appreciated from FIGS. 3 and 4, a [0033] wire 30 can be installed running the length of the pole 10, either in a notch 31 in the wood body 20, or simply on the outer surface of the wood body. In either case, the composite material 12 is wrapped over the wire 30 to protect it and secure it in place. The wire 30 can extend in a straight line, spiral around the pole, or have another configuration to function as an antenna. As an alternative, the wire 30 can also act as a grounding device to prevent stray currents from short arcing across the insulators mounted on the pole and to take any stray currents at the ground. A plurality of wires 30 to serve a plurality of functions can be applied to the pole.
As can be appreciated from FIGS. 5 and 7-[0034] 9, the strips 26-28 of composite reinforcement material 12 wrapped around the wood bodies 20, and additional strips, if used, such as strips S4 and S5 of the pole 10′ of FIG. 5, are made from strips of parallel high tensile strength non-metallic filaments, such as glass fibers, having various orientations. In each case, the fibers are arranged in parallel groups and embedded in a matrix of a curable resin, such as an isophthalic polyester resin, to form a composite reinforcement material having high strength. Such resins are wet and viscous before curing and, preferably, the strips of high tensile strength filaments are saturated with the resin before the strips are wrapped helically around the wood body 20. When this is done, the resin causes the strips to adhere to the wood body or to underlying strips. After the wood body 20 is wrapped, the resin is cured by conventional means. The cured resin makes the composite reinforcement material 12 impervious to the ingress of moisture.
FIG. 6 schematically shows a portion a type of [0035] strip 32, called a “matt”, which contains thousands of randomly oriented fibers or filaments 34, such as glass fibers, either chopped or continuous strands, adhered to one another. Such a strip is not nearly as strong as strips having parallel filaments but is very conducive to absorbing resin, and the resin acts as a barrier to ultraviolet rays, moisture and other elements. Each line in FIG. 6 represents dozens of filaments. Actually, there are many more dozens of fibers 34 adhered together per square inch than is indicated by FIG. 6, and the open spaces are much smaller than indicated. Such a strip 32 can be placed around the strips 26-28 designed for high strength, as is shown in FIG. 4.
FIG. 7 shows a [0036] strip 36 made of bundles 38 of high tensile strength filaments all oriented parallel to the length of the strip. A few strands 40 of transverse thread are used to hold the longitudinal filaments 38 together. Each bundle 38 of filaments indicated in FIG. 7 contains hundreds or thousands of high-strength filaments of glass or other material.
FIG. 8 shows a [0037] strip 42 in which bundles 44 of longitudinal filaments are woven with bundles 46 of transverse filaments. Again, there are at least hundreds of filaments in each bundle. About 80% of the filaments by weight can be longitudinal and about 20% of the filaments by weight can be transverse (80/20), or about 50% can be longitudinal and about 50% transverse (50/50). Any relative amounts of longitudinal and transverse filaments can be chosen in order to satisfy the strength requirements for the loads the pole will bear, [longitudinal for bending; circumferential for ?] Rather than being woven, the bundles 44 and 46 can be stitched together at right angles to one another. It can be particularly useful to choose the angles between the bundles 44 and the length of the strip 42 and between the bundles 46 and the length of the strip such that, when the strip 42 is wound around the wood body 20 at a helical angle, the bundles 44 extend precisely circumferentially around the wood body and the bundles 46 extend precisely longitudinally, or vice versa.
FIG. 9 shows a [0038] strip 48 in which all of the high tensile strength filaments, which are in bundles 50, extend transverse to the length of the strip. Each bundle 50 contains hundreds of filaments. A few longitudinal threads 52 are used to hold the transverse bundles 50 together.
At least when the strips of composite material defined by the high tensile strength filaments and the resin are cured, the strips have tremendous tensile strength in a direction parallel to the filaments. For each of the strips relied on to provide strength in one or more specific directions, which, among the illustrated strips, includes the strips of FIGS. [0039] 7-9, the filaments comprise about 70% by weight of the composite strip of filaments and resin and about 50% by volume, when the filaments are glass filaments or fibers.
The various types of strips of high strength filaments can be used in various combinations, depending upon the properties desired. If it is desired to particularly increase the flexural strength and stiffness of the wood body [0040] 20, more layers of reinforcement formed by strips having transverse filaments, such as the strip 48 of FIG. 9, are used. It can be appreciated that, when a strip of the material of FIG. 9 is wrapped around an elongate wood body 20, the filaments will extend generally longitudinally of the wood body. The filaments are not precisely longitudinal because of the angle of the helix along which the strip is laid. However, since the angle ‘a’ of the helix is small (e.g., 14.5°), the tensile strength component of the filaments is almost entirely in the longitudinal direction of the wood body 20. Similarly, for the strips 36 of FIG. 7, the tensile strength component of the filaments is almost entirely in the circumferential direction of the wood body 20, when the strip is wound helically around the wood body.

The following table shows the results of flexural bend tests on 4″-diameter wood test poles (peeler poles, center heart). Each test pole was 40″ long and was place horizontally on supports spaced 28″ apart, with a force imposed by a slow moving machine element at the center of the 28″ span of the test pole between the supports. Thus, the force was applied transverse to the length of the pole by the machine element, which started from a position in engagement with the pole.

	TABLE 1


	Load in Lbs.

	Test Sample	A	B	Average

Bare (Control)		5,094	5,564
Bare (Control)	6,741	4,859
System 1	6,737	6,931	6,834
System 2	12,072	12,878	12,475
System 3	13,613	13,841	13,727
System 4	7,975	8,178	8,076
System 5	17,663	19,150	18,406
System 6	19,342	20,556	19,949

With respect to the various systems of strips wrapped around the test poles for which the test results are shown in Table [0042] 1, there are three layers of strips used in Systems 1-3 and five layers used in Systems 4-6. For System 1, the innermost layer has randomly oriented filaments, such as the strip 32 of FIG. 6, and the middle and outer layers are made from strips in which all of the filaments are longitudinal, such as the strips 36 of FIG. 7. In System 2, the inner layer is made from strips comprising woven filaments of which 80% are longitudinal and 20% are transverse, such as the strips 42 of FIG. 8. The middle and outer layers are made from strips in which all of the filaments are longitudinal. For System 3, the innermost layer is made from a strip in which all of the filaments are transverse, such as the strip 48 of FIG. 9, and the outer two layers are made from strips in which all of the filaments are longitudinal.
In [0043] System 4, the two innermost layers are made from strips in which the filaments are randomly oriented, and the other three layers are made from strips in which all of the filaments are longitudinal. In System 5, the two innermost layers are made from strips of woven filaments, of which 80% by weight are longitudinal and 20% by weight are transverse. The other three layers are made from strips in which all of the filaments are longitudinal. In System 6, the two innermost layers are made from strips in which all of the filaments are transverse, and the other three layers are made from strips in which all of the filaments are longitudinal.
FIG. 10 is a graph of the vertical load in pounds on the bare test pole of Column A of Table 1 versus the position of the movable test machine element in inches from the starting position. The force on the pole increased with the movement of the test machine element until 6,741 lbs. was reached. After that point, the bare test pole broke and the load supporting ability of the pole dropped precipitously. [0044]
FIG. 11 is a load versus position graph for the test pole in Column A of Table [0045] 1 with the System 3 reinforcement according to the present invention. It can be appreciated from FIG. 4 that the System 3 reinforcement comprises an inner layer or wrapping of composite material made from a strip in which all of the filaments are transverse, as shown in FIG. 9. The middle and outer layers are made from strips in which all of the filaments are longitudinal, as shown in FIG. 7. As can be seen from FIG. 11, the load increased with increasing movement of the test machine element to 13,613 lbs. At that point, there was a slight decrease in the load, indicating a failure of the test pole, but the pole continued to bear a substantial load for about ⅓ of an inch additional travel of the machine test element. Thus, there was some warning before a complete failure of the test pole.
In the 5-layer reinforcement of the present invention according to System [0046] 6, FIG. 12 shows that the test pole in Column A of Table 1 withstood 19,342 lbs., and there was considerable additional travel by the machine test element before there was a sudden large drop in load supporting ability from about 17,500 lbs. to about 8,750 lbs. FIG. 13 shows that, with the System 6 test pole of Column B, the ultimate load before failure was 20,556 lbs., after which there was a substantial decrease in load bearing ability to a lower plateau at about 12,400 lbs., before a further drop in a load bearing ability with a substantial additional movement of the machine test element.
As can be seen from FIG. 4, the outermost layer of composite reinforcement can be covered by a layer to protect the composite reinforcement layers from degradation by ultraviolet light and weathering. The barrier layer can comprise nylon, Reemay polyester or other polyester fibers in a strip which is would helically around and covering the underlying composite reinforcement layers. [0047]
Although the present invention has been described herein in connection with new utility poles, it is understood that the present invention can be used in connection with utility poles already in service, whether or not they are damaged or weakened. [0048]
As can be seen from FIG. 14, an H-[0049] tower 58 can be constructed in accordance with the present invention. The H-tower 58 includes two uprights 60, each having the same construction of the utility pole 10 of FIGS. 1 and 2, including the composite reinforcement material 12. The uprights 60 are connected by a crossbeam 62 that is also reinforced with the composite reinforcement material 12. For the cross beam 62, the composite reinforcement material 12 typically has a uniform thickness across the entire crossbeam, and the crossbeam typically is not tapered. Of course, the thickness of composite reinforcement material 12 and the cross section of the crossbeam 62 can vary where conditions warrant. Both the uprights 60 and the crossbeam 62 are covered with the composite reinforcement 12 where they are joined to one another. Holes can be drilled through the uprights 60 and the crossbeam 62, including the composite reinforcement material 12, to receive bolts for securing the crossbeam to the uprights.
The present invention can also be used to reinforce wood cores for use as marine pilings. Such marine pilings have many of the same advantages as reinforced utility poles according to the present invention. In addition, the wrapping of the wood cores with the strips of composite reinforcement material helps prevent the resultant reinforced marine pilings from splitting when they are driven into the earth. The reinforcement protects the pilings from elements which tend to cause the pilings to deteriorate. [0050]
Having thus described the present invention and its preferred embodiments in detail, it will be readily apparent to those skilled in the art that further modifications to the invention may be made without departing from the spirit and scope of the invention as presently claimed. [0051]

Claims

What is claimed is:

1. A reinforced wood pole comprising:

an elongated wood body defined solely by a core of a tree trunk; and

at least one layer of a strip of composite reinforcing material extending in a helix around and in engagement with the wood body, the helix defining adjacent convolutions in continuous contact the composite material comprising parallel continuous high tensile strength fibers extending throughout the strip, and a resin matrix encapsulating the fibers to define the strip.

2. The reinforced wood pole of claim 1, wherein the fibers are nonmetallic.

3. The reinforced wood pole of claim 1, wherein the pole has a top end and a 2 bottom end, and the reinforcing covers the entire pole, except the bottom end.

4. The reinforced wood pole of claim 1, wherein the material of the wood body has a strength such that a wood body having a diameter of 4 inches has insufficient strength in itself to withstand a load of 7,000 pounds.

5. The reinforced wood pole of claim 1, wherein the strip contains a first plurality of the fibers extending longitudinally in the strip and a second plurality of the fibers extending transversely in the strip, and said fibers of said first and second pluralities are glass fibers and comprise approximately 70% by weight of the strip.

6. The reinforced wood pole of claim 5, wherein the strip extends helically around the pole at an angle of from about 5° to about 25°.

7. The reinforced wood pole of claim 1, further comprising a plurality of layers of the strips.

8. The reinforced wood pole of claim 7, wherein at least one of the number of layers of the strips and the thickness of the strips decreases in a direction from the bottom of the pole to the top of the pole.

9. The reinforced wood pole of claim 8, wherein the pole is secured in the ground, and the largest number of layers of the strips extends from the bottom of the pole to more than one-third the height of the pole above ground.

10. The reinforced wood pole of claim 1, wherein all of the fibers of at least one of said strips extend transversely in the strip and generally longitudinally with respect to the elongate wood body.

11. The reinforced wood pole of claim 10, wherein the fibers which extend transversely are glass fibers, and said glass fibers comprise approximately 70% by weight of said at least one strip of composite reinforcement material.

12. The reinforced wood pole of claim 10, comprising a plurality of said layers, wherein all of the fibers of at least one of said strips extend longitudinally in the strip and generally circumferentially with respect to the elongate wood body.

13. The reinforced wood pole of claim 1, further comprising an electrically conductive wire extending longitudinally under the composite reinforcing material, from the top of the pole to the bottom of the pole.

14. The reinforced wood pole of claim 1, further comprising a barrier layer of a material defining a barrier against ultraviolet light, said barrier layer substantially covering the composite reinforcing material.