Adjustable form for a concrete stairway

An apparatus for forming steps within a concrete stairway, wherein each step has a rise and a run. The apparatus includes a stringer rail, one or more riser brackets and a plurality of fasteners. The stringer rail has a lengthwise-extending channel. Each riser bracket has a panel leg and a support leg, wherein one end of the support leg is attached to panel leg. The fasteners are selectively slidable within the rail channel. One of the fasteners attaches the panel leg to the rail and another of the fasteners attaches the support leg to the rail. Each fastener is configurable in a first mode where the fastener is slidably attached to the rail. Each fastener is configurable in a second mode where the fastener is fixedly attached to the rail.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates to concrete forms in general, and to adjustable reusable devices for forming concrete stairs in particular.

2. Background Information

Concrete stairs are a desirable, durable, and relatively inexpensive option for providing pedestrian access between different elevations. As can be seen inFIG. 1, concrete stairways12typically include one or more steps14, each having a riser16and a tread18. The riser16extends from bottom end20to a top end22defining a rise24. The riser16is arranged substantially parallel to, or slightly offset by an angle α (e.g., 1 to 5 degrees) from, a vertical plane (e.g., a y-z plane). A tread18may be described as extending from the top end22of the riser16to a distal end26(e.g., a bottom end20of a riser16in an adjacent step14) defining a run28. The tread18is arranged offset by an angle β from the riser16(e.g., 90°−α). In embodiments where the treads18are substantially parallel to the horizontal plane, the angles α and β are typically complementary.

One of the drawbacks to concrete stairways is that they are difficult to properly produce, particularly if the stairway is wide and has a large number of steps. The concrete is initially in a semi-liquid state and must be held in place by a form. If the stairway is large enough, the semi-liquid concrete will present a substantial load on the form, and will need to be vibrated during the forming process to ensure the concrete is properly settled. The vibration typically present an additional loading on the forms. As the concrete cures, the exposed surfaces of the concrete must be carefully finished to provide the desired surface texture. In many instances, concrete stairs produced on a build-site are custom formed from lumber, which forms are discarded after the single use. This manner of forming a concrete stair is consequently time-consuming, expensive, and has a substantial risk of error (e.g., forms not assembled correctly vis-à-vis dimensions, forms deflect/warp or break under load, etc. Currently available devices for forming stairs have not met commercial success. These devices often have limited configurability, or are difficult to use, or impede the user's ability to access the concrete during the pour and finishing thereafter, or some combination thereof.

What is needed is a device that can be used to form concrete stairs, one that is reusable, one that can handle the loads associated with large stairs, one that facilitates the pour and finishing of the stairs, and one that is easily configurable to handle a variety of different stair configurations.

SUMMARY OF THE DISCLOSURE

According to an aspect of the invention, an apparatus is provided for forming steps within a concrete stairway, wherein each step has a rise and a run. The apparatus includes at least a pair of stringer rails, a plurality of riser brackets, and a plurality of fasteners. Each rail has a lengthwise-extending channel. Each riser bracket has a panel leg and a support leg, wherein one end of the support leg is attached to panel leg. The fasteners are selectively slidable within the rail channel. One of the fasteners attaches the panel leg to the rail and another of the fasteners attaches the support leg to the rail. Each fastener is configurable in a first mode where the fastener is slidably attached to the rail. Each fastener is configurable in a second mode where the fastener is fixedly attached to the rail.

According to another aspect of the present invention, the apparatus further includes a lateral brace that extends between the rails, and is attachable to each rail. The lateral brace has a length that may be adjustable to accommodate different staircase widths.

The present invention stair forming apparatus provides several advantages over the prior art. For example, it is reusable and is easily configurable to handle a variety of different stair configurations; e.g., different rise/run, number of stairs, staircase width, etc. The present device can readily handle the loads associated with large stairs. For example, the amount of concrete necessary for a wide staircase with a large number of stairs can cause prior art devices to bow and otherwise distort, particularly in the middle of the wide stair. With the present device, additional stringer rails and lateral braces can be added to accommodate the load, with each rail attached to each brace. Such an application also illustrates another advantage of the present invention, namely that it facilitates the pour and finishing of the stairs. Specifically, during the pouring and finishing processes, the user can support himself on the lateral braces without altering the form configuration and have easy access to the concrete for pouring and finishing and removal of riser panels.

DETAILED DESCRIPTION OF THE INVENTION

Referring toFIG. 2, an adjustable concrete form10is provided operable to form a poured concrete stairway12. The adjustable concrete form10includes a plurality of stringer rails30, a plurality of riser brackets32, a plurality of fasteners34and, optionally, one or more adjustable lateral brace36and one or more riser panels38. The adjustable concrete form10can be used with a variety of site conditions, cheek walls, etc.

Each stringer rail30extends between a bottom end40and a top end42, defining a length44extending therebetween. As can be seen inFIG. 4, each stringer rail30includes a mid section46(e.g., a brace mounting section) extending between a first sidewall48and a second sidewall50. In preferred embodiments, the mid section46includes one or more brace fastener apertures52, which apertures52are typically either circular or elongated. The first and the second sidewalls48and50extend in parallel from the mid section46to respective distal ends54and56. The distal ends54and56of the first and the second sidewalls48and50each include an inwardly extending flange58,60. In some embodiments, each flange58,60has a plurality of detents (e.g., teeth) disposed along a flange lip62. The flanges58,60of the first and the second sidewalls48and50are separated by a distance64defining a channel66therebetween. The channel66extends lengthwise between the bottom and the top ends40,42of the stringer rail30. An example of a suitable rail is a length of the MQ series, slotted stainless steel channel manufactured by Hilti Corporation. The present invention, however, is not limited to any particular type of rail.

Referring toFIGS. 3-6, each riser bracket32includes a panel leg68and a support leg70. The panel leg68extends between a top end72and a bottom end74defining a length76(seeFIG. 5). The panel leg68includes a first mounting section78and a second mounting section80. The first mounting section78typically includes at least one riser panel fastener aperture82. The second mounting section80includes a rail fastener aperture84and a support leg fastener aperture86. The rail fastener aperture84is disposed proximate the top end72of the panel leg68. The support fastener aperture86is disposed proximate the bottom end74of the panel leg68. The panel leg68may be formed from a length of angle iron, where the first mounting section78is perpendicular to the second mounting section80. Further, the top end72and/or the bottom end74of the second mounting section80can each include an acute edge88,90. The acute edge88of the top end72of the second mounting section80is disposed a distance92from first mounting section78, and is offset by an angle θ1relative to the length76of the panel leg68. The acute edge90of the bottom end74of the second mounting section80is offset by an angle θ2relative to the length76of the panel leg68. The present invention, however, is not limited to the aforesaid configuration. In other embodiments, the panel leg can be constructed from, for example, a length of the MQ series, slotted stainless steel channel manufactured by Hilti Corporation. The support leg70extends between a first end94and a second end96. The support leg70includes a panel leg fastener aperture98and a rail fastener aperture100. The panel leg fastener aperture98is disposed proximate the first end94of the support leg70. The rail fastener aperture100is disposed proximate the second end96of the support leg70.

The bottom end74of the panel leg68is pivotally attached to the first end94of the support leg70. For example, a bolt102can be inserted through the support leg fastener aperture86of the panel leg68and the panel leg fastener aperture98of the support leg70, and loosely secured with a nut104(seeFIG. 3).

Each fastener34is adapted to attach one of the riser brackets32to a respective one of the stringer rails30; e.g., the panel leg68and a support leg70of each riser bracket32is attached to the stringer rail30. In the embodiment inFIG. 3, each fastener34includes a rail saddle106and a mounting bracket108. Referring toFIG. 7, the rail saddle106includes a clamping element110and a slide element112. The clamping element110and the slide element112are adapted to clamp the flanges58and60of the stringer rail30between the clamping element110and the slide element112(e.g., seeFIG. 3). In the embodiment inFIG. 7, the clamping element110includes a threaded aperture114and a plurality of detents116. The detents116are adapted to mate with the detents62(seeFIG. 4) on the flanges58and60of each stringer rail30(seeFIG. 3) for inhibiting lengthwise movement along the stringer rail30. An example of a suitable rail saddle is the MQA R Pipe Ring Saddle manufactured by Hilti Corporation. The present invention, however, is not limited to any particular rail saddle configuration.

Referring now toFIG. 8, the mounting bracket108extends between two ends118,120. The mounting bracket108includes a riser bracket mounting section122and a saddle mounting section124. The riser bracket mounting section122includes a fastener126extending outwardly from an outer surface128thereof; i.e., away from the saddle mounting section124. The saddle mounting section124includes a rail saddle fastener aperture130. The mounting bracket108may, for example, be constructed from a length of angle iron, where the riser bracket mounting section122is disposed perpendicular to the saddle mounting section124. The present invention, however, is not limited to the aforesaid configuration.

Referring toFIG. 3, the rail saddle106is connected to the saddle mounting section124of the mounting bracket108via, for example, a bolt132. Specifically, the bolt132extends through the saddle fastener aperture124(seeFIG. 6B) in the mounting bracket108and into the threaded aperture114(seeFIG. 6A) in the clamping element110of the rail saddle106.

Referring toFIG. 2, each adjustable lateral brace36extends, for example, horizontally (e.g., along the x-axis) between two ends132,134. Each adjustable lateral brace36includes a plurality of rail fastener apertures136disposed along its length. An example of a suitable lateral brace is a length of the MQ series, slotted stainless steel channel manufactured by Hilti Corporation. The present invention, however, is not limited to any particular type of lateral brace. In the specific embodiment shown inFIG. 1, each adjustable lateral brace36is configured having an adjustable length. For example, each adjustable lateral brace36can include first and second brace members137and139that are slidably connected via a brace clamp141.

Each riser panel38extends, for example, horizontally (e.g., along the x-axis) between two ends138,140. Each riser panel38has a height that is sized equal to the rise24for each respective step14to be formed. Each riser panel38includes a plurality of panel leg fastener apertures (not shown) disposed along its length. Typically, the riser panels38are constructed from wood planks; however, the present invention is not limited thereto.

The stringer rails30are disposed at an angle φ relative to the horizontal plane (i.e., the x-z plane). The stringer rails30on each side of the adjustable concrete form10can be attached to an adjacent wall142,144, or immobilized in any other suitable manner. For example, the stringer rails30can be attached to the adjacent wall142,144via L-brackets154bolted to the rails30. The adjustable lateral braces36are disposed substantially perpendicularly across each of the stringer rails30. Each adjustable lateral brace36is attached to the mid section46of each stringer rail30, for example, via a bolt146extending through respective rail and stringer fastener apertures136,52. Advantageously, in this configuration, the adjustable lateral braces36can serve dual purposes of (i) laterally securing and positioning the stringer rails30, and (ii) providing staging such that a user can position himself over the adjustable concrete form10during the pouring and finishing of the stairs, using the brace36to support his weight.

Referring still toFIG. 2, each riser bracket32is disposed along the length44of one of the respective stringer rails30. Typically, each riser bracket32is disposed a first distance148from each adjacent riser bracket32; however, the present invention is not limited to such an equidistant spacing. The first distance148between adjacent riser brackets32is sized as a function of the run28for each tread18to be formed. Referring now toFIG. 3, the panel leg68is disposed a second distance150from the support leg70in each respective riser bracket32. The second distance150between respective panel and support legs68and70is chosen to establish the angles α and β (seeFIG. 1) for each step14to be formed (i.e., the offset angle between the riser16to be formed and the vertical plane, and the offset angle between the tread18and the riser16to be formed). The angle β (seeFIG.1) is also function of the first distance148between adjacent riser brackets32and, more specifically, the vertical distance152between respective ends74of adjacent panel legs68.

The riser panels38are typically disposed perpendicularly across each of the stringer rails30. Each riser panel38is attached to the panel legs68of respective riser brackets32on each stringer rail30, for example, via screws (not shown) respectively extending through the panel leg and into the riser panel38.

The fasteners34can operate in a plurality of modes of operation. For example, during a first mode of operation (e.g., when the adjustable concrete form10is being setup or disassembled), the bolts132for the fasteners34are loosened such that the riser bracket legs68,70can be slid along the stringer rail30into or out of the aforesaid configuration. In another example, during a second mode of operation (e.g., once the angles α and β and the first and the second distances for each step14have been set), the bolts132for the fasteners34can be tightened to securely attached (e.g., clamp) the fasteners34to the stringer rails30. Each of the riser brackets32, therefore, are fixed relative to the stringer rails30and are ready to support the weight of concrete poured into the adjustable concrete form10.

While various embodiments of the present invention have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the present invention is not to be restricted except in light of the attached claims and their equivalents.