Patent Publication Number: US-7591119-B2

Title: Method and apparatus for increasing the capacity and stability of a single-pole tower

Description:
This application is a continuation of and claims priority benefits to U.S. patent application Ser. No. 09/706,216, entitled “Method and Apparatus for Increasing the Capacity and Stability of a Single-Pole Tower,” and filed on Nov. 3, 2000 now U.S. Pat. No. 6,453,636. U.S. patent application Ser. No. 09/706,216 is a continuation of an claims priority benefits to U.S. patent application Ser. No. 09/557,266, entitled “Method and Apparatus for Increasing the Capacity and Stability of a Single-Pole Tower,” and filed on Apr. 24, 2000 now abandoned. 

   TECHNICAL FIELD 
   The present invention relates generally to a method and an apparatus for increasing the capacity and stability of a single-pole tower. More particularly, the invention relates to a method and an apparatus that employs a sleeve and an array of load transfer pins to add structural stability to a single-pole tower and thereby increase its capacity to support additional equipment and withstand environmental loads. 
   BACKGROUND OF THE INVENTION 
   The increase in wireless telecommunications traffic has resulted a concomitant incise in the need for pole-mounted transmission equipment of all kinds. Not only do wireless service providers need to install equipment covering new geographic areas, competing service providers and others also need to install additional equipment covering the same or similar geographic areas. To date, the solution to both problems normally includes purchasing additional land or easements, applying for the necessary government permits and zoning clearances, and constructing a new tower for the new transmission equipment. 
   Purchasing land or easements, however, is becoming increasingly expensive, particularly in urban areas where the need for wireless telecommunications is greatest. Zoning regulations often limit the construction of new towers in the vicinity of existing towers or may prohibit the construction of new towers in the most suitable locations. The expense and delay associated with the zoning process often may be cost-prohibitive or so time-consuming that construction of the new tower is not feasible. Even when zoning regulations can be satisfied and permits can be obtained, the service provider must then bear the burden and expense associated with the construction and the maintenance of the tower. 
   The tower itself must be designed to support the weight of the telecommunications transmission equipment as well as the forces exerted on the pole by environmental factors such as wind and ice. The equipment and the environmental factors produce forces known as bending moments that, in effect, may cause a single-pole tower to overturn if not designed for adequate stability. Traditionally, single-pole towers have been designed to withstand the forces expected from the equipment originally installed on the pole. Very few single-pole towers, however, are designed with sufficient stability to allow for the addition of new equipment. 
   Thus, there is a need for a method and an apparatus for increasing the capacity and stability of a single-pole tower that will support the weight of additional equipment and support the additional environmental forces exerted on the pole. At best, the prior art shows various brackets used for restoring the strength of a weakened or damaged section of a wooden pole. An example of a known pole restoration system is shown in U.S. Pat. No. 4,991,367 to McGinnis entitled, “Apparatus and Method for Reinforcing a Wooden Pole.” This reference describes an apparatus that employs a series of braces linked together around the circumference of a tapered pole. The braces are then forced downward on the pole to wedge the assembly tightly against the pole to provide support. This system does not include an anchorage to the ground or base of the pole. 
   A number of other known pole restoration systems employ a first part attached to the damaged section of the pole and a second part that is driven into the ground to provide support. An example of such a system is shown in U.S. Pat. No. 4,756,130 to Burtelson entitled, “Apparatus for Reinforcing Utility Poles and the Like.” This apparatus uses a series of brackets and straps attached to ground spikes. Another example of a known pole restoration system is shown in U.S. Pat. No. 4,697,396 to Knight entitled, “Utility Pole Support.” This reference describes an apparatus with a series of brackets attached to a wooden utility pole. A series of tapered spikes are anchored on the brackets and then driven into the ground to provide support. Additional examples of such a system are shown in U.S. Pat. Nos. 5,345,732 and 5,815,994, both issued to Knight &amp; Murray, entitled “Method and Apparatus for Giving Strength to a Pole” and “Strengthening of Poles,” respectively. These references describe an apparatus with a nail or bridging beam driven through the center of the wooden pole. The nail is attached by linkages to a series or circumferential spices that are then driven into the ground to provide support. 
   In each of these systems, the brackets are fixably attached to a damaged wooden utility pole to provide a firm anchor for the ground spikes. The spikes are driven into the ground immediately adjacent the pole to wedge the spike tightly against the side of the pole. The functionality of each of these systems depends, therefore, on the rigid attachment between the pole brackets and the spikes as well as the compression fit of the spikes between the ground and the pole. Further, these ground-based systems only function when the damaged pole section is sufficiently near the ground for the bracket assembly to be attached to the ground spikes. The capacity of these known systems to resist bending moments is dependent upon the height of the damaged section relative to the ground as well as the characteristics of the soil and other natural variables. Moreover, each of these systems describes an apparatus for the purpose of restoring a damaged pole to its original capacity, not for the purpose of bolstering an existing pole to increase its capacity. 
   Thus, there remains a need for a method and apparatus for increasing the capacity and stability of a single-pole tower that will support the weight of additional equipment and support the additional environmental forces exerted on the pole, while providing sufficient stability to resist the forces known as bending moments exerted by the new equipment and the environmental forces. Such a method and an apparatus should accomplish these goals in a reliable, durable, low-maintenance, and cost-effective manner. 
   SUMMARY OF THE INVENTION 
   The present invention provides a method and an apparatus for increasing the capacity and stability of a single-pole tower. The invention thus provides a support structure for use with an existing single pole tower. The single pole tower has a pole anchored to a foundation and supports a first load. The support structure has a number of sleeves surrounding the pole. The sleeves may extend beyond the height of the existing single pole tower. A first one of the sleeves is anchored to the foundation. A second load is attached to a second one of the sleeves. 
   Specific embodiments of the present invention include the sleeves being made out of a metal such as a structural pipe with a minimum yield stress of about 42 ksi. The sleeves may have a first half and a second half. Each half may have a first side with a first sleeve tab and a second side with a second sleeve tab. The sleeve tabs may have a number of apertures positioned therein. The sleeves also may include a first end with a first flange plate and a second end with a second flange plate. The flange plates also may have a number of apertures positioned therein. The sleeves also may include a number of load transfer pins. The load transfer pins may have a bolt and one or more nuts. The pins extend from the sleeves to the pole so as to stabilize the loads. The pins may be radially spaced around a vertical center axis of the sleeves. The sleeves may include a plurality of access ports positioned therein. The second load may include one or more telecommunications arrays. 
   There may be a number of sleeves, such as a first sleeve, a second sleeve, and a third sleeve. The second flange plate of first sleeve is anchored to the foundation. The first flange plate of the first sleeve may include a dimension to accommodate the second flange plate of the second sleeve while the first flange plate of the second sleeve may include a dimension to accommodate the second plate of the third sleeve. The first end of the third sleeve may include a cover plate. 
   Another embodiment of the present invention provides a support structure for supporting a first load and for use with an existing single pole tower. The single pole tower includes a pole anchored to a foundation. The pole supports a second load. The support structure includes a first sleeve attached to the foundation and a second sleeve attached to the first sleeve. The first load is attached to the second sleeve. The sleeves surround the pole. The second sleeve may be attached to the first sleeve via one or more joinder sleeves. 
   A further embodiment of the present invention provides a support structure for supporting a load and for use with an existing single pole tower. The single pole tower may include a pole anchored to a foundation. The support structure may include a number of sleeves surrounding the pole. One of the sleeves may be anchored to the foundation and another one of the sleeves may support the load. A number of load transfer pins may be positioned along the sleeves. The pins extend from the sleeves to the pole so as to stabilize the load. 
   A further embodiment of the present invention provides a support structure for supporting a load. The support structure includes a single pole tower and a sleeve surrounding the pole. The pole and the sleeve are anchored to a foundation. The sleeve supports the load. A number of sleeves may be used with a first sleeve anchored to the foundation, a second sleeve supporting the load, and one or more joinder sleeves positioned between the first sleeve and the second sleeve. The pole also may support a second load. The total height of the number of sleeves may extend beyond the height of the existing single pole tower. A number of load transfer pins may be positioned along the sleeve. The pins extend from the sleeve to the pole so as to stabilize the load. 
   A method of the present invention provides for placing an additional load on a single pole tower. The single pole tower includes a pole anchored to a foundation. The method includes the steps of positioning one or more sleeves around the pole, anchoring the sleeves to the foundation, and supporting the additional load on the sleeves. A first one of the number of sleeves may be anchored to the foundation, a second one of the sleeves may be supporting the additional load, and one or more joinder sleeves may attach the first and the second sleeves. The method may further include the step of attaching a number of load transfer pins to the sleeves so as to stabilize the additional load. 
   Thus, it is an object of the present invention to provide an improved method and apparatus for increasing the capacity and stability of a single-pole tower. 
   It is another object of the present invention to provide an improved method and apparatus for increasing the capacity and stability of a single-pole tower wherein the apparatus will support the weight of additional equipment and the additional environmental forces exerted on the pole. 
   It is still another object of the present invention to provide an improved method and apparatus for increasing the capacity and stability of a single-pole tower wherein the apparatus will support the weight of additional equipment and the additional environmental forces exerted on the pole while also providing sufficient stability to resist the forces known as bending moments caused by the new equipment and the environmental forces. 
   Other objects, features, and advantages of the present invention will become apparent upon reading the following detailed description of the preferred embodiment of the invention when taken in conjunction with the drawings and the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view of the support structure of the present invention surrounding an existing tower. 
       FIG. 2  is a plan view of a bottom sleeve section of the present invention showing the access ports, the load transfer bolts, and the flange plates. 
       FIG. 3  is a plan view of a top sleeve section of the present invention showing the access ports, the load transfer bolts, and the flange plates. 
       FIG. 4  is a top cross-sectional view of the sleeves and the existing pole. 
       FIG. 5  is a side plan view of the load transfer bolts. 
       FIG. 6  is an exploded view of the sleeves. 
       FIG. 7  is a sectional view of the sleeve at the base showing the beams, the anchoring means, and the foundation as disclosed in one embodiment. 
       FIG. 8  is a top cross-sectional view of the sleeve near the base showing the beams, the anchoring means, and the foundation as disclosed in one embodiment. 
   

   DETAILED DESCRIPTION OF THE DISCLOSED EMBODIMENT 
   Referring now in more detail to the drawings, in which like numerals indicate like elements throughout the several views,  FIG. 1  shows a single pole tower  10  for use with the present invention. As is well known in the art, the single pole tower  10  generally includes a pole  20  of varying height. The pole  20  is generally a hollow structure made from various types of steel, composite materials, or other types of sufficiently rigid materials. The pole  20  may be a tapered structure such that it decreases in width as its height increases. The pole  20  may be mounted on a foundation  30  by a base plate  40  and a plurality of anchor bolts  50 . The foundation  30  is generally a reinforced concrete structure that may by anchored by conventional means. The base plate  40  and the anchor bolts  50  are generally made from various types of steel or other types of sufficiently rigid materials. One or more loads  60  may be fixedly attached to the pole  20 . In the present embodiment, the load  60  may include one or more types of conventional telecommunication arrays  70  fixedly attached by bolts or other conventional types of attachment means. Such telecommunication arrays  70  are well known in the art. 
     FIGS. 1-3  show the support structure  100  of the present invention. The support structure  100  includes one or more sleeves  110 . The sleeves  110  may be up to about thirty (30) feet in length. Sleeves  110  of more than thirty (30) feet may be used. As is shown particularly in  FIGS. 2-3 , the sleeves  110  each may be a two (2) part structure with a first half  120  and a second half  130 . The halves  120 ,  130  have a largely semi-circular portion  140 , a first side  150 , a second side  160 , a top portion  170 , and a bottom portion  180 . The semi-circular portion  140  extends in width from the first side  150  to the second side  160  and in length from the top portion  170  to the bottom portion  180 . The halves  120 ,  130  of the sleeves  110  may be a molded structure or may be manufactured by other types of conventional construction means. The halves  120 ,  130  may be made from substantially rigid materials such as hot-dipped galvanized ASTM A572 structural pipe having a minimum yield stress of about 42 ksi. It will be appreciated that other materials are equally suitable for the method and apparatus disclosed herein depending upon the desired characteristics of the support structure  100  as a whole. 
   Both halves  120 ,  130  may have a first sleeve tab  190  extending substantially perpendicularly from the semicircular portion  140  along the first side  150  of the halves  120 ,  130  and a second sleeve tab  200  extending substantially perpendicularly from the semi-circular portion  140  along the second side  160  of the halves  120 ,  130 . The sleeve tabs  190 ,  200  may be a unitary element with the halves  120 ,  130  (i.e., molded therewith) or the sleeve tabs  190 ,  200  may be a flat bar or a similar structure that is welded to the halves  120 ,  130 . The welding preferably should comply with AWS A5.1 or A5.5, E70xx standards. The sleeve tabs  190 ,  200  may be made from the same material as the halves  120 ,  130 . Alternatively, the sleeve tabs  190 ,  200  also may be made from a hot-dipped galvanized ASTM A-36 structural steel or similar materials if the sleeve tabs  190 ,  200  are welded to the halves  120 ,  130 . 
   The sleeve tabs  190 ,  200  may have a plurality of apertures or bolt holes  210  therein that align so as to connect the respective halves  120 ,  130  by bolts  215  or other conventional types of fastening means. The bolts  215  preferably should comply with ASTM A-325 standards. When joined along the sleeve tabs  190 ,  200 , the halves  120 ,  130  of the sleeves  110  form a largely hollow structure with a diameter slightly greater that the greatest diameter of that section of the pole  20  the particular sleeve  110  is intended to surround. 
   The sleeves  120 ,  130  may have a first flange plate  220  encircling the top portion  150  of both halves  120 ,  130  and a second flange plate  230  encircling the bottom portion  180  of both halves  120 ,  130 . The flange plates  22 o,  230  may be a flat semicircular bar or a similar structure that is welded to the halves  120 ,  130  of the sleeve  110 . The welding preferably should comply with AWS A5.1 or A5.5, E70xx standards. The width of the Age plates  220 ,  230  may vary so as to accommodate the additional sleeves  110  of varying size. The flange plates  220 ,  230  may have a plurality of apertures or bolt holes  240  therein so as to connect the sleeves  110  by a number of bolts  245  or by other conventional types of fastening means as described in more detail below. The bolts  245  should comply with AST A-325 standards. The flange plates  220 ,  230  may be made from the same material as the halves  120 ,  130 . Alternatively, the flange plates  220 ,  230  also may be made from hot-dipped galvanized ASTM A-36 structural steel or similar materials if the flange plates  220 ,  230  are welded to the halves  120 ,  130 . 
     FIGS. 1 and 4  show the sleeve  110 , in this case a first sleeve  250 , encircling an existing pole  20  and attached to the existing foundation  30 . The sleeve  250  may be attached to the foundation  30  by a number of the bolts  245  anchoring the second flange plate  230  of the bottom portion  180  of each half  120 ,  130  of the sleeve  250 . The halves  120 ,  130  of the sleeve  250  are positioned around the existing pole  20  such that the central vertical axis of sleeve  250  is centered on the effective center vertical axis of existing pole  20 . The size of the bolts  245  will depend upon the size and intended use of the support structure  100  as a whole. The first sleeve  250  may have a number of cutout portions  270  therein along the bottom portion  130  of each half  120 ,  130  so as to accommodate either the existing anchor bolts  50  or the bolts  245  for use herewith. The second flange plate  230  also may be fixedly connected to existing base plate  40 . 
   FIGS  7  and  8  show the existing foundation  30  and a new foundation  430 . A number of beams  480  may be attached to the sleeve  110  to facilitate anchoring and to provide additional structural support and stability. The beams  480  may be positioned around the sleeve  110  and may extend outward radially. Each beam  480  may be shaped at its attachment to the sleeve  110  to form a close fit. The sleeve  110  may be attached to the existing foundation  30  or to the new foundation  430  using a number of new anchor bolts  450 . The beams  480  may include a number of stiffener plates  490  adjacent the new anchor bolts  450 . The number and size of the beams  480 , the stiffener plates  490 , and the new anchor bolts  450  will depend upon the size and intended use of the support structure  100  as a whole. 
   Positioned along the length of the sleeves  110  may be a number of load transfer pins  300 . As is shown in  FIG. 5 , the load transfer pins  300  each may include a bolt  310  and one or more nuts  320 . Similar types of load transfer means may be used, The bolt  310  may be positioned within one of a number of load transfer boltholes  330  located along the length of the sleeves  110 . One of the nuts  320  may be positioned on the bolt  310  on the inside of the sleeve  110  and one nut  320  may be positioned on the bolt  310  on the outside. The bolt  310  extends and contacts the existing pole  20 . The bolt  310  may be turned until contact is made with the existing pole  20 , at which time the outer nut  320  is tightened to firmly secure the load transfer pin  300 . 
     FIG. 2  illustrates the location of the holes  330  for the load transfer pins  300  in the first sleeve  250 . The load transfer pins  330  may be spaced in an array that is suitable for the expected load to be supported by the support structure  100 . The load transfer pins  300  are spaced apart in an array both vertically and radially. Vertical spacing is designed relative to the height the sleeves  110 . Radial spacing is designed relative to the vertical center axis of sleeves  110 . As is shown, the load transfer pins  50  may be vertically spaced about twelve (12) to sixty (60) inches apart and radially spaced about ninety degrees (90°) apart. 
   The sleeves  110  also may have one or more access ports  340  positioned therein. The access ports  340  may be apertures of varying size and shape in the sleeves  110 . The access ports  340  provide access to the interior wires or cables on the existing pole  20  for inspection, repair, or the addition of new wing or cables. 
   As is shown in  FIGS. 1 and 6 , a number of the sleeves  110  may be combined herein. For example,  FIG. 6  shows the use of three sleeves  110 , the first sleeve  250 , a second sleeve  350 , and a third sleeve  360 . Any number of the sleeves  110  may be used. The sleeves  110  may be of varying size in terms of shape, length, width, or thickness. Further, sleeves  110  of varying size and shape may be used together. As described above, the existing pole  20  is likely to be tapered in width as the pole  20  extends in height. Each sleeve  250 ,  350 ,  360  therefore may be progressively smaller in height, width, and thickness. 
   For example, the first sleeve  250  may have a height of about twenty (20) feet, a width of about forty-two (42) inches, and a thickness of about ⅝-inch, the second sleeve  350  may have a height of about twenty (20) feet, a width of about thirty-six (36) inches, and a thickness of about ⅝-inch; and the third sleeve  360  may have a height of about fifteen (15) feet, a width of about thirty (30) inches, and a thickness of about ⅝-inch or less. The first flange plate  220  of the first sleeve  250  accommodates the second flange plate  230  of the second sleeve  350  while the first flange plate  220  of the second sleeve  350  accommodates the second flange plate  230  of the third sleeve  360 . For example, the first flange plate  220  of the first sleeve  250  and the second flange plate  230  of the second sleeve  350  may have a diameter of about forty-eight (48) inches while the first flange plate  220  of the second sleeve  350  and the second flange plate  230  of the third sleeve  360  each may have a diameter of about forty-two (42) inches. The sleeves  250 ,  350 ,  360  are connected by the bolts  245  as described above. Each sleeve  250 ,  350 ,  360  also has a plurality of load transfer pins  300  as described above. 
   The third sleeve  360 , or whichever sleeve  110  is positioned on top, may be sealed at the top with a cover plate  370 . The cover plate  370  extends in a close fit from the perimeter of the existing pole  20 . The cover plate  370  may be sealed in a watertight fashion with a silicone sealant. The cover plate  370  may be constructed of ¼-inch steel, such as hot-dipped galvanized ASTM A-36 structural steel or similar materials. The cover plate  370  may be welded to the top of the third sleeve  360 . 
   Positioned on the support structure  100  may be one or more telecommunications arrays  380 . The telecommunication arrays  380  may be of conventional design and may be identical to the existing telecommunication array  70 . The telecommunication arrays  380  may be attached to the support structure  100  by bolts or by other conventional types of attachment means. As is shown in  FIG. 1 , the existing telecommunication array  70  may remain positioned on the existing pole  20  while new arrays  380  are added to the support structure  100 . Alternatively, the original array  70  and the new arrays  380  may be positioned on the support structure  100 . The support structure  100  may have a height that is less than, equal to, or greater than the height of the existing pole  20 . The support structure  100  may support any type of load in addition to the telecommunications arrays  380 . 
   In use, the support structure  100  as described herein should be able to support loads of about two thousand (2,000) to forty thousand (40,000) pounds at heights of between about thirty (30) to two hundred fifty (250) feet while withstanding basic wind speeds of up to about seventy (70) miles per hour or a combined environmental load of wind at about sixty (60) miles per hour and a layer of radial ice of about one-half-inch thick surrounding the support structure  100 . The support structure  100  has adequate independent strength and stability to support its telecommunication arrays  380  while also combining with the existing pole  20  via the load transfer pins  300  to provide superior strength and stability to the combined structure as a whole. The present invention thus provides an apparatus and method for increasing the load and stability of single pole towers so as to increase the number of telecommunication arrays in use without the need to build additional towers. 
   It should be apparent that the foregoing relates only to a preferred embodiment of the present invention and that numerous changes and modifications may be made hem without departing from the spirit and scope of the invention as defined by the following claims.