US2239428A - Stair structure - Google Patents

Description

April 22, 1941. WCHAUD ETAL 2,239,428

STAIR STRUCTURE Filed Jan. 18, 1940 2 Sheets-Sheet 1 FM 5 7 U M 52AM Vjw flw 5 April 22, 1941. MlCHAUD ETAL 2,239,428

STAIR STRUCTURE Filed Jan. 18, 1940 2 Sheets-Sheet 2 5:5 Henry 19., Michorucf I J mes A, M clvcrud Patented Apr. 22, 1941 UNITED STATES PATENT OFFICE STAIR STRUCTURE Henry A. Michaud and James A. Michaud,

Hodge, La.

Application January 18, 1940, vSerial No. 314,424

4 Claims. (Cl. 72-96) This invention relates to stair structure built up of units of reinforced concrete intimately fitted and joined together to provide a comparatively light but durable and efficient stairway.

An important object of the invention is to provide stringer units of reinforced concrete and adapted to be secured to a support and providing horizontal and vertical surfaces for step tread and riser parts.

Another important object of the invention is to provide step units each in the form of a reinforced concrete casting to provide tread parts and riser parts for engaging respectively with the tread and riser surfaces of the stringer units.

A further important object is to provide improved joints and inter-fitting engagement of the units so that they will rigidly be held against lateral displacement or tipping.

A further important object is to provide improved reinforcements for the step units comprising preferably transversely extending metal bars in the tread portions and vertical bars in the riser portions, with the horizontal and vertical bars forming a rigid integral reinforcing structure as by being welded together, such metal reinforcement then relieving the concrete of strain and strengthening the step units against breakage.

Still another important object is to utilize the rear ends of the horizontal reinforcing bars of a tread part to be engaged by the riser part of the next step unit so that the step units will be held down at their rear ends against tipping under weight on the projecting nose portions of the treads which overhang the risers.

The invention also embodies other improved features of construction and arrangement, and all the features of the invention are incorporated in the structure shown on the drawings, on which drawings:

Figure 1 is a perspective view of our improved stair structure and part of a supporting structure to which the stair structure is applied;

Figure 2 is a transverse section of the stair structure;

Figure 3 is a section on plane III-III Figure 2;

Figure 4 is a section on plane IV-IV Figure 2;

Figure 5 is a section on plane V-V Figure 3;

Figure 6 is a section on plane VIVI Figure 3;

Figure 7 is the rear end view of one of the stringer units showing a supporting plate anchored to the stringer; and

Figure Bis an enlarged view of the horizontal and vertical reinforcing bars of a step unit, welded together.

The stair structure shown comprises the stringer units A and the step units B. The stringer units, when in service, extend diagonally downwardly from a support to the ground. Figure 1 shows the stringers extending downwardly from a support structure S to the ground. At their inner ends, the stringers have the vertical faces I0 for engaging against the support, and at their lower ends the stringers have the horizontal surfaces 1 I for engagement with the ground or with a base or foundation block l2 of concrete laid in the ground. Metal reinforcing rods or bars I 3 extend through each stringer unit for strengthening the concrete, and on their upper sides the stringer units are shaped to provide the horizontal tread receiving surfaces I4 and the vertical riser receiving surfaces l5.

A metal plate or bracket I6 is secured to the inner end ID of each stringer and preferably set into a recess I1, and anchor rods l3 extend from the plate to be embedded in the concrete, the rods preferably having hooked inner ends and are rigidly secured to the plate as by riveting or welding. These plates at their inner ends have holes IQ for receiving screws or bolts 20 for engagement with a support such as the support S, whereby the stringers may be rigidly secured at their upper ends to the supports.

Each step unit B is cast integral of concrete and comprises a tread 2| and a riser 22. Each tread has a number of longitudinally extending reinforcing metal bars 23 extending therethrough, and each tread may have one or more longitudinally extending reinforcing bars 24 extending therethrough. Each tread has a number of transverse reinforcing bars 25 therein and each tread has a number of transverse reinforcing bars 26.

Each tread 21 at its front extends a distance beyond to overhang the corresponding riser as indicated at 21, and the cross bars 25 in the tread extend well into the overhanging part 21 so as to strengthen this part. The transverse bars 26 of the risers meet the transverse bars 25 of the treads and are rigidly secured thereto as by welding so that the secured together bars provide rigid substantially T-shaped metal reinforcing structures for the step units to relieve the concrete of overstrain which might cause cracking or breakage thereof, particularly at the juncture of the tread and riser elements, when the units are subjected to bumps or blows during shipment or handling thereof. ihe reinforcing structures could be formed by bending a length of bar to form horizontal and vertical legs, but by welding the riser reinforcing bars to the tread bars at an intermediate point thereof, the outer ends of the riser bars will afford strengthening for the overhanging or nose portions 21 of the treads.

The step units are mounted on the stringers A, the treads being of a width so that the risers of one step unit will engage between the corresponding face l5 of the stringer and the rear edge of the tread of the next lower step unit. All or some of the transverse reinforcing bars 25 of the treads may project rearwardly a distance provided to receive the bar ends 25' when the stair is assembled so' that the risers will then engage with the bars and one step unit will thus hold'the next step unit down at its rear end to prevent tilting or tipping of the step unit particularly under weight applied on the overhanging or nose portion 2'! of the step units. The step units are all cast in the same mold, and the ends 25 of the cross reinforcing bars in the tread of the upper step unit may be left and utilized to support the stair structure, or this end may be cut off.

As indicated at 29, the lower inner corners of the risers are beveled to fit the correspondingly beveled corners of the stringers, this arrangement widening the stringers at step corners and strengthening the stringers against cracking at the corners. The longitudinally extending inner and outer corners between the treads and the risers are also filled in or beveled as indicated at 33, and the corners between the overhanging ends of the treads and the ends of the corresponding risers are also beveled or filled in as indicated at 3! so that these corners are strengthened to correspondingly increase the strength of connection between the tread and riser.

The stringers at their tread receiving surfaces id have notches or grooves 32 for receiving tongues 33 at the ends of the tread, these tongue and groove connections holding the treads against forward slipping on the stringers. At its rear end, each tread of the depending lip or rib 3 forming an integral part thereof to extend lengthwise on'the tread between the stringers, these lips or ribs increasing the thickness and strength of the treads at the back edges thereof and the ribs also serve to hold the step unit against longitudinal slipping or displacement on the stringers. As best shown on Figure 5, the ends of the treads have the portions 35 extending downwardly along the outer sides of the stringers below the stringer tread receiving tops M, and these portions 35 also align the treads on the stringers and prevent lateral or side slip of the step units on the stringers.

Where a concrete base block I2 is use-d for supporting the stair structure at its lower end, this block may be recessed to provide side abutments 3% for holding the stringers against lateral displacement, and a front abutment or shoulder 3'! against which the lower riser 22 abuts, the concrete block thus holding the stair structure against lateral and transverse displacement at its lower end, so that with the concrete block, and the screws or bolts 29, the stair structure will be rigidly located between a support such as S and the ground,

We have thus produced a very practical and emcient and economically constructed stair structure, the stringer units and the step units being economically molded or cast from concrete, and the units being quickly and readily assembled, and when assembled will hold themselves in proper position and against displacement. We have shown one practical and efficient embodiment of the various features of our invention but we do not desire to be limited to the exact construction and arrangement shown and described as changes and modifications may be made without departing from the scope of the invention.

We claim as follows:

1. A stairway assembly comprising stringer elements of reinforced concrete and presenting tread and riser surfaces, integral step units of reinforced concrete each comprising a tread element and a downwardly extending riser element for application to the tread and riser surfaces of said stringers, 'said tread elements at their ends having depending tongues and said stringers having grooves for receiving said tongues whereby said step units will be held against forward displacement on said stringers, a reinforcing rib on the underside of each tread element adjacent the rear edge thereof and extending between the inner sides of the stringers, said tread elements at their outer ends having depending portions engaging with the outer sides of said stringers and cooperating with said reinforcing ribs to hold said step units against lateral displacement on said stringers, and metal brackets permanently rigidly anchored to the upper ends of said stringore for attachment to a support to which the stair assembly is to be applied.

2. A stairway assembly comprising stringer elements in the form of precast reinforced concrete units presenting tread and riser surfaces, integral step units precast of concrete and each comprising a tread part and a downwardly extending riser part for engaging the tread and riser surfaces of the stringers, said tread parts extending a distance beyond the respective riser parts to overhang said riser parts, transversely extending reinforcing metal rods in said tread parts extending into the overhanging portions thereof, transversely extending reinforcing rods in the riser parts welded at their upper ends to the tread part reinforcing rods at points intermediate the ends of said tread part rods whereby to form rigid T-shaped reinforcing structures for the step units, the reinforcing bars of the tread parts projecting a distance rearwardly beyond the rear edges of the tread parts and the risers having notches in their lower ends whereby when the step units are assembled on the stringers said riser notches will receive the projectingends of the reinforcing rods and tipping of the step structures will be prevented, and cooperating abutments on the tread parts and stringers for holding the step units against lateral displacement on the stringers.

3. A stair assembly comprising spaced apart stringers each in the form of a precast reinforced concrete unit presenting tread and riser receiving surfaces, integral step units each precast of concrete and comprising a tread element and a downwardly extending riser element for engaging the tread and riser surfaces on the stringers, the width of the tread elements being such that the riser of one step unit will engage at its lowerend behind the tread element of the next lower step unit, transversely extending reinforcing metal rods in the tread elements and projecting a distance rearwardly beyond the rear ends of said elements, the riser elements at their lower edges being notched whereby when the step units are assembled on the stringers the riser notches of one unit will receive the projecting ends of the reinforcing tread bars of the next lower unit to hold the next lower unit against tipping, and cooperating abutments on the said elements and stringers for holding said step units against lateral displacement.

4. In a stair assembly, a precast concrete step unit comprising a horizontal tread element and a vertical riser element set inwardly a distance from the front edge of the tread element, integral T-shaped metal reinforcing bars having their vertical legs embedded in said riser element and their horizontal legs embedded in the tread element, the rear ends of the horizontal legs of said reinforcing structures projecting a distance rearwardly beyond the rear edge of the tread element and the riser element having cross slots in its lower edge in alignment with said projecting ends whereby when step units are assembled to form a stair the cross slots of one riser will receive the projecting ends of the reinforcing structures of the next lower tread unit.

HENRY A. MICHAUD. JAMES A. MICI-IAUD.

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