Abstract:
An unbonded post-tension strand protector ( 200 ) and related method of use is provided. The unbonded post-tension strand protector is used to protect one or more unbonded post-tension strands ( 101 ) embedded in concrete from damage due to drilling or chipping. Unbonded post-tension strands embedded in poured concrete are tensioned to improve the compressive strength of concrete. The unbonded post-tension strand protector is placed over at least one selected portion of an unbonded post-tension strand ( 101 ).

Description:
STATEMENT OF THE TECHNICAL FIELD 
       [0001]    The present invention relates to a device and method for protecting strands used in pre-stressed concrete. More particularly, the invention relates to a protector and method for protecting unbonded post-tension strands. 
       DESCRIPTION OF THE RELATED ART 
       [0002]    Concrete has long been used in the construction industry for its great compressive strength. However, concrete is inherently weak when placed under tension. For general strengthening, concrete has been reinforced by the use of steel reinforcement bars, called rebar, inside poured concrete. The high tensile strength of steel, combined with concrete&#39;s great compressive strength provides improved results under both tension and compression when the structure is cast. 
         [0003]    To further overcome concrete&#39;s natural weakness in tension, methods of pre-stressing concrete with the use of steel have been developed. The principle behind pre-stressed concrete is that compressive stresses induced by high-strength “tendons” in a concrete member before loads are applied will balance the tensile stresses imposed in the member during service. Pre-stressing removes a number of design limitations conventional reinforced concrete places on span and load. Pre-stressed concrete methods are used to produce beams and floors with longer unsupported spans than is practical with ordinary reinforced concrete. This allows architects and engineers to design and build lighter and shallower concrete structures without sacrificing strength. 
         [0004]    When referring to a “tendon,” it is a term that encompasses several components. This includes a strand, which is a cable that is conventionally manufactured in ½ inch, or 6/10 inch diameter sizes. This strand is made from very high-tensile-strength steel wire, usually seven wires twisted together. In addition, the term also includes an anchorage having a cast-iron bearing plate and special wedges to secure the strand inside an anchor housing. 
         [0005]    There are two main methods for inducing compressive strength in pre-stressed concrete: pre-tensioning and post-tensioning the steel reinforcement. In pre-tensioning, the steel is stretched before the concrete is poured. High-strength tendons are placed between two abutments is poured into molds around the tendons and allowed to cure. Once the concrete reaches the required strength, the stretching forces are released. As the steel of the tendons reacts to return to its original length, the tensile stresses are transferred into a compressive stress in the concrete. 
         [0006]    In contrast, post-tensioning stretches the steel after the concrete hardens. Notably, the concrete is cast around but does not contact the unstretched steel. There are two types of post-tension systems: bonded and unbonded. With a bonded system, steel, aluminum, or plastic ducts are positioned in the formed area where tension would otherwise occur in the concrete element. The ducts are then attached to anchorages at either end. Once the poured concrete has hardened to the required strength, the strands are threaded through the ducts and tensioned. The tendons are tensioned by hydraulic jacks that urge against the concrete member itself. When the tendons have been stretched to design specifications, they are locked in position to maintain tension after the jacks have been removed. Thus, the locking action imparts a tensile force to the concrete. The ducts are then filled with a special grout designed to protect the tendons from corrosion. 
         [0007]    Unbonded systems do not employ a duct system like the bonded systems described above. Instead, unbonded systems use stands surrounded with special corrosion-inhibiting grease and encased in waterproof plastic sheaths. This assembly is positioned within a mold and then has concrete poured around it, similar to standard reinforced concrete. Unbonded systems are conventionally used for building and floor slab construction, while bonded systems are used mostly for bridge construction. 
         [0008]    Once the pre-stressed concrete members have been incorporated into the overall design of a structure, other features of the structure can be installed. Such features can include, but are not limited to: the installation of doors and windows, installing anchor bolts into elevator beams, laying plumbing and electric piping, installation of column and sheer walls, and attaching anchor supports on balconies where personnel hoist braces are attached. These features typically require drilling and/or chipping of the pre-stressed concrete which is tensioned using unbonded post-tension stands. Aside from the plastic sheath, the unbonded strands are relatively unprotected from drilling or chipping when installing the other features of the structure. 
         [0009]    Sometimes in the process of drilling and/or chipping, a construction worker will accidentally damage the highly tensioned strands that are hidden within the concrete. Given the extremely high tension force of these strands (typically 30,000 pounds of force), the slightest nick, cut, or impact to these strands can result in the strand popping out of the concrete structure with extreme force. It is akin to a stretched rubber band that snaps. This is a potential safety hazard that has resulted in a great number of construction injuries (i.e. impalements, lacerations, amputations) and deaths. 
         [0010]    In addition to the problem of construction worker safety, a cut strand compromises the strength and stability of the concrete structure itself. This could lead to immediate or gradual structural failure as greater stress and strain is applied to the remainder of the structure. When there are apparent indications of strand damage (i.e. the strand popping out of the concrete body), there may be a chance to repair the concrete structure before any additional or irreversible damage is incurred. However, repairing these unbonded post-tension systems is quite expensive and dangerous. 
         [0011]    There are also instances where there could be no immediate indication that the strands and the pre-stressed concrete have been compromised. Unfortunately, in the absence of external indicators there is no non-invasive way, such as X-ray analysis, of detecting whether a pre-stressed concrete form has in fact been compromised. Considering that a typical concrete floor slab can have between 100-300 hidden strands, the task of inspecting each strand can be daunting. 
         [0012]    To date, the problem of protecting unbonded post-tension strands from drilling and chipping has gone unsolved. Therefore, what is need in the art is a device and method that can protect unbonded post-tension strands from drilling or chipping. At the same time, the device should be adapted such that it can be strategically and removably placed in a location where selected portions of the unbonded post-tension strands(s) are protected from damage. Such a device and method would minimize both weight and construction cost, while reducing the risk of potentially life-threatening injures. 
       SUMMARY OF THE INVENTION 
       [0013]    The invention is an unbonded post-tension strand protector. The protector includes a plate that is sized and shaped to be place over at least one selected portion of the unbonded post-tension strand. The one or more selected portions are protected from damage caused by drilling or chipping. Moreover, the one or more selected portions are located in several locations. These locations include under and over doors and windows, adjacent to elevator beams where anchor bolts will be installed, around sleeves for plumbing and electric lines, where column and sheer wall forms are to be installed, on balconies where personnel hoist braces are attached, or at portions of a cast concrete body that require drilling or chipping. 
         [0014]    In another aspect of the invention, the invention relates to a protector for protecting one or more unbonded post-tension strands. The protector includes one or more plates having an elongated length and a predetermined width. Moreover, a portion of the plate(s) are located in proximity to one or more unbonded post-tension strands for protecting the unbonded post-tension strand(s) along the elongated length of the plate(s). 
         [0015]    In one embodiment of the invention, the plate is formed of steel. In addition, there are several embodiments of the plate&#39;s size and shape. According to one embodiment of the invention, the plate is sized and shaped to be removably clipped to at least one unbonded post-tension strand. In another embodiment, the plate includes a planar shape. The planar shape attaches to the unbonded post-tension strand using clamps extending from the plate. Another embodiment, the plate is comprised of at least one recess. The recess partially encases each unbonded post-tension strand. As an alternative, each recess is located adjacent to one another. As another separate embodiment, a first plate is sized and shaped to be removable clipped to at least one unbonded post-tension strand. Moreover, a second plate is shaped and sized to be removably clipped to the first plate. 
         [0016]    In another aspect of the invention, the invention relates to a method for protecting one or more unbonded post-tension strands in a pre-cast concrete body. The method includes selecting one or more unbonded post-tension strand having either a half inch, three-eight inch, or six-tenth inch diameter. At least one unbonded post-tension strand is positioned in a pre-cast concrete body before the concrete is cast in the pre-cast concrete body. Selected portions of one or more unbonded post-tension strands to be protected are determined. 
         [0017]    The selected portions are placed in a location where said selected portions are protected from damage caused by drilling or chipping. According to one aspect of the method, the selected portions are placed under and over windows, adjacent to elevator beams where anchor bolts are to be installed, around sleeves for plumbing and electric lines, where column and sheer wall forms are to be installed, on balconies where personnel hoist braces are attached, and portions of a cast concrete body that require drilling or chipping. 
         [0018]    The selected portions of the one or more unbonded post-tension strands are protected by placing a least a portion of a protective layer, adjacent to the selected portion. According to one embodiment, the protective layer of the protecting step includes a first plate that is sized and shaped to be clipped to one or more unbonded post-tension strands. As an alternate embodiment, a second plate is sized and shaped to be clipped to the first plate. According to another embodiment, the protective layer of the protecting step includes a planar shaped plate that attaches to the unbonded post-tension strand using clamps extending from the planar shaped plate. According to yet, another embodiment, the protective layer of the protecting step is selected to have one or more recesses configured to partially encase one or more unbonded post-tension strands. A plurality of equally-spaced unbonded post-tension strands is uniformly aligned by joining a plurality of protective layers. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a perspective view of segments of a plurality of strand(s) are arranged in a concrete body that is useful for understanding the invention; 
           [0020]      FIG. 2  is a perspective view of a first embodiment of the unbonded post-tension strand protector that is useful for understanding the invention; 
           [0021]      FIG. 3  is a cross-sectional view of the first embodiment of the unbonded post-tension strand protector shown in  FIG. 2  along the line  3 - 3  that is useful for understanding the invention; 
           [0022]      FIG. 4  is a perspective view of a second embodiment of the unbonded post-tension strand protector that is useful for understanding the invention; 
           [0023]      FIG. 5  is a cross-sectional view of the second embodiment of the unbonded post-tension strand protector shown in  FIG. 4  along the line  5 - 5  that is useful for understanding the invention; 
           [0024]      FIG. 6  is a perspective view of a third embodiment of the unbonded post-tension strand protector shown that is useful for understanding the invention; 
           [0025]      FIG. 7  is a cross-sectional view of the third embodiment of the unbonded post-tension strand protector shown in  FIG. 8  along the line  7 - 7  that is useful for understanding the invention; 
           [0026]      FIG. 8  is a perspective view of a first embodiment of the unbonded post-tension strand protector that is useful for understanding the invention; 
           [0027]      FIG. 9  is a cross-sectional view of the first embodiment of the unbonded post-tension strand protector shown in  FIG. 8  along the line  9 - 9  that is useful for understanding the invention; and 
           [0028]      FIG. 10  is a flow diagram of a method for protecting unbonded post-tension strands that is useful for understanding the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]      FIG. 1  is a perspective view of segments of a plurality of conventional unbonded post-tension strands  101  disposed within a cutaway portion of a hardened concrete body  105 . Each unbonded post-tension strand  101  is usually manufactures in standard ½ inch, ⅜ inch, or 6/10 inch diameter sizes. However, the diameter of the unbonded post-tension strand  101  is not intended to be limiting, as other diameters can also be used. The unbonded post-tension strand  101  is typically formed using very high-tensile-strength wire, usually seven wires  102  twisted together. Each wire  102  is typically made of steel, although other materials having similar tensile strengths can be used. Moreover, it should be understood that the number of wires  102  used to form the strand  101  is not intended to be limiting. The wires  102  are encapsulated by a sheath  103 . The sheath  103  can be preferably made from plastic or other moisture-resistant material. A corrosion-inhibiting grease (not shown) is disposed between the sheath  103  and the wires  102 . Before concrete is poured, the plurality of unbonded post-tension strands  101  are positioned within a concrete mold, similar to standard reinforced concrete. Once the concrete has been poured over the unbonded post-tension strands  101 , the unbonded post-tension strands  101  become hidden from view. 
         [0030]    At least one region  100  outlines selected portions of the plurality of unbonded post-tension strands  101  that are to be protected from potential damage caused by drilling and/or chipping through the concrete body  105  to the point the it impacts the underlying unbonded post-tension strands  101 . Typically locations where region  100  can be found include where drilling and/or chipping occurs. These locations include, but are not limited to, under and over doors and windows, adjacent to elevator beams where anchor bolts are to be installed, around sleeves for plumbing and electric lines, where column and sheer wall forms are to be installed, and on balconies where personnel hoist braces are attached. 
         [0031]    To protect the selected portions of the plurality of unbonded post-tension strands  101 , an unbonded post-tension strand protector  200  ( FIG. 2 ) is placed over the selected portions of the unbonded post-tension strands  101  desired to be protected from drilling and chipping generally underlying the region  100 . 
         [0032]    Referring now to  FIG. 2 , shown is a perspective view of one embodiment of an unbonded post-tension strand protector  200  located on selected portions of the unbonded post-tension strands  101 . The unbonded post-tension strand protector  200  is designed to protect the adjacent unbonded post-tension strand  101  generally underlying the region  100  ( FIG. 1 ). The unbonded post-tension strand protector  200  comprises a U-shaped plate  201 . The U-shaped plate  201  is further comprised of a first planar portion  202 , a second planar portion  204  that is spaced apart from and parallel to the first planar portion  202 , an arcuate portion  203  that is connected to the first and second planar portions  202 ,  204 , and an open side portion  205  located opposite the arcuate portion  203 . 
         [0033]    Referring now to  FIG. 3 , shown is a cross-section of the unbonded post-tension strand protector  200  taken along the line  3 - 3  of  FIG. 2  that is useful for understanding the invention. Distal ends  302  of the U-shaped plate  201  are each formed with an undulation  303 . The undulations  303  are intended to securely fasten the unbonded post-tension strand  200  over the selected region  100  of the unbonded post-tension strand  101 . Each undulation  303  is curved away from the other such that each of their respective convex portions  304  are spaced from and facing each other. The closet distance between convex portions  304  is less than the diameter of the unbonded post-tension strand  101 . 
         [0034]    The U-shaped plate  201  is sized and shaped to be clipped to one or more unbonded post-tension strands  101 . In this regard, the word “clipped” means that the unbonded post-tension strand  101  is inserted through the opens side portion of the U-shaped plate  201  and is secured within the U-shaped plate  201 . The unbonded post-tension strand(s)  101 , when clipped, would be bounded by the first planar portion  202 , the second planar portion  204 , the arcuate portion  203 , the convex portions  304 . The U-shaped plate  201  is designed to protect the top side, bottom side and a single side of the unbonded post-tension strand  101  from any drilling or chipping that would otherwise damage the unbonded post-tension strand  101 . According to a preferred embodiment, the U-shaped plate  201  is formed of a hard material, such a steel. However, the invention in not limited in this regard and other materials can be used so long as the U-shaped plate  201  can resist penetration by a drill bit  210  or a tip of a chipping hammer (not shown). 
         [0035]    The unbonded post-tension strand protector  200  is advantageous in that it permits the construction worker to adjust the position of the unbonded post-tension strand protector  200  relative to the unbonded post-tension strand  101 . In addition, it is advantageous to place the U-shaped plate  201  on selected portions of the elongated length of the unbonded post-tension strand  101  as compared to placing the U-shaped plate  201  along the entire length of the unbonded post-tension strand  101 . The advantage is that the above arrangement minimizes the additional weight and cost of the overall structure by using the minimum amount of material forming the unbonded post-tension strand protector  200 . 
         [0036]    Referring now to  FIG. 4 , shown is a perspective view of another embodiment of an unbonded post-tension strand protector  400 . Similar to the previous embodiment of the unbonded post-tension strand protector  200 , the unbonded post-tension strand protector  400  is designed to protect at least a portion of the unbonded post-tension strand  101  delineated by region  100 , shown in  FIG. 1 . The unbonded post-tension strand protector  400  comprises a planar-shaped plate  401 . Although, the planar-shaped plate is preferably rectangular, the invention should not be limited in this regard. Other plate shapes are possible so long as the plate is dimensioned such that the surface of the plate provides a barrier of protection of at least one unbonded post-tension strand  101  from drilling or chipping in the selected region. The planar-shaped plate  401  attaches to one or more unbonded post-tension strands  101  using at least one clamp  402  (best seen in  FIG. 5 ). The clamp  402  is preferably C-shaped, such that the clamp  402  has an improved grasp of each unbonded post-tension strand  101 . However, this is in no way meant to be limiting as there could be other clamp shapes that can effectively grasp the unbonded post-tension strand  101 . The claim  402  can be made from a resilient material. If the resilient material is a metal, the clamp  402  can be attached to the planar-shaped plate  401  by welding the clamp to the planar-shaped plate  401 . If the resilient material is a non-metal such as plastic, the clamp  402  can be attached to the planar-shaped plate  401  using screws (not shown). However, the invention should not be limited in this regard. 
         [0037]    Referring now to  FIG. 5 , shown is a cross-section of the unboned post-tension strand protector  400  taken along line  5 - 5  of  FIG. 4 . The planar-shaped plate  401  is designed to protect the top or bottom sides of the unbonded post-tension strand  101  from any drilling or chipping that would otherwise damage the unbonded post-tension strand  101 . According to a preferred embodiment, the planar-shaped plate  401  is formed of a hard material, such as steel. However, the invention is not limited in this regard and other materials can be used so long as the planar-shaped plate  401  can resist penetration by a drill bit  210  or a tip of a chipping hammer (not shown). The planar-shaped plate  401  can be configured to protect one or more unbonded post-tension strands  101 . Another advantage of this configuration is that the clamps  402 , and hence the planar-shaped plate  401  can slidably adjust depending on the region that is to be protected. This is accomplished by sliding the planar-shaped plate  401  and its attached clamps  402  along the elongated length of the unbonded post-tension strand(s)  101 . Alternatively, if there is one clamp  402  attached to the planar-shaped plate  401 , it is possible to also slidably adjust the planar-shaped plate  401  by rotating the clamp  404  around the periphery of the unbonded post-tension strand  101 . This enables the planar-shaped plate  401  to protect side and angled regions of the unbonded post-tension strand  101  in additional to the top or bottom sides. 
         [0038]    Referring now to  FIG. 6 , shown is a perspective view of another embodiment of an unbonded post-tension strand protector  600 . Similar to the previous two embodiments  200 ,  400 , the unbonded post-tension strand protector  600  is designed to protect at least a portion of the region of the unbonded post-tension strand  101  delineated by region  100 , shown in  FIG. 1 . The unbonded post-tension strand protector  600  comprises a barrel-vaulted pate  601 . The barrel-vaulted plate  601  is formed by at least one recess  602 . Each recess  602  partially encases a respective unbonded post-tension strand  101 . If a plurality of recesses  602  are employed to protect adjacent unbonded post-tension strands  101 , each recess  602  is positioned adjacent one another by welding abutting side portions  603  of each barrel vaulted pate  601 . This allows for improved alignment of the unbonded post-tension strands  101  before setting them in concrete. The barrel-vaulted plate  601  should be dimensioned such that the surface of the plate provides a barrier of protection for a portion of at least one unbonded post-tension strand  101  from drilling or chipping in the selected region. 
         [0039]    Referring now to  FIG. 7 , shown is a cross-section of the unbonded post-tension strand protector  600  taken along line  7 - 7  of  FIG. 6 . The barrel-shaped plate  601  is designed to protect the top side of the unbonded post-tension strand  101  from any drilling or chipping that would otherwise damage the unbonded post-tension strand  101 . Alternatively, the barrel-shaped plate  601  can be positioned underneath the unbonded post-tension strand  101  such that portions of the unbonded post-tension strand  101  is protected from any drilling or chipping that can damage the underside portions of the unbonded post-tension strand  101 . The barrel-shaped plate can be secured to the unbonded post-tension strand  101  using tie wraps (not shown). The barrel-shaped plate  601  is preferably formed of a hard material, such as steel. However, the invention is not limited in this regard and other materials can be used so long as the barrel-shaped plate  601  can resist penetration by a drill bit  210  or a tip of a chipping hammer (not shown). The barrel-shaped plate  601  can be configured to protect one or unbonded post-tension strands  101 . Another advantage of this configuration is that the barrel-shaped plate  601  can slidably adjust depending on the region that is to be protected. 
         [0040]    Referring now to  FIG. 8 , shown is a perspective view of an embodiment of an unbonded post-tension strand protector  800  located on selected portions of the unbonded post-tension strands  101 . The unbonded post-tension strand protector  800  is designed to protect the adjacent unbonded post-tension strand  101  generally underlying the region  100  ( FIG. 1 .) The unbonded post-tension strand plate  802 . The first U-shaped plate  801  is identical in shape as compared to the U-shaped plate  201 , described earlier. Structurally, the first U-shaped plate  801  comprises a first planar portion  803 , a second planar portion (shown in  FIG. 9  as  804 ) that is spaced apart from and parallel to the first planar portion  803 , a first arcuate portion  805  that is connected to the first and second planar portions  803 ,  804 , and a first open side portion  806  located opposite the first arcuate portion  805 . 
         [0041]    The second U-shaped plate  802  is identically shaped as the first U-shaped plate  801 , yet different in size. The second U-shaped plate  802  is comprised of a third planar portion  807 , a fourth planar portion  808  that is spaced apart from and parallel to the third planar portion  807 , a second arcuate portion  809  that is connected to the third and fourth planar portions  807 ,  808 , and a second open side portion  809  located opposite the second arcuate portion  809 . The principal difference between the first and second U-shaped plates is that the second arcuate portion  809  is larger than the first arcuate portion  805 . As a result, the distance separating the third and fourth planar portions  807 ,  808  is larger than the distance separating the first and second planar portions  803 ,  804 . This allows the second U-shaped plate  802  to fit over the first U-shaped plate  801 . 
         [0042]    Referring now to  FIG. 9 , shown is a cross-section of the unbonded post-tension strand protector  800  taken along the line  9 - 9  of  FIG. 8  that is useful for understanding the invention. First distal ends  902  of the first U-shaped plate  801  are each formed with a first undulation  903 . The first undulations  903  are intended to securely fasten the first U-shaped plate  801  over the selected region  100  (shown in  FIG. 1 ) of the unbonded post-tension strand  101 . Each first undulation  903  is curved away from the other such that each of their respective first convex portions  904  are spaced from and facing each other. The closest distance between first convex portions  904  is less than the diameter of the unbonded post-tension strand  101 . 
         [0043]    In addition, second distal ends  905  of the second U-shaped plate  802  are each formed with a second undulation  906 . Each second undulation  906  is curved away from the other such that each of their respective second convex portions  907  are spaced from and facing each other. Since the second undulations  906  are intended to securely fasten the second U-shaped plate  802  to the first U-shaped plate  801 , the closest distance between second convex portions  907  is less than the closest distance between first and second planar portions  803 ,  804 . 
         [0044]    The first U-shaped plate  801  is sized and shaped to be clipped to one or more unbonded post-tensions strands  101 . A second U-shaped plate  802  is sized and shaped to be clipped over the first U-shaped plate  801 . In this regard, the word “clipped” means that the first U-shaped plate  801 , which is already secured to a portion of the unbonded post-tension strand  101 , is in turn inserted through the second open side portion of the second U-shaped plate  802 . The first and second U-shaped plates  801 ,  802  are clipped to one another such that they are arranged in opposite orientations relative to each other. The first U-shaped plate  801  is secured within the second U-shaped plate  802 . The first U-shaped plate  801 , when clipped, would be bounded by the third planar portion, the fourth planar portion, the second arcuate portion, and the second convex portions. In effect, the portion of the unbonded post-tension strand  101  secured by the unbonded post-tension strand protector  800  would now be protected on all sides from any drilling or chipping that would otherwise damage the unbonded post-tension strand discussed in embodiment  200  of the unbonded post-tension strand protector, shown in  FIGS. 2 and 3 . 
         [0045]    According to a preferred embodiment, the first and second U-shaped plates  801 ,  802  are formed of a hard material, such as steel. However, the invention is not limited in this regard and other materials can be used so long as the first U-shaped plate  801  and the second U-shaped plate  802  can resist penetration by a drill bit  210  or a tip of a chipping hammer (not shown). 
         [0046]    Referring now to  FIG. 10 , shown is a process flow diagram illustrating a method for protecting at least one unbonded post-tension strand in a pre-cast concrete body using the apparatus illustrated in  FIGS. 2-9 . Method  1000  begins with step  1002  and continues with step  1004 . In step  1004 , at least one unbonded post-tension strand is selected. After selecting the unbonded post-tension strand, method  1000  continues with step  1006  where at least one unbonded post-tension strand is positioned in a pre-cast concrete body before the concrete is cast in the concrete body. In step  1008 , selected portion(s) of at least one unbonded post-tension strand to be protected is/are identified. In step  1010 , the selected portion(s) of one or more unbonded post-tension strands is/are protected by placing at least a portion of a protective layer adjacent to the selected portions. The method ends with step  1012 . 
         [0047]    All of the apparatus and methods disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the invention has been described in terms of preferred embodiments, it will be appreciated by those skilled in the art that variations may be applied to the apparatus, methods and sequence of steps of the method without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain components may be added to, combined with, or substituted for the components described herein while the same or similar results would be achieved. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined. Accordingly, the particular arrangements disclosed are meant to be illustrative only an not limiting as to the scope of the invention which is to be given the full breadth of the appended claims and any and all equivalents thereof.