1. Technical Field
The present disclosure relates generally to chairs and spacers that are used in construction activities for the support of steel reinforcement members within concrete structures, and in particular to a stackable chair that reliably retains reinforcement bars, post-tension cables, rods, and the like.
2. Description of the Related Art
Chairs or spacers are commonly used in the construction industry for the support and positioning of steel reinforcement members such as post-tension cables and/or reinforcement bars (“rebar”) a proper distance above a surface. Rebar is usually arranged in rows or grids within an area into which concrete is to be poured, and held loosely in place while concrete is placed around it. In normal use, a receiving area formed on the chair will contact and support the rebar while the base of the chair rests on a deck or on a grade.
Proper spacing and arrangement of steel reinforcement members in concrete slabs according to known engineering and architectural specifications impacts the structural strength and integrity of the concrete structure. Such steel reinforcement requires sufficient cover to avoid exposing the steel to the effects of moisture-penetrating corrosion. Once the steel is exposed to the effects of chemical-laden moisture, corrosion starts taking effect.
Known prior art chairs have desirable features which provide the proper support of rebar or post-tension cables safely within a concrete structure. Some chairs also have additional desirable features. For example, U.S. Pat. No. 5,729,949 to Hartzheim discloses a readily stackable chair with a hollow-conical body that minimizes the amount of shipping and storage space required. These chairs have support legs with apertures between them to allow concrete to flow into the hollow interior of the chair. A worker can carry many chairs at one time and place numerous chairs at a construction site without repeated trips to a storage area.
U.S. Pat. No. 6,089,522 to Haslem et al. discloses a stackable high chair having a lower base portion, an upper connecting portion and an upper support surface. The upper support surface includes bisecting cross members which join opposing corners of the upper support surface. Inclined ramps extend upwardly from the support surface and serve to position the rebar along the upper surface. The upper support surface also includes a plurality of holes which allow a head piece to be mounted to the chair, thereby allowing the height of the chair to be readily adjusted.
While the prior art chairs described above may be useful for their respective, particular objectives, a need exists for a stackable chair that is tall enough to support rebar a significant distance above a surface, yet has a simple and strong construction. A further need exists for an economical chair having a uniform base portion and an integral but adaptable receiving area portion, such that a plurality of chairs providing support at different heights may be manufactured using a single molding apparatus.
Accordingly, one objective of the present invention is to provide a chair with a simple yet strong design that is tall enough to support rebar a significant distance above a surface. It is also an objective to provide a tall chair that is light in weight yet able to securely support rebar. Yet another objective is to provide a tall rebar support chair with a wide base that allows the chair to stand securely. It is a further objective to provide a rebar support chair that can be stacked within another chair to provide a more efficient method for packaging, storage, and shipment. It is also a further objective to provide a rebar support chair including an integral receiving area that is adaptable for supporting rebar at different heights above support surface yet manufacturable using a single molding apparatus. Yet another objective is to provide a plastic chair made of durable, non-corroding materials that is easy to manufacture and easy to use.
Briefly stated, these objectives are accomplished by a generally funnel-shaped support chair having a hollow body with an inner surface, an outer surface, a receiving area, and a base. The base defines a lower opening and is adapted to rest on a planar support surface. The receiving area is adapted to receive and support the rebar. The lower opening of the chair is larger than the receiving area, and the inner and outer surfaces are substantially complementary to each other to allow a plurality of chairs to be stacked within each other for storage and shipment. Additionally, the stacking feature allows a worker to carry a stack of chairs at the job site as he places them at desired locations.
In one aspect of the disclosure, the receiving area includes a first and a second pair of curved notches, with the second pair being oriented ninety degrees from the first pair. The first pair of notches has a first depth, and the second pair of notches has a second depth. The first pair is deeper than the second pair, and the chair is thus able to support rebar at different heights and in perpendicular relationships to one another. The receiving area may optionally include a plurality of bridges. A bridge is a band of material that spans the distance within the body of the chair between each of the pairs of notches. The bridges can assist to further increase the supporting strength of the chair, and can connect the medial, lowest portions, or troughs, of the notches.
In another aspect of the disclosure, the base includes a plurality of support legs which define a plurality of apertures, and the apertures allow poured concrete to pass fluidly through the chair. The apertures are preferably arch-shaped, and the support legs preferably have a thickened band of material around the apertures, such that the strength of the chair is reinforced by these thickened areas to allow the support legs to be longer yet retain their strength. In one particular aspect, the base has four support legs, with two of the support legs further including foot members extending horizontally outwardly therefrom, the other two support legs lacking a foot member. In such an aspect, the foot members extend from support legs which are diametrically opposed from one another. In another particular aspect, the base has four support legs, with adjacent support legs being joined by a horizontal strut. In such an aspect, the horizontal struts collectively form a closed, geometrically shaped hoop to prevent buckling or spreading of the support legs.
In another aspect of the disclosure, the base includes upper and lower support legs. The lower support legs are the primary set of legs and are larger than the upper support legs. The receiving area is supported by both the upper and lower support legs, with the upper legs extending downwardly from the receiving area, and the lower support legs extending downwardly from the upper support legs. In one particular aspect, the upper legs can include upwardly extending ribs on their outer surface. These ribs extend along each of the upper support legs between the junction of the lower and upper legs. In such an aspect, the chair can be made to be significantly taller than other chairs of the prior art, and also be light in weight yet strong enough to support rebar securely, and without collapsing under the weight of the rebar. Preferably the chair is advantageously manufactured as a single piece of material, such that the chair can have the height and strength of a chair having a head piece seated on top of a base chair, yet be a single, tall chair with two sets of support legs.
In accordance with another aspect of the disclosure, the body of the chair has multiple substantially straight sides and a substantially square cross-section having rounded corners, with an inner surface that is complementary to the outer surface to allow a plurality of chairs to be stacked together, one inside the other, for storage and shipment. The chair may also have an elliptical, oval or hybrid cross-section. The chair preferably has a wide base which is adapted to rest on a flat support surface. The lower opening is defined by the base and is preferably larger than the upper receiving area, and the inner and outer surfaces are preferably substantially complementary to each other.
In accordance with another aspect of the disclosure, a chair includes an adaptable receiving area having a vertical fin defining an open notch. The receiving area of the chair also preferably includes a gusset projecting perpendicularly from the vertical fin and extending upward to further define the medial, lowest portion of the notch. In one particular aspect, the receiving area of the chair includes four vertical fins defining a first and a second pair of opposed open notches, with first and second pairs of notches being oriented at ninety degrees from each other. The medial, lowest portion of the first pair of notches is located at a lower height than the corresponding portion of the second pair of notches, and the chair is thus able to support rebar at different heights and in perpendicular relationships to one another. Preferably, the receiving area also includes a gusset projecting perpendicularly inward from each vertical fin and extending upward to the medial, lowest portion of each notch to further increase the supporting strength of the vertical fins. In another particular aspect, the receiving area of the chair includes one vertical fin defining an open notch, and a pair of gussets projecting perpendicularly outward from the vertical fin and extending upward to the medial, lowest portion of the notch to both increase the supporting strength of the vertical fin and provide a resistance to tipping.
In accordance with another aspect of the disclosure, the receiving area and the base are integrally formed together from a durable, non-corroding polymeric material. The chairs are easy to manufacture in this fashion, and packaging and storage of the chairs can be done quickly and easily because the chairs are also stackable. These and other aspects of the disclosure will be more fully appreciated with respect to the following drawings and detailed description.
Referring now to
The chair of
The apertures 36 between the support legs 32 are preferably arch-shaped and allow fluid concrete to pass through the body 10 beneath the level of the receiving area 14. The large openings provided by the apertures 36 maximize the free flow of concrete into and around chair 8. The support legs 32 preferably have a thickened band of material 40 around the apertures 36, such that the strength of the chair is reinforced by these thickened areas 40 to allow the support legs 32 to be longer yet retain their strength. As shown, the base 12 has four support legs 32, with two of the support legs further including foot members 34 extending horizontally outwardly therefrom, the other two support legs lacking a foot member. In
As a non-limiting example of how the reinforcement members 38 and 39 are placed within the chair 8, reinforcement member 38 is initially positioned over the receiving area 14 and then lowered into the deep notches 24a. Reinforcement member 39 is then lowered into the shallow pair of notches 24b. Notch pairs 24a are preferably deep enough to allow reinforcement member 38 to sit within the receiving area 14 while also allowing member 39 to sit completely within the shallow notch pairs 24b without interference from member 38.
As shown in
The lower and upper apertures 136, 137 between the lower and upper support legs 132, 133, respectively, are preferably arch-shaped and allow fluid concrete to pass through the body 110 beneath the level of the receiving area 114. The large openings provided by the apertures 136, 137 maximize the free flow of concrete into and around chair 108. The lower support legs 132 preferably have a thickened band of material 140 around the lower apertures 136, such that the strength of the chair is reinforced by these thickened areas 140 to allow the lower support legs 132 to be longer yet retain their strength.
The receiving area 114 shown in
The receiving area 114 of
Apertures are shown in
As illustrated in
As shown in
Referring now to
The first pair of notches 224a and the second pair of notches 224b are oriented at ninety degrees from each other, with the medial, lowest portion, of the first pair of notches 224a being located at a lower height than the corresponding portion of the second pair of notches 224b. Thus, a single chair 208 may support rebar at different heights and in perpendicular relationships to one another. For example, a chair 208 may support a single portion of rebar at one of two heights above a support surface, e.g., at 5.25″ or at 5.5″ above grade, or support a rebar grid in an overlapping, perpendicular relationship, e.g., at 5.25″ and 5.5″ above grade.
The receiving area 214 of a plurality of chairs 208 is adaptable such that different chairs 208 may provide support at different heights above a support surface yet be manufacturable using a single molding apparatus. The receiving area 214 is adapted by altering the length of the vertical fins 250 to vary the height of the medial, lowest portion of the notches 224. For example, a second chair 208 having longer vertical fins 250 but an essentially identical base 212 may support a single portion of rebar at one of two other heights above a support surface, e.g., at 5.75″ and 6.0″ above grade, such that two slightly varying chairs 208 may manufactured which collectively offer support for rebar at four differing heights above a support surface. Advantageously, altering the manufactured length of the vertical fins 250 permits a supplier to produce a line of such varying chairs using a single molding apparatus, as described below.
In aspects such as the one described above, each vertical fin 250 is preferably reinforced by a perpendicular gusset 252 projecting inwardly from the vertical fin 250 and extending upward to further define the medial, lowest portion of the associated notch 224. The gusset 252 increases the supporting strength of the vertical fin, preventing both lateral deformation and localized crushing of the fin by rebar, post-tension cable, and the like that is received in the notch. The manufactured length of the gussets 252 may also be altered to permit production of varying chairs using a single molding apparatus.
The receiving area 414 includes a vertical fin 450 defining an open notch 424 and a pair of opposing gussets 452 projecting perpendicularly outward from the vertical fin 450. The gussets 452 may each extend upward to further define the medial, lowest portion of the notch 424. The gussets 452 increase the supporting strength of the vertical fin, and may also provide a resistance to tipping by reducing the tendency of rebar to catch on the edges of the open notch 424, and by repositioning a rebar's applied weight toward that portion of the chair 408 having a tendency to rotate upward in response to a longitudinal movement of the rebar. With particular reference to the structure shown in
In aspects such as the one described above, when multiple chairs are stacked, interference between the legs 432 of one chair 408 and the hoop 446 of a second chair 408 will substantially constrain horizontal movement of the bottom of the second chair 408. The efficiency of such stacking will vary depending upon the length of the vertical fin 450, but still permit storage and shipment within a reduced volume, and still permit a worker to carry many chairs at one time at a construction site.
As discussed above, altering the manufactured length of the vertical fins 250, 350, 450 permits a supplier to produce a line of chairs providing support at different heights using a single molding apparatus. Referring now to
The mold may also include a first adjustable blade 520 having a cross-section corresponding to the cross-section of the first vertical fin 250, a second adjustable blade 520 having a cross-section corresponding to the cross-section of the second vertical fin (if present), etc. Each adjustable blade 520 may be fully inserted into its corresponding channel 510 such that the inserted end 525 of the blade 520 defines a top surface of the notch in the receiving area of the chair. However, each adjustable blade 520 may also be partially withdrawn into its corresponding channel 510 such that material may enter the channel 510 to form a vertical fin 250, with the inserted end 525 of the blade 520 defining a top surface of the notch 224 in the vertical fin 250. By adjusting the insertion of each blade 520, a supplier may adjust the length of the vertical fins 250, 350, 450 in a chair to produce a plurality of chairs providing support at different heights above a support surface using a single molding apparatus.
In aspects where gussets 252, 352, 452 are present, the mold may include a channel 510 and blade 520 having cross-sections corresponding to the cross-section of the vertical fin 250, 350, 450 and the associated gusset(s) 252, 352, 452. The inserted end 525 of the blade 525 will consequently further define the top surface of the associated gusset(s) 252, 352, 452 and preferably further define the structure associated with the medial, lowest portion of the notch 224, 324, 424.
The chairs disclosed herein can be made significantly taller than most chairs of the prior art, and are also light in weight yet strong enough to support rebar securely, without collapsing under the weight of the rebar. Preferably the chairs are advantageously manufactured as a single piece of material, and constructed from a resilient polymeric material and, more specifically, constructed of a plastic or resin material. In this manner, the chairs can have the height and strength of a chair with a head piece seated on top of a base chair, yet be a single, tall chair. Further, the chairs are most preferably made of polypropylene and are one-piece injection molded. One of ordinary skill in the art will recognize that other materials exhibiting similar characteristics of being lightweight, strong and resilient can be used, such as polyethylene, a combination of polypropylene and polyethylene, and other known materials.
The present invention has been disclosed in detail in connection with the preferred embodiments. While there are many modifications that can be made without departing from the scope of the present invention, the present invention is defined by the claims that follow.
This application is a continuation-in-part of U.S. patent application Ser. No. 10/606,498, filed Jun. 26, 2003, the entirety of which shall be incorporated herein by reference.
Number | Date | Country | |
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Parent | 10606498 | Jun 2003 | US |
Child | 11626331 | Jan 2007 | US |