Patent application title: Reinforcement bar support
Kiel E. Strahin (Stock Bridge, GA, US)
IPC8 Class: AE04C512FI
Class name: Static structures (e.g., buildings) assembled in situ-type anchor or tie with feature engaging form
Publication date: 2010-02-04
Patent application number: 20100024346
The proposed support is preferably constructed from high-compression
concrete and may be custom-dimensioned according to project requirements.
The support may have one or more bearing pads at one or more heights
which may include one or more anchoring arms. The support may include a
bore sized to accommodate a range of rebar sizes. A length of pre-cut
angled rebar may be may be cast in place or may be secured within the
bore by epoxy or other means at the time of manufacture or in the field.
To maximize stability and overcome low soil-bearing capacity, the bottom
surface area of the support is preferably larger than the bearing pad
surface area. At least two opposing sides of the support include at a
shear-key to anchor the support within the finished slab.
1. A support structure comprising:a body having a bottom surface and a top
surface, and wherein the body has at least one inclusion between the top
surface and the bottom surface for vertically anchoring the support
structure in a finished concrete slab.
2. The support structure recited in claim 1 wherein the area of the bottom surface is greater than the area of the top surface.
3. The support structure recited in claim 2 wherein the shape of the support structure is at least one of frusto-pyramidal and frusto-conical.
4. The support structure recited in claim 2 and further comprising an anchoring structure.
5. The support structure recited in claim 4 wherein the anchoring structure a has a first end, a second end, and a midsection extending between the first and second ends.
6. The anchoring structure recited in claim 5 wherein the midsection includes at least one bend.
7. The anchoring structure recited in claim 5 wherein at least one of the first and second ends of the anchoring structure has a circumference which is greater than the circumference of the midsection.
8. The support structure recited in claim 4 wherein the anchoring structure is a bore extending into the support structure.
9. The anchoring structure recited in claim 8 and further comprising a support member having a first end, a second end, wherein the support structure includes at least one bend and wherein the first end of the support member is supported within the bore.
10. The support structure recited in claim 4 wherein the length of the bottom surface exceeds the width of the bottom surface.
11. The support structure recited in claim 10 wherein the top surface of the support structure comprises at least a first section at a first height relative to the bottom surface, and a second section at a second height relative to the bottom surface, and wherein the height of the first section exceeds the height of the second section.
12. A process for manufacturing a support structure comprising the steps of:providing a form having a floor and a side wall, and having a height, length, and width which correspond to a set of desired support dimensions;placing a first bearing pad insert, having at least one of a support groove and a through bore, onto the floor of the form;performing at least one of inserting a dowel into a through bore on the bearing pad insert, the size of the dowel corresponding with the dimensions of the support bore to be formed in the support structure, and inserting an inverted anchoring arm into a support groove on the bearing pad insert;placing a first shear key insert within the form;pouring a concrete mixture into the form and allowing the concrete mixture to set; andafter allowing the support structure to cure completely, removing the support structure from the form.
13. The process recited in claim 12, and further comprising the step of lining the form with a non-stick liner prior to installing the shear key insert.
14. The process recited in claim 12, and further comprising the step of coating the liner with a releasing agent prior to pouring the concrete mixture.
15. The process recited in claim 12, and further comprising the step of applying a sealant between the bearing pad insert and the form prior to pouring the concrete mixture.
16. The process recited in claim 12 and wherein the pouring a concrete mixture into the form step includes the steps of pouring a succession of concrete layers and smoothing each layer before the subsequent layer is poured.
17. The process recited in claim 12 and further comprising the step of selecting a second bearing pad insert which includes at least one of a support groove and a through bore and placing the second bearing pad insert into the form on top of a step insert provided adjacent the side wall.
18. The process recited in claim 12, and further comprising the steps of:providing a high-strength reinforcing member which has been right-angle cut to a specified length and has been angled to form a first end and a second end;applying a cement to the first end of the reinforcing member; andinserting the first end of the reinforcing member into the support bore to fix the reinforcing member into the support structure.
19. A process for using a support structure comprising the steps of:determining the site designated for concrete slab placement;placing a support structure having a body with a top surface and a bottom surface, the top surface including at least one of an anchoring arm and an elevated support member, atop at least one of grade and decking; andpouring concrete to a level over the support structure to form a concrete slab.
20. The process recited in claim 19 and further comprising the steps of securing at least one of a component of a reinforcing mat or a component of a post-tension cable to at least one of the anchoring arm and elevated support member.
FIELD OF THE INVENTION
The present invention relates to improved technology in the field of reinforcement bar support structures used in concrete construction, and more particularly to an economical, precast, high-compression concrete support structure which has a size and overall configuration that is application-specific, which has a footprint that overcomes low soil-bearing capacity where the support is used directly adjacent grade, which eliminates the need for continuous runners on metal decking, which stably supports reinforcement material prior to placement of wet concrete during slab formation, which facilitates convenient tie wire attachment of reinforcement material with a minimum of effort, and which interlocks with the finished concrete slab.
BACKGROUND OF THE INVENTION
Various structures are currently available for supporting reinforcement bar (rebar) prior to pouring concrete to form a slab. The support is needed to raise the rebar to a sufficient height to embed it properly within the resulting slab. One widely used conventional support structure is a "wire chair," which typically consists of two or more metal legs, usually steel. Wire chairs may include only a few legs or may include multiple sets of legs with one or more bolsters extending between them. Bolstered wire chairs are generally more expensive than smaller chairs, but their narrow footprint makes them one of the only options currently available for use on corrugated metal decking such as that which typically underlays second or greater story slabs.
Because most wire chair legs are small diameter, they are prone to sink into subgrade when used directly adjacent grade, especially where expansive soil conditions exist, for example in low-lying areas. Although some wire chairs include feet or dowels which extend parallel to ground, the feet are usually so small that this added protection against sinkage is negligible. Sinking can cause the wire chairs to protrude from the resulting slab and wick moisture into the slab and to the rebar, which may lead to rust and/or structural weaknesses. As a result, most wire chairs require plates affixed to the legs to enlarge the footprint area. The cost of wire chairs increases based on size and quantity of additional foot plates necessary to avert sinkage. Even where the cost of plate-enhanced wire chairs may be feasible, the increased footprint area they may provide may still be insufficient to appreciably prevent sinkage. The spindly structure of wire chairs also makes them especially prone to inadvertent lateral displacement.
Another concern with wire chairs is their propensity to form rust. This may be especially problematic in finished overhead slabs where any rust that forms may be visible and may also come into contact with humidity or rainwater and cause damaging runoff (for example, to vehicles parked in cement parking garage structures). Consequently, wire chairs for use in overhead slabs generally require the added expense of plastic tips, epoxy, or some other protective coating to try to prevent rust with varying degrees of success.
Finally, the price of even the most simple conventionally available wire chairs can be quite high, which can significantly impact total cost of construction where large numbers of wire chairs are needed. In commercial building projects, it is not unusual to need as many as 30,000 wire chairs. Cost is greater where coated chairs are necessary. The cost may increase even further where bolstered chairs are needed for metal decking. Finally, in thicker concrete slabs with more than one layer of reinforcement, the number of chairs needed may easily double.
The high cost of wire chairs may lead builders to use shorter, less expensive chairs that fall shy of the 3-inch minimum height required by national building code. Cutting chair height could compromise the structural integrity of the finished slab since the height of the chairs directly affects placement of reinforcement within the slab.
Other conventional rebar supports include dobies, often available only in pallet quantities. In plainest form, a dobie is a 6-sided square or rectangular block around which tie wire must be wrapped to when securing supported rebar. Wire wrapping the circumference of the dobie requires displacing the dobie, which may be problematic where initial placement is important. Further, circumferential wrapping requires significant time and labor, more so in sizeable construction projects. Plain dobies also include no features for keeping rebar in position, which may increase time and labor required if repositioning is necessary prior to wiring the rebar in place. Limited availability may also negatively impact costs where odd or ongoing quantities are needed. Finally, because the plain dobie is smooth-sided, it does not integrate with the finished slab. Consequently, a sizeable cold joint is created, which may cause the dobie to shift or settle and could lead to structural weaknesses in the finished slab.
A second type of conventionally available dobie is essentially identical to the plain dobie except that it includes a set of tie wires with which to secure supported rebar. The tie wires are typically 16-gauge annealed wire, which easily forms rust with exposure to the elements and subsequently becomes brittle and prone to breakage. This is especially a concern where the dobie will not be used immediately and may be exposed to moisture in the interim between acquisition and usage, almost always the case in construction projects. Despite the high potential for breakage of tie wires, the wire dobie may be up to 70% more costly than the plain dobie. Further, where breakage occurs, time and labor is likely to be lost on circumferential wrapping just as with the plain dobie.
A third type of conventionally available dobie is a combination dobie. The combination dobie has an elongate rectangular shape that allows for use at one of two heights depending on whether it is positioned on a short side or a long side. Combination dobies include a channel for keeping supported rebar in position prior to wiring, usually along one long side and one short side. During use, at least three sides of the combination dobie will remain unintegrated with the finished slab, making it subject to the same cold joint problems described above. Moreover, time and labor is likely to be lost on circumferential wrapping just as with the plain dobie.
A fourth conventionally available dobie is a dowel dobie, similar to the combination dobie except that one of the two channels is replaced by a hole. The channel may be used to support a reinforcing mat at a lower height, or the hole may be fitted with rebar to elevate a reinforcing mat. Because a single channel (or alternatively the hole) will not sufficiently anchor the dowel dobie within the finished slab, settling and slab integrity are still concerns.
Another conventional structure for supporting rebar, yet one which is not generally approved by structural engineers or inspectors, is concrete brick, usually constructed from lower-strength (typically 1500 psi) concrete. National building standards require at least 3 inches between a reinforcing layer and grade, necessitating a minimum 3-inch support. Despite the fact that concrete bricks may not satisfy code, contractors often resort to using them because they may be cheap and, positioned with their largest surface area side adjacent soil, they may overcome low soil-bearing capacities better than currently available alternatives.
What is therefore needed is a structural support which is constructed of high-compression concrete, can stably support reinforcement materials during concrete slab formation, is designed to overcome low soil-bearing capacities, eliminates the need for bolstered chairs on metal decking, minimizes the possibility of rust in the finished slab, facilitates convenient tie wire attachment with minimum effort, securely integrates with the finished slab to minimize the possibility of settling and shifting, is pre-cast to satisfy code and construction specifications, yet is economical.
SUMMARY OF THE INVENTION
The support of present invention is affordable, effective, and superior to conventionally available alternatives. The proposed support may be pre-cast to specification. The support is preferably constructed of high-compression concrete, typically exceeding 2,500 psi. The overall shape of the support may be, but is not limited to, any shaped base leading up to an upper surface and may be frusto-pyramidal with as little as three sides, to an infinite number of sides (of any shape) to approach a frusto-conical shape, as well as any other shape which lends itself to the present invention. The height of the support may vary based on the height of the slab, the relative height needed for the rebar reinforcing layer, or code requirements. The support may be cast with multi-level bearing pads where a single slab will include more than reinforcing layer. The width and length of the support may be varied according to structural engineering and code requirements of a given construction project.
The support may include one or more anchoring arms which may be sized according to the size of reinforcement material to be supported. The anchoring arms are preferably constructed from steel, including, but not limited to, plain, hot dipped galvanized, or stainless. Reinforcement material may be conveniently wired to one or both anchoring arms without displacing the support. The anchoring arms may be cast in place during manufacturing, and may preferably be situated a sufficient distance from the edges of the bearing pad surface to prevent the finished slab from cracking over the anchoring arms.
The support may include a blind bore which may be sized to accommodate a range of rebar sizes. Pre-cut angled rebar may be fixed in the bore at manufacture or in the field for supporting a reinforcing mat or post-tension cable at an elevated height. The rebar may be secured in the bore by epoxy or other effective means or may even be cast in place.
The base of the support is preferably larger than the bearing pad surface area to maximize stability, to overcome low soil-bearing capacity, and to broaden the variety of applications in which the support can be used effectively. The sides of the support are preferably sloped, with slope dependent upon both the height of the support and the dimensions of the bearing pad surface and base. Because the support is preferably constructed entirely of concrete with no metal projections which may form rust, the potential for exposed rust in a finished slab is virtually eliminated. The support may also be used successfully on corrugated metal decking as the base may be easily sized to span adjacent ridges or fit within the troughs between ridges.
The support may preferably include one or more shear-keys to help anchor the support in the finished slab. The shear-keys may be any of a variety of shapes, including, but not limited to, cylindrical, square, trapezoidal, pyramidal, angular, or other.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention, its configuration, construction, and operation will be best further described in the following detailed description, taken in conjunction with the accompanying drawings in which:
FIG. 1 is a perspective view of a first embodiment of the support of the present invention having a cylindrically-shaped shear key on each of two opposing sides and a bearing pad with a pair of anchoring arms extending therefrom;
FIG. 2 is a side view of the support of FIG. 1 in which the full length of one of the cylindrically-shaped shear keys and one of the anchoring arms is visible, and FIG. 2 further details the anchoring arm;
FIG. 3 is a perspective view of a second embodiment of the support of the present invention having a cylindrically-shaped shear key on each of two opposing sides and having a blind bore opening onto a bearing pad;
FIG. 4 is a side view of the support of FIG. 3 in which one of the cylindrically-shaped shear keys is visible, and illustrates further details of the blind bore and includes a length of rebar vertically positioned in the blind bore;
FIG. 5 is a perspective view of a third embodiment of the support of the present invention having a cylindrically-shaped shear key on each of two opposing sides and a bearing pad with an anchoring arm extending therefrom and a blind bore therein;
FIG. 6 is a side view of the support of FIG. 5 in which one of the cylindrically-shaped shear keys is visible, and illustrates further details of the anchoring arm and the blind bore and includes a length of rebar positioned vertically within the blind bore;
FIG. 7 is a perspective view of a fourth embodiment of the support of the present invention having a cylindrically-shaped shear key on each of two opposing sides, an angled shear key, a blind bore opening onto an upper bearing pad, and an anchoring arm extending from a lower bearing pad;
FIG. 8 is a side view of the support of FIG. 7 in which the angled shear key and one of the cylindrically-shaped shear keys is visible, and illustrates further details of the anchoring arm and blind bore and includes a length of rebar positioned vertically in the blind bore;
FIG. 9 is a plan view of the support of FIG. 5 which illustrates the positioning of the support relative to two reinforcing layers within a single concrete slab;
FIG. 10 is a plan view illustrating installation of the support of FIG. 3, including a post-tension cable sheath and enclosed cable suspended from a pair of supports;
FIG. 11 is a top view of a gang form with multiple compartments for constructing multiple supports simultaneously;
FIG. 12 is a top view of a bearing plate insert which includes a through bore and a support groove;
FIG. 13 is a cross-sectional view of the compartment of FIG. 11 outfitted for constructing supports such as the third embodiment of the support;
FIG. 14 is a cross-sectional view of the compartment of FIG. 11 outfitted for constructing supports such as the fourth embodiment of the support;
FIG. 15 is a top view of a fifth embodiment of the support of the present invention having a blind bore, an anchoring arm, three sloped sides, a shear key, and an overall frusto-pyramidal shape;
FIG. 16 is a top view of a sixth embodiment of the support of the present invention having a blind bore, an anchoring arm, eight sloped sides, a shear key, and an overall frusto-pyramidal shape;
FIG. 17 is a top view of a seventh embodiment of the support of the present invention having a blind bore, an anchoring arm, one continuous sloped side, a shear key, and an overall frusto-conical shape; and
FIG. 18 is a top view of an eighth embodiment of the support of the present invention having a blind bore, a pair of anchoring arms, one continuous sloped side, a pair of shear keys, and an overall elongate frusto-conical shape.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
The description and operation of the invention will be best initiated with reference to FIG. 1, which is a perspective view of a first embodiment of the bar support 51 of the present invention which is ideal for slabs under 8 inches thick requiring only a single layer of reinforcement. Support 51 may preferably be constructed of a high-compression concrete such as 2,500 psi or greater. Support 51 may be frusto-pyramidal shaped, the embodiment shown being a pyramid with four sides, but which may also have three sides, or more than four sides, or any up to an infinite number of sides, and the shape of which may also be conic, cylindrical, or frusto-conical. The support 51 may have a first side 55, a second side 57, a third side 61 oppositely disposed from first side 55, and a fourth side 63 oppositely disposed from second side 57.
Support 51 may have a bearing pad surface 65 and a base surface indicated by hooked arrow 67. The area of base 67 may preferably be larger than that of bearing pad surface 65 to increase stability of support 51 and facilitate ease of use in a variety of applications. The larger area of base 67 is ideal where soil-bearing capacity is lessened by wet conditions such as those in low-lying areas or where underground water is a concern. Additionally, because base 67 may be customized to a given size, support 51 is optimal for use on metal decking, where corrugations make the use of conventional supports difficult because they may tilt if the base size is only slightly larger than a corrugation trough.
Bearing pad surface 65 may include a first anchoring arm 69 and possibly a second anchoring arm 71. Anchoring arms 69 and 71 may preferably be constructed from bent rods of any cross sectional shape which may preferably range from 3/32 to 3/8 inch in diameter, depending on the size of rebar to be supported and engineering specifications. Anchoring arms 69 and 71 may preferably be fabricated from steel, which may be, but is not limited to, plain, hot dipped galvanized, mill galvanized, or stainless. Anchoring arms 69 and 71 may preferably be cast in place in support 51 and positioned 1/4 to 3/4 inch from edges of bearing pad surface 65 to prevent the finished slab from cracking over anchoring arms 69 and 71.
First side 55 may include a first shear key 75 and third side 61 may include a second shear key 77. A third or fourth shear key may also be present. The overall shape of support 51 and opposing shear keys 75 and 77 help to anchor support 51 in place, potentially minimizing shifting and settling and the consequent potential for developed structural deficiencies in the finished slab.
Although support 51 is illustrated in FIG. 1 as having two shear keys 75 and 77, any or all of sides 55, 57, 61, and 63 may conceivably include other shear keys. Shear keys 75 and 77 are illustrated in FIG. 1 as cylindrically-shaped voids but may be any shape forming an irregularity, including, but not limited to, square, rectangular, trapezoidal, angular, or other shape that would facilitate anchoring support 51 in place in a finished slab. Because strength of shear keys 75 and 77 will be determined by the strength of concrete in the finished slab, support 51 may preferably be constructed from about the same or greater strength concrete as that of the finished slab.
Also illustrated in FIG. 1 are dimensions of support 51. Overall height H1, measured from bearing pad surface 65 to base 67, may be from about 3/4 to about 12 inches, depending on the planned slab thickness, the thickness of concrete required above the level of reinforcement and/or building code. Width W1 and length L1 of bearing pad surface 65 may each range from about 1 to about 4 inches and may be driven by H1 and the size of base 67. Width W2 and length L2 of base 67 may each range from about 4 to about 12 inches. Area of base 67 may be prescribed based upon soil conditions or other engineering concerns.
Based on the possible measurements for H1, W1, W2, L1 and L2, angle α may range from about 97° (at maximum H1 of 12 inches, minimum W1 and L1 of 1 inch, and minimum W2 and L2 of 4 inches) to about 170° (at minimum H1 of 3/4 inch, maximum W1 and L1 of 4 inches, and maximum W2 and L2 of 12 inches). Similarly, angle β may range from about 10° to about 83°. Because support 51 is symmetrical, the possible ranges of angles δ and ε will be similar to those described for angles α and β.
FIG. 2 is a side view of support 51 of FIG. 1 in which first side 55, first cylindrically-shaped shear key 75, and first anchoring arm 69 are visible. The depth of shear key 75 measured from first side may preferably be about 1/4 inch to ensure a shear strength sufficient to keep support 51 in place in the finished slab, but may also be as great as 1/2 inch, for example where height H1 exceeds 6 inches and the area of base 67 exceeds 36 inches. Distance D1 between bottom edge of shear key 75 and base 67 may preferably be about 3/4 inch, but may exceed 3/4 inch if engineering specifications require.
Height H2 of anchoring arm 69 relative to bearing pad surface 65 may preferably be about 3/8 to about 1 inch. Depth D2 of anchoring arm 69 in support 51 may preferably be about 1/2 to about 2.5 inches. FIG. 3 illustrates anchoring arm 69 as a nail having a nailhead 79 and, tip 81, and main body 83, but anchoring arm 69 could conceivably be reversed 180°, and either end of anchoring arm 69 could include an end such as nailhead 79 having a circumference greater than the circumference of the exposed portion of anchoring arm 69, the term "circumference" not limiting the shape of anchoring arm 69 but including the sum of the cross-sectional boundary lengths of any of a variety of possible cross sectional shapes. Further, anchoring arm 69 could conceivably be a simple rod which may have a cross-sectional diameter of any shape, such as round, square, octagonal, triangular, or any other shape, and which may have straight ends or may include angled ends to help secure anchoring arm 69 withing support 51.
FIG. 3 is a perspective view of a second embodiment of the bar support 85 of the present invention which is ideal for use in slabs under 6 feet thick requiring only a single reinforcing mat. Support 85 has dimensions similar to those described for support 51 in FIGS. 1 and 2. Rather than having anchoring arms, support 85 may include a blind bore 87 extending partially through support 85 and opening onto bearing pad surface 65 at opening 89.
FIG. 4 is a side view of support 85 of FIG. 3 in which shear key 75 is visible, and FIG. 4 further illustrates a length of angled rebar 91 positioned vertically in bore 87. Rebar 91 may preferably include a bend of about 90 degrees, creating a horizontal portion 93 and a vertical portion 97. Horizontal portion 93 facilitates support of either a single reinforcing mat or a post-tension cable at a specified elevation. To ensure that a reinforcing mat will be supported at the proper height, vertical portion 97 of rebar 91 may be cast in place or may be otherwise fixed in place in bore 87 during manufacture, preferably using a glue cement, such as epoxy. Alternatively, rebar 91 may be secured in place in the field using epoxy or any other means by which rebar 91 may be fixed at the proper height.
D3 indicates the depth of bore 87 in support 85. To effectively support rebar 91, bore 87 may preferably be at least 2 inches deep. Further, for optimal structural integrity of support 85, there may be at least one inch between bottom of bore 87 and base 67. Consequently, H1 for support 85 may preferably be at least 3 inches to accommodate bore 87.
Diameter D4 of bore 87 and opening 89 may be sized to accommodate rebar from about 3/8 inch (#3 bar) to about 1 inch (#8 bar). Though FIG. 4 illustrates horizontal portion 93 of rebar 91 in a random position, rebar 91 may be rotated 360° in any direction prior to being secured in bore 87. Rebar 91 may preferably be grade 60 (60,000 psi tensile strength) or better, free of rust scale, and may be epoxy coated to prevent rust formation.
Height H3 may be determined by where the reinforcing mat is to be located within the finished slab. If necessary, height H4 may also be varied by vertically adjusting rebar 91 prior to securing it in bore 87.
FIG. 5 is a perspective view of a third embodiment of the bar support 99 of the present invention which is ideal for use in slabs requiring both an upper and a lower reinforcing mat. Support 99 may have a first short side 103, a first long side 105, a second short side 109 oppositely disposed from first short side 103, and a second long side 111 oppositely disposed from first long side 105. Like supports 51 and 85 described in FIGS. 1 through 4, first short side 103 of support 99 may include a first shear key 113 and second short side 109 may include a second shear key 117. Any of sides 103, 105, 109, and/or 111 may conceivably include other shear keys of the same or other shape. Support 99 may also include a bearing pad surface 119 and base 121.
Support 99 may include a blind rebar support bore 123 extending partially through support 99 and opening onto bearing pad surface 119 at opening 125. In addition to support bore 123, support 99 may include an anchoring arm 127 subject to specifications similar to those described for anchoring arms 69 and 71 of FIGS. 1 and 2 above.
FIG. 5 illustrates salient dimensions of support 99, which are similar to those described for support 51 of FIGS. 1 and 2 and support 85 of FIGS. 3 and 4, with the exception of width W1 and width W2, which may be greater than those specified for supports 51 and 85 to insure sufficient space for securing both support bore 123 and anchoring arm 127 and to provide sufficient lateral stability once a second level of reinforcement is introduced. Accordingly, W1 and L1 for support 99 may both range from about 1 to about 4 inches. W2 may range from about 6 to about 12 inches, and L2 may range from about 4 to about 10 inches.
Angle α in FIG. 5 may range from about 94° (at maximum H1 of 12 inches and minimum L1 of 1 inches, W1 and L2 of 4 inches, and W2 of 6 inches) to about 166° (at minimum H1 of 3/4 inch and maximum W1 of 6 inches, L1 of 4 inches, W2 of 12 inches, and L2 of 10 inches). Similarly, angle β may range from about 86° to about 14°, angle δ may range from about 97° to about 144°, and angle ε may range from about 83° to about 36°.
FIG. 6 is a side view of support 99 of FIG. 5 in which shear key 113 is visible, and FIG. 6 further illustrates a length of rebar 131 positioned vertically in support bore 123. Rebar 131 is subject to specifications similar to those described for rebar 91 in FIG. 4 and may be similarly angled to form a horizontal portion 133 and a vertical portion 135.
Measurements H2, H3, H4, D2, D3 and D4 are all subject to specifications similar to those described for similar features in the previous figures. Anchoring arm 127 is subject to specifications similar to those described for anchoring arms 69 and 71 of FIGS. 1 and 2, including 137 and tip 139.
FIG. 7 is a perspective view of a fourth embodiment of the bar support 143 of the present invention which is ideal for use in slabs on elevated decking where both an upper and a lower reinforcing mat are required. Support 143 is essentially a two-level version of support 99 which combines the longer base length of support 99 of FIGS. 5 and 6 with both an upper bearing pad surface 147 and a lower bearing pad surface 149. Support 143 may be defined by a first side 151, a second side 153, an third side 155 oppositely disposed from first side 151, a fourth side 159 oppositely disposed from second side 153, and a fifth side 161 adjacent lower bearing pad surface 149. Support 143 may also include a base surface 163.
First side 151 may include a cylindrically-shaped first shear key 165 and third side 155 may include a cylindrically-shaped second shear key 167 adjacent lower bearing pad surface 149. An angled third shear key 171 may be defined by fifth side 161. Shear keys 165, 167, and 171 are not constrained by the shapes shown, but may be any shape which helps to anchor support 143 in a finished slab.
Support 143 may include a blind bore 173 opening onto upper bearing pad surface 147 at opening 175 and an anchoring arm 177 on lower bearing pad surface 149. The specifications for bore 173 and anchoring arm 177 are similar to those described for similar features of support 99 in FIGS. 5 and 6.
Width W1 of upper bearing pad surface 147 may range from about 1 to about 10 inches, and length L1 may range from about 1 to about 8 inches. Width W2 of base 163 may range from about 6 to about 12 inches and length L2 of base 163 may range from about 4 to about 10 inches. Width W3 of lower bearing pad surface 149 may range from about 1 to about 10 inches, and width L3 may range from about 1 to about 8 inches.
Angle α may range from about 101° (at maximum H1 of 12 inches, and minimum W1 and L1 of 1 inches, W2 of 6 inches, and L2 of 4 inches) to about 144° (at minimum H1 of 3/4 inch and maximum W1 of 10 inches, L1 of 8 inches, W2 of 12 inches, and L2 of 10 inches). Angle β may range from about 79° to about 36°.
Although lower bearing pad surface 149 is shown with L3 equal to L2, L3 may be narrower than L2, for example if lower bearing pad surface 149 was tapered or if second and fourth sides 153 and 159 were indented along lower bearing pad surface 149. Conversely, L3 may be greater than L2 if second and fourth sides 153 and 159 were widened along lower bearing pad surface 149. Furthermore, although second and fourth sides 153 and 159 are shown as having a continuous slope from first side 151 to fifth side 161, their slope could conceivably change between upper bearing pad surface 147 and lower bearing pad surface 149. For example, second and fourth sides 153 and 159 may be angled farther inward toward lower bearing pad surface 149 or farther outward away from lower bearing pad surface 149.
FIG. 8 is a side view of the support 143 looking along line 8-8 of FIG. 7. Ranges for D2, D3, D4, H1, H2, H3, and H4, are similar to those described for similar features of support 99 in FIGS. 5 and 6. For elevated decking, code generally requires that a lower reinforcing mat be no less than 3/4 inch from the decking. Accordingly, height H5 between lower bearing pad surface 149 and base 163 may range from about 3/4 inches to about 2.75 inches. Angle δ may range from about 97° at maximum H1 to about 144° at minimum H1. Angle ε may range from about 83° to about 36°.
For structural soundness, the angular shape of third shear key 171 may preferably be employed only where H5 is less than about 1.5 inches. The features of anchoring arm 177 are similar to the features of anchoring arms described in previous figures, including nailhead 179 and tip 181.
FIG. 9 is plan view which illustrates support 99 in a finished concrete slab 183 adjacent grade 185. First long side 105 of support 99 and profiles of first and second shear keys 113 and 117 are visible. A first reinforcing bar 187 may be secured to anchoring arm 127 with tie wire 189 and may be a component of a lower reinforcing mat 191. A second reinforcing bar 195 may be secured to horizontal portion 133 of rebar 131 with a first tie wire 197 and may be a component of an upper reinforcing mat 199. Upper reinforcing mat 199 may be secured to second reinforcing bar 195 by a second tie wire 201. Finished slab 183, including top surface 203, results from pouring concrete over support 99 above grade 185.
FIG. 10 is 2-dimensional installation view illustrating two supports 85 which are similar in appearance but which may or may not be identical. Supports 85 are shown elevating a post tension cable sheath 207 and enclosed wire 209. Each support 85 is shown adjacent grade 211 with first short side 103 and first shear key 75 visible. Post tension cable sheath 207 with enclosed wire 209 may be extended over horizontal portion 93 of rebar 91 of each support 85 and may be secured by tie wire 213. Base 67 is designed to optimize stability and minimize slack in post tension cable sheath 207 and enclosed wire 209 as most applications generally require post tension cable sheath 207 to be as straight as possible prior to pouring the planned slab.
A description of the process used to form various embodiments of the support of the present invention is best initiated with reference to support 99, although the process may be used to form any of supports 51, 85, 99, or 143 in the previous FIGS. 1 through 10 or any of supports 287, 301, and 315 in subsequent FIGS. 15 through 17.
FIG. 11 is a top view of an empty gang form 215. Gang form 215 may be constructed from any of a variety of materials, though wood is ideal for cost and availability. For simplicity, gang form 215 is illustrated with only two compartments 217, each of which has a floor 219, a first short side wall 221, a first long side wall 223, a second short side wall 227, and a second long side wall 229. In fact, gang form 215 may have any number of compartments 217. Additionally, although each compartment 217 is shown as generally rectangular, each may also be generally square or any other shape which facilitates formation of the proposed support.
FIG. 12 is a perspective view of a bearing plate insert 231 for use in gang form 215 of FIG. 11. Bearing pad insert 231 may have a top surface 233, bottom surface 234, first short side wall 235, a first long side wall 239, second short side wall 241, and second long side wall 243, all of which may be complimentary in length and slope to side walls 221, 223, 227, and 229 of compartment 217. Although bearing pad insert 231 may include a through bore 245 and a support groove 247 bisecting top surface 233, it is conceivable for bearing pad insert 231 to have any number of similar through bores and/or grooves, depending on the type of support to be formed.
Continuing to use support 99 as an example, to achieve the proper height between anchoring arm 127 and bearing pad surface 119, groove 247 may preferably be from about 1/2 to about 3/4 inch deep, the depth being sufficient to support the "nail" without an interference fit. Groove 247 may extend completely across bearing pad insert 231 to allow for custom length or placement of an anchoring arm. Groove 247 may preferably be from about 1/4 to about 1/8 inch in diameter. Similarly, through bore 245 may preferably have a diameter from about 1/2 to about 1 inch to accommodate various rebar sizes.
FIG. 13 is a cross-sectional view of a compartment 217 of gang form 215 of FIG. 11 which has been outfitted to form a support such as support 99 of FIGS. 5 and 6. Bearing pad insert 231 may preferably be adjacent floor 219 such that side walls 235 and 241 are adjacent side walls 221 and 227, respectively, of compartment 217. A sealant 249, such as caulk or tape, may be used to seal any gaps between bearing pad insert 231 and side walls 235, 239, 241 and 243 of compartment 217.
Bearing pad insert 231 is shown with anchoring arm 127 inverted in support groove 247 and a dowel 251 inserted in through bore 245 to form rebar support bore 123. Dowel 251 may vary in height depending upon the desired depth of a given bore. A liner 253 may be seen adjacent side walls 221 and 227 and may preferably extend along all side walls of compartment 217. Liner 253 may preferably be constructed from material which will facilitate easy removal of a finished support from compartment 217, such as plastic, vinyl, or metal, for example. Further, liner 253 may be coated with a release agent prior to pouring support 99 to make the resulting support 99 easier to remove from form 215.
A first shear key insert 255 may preferably be installed adjacent or attached to liner 253 along first short side wall 221 and a second shear key insert 257 may preferably be installed adjacent or attached liner 253 along second short side wall 227. Shear key inserts 255 and 257 are illustrated as cylindrically-shaped but may be any shape, including trapezoidal, square, angled, or pyramidal, for example. Other shear key inserts may be added as necessary.
FIG. 13 illustrates a container 259 from which high-compression concrete 263 may be poured into compartment 217. At an end-user's option, concrete test cylinders may be made and tested for strength to ensure compliance with American Concrete Institute standards. Preferably, concrete 263 may be prepared no more than 30 minutes prior to pouring and may be poured in 1-inch layers. Each layer may preferably be consolidated (for example by smoothing with a cylindrical rod) prior to pouring successive layers. The final layer of concrete 263 may preferably be leveled even with the top edge of form 215 and smoothed with a leveling bar to produce a flat finish on the exposed base 121.
After approximately 4 to 6 hours, support 99 may be removed from compartment 217 by inverting form 215 and gently tapping to break any bonds between form 215 and concrete 263. Once support 99 is free of form 215, form 215 may be lifted away, leaving liner 253 in place to protect support 99 from vibration and movement as it continues to cure. Optimally, support 99 should be cured at least 24 hours before removing it from liner 253. During the curing process, base 121 may be engraved with information which may include, but is not limited to, specifications of the support useful for forensic purposes.
Rebar 131 may preferably be cut to a pre-specified length according to project requirements. It may be preferable for the load-bearing end of rebar 131, which may ultimately be inserted into support bore 123, to be cut as nearly as possible to 90° relative to vertical portion 135 to prevent loading and punching. Rebar 131 may be secured in bore 131 at the time of manufacture or later in the field. Further, although a considerably more complicated endeavor, rebar 131 may be cast in place in support 99 during manufacture.
A description of the process used to form various embodiments of the support of the present invention is best continued with reference to support 143, although the process may be used to form any of supports 51, 85, 99, or 143 in the previous FIGS. 1 through 10 or any of supports 287, 301, and 315 in subsequent FIGS. 15 through 17.
FIG. 14 is a cross-sectional view of a compartment 217 in form 215 of FIG. 11 which has been outfitted to form a support such as bi-level support 143 of FIGS. 7 and 8, for example. A first bearing pad insert 265 may be adjacent floor 219, including a dowel 267 for forming bore 173. A step insert 269 may be installed adjacent second short side wall 227 and floor 219. A liner 271 may be installed adjacent first short side wall 221, step insert 269 and side wall 227. A first cylindrically-shaped shear key insert 275 may be installed adjacent liner 271 along first short side wall 221, and a second cylindrically-shaped shear key insert 277 may be installed adjacent liner 271 along step insert 269. An angled shear key insert 279 may be installed adjacent second short side wall 227. A second bearing pad insert 281 is shown adjacent step insert 269 and second short side wall 227, including inverted anchoring arm 177 with nailhead 179. Compartment 217 may be filled with concrete 283 by process similar to that described in FIG. 13.
FIG. 15 is a top view of a support 287. A bearing pad 289 may have a bore 191 and an anchoring arm 193, either singly or in combination. Three sloped sides 295 extend between bearing pad 189 and the outside edge of a base 297. Sides 295 may include shear keys 296, which may number greater or fewer than shown. Support 287 may have an overall frusto-pyramidal shape with "N" sides, where N represents the total number of sides, which may range from three (as in support 287 of FIG. 15) to any intermediate number between three and infinity (see FIG. 16, for example, where N is 8) to an infinite number of sides, which may result in a frusto-conical shaped support (see FIG. 17, for example).
FIG. 16 is a top view of a support 301 which represents an exemplar intermediate step in the progression of support shapes possible as the number of sides N of a given frusto-pyramidal support approaches infinity. Support 201 may include bearing pad 303 with bore 305, anchoring arm 307, or any combination thereof. Eight sloped sides 309 (i.e., N=8) may extend between bearing pad 303 and the outside edge of a base 311, but N may be any number, and, as N approaches infinity, a frusto-conical shaped support such as that in FIG. 17 may result. Sides 309 may include shear keys 310, which may number greater or fewer than shown.
FIG. 17 is a top view of a support 315 which may have a bearing pad 317 with bore 319, anchoring arm 321, or any combination thereof. A single, continuous sloped side (N=∞) 323 may extend between bearing pad 317 and the outside edge of a base 325, which may result in an overall frusto-conical shaped support 315. Side 323 may include shear key 324, which may be continuous along side 323 as shown or may be discontinuous along side 323 such as in FIG. 18.
FIG. 18 is a top view of support 329 which may have an elliptically-shaped bearing pad 331, bore 333, pair of anchoring arms 335, or any combination thereof. Like support 315 of FIG. 17, support 329 may have a single, continuous sloped side (N=∞) 337 extending between bearing pad 331 and the outside edge of an elliptically-shaped base 339, which may result in an overall elongate frusto-conical shaped support 329. Side 337 may include opposing shear keys 341, which may alternatively be continuous along side 337 such as shear key 324 of support 315 of FIG. 17.
Although the invention has been derived with reference to particular illustrative embodiments thereof, many changes and modifications of the invention may become apparent to those skilled in the art without departing from the spirit and scope of the invention. Therefore, included within the patent warranted hereon are all such changes and modifications as may reasonably and properly be included within the scope of this contribution to the art.
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