Abstract:
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.

Description:
This application claims priority to U.S. Provisional Patent Application No. 61/320,957 filed on Apr. 5, 2010. 
    
    
     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 in  FIG. 1 , concrete stairways  12  typically include one or more steps  14 , each having a riser  16  and a tread  18 . The riser  16  extends from bottom end  20  to a top end  22  defining a rise  24 . The riser  16  is 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 tread  18  may be described as extending from the top end  22  of the riser  16  to a distal end  26  (e.g., a bottom end  20  of a riser  16  in an adjacent step  14 ) defining a run  28 . The tread  18  is arranged offset by an angle β from the riser  16  (e.g., 90°−α). In embodiments where the treads  18  are 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&#39;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. 
     The foregoing features and the operation of the invention will become more apparent in light of the following description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a prior art concrete stairway 
         FIG. 2  is a perspective diagrammatic illustration of the present invention stair forming apparatus. 
         FIG. 3  is a perspective diagrammatic illustration of a portion of the present invention stair forming apparatus. 
         FIG. 4  is a perspective diagrammatic illustration of a section of a rail portion of the present invention stair forming apparatus. 
         FIG. 5  is a diagrammatic illustration of a panel leg included in the adjustable concrete form in  FIG. 3 . 
         FIG. 6  is a diagrammatic illustration of a support leg included in the adjustable concrete form in  FIG. 3 . 
         FIG. 7  is a perspective diagrammatic illustration of a rail saddle included in the adjustable concrete form in  FIG. 3 . 
         FIG. 8  is a perspective diagrammatic illustration of a mounting bracket included in the adjustable concrete form in  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIG. 2 , an adjustable concrete form  10  is provided operable to form a poured concrete stairway  12 . The adjustable concrete form  10  includes a plurality of stringer rails  30 , a plurality of riser brackets  32 , a plurality of fasteners  34  and, optionally, one or more adjustable lateral brace  36  and one or more riser panels  38 . The adjustable concrete form  10  can be used with a variety of site conditions, cheek walls, etc. 
     Each stringer rail  30  extends between a bottom end  40  and a top end  42 , defining a length  44  extending therebetween. As can be seen in  FIG. 4 , each stringer rail  30  includes a mid section  46  (e.g., a brace mounting section) extending between a first sidewall  48  and a second sidewall  50 . In preferred embodiments, the mid section  46  includes one or more brace fastener apertures  52 , which apertures  52  are typically either circular or elongated. The first and the second sidewalls  48  and  50  extend in parallel from the mid section  46  to respective distal ends  54  and  56 . The distal ends  54  and  56  of the first and the second sidewalls  48  and  50  each include an inwardly extending flange  58 ,  60 . In some embodiments, each flange  58 , 60  has a plurality of detents (e.g., teeth) disposed along a flange lip  62 . The flanges  58 , 60  of the first and the second sidewalls  48  and  50  are separated by a distance  64  defining a channel  66  therebetween. The channel  66  extends lengthwise between the bottom and the top ends  40 , 42  of the stringer rail  30 . 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 to  FIGS. 3-6 , each riser bracket  32  includes a panel leg  68  and a support leg  70 . The panel leg  68  extends between a top end  72  and a bottom end  74  defining a length  76  (see  FIG. 5 ). The panel leg  68  includes a first mounting section  78  and a second mounting section  80 . The first mounting section  78  typically includes at least one riser panel fastener aperture  82 . The second mounting section  80  includes a rail fastener aperture  84  and a support leg fastener aperture  86 . The rail fastener aperture  84  is disposed proximate the top end  72  of the panel leg  68 . The support fastener aperture  86  is disposed proximate the bottom end  74  of the panel leg  68 . The panel leg  68  may be formed from a length of angle iron, where the first mounting section  78  is perpendicular to the second mounting section  80 . Further, the top end  72  and/or the bottom end  74  of the second mounting section  80  can each include an acute edge  88 ,  90 . The acute edge  88  of the top end  72  of the second mounting section  80  is disposed a distance  92  from first mounting section  78 , and is offset by an angle θ 1  relative to the length  76  of the panel leg  68 . The acute edge  90  of the bottom end  74  of the second mounting section  80  is offset by an angle θ 2  relative to the length  76  of the panel leg  68 . 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 leg  70  extends between a first end  94  and a second end  96 . The support leg  70  includes a panel leg fastener aperture  98  and a rail fastener aperture  100 . The panel leg fastener aperture  98  is disposed proximate the first end  94  of the support leg  70 . The rail fastener aperture  100  is disposed proximate the second end  96  of the support leg  70 . 
     The bottom end  74  of the panel leg  68  is pivotally attached to the first end  94  of the support leg  70 . For example, a bolt  102  can be inserted through the support leg fastener aperture  86  of the panel leg  68  and the panel leg fastener aperture  98  of the support leg  70 , and loosely secured with a nut  104  (see  FIG. 3 ). 
     Each fastener  34  is adapted to attach one of the riser brackets  32  to a respective one of the stringer rails  30 ; e.g., the panel leg  68  and a support leg  70  of each riser bracket  32  is attached to the stringer rail  30 . In the embodiment in  FIG. 3 , each fastener  34  includes a rail saddle  106  and a mounting bracket  108 . Referring to  FIG. 7 , the rail saddle  106  includes a clamping element  110  and a slide element  112 . The clamping element  110  and the slide element  112  are adapted to clamp the flanges  58  and  60  of the stringer rail  30  between the clamping element  110  and the slide element  112  (e.g., see  FIG. 3 ). In the embodiment in  FIG. 7 , the clamping element  110  includes a threaded aperture  114  and a plurality of detents  116 . The detents  116  are adapted to mate with the detents  62  (see  FIG. 4 ) on the flanges  58  and  60  of each stringer rail  30  (see  FIG. 3 ) for inhibiting lengthwise movement along the stringer rail  30 . 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 to  FIG. 8 , the mounting bracket  108  extends between two ends  118 ,  120 . The mounting bracket  108  includes a riser bracket mounting section  122  and a saddle mounting section  124 . The riser bracket mounting section  122  includes a fastener  126  extending outwardly from an outer surface  128  thereof; i.e., away from the saddle mounting section  124 . The saddle mounting section  124  includes a rail saddle fastener aperture  130 . The mounting bracket  108  may, for example, be constructed from a length of angle iron, where the riser bracket mounting section  122  is disposed perpendicular to the saddle mounting section  124 . The present invention, however, is not limited to the aforesaid configuration. 
     Referring to  FIG. 3 , the rail saddle  106  is connected to the saddle mounting section  124  of the mounting bracket  108  via, for example, a bolt  132 . Specifically, the bolt  132  extends through the saddle fastener aperture  124  (see  FIG. 6B ) in the mounting bracket  108  and into the threaded aperture  114  (see  FIG. 6A ) in the clamping element  110  of the rail saddle  106 . 
     Referring to  FIG. 2 , each adjustable lateral brace  36  extends, for example, horizontally (e.g., along the x-axis) between two ends  132 , 134 . Each adjustable lateral brace  36  includes a plurality of rail fastener apertures  136  disposed 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 in  FIG. 1 , each adjustable lateral brace  36  is configured having an adjustable length. For example, each adjustable lateral brace  36  can include first and second brace members  137  and  139  that are slidably connected via a brace clamp  141 . 
     Each riser panel  38  extends, for example, horizontally (e.g., along the x-axis) between two ends  138 ,  140 . Each riser panel  38  has a height that is sized equal to the rise  24  for each respective step  14  to be formed. Each riser panel  38  includes a plurality of panel leg fastener apertures (not shown) disposed along its length. Typically, the riser panels  38  are constructed from wood planks; however, the present invention is not limited thereto. 
     The stringer rails  30  are disposed at an angle φ relative to the horizontal plane (i.e., the x-z plane). The stringer rails  30  on each side of the adjustable concrete form  10  can be attached to an adjacent wall  142 ,  144 , or immobilized in any other suitable manner. For example, the stringer rails  30  can be attached to the adjacent wall  142 ,  144  via L-brackets  154  bolted to the rails  30 . The adjustable lateral braces  36  are disposed substantially perpendicularly across each of the stringer rails  30 . Each adjustable lateral brace  36  is attached to the mid section  46  of each stringer rail  30 , for example, via a bolt  146  extending through respective rail and stringer fastener apertures  136 ,  52 . Advantageously, in this configuration, the adjustable lateral braces  36  can serve dual purposes of (i) laterally securing and positioning the stringer rails  30 , and (ii) providing staging such that a user can position himself over the adjustable concrete form  10  during the pouring and finishing of the stairs, using the brace  36  to support his weight. 
     Referring still to  FIG. 2 , each riser bracket  32  is disposed along the length  44  of one of the respective stringer rails  30 . Typically, each riser bracket  32  is disposed a first distance  148  from each adjacent riser bracket  32 ; however, the present invention is not limited to such an equidistant spacing. The first distance  148  between adjacent riser brackets  32  is sized as a function of the run  28  for each tread  18  to be formed. Referring now to  FIG. 3 , the panel leg  68  is disposed a second distance  150  from the support leg  70  in each respective riser bracket  32 . The second distance  150  between respective panel and support legs  68  and  70  is chosen to establish the angles α and β (see  FIG. 1 ) for each step  14  to be formed (i.e., the offset angle between the riser  16  to be formed and the vertical plane, and the offset angle between the tread  18  and the riser  16  to be formed). The angle β (see  FIG.1 ) is also function of the first distance  148  between adjacent riser brackets  32  and, more specifically, the vertical distance  152  between respective ends  74  of adjacent panel legs  68 . 
     The riser panels  38  are typically disposed perpendicularly across each of the stringer rails  30 . Each riser panel  38  is attached to the panel legs  68  of respective riser brackets  32  on each stringer rail  30 , for example, via screws (not shown) respectively extending through the panel leg and into the riser panel  38 . 
     The fasteners  34  can operate in a plurality of modes of operation. For example, during a first mode of operation (e.g., when the adjustable concrete form  10  is being setup or disassembled), the bolts  132  for the fasteners  34  are loosened such that the riser bracket legs  68 ,  70  can be slid along the stringer rail  30  into 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 step  14  have been set), the bolts  132  for the fasteners  34  can be tightened to securely attached (e.g., clamp) the fasteners  34  to the stringer rails  30 . Each of the riser brackets  32 , therefore, are fixed relative to the stringer rails  30  and are ready to support the weight of concrete poured into the adjustable concrete form  10 . 
     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.