AU2021209297A1 - A modular staircase assembly - Google Patents

Abstract

A modular staircase assembly 10, including a base frame having a base 12 for resting on a floor surface and four vertically upstanding posts 14 arranged in a square or rectangular configuration. A first modular staircase unit 22 being connected to the 5 posts 14 by four adjustment sleeves 20 that are slidable relative to the posts 14 for movement up and down the posts 14. The sleeves 20 are fixable to the posts 14 at a selected vertical position. The first modular staircase unit 22 further including a staircase 38. The first modular staircase unit 22 being shiftable vertically by altering the selected vertical position at which the adjustment sleeves 20 of the first modular 10 staircase unit 22 are fixed to the posts 14. Fig. 1 '0170 3222

Description

'0170

A MODULAR STAIRCASE ASSEMBLY

Technical Field

[0001] The present invention relates generally to modular staircase assemblies that are used in the construction industry, in particular the tunnelling or excavation industries.

Background of the Invention

[0002] The discussion of the background to the invention that follows is intended to facilitate an understanding of the invention. However, it should be appreciated that the discussion is not an acknowledgement or admission that any aspect of the discussion was part of the common general knowledge as at the priority date of the application.

[0003] The tunnelling and excavation industries are often required to excavate deep into the ground and for personnel access to within the excavation, various arrangements can be used. For example, vertical lifts can be employed, whereby a vertical lift structure is installed and a lift platform or cage can be raised and lowered as required.

[0004] Alternatively, and for more shallow excavations, ladders can be lowered into the excavation and these include safety ladders whereby personnel descending or ascending the ladder have a safety cage about them.

[0005] A difficulty with many arrangements provided for access to deeper excavations, is that the height or depth of the access arrangement is not easily altered. This is not a problem where the depth of the excavation does not change, but in many excavations, the depth of the excavation will grow as excavation continues and in those excavations, continued personnel access to the full depth of the excavation is required as the depth of the excavation grows. This means that whatever access arrangement is employed, there is a need to increase the length of the access arrangement in terms of height or depth, as the excavation grows, in order to continue to provide personnel access to the full depth of the excavation.

[0006] Moreover, even where the depth of the excavation does not change, the depth of one excavation will be different to another and so modular staircase assemblies that are height adjustable are useful to

[0007] In some arrangements, stairs are constructed for personnel to ascend or descend into an excavation. The height of stairs is difficult to adjust although the present applicant has developed a height adjustable stair arrangement which is the subject of Australian Innovation Patent 2017101593. The modular staircase assembly of Patent 2017101593 allows the height or depth of a staircase to be increased from the top of the staircase by progressively adding additional staircase units.

[0008] Other access arrangements that preceded the filing of Patent 2017101593 permitted the addition of staircase units to the bottom of an existing staircase structure as the depth of the excavation increased. This allows the access arrangement to be lengthened to continue to provide access to the full depth of an excavation. However, the additional staircase units that are attached to the bottom of the existing staircase structure must be lowered into the excavation such as by crane and installed to the bottom end of the existing staircase structure and this typically means that after lowering a staircase unit, it then needs to be lifted slightly into connection with the bottom or free end of the existing staircase structure for the new staircase unit to be attached to the existing staircase structure. Where the excavation is deep, the lowering and subsequent lifting can be time consuming and difficult. Arrangements of this kind, while permitting an increase in the length or depth of the access arrangement, are nevertheless inconvenient in relation to the manner in which the depth increase is created.

[0009] Modular staircase assemblies are also used to form a working platform for personnel, for example for personnel working in elevated positions.

[0010] The present invention seeks to provide a modular staircase assembly that is height adjustable and that facilitates addition of modular staircase units to the assembly.

Summary of the Invention

[0011] According to a first aspect of the present invention there is provided a modular staircase assembly, including:

a base frame having a base for resting on a floor surface and four vertically upstanding posts arranged in a square or rectangular configuration,

a first modular staircase unit being connected to the posts by four adjustment sleeves that are slidable relative to the posts for movement up and down the posts, the sleeves being fixable to the posts at a selected vertical position, the first modular staircase unit further including a staircase,

the first modular staircase unit being shiftable vertically by altering the selected vertical position at which the adjustment sleeves of the first modular staircase unit are fixed to the posts of the base frame.

[0012] A modular staircase assembly according to the invention advantageously allows height adjustment by shifting the selected vertical position at which the adjustment sleeves of the first modular staircase unit are fixed to the posts of the base frame. Moreover, the modular staircase assembly according to the invention advantageously enables the addition of modular staircase units to the modular staircase assembly.

[0013] It follows, that according to a second aspect of the present invention there is provided a modular staircase assembly, including:

a base frame having a base for resting on a floor surface and four vertically upstanding posts arranged in a square or rectangular configuration,

a first modular staircase unit being connected to the posts by four adjustment sleeves that are slidable relative to the posts for movement up and down the posts, the sleeves being fixable to the posts at a selected vertical position, the first modular staircase unit further including a staircase,

an upper end of the first modular staircase unit being releasably connected to a second modular staircase unit, the second modular staircase unit including a staircase, each of the first and second modular staircase units being shiftable vertically by altering the selected vertical position at which the adjustment sleeves of the first modular staircase unit are fixed to the posts of the base frame.

[0014] A modular staircase assembly according to the invention advantageously allows height adjustment by shifting the selected vertical position at which the adjustment sleeves of the first modular staircase unit are fixed to the posts of the base frame and by enabling the addition of modular staircase units to the modular staircase assembly.

[0015] A modular staircase assembly according to the invention can be a stationary installation or a mobile installation. For a stationary installation, the base frame can have feet for engaging the floor surface on which the base frame rests. The modular staircase assembly can be moved by forklift or crane when required. The feet can be height adjustable for levelling the modular staircase assembly on the floor surface.

[0016] Alternatively, for a mobile installation, the base frame can have rollers or castors for rolling along the floor surface on which the base frame rests. The rollers or castors should be brakable to brake the rollers against rolling movement when the modular staircase assembly is in the correct position, or other movement resisting arrangements can be employed, such as roller chocks or the like.

[0017] The first modular staircase unit can be connected to access stairs so that when the first modular staircase unit is elevated above the floor surface on which the modular staircase assembly is located, personnel can access the first modular staircase unit by the access stairs. The access stairs can extend from the floor surface to a lower end of the staircase of the first modular staircase unit. The access stairs can extend at an acute angle from the floor surface on which the base frame rests up to the lower end of the staircase.

[0018] The access stairs will have a floor surface engagement end and a first modular staircase unit connection end and in some forms of the invention, the access stairs are pivotably connected to the first modular staircase unit at the connection end so that the access stairs pivot relative to the first modular staircase unit to a greater acute angle as the first modular staircase unit is shifted upward relative to the posts of the base frame. This advantageously means that as the first modular staircase unit is lifted, the access stairs pivot about their connection with the first modular staircase unit to a more acute angle relative to the modular staircase assembly but importantly, they maintain contact with the floor surface, so that personnel using the access stairs to access the first modular staircase unit can continue to access the stairs from the floor surface despite the elevated height of the first modular staircase unit.

[0019] The staircase of the first modular staircase unit can have any suitable form. In some forms of the invention, the staircase has a bottom landing from which a first stair portion of the first modular staircase unit staircase extends upwardly. The staircase can also have a top landing to which a second stair portion of the first modular staircase unit staircase extends. The top landing can directly overlie the bottom landing or the top landing can be offset from overlying the bottom landing. The staircase can have an intermediate landing between the top and bottom landings. The first stair portion of the staircase can extend upwardly in a first direction to the intermediate landing and the second stair portion can extend from the intermediate landing upwardly in a second direction, opposite the first direction, to the top landing. This forms the staircase into two flights, separated by the intermediate landing.

[0020] Alternatively, the staircase of the first modular staircase unit can have top and bottom landings and a first stair portion extends upwardly from the bottom landing and a second stair portion extends downwardly from the top landing and the first and second stair portions being coextensive, so that the staircase is formed as a single flight.

[0021] The first modular staircase unit can have a square or rectangular bottom connector which connects at or adjacent its corners to the four adjustment sleeves of the base frame and the bottom connector can support a bottom section of the staircase of the first modular staircase unit. The bottom connector can include supporting or strengthening beams to support components of the first modular staircase unit or to strengthen the bottom section of the staircase. The bottom connector may for example, provide strength and stiffness to the upstanding posts of the base frame. Where the first modular staircase unit includes a bottom landing, the bottom landing can be supported on the bottom connector.

[0022] The first modular staircase unit can also include a square or rectangular top connector which connects at or adjacent its corners to the four adjustment sleeves. The top connector can also connect to a top section of the staircase of the first modular staircase unit. This may be a top section of the stairs of the staircase, or it may be a top landing of the staircase. The top connector can also include a connection arrangement for connecting with the second modular staircase unit. This connection arrangement may include lugs that are formed on the top connector that are positioned for cooperation with lugs that are formed on a bottom section of the second modular staircase unit, such as on a bottom connector of the second modular staircase unit. The cooperating lugs can include openings through which bolt connectors can extend to bolt the lugs together, and thus to bolt and secure the first and second modular staircase units together. Other connection arrangements can be employed.

[0023] The first modular staircase unit can have four uprights that are releasably connected to the respective adjustment sleeves, so that the first modular staircase unit can be attached to and released from the base frame by connecting and disconnecting the four uprights from the respective adjustment sleeves. In this arrangement, the bottom connector (if provided) can connect to a bottom section of the uprights and the top connector (if provided) can connect to a top section of the uprights.

[0024] The staircase of the second modular staircase unit can have a bottom landing from which a first stair portion of the second modular staircase unit staircase extends upwardly. In that arrangement, the staircase of the first modular staircase unit can extend to the bottom landing of the second modular staircase unit and can connect to the bottom landing. Alternatively, the first modular staircase unit can have a top landing and the second modular staircase unit can have a bottom landing and the respective top and bottom landings can cooperate to form a landing common landing between the first and second modular staircase units. Alternatively, the first modular staircase unit can have a top landing and the first stair portion of the second modular staircase unit staircase can connect to and extend upwardly from the top landing. In these arrangements, a landing is created between the first and second modular staircase units and the landing can be a top landing of the first modular staircase unit, a bottom landing of the second modular staircase unit, or a combination landing in which each of the first and second modular staircase units provides part of that landing.

[0025] The staircase of the second modular staircase unit can have a top landing to which a second stair portion of the second modular staircase unit staircase extends. The second stair portion can extend from an intermediate landing between the top and bottom landings like that described for the first modular staircase unit, or the first and second stair portions of the second modular staircase unit can be coextensive between the top and bottom landings with no intermediate landing between them. The top landing of the second modular staircase unit can be a platform to accommodate multiple personnel, for example allowing multiple personnel to work from the top landing. The top landing can be fenced by a railing for safety purposes. The railing can include a gate for accessing the top landing.

[0026] To increase the surface area of the top landing of the second modular staircase unit, the top landing can have a cantilever portion that extends out beyond the periphery of the four posts of the base frame.

[0027] The second modular staircase unit can have four uprights to which the staircase of the second modular staircase unit is attached. The bottom ends of the four uprights can be releasably connected to the upper end of the first modular staircase unit. The bottom ends of the four uprights can, for example, releasably connect to the upper ends of the four uprights (if provided) of the first modular staircase unit. The connection between the respective bottom and upper ends of the uprights can be by one of the ends including a sleeve into which the other of the ends enters. Other connection arrangements can be employed.

[0028] The adjustment sleeves facilitate upward and downward movement of the first and second modular staircase units relative to the base frame. The adjustment sleeves are fixed to the posts at a selected vertical position that can be changed as required to reposition the sleeves and thus the first and second modular staircase units when the height of the modular staircase assembly needs to be increased or decreased. In some forms of the invention, the posts and the adjustment sleeves each having openings that can be brought into registration for receipt of a pin. With a pin received in each post and adjustment sleeve, the height of the adjustment sleeves, and thus the height of the first and second modular staircase units, is set. Lifting of the adjustment sleeves can be assisted by crane for example, whereby a crane is connected to the adjustment sleeves, or to one of the first and second modular staircase units, and the crane takes the weight of the adjustment sleeves and the first and second modular staircase units while the pins are removed. The crane can then lift the adjustment sleeves and the first and second modular staircase units until a selected new set of openings in the posts and the adjustment sleeves is in registration and the pins can then be reinserted in the openings and the new height of the modular staircase assembly is established. Where the modular staircase assembly is to have a permanent height for a particular installation, this process needs to be carried out only once upon installation of the modular staircase assembly, but where the height of the modular staircase assembly is to change as requirements change, then this process can be repeated as required.

[0029] It is also possible that the modular staircase assembly can include an arrangement for lifting and lowering the first and second modular staircase units. This could comprise a jacking arrangement, that for example acts centrally of the first modular staircase unit to apply a lifting or lowering load to the first modular staircase unit, or jacking units might attach to each of the posts of the base frame. The jacking units could be manually operated or hydraulically operated for example.

[0030] While the modular staircase assembly according to invention has been described as having just two modular staircase units, it is within the scope of the present invention for the assembly to have a third modular staircase unit that includes a staircase and which can be shiftable vertically with the first and second modular staircase units. In fact, any number of modular staircase units can be included in a modular staircase assembly according to the present invention.

Brief Description of the Drawings

[0031] In order that the invention may be more fully understood, some embodiments will now be described with reference to the figures in which:

[0032] Figure 1 illustrates a perspective view of a first aspect of the present invention in which a single modular staircase unit is employed in a modular staircase assembly.

[0033] Figure 2 is a side view of the modular staircase assembly of Figure 1.

[0034] Figure 3 illustrates a perspective view of modular staircase assembly according to a second aspect of the present invention, in which first and second modular staircase units are employed.

[0035] Figure 4 is a side view of the modular staircase unit of Figure 4.

[0036] Figure 5 is a detailed view of the connection between the first and second modular staircase units of Figure 3.

[0037] Figure 6 is a modified version of the modular staircase assembly of Figure 3.

Detailed Description

[0038] Figure 1 is a perspective view of a modular staircase assembly 10 according to a first aspect of the invention. The modular staircase assembly 10 of Figure 1 includes a base frame 12 that includes four vertically upstanding posts 14 that extend from a generally rectangular bottom frame 16. The base frame 12 includes four feet 18 for resting on a floor or ground surface and that include a height adjusting structure that can be used for leveling the modular staircase assembly 10 on uneven ground.

[0039] The posts 14 are shown received within four adjustment sleeves 20. The sleeves 20 can move up and down the posts 14 and can be fixed relative to the posts 14 by pins (not shown) that are insertable through openings that are formed through the posts 14 and the sleeves 20. The posts 14 can include a plurality of openings along their vertical length, while the adjustment sleeves 20 can include one or more openings. Selection of the position of the sleeves 20 on the posts 14 is made by aligning openings in the respective posts 14 and sleeves 20 and extending one or more pins through one or more of the aligned openings. Once a pin or pins has been inserted through aligned openings in each of the four combined posts 14 and sleeves 20, the sleeves 20 are secured in a fixed height position on the posts 14. The position of the sleeves 20 on the posts 14 can be adjusted by removal of the pins, by alignment of different sets of openings in the posts 14 and sleeves 20 and reinsertion of the pins through those aligned openings.

[0040] The adjustment sleeves 20 of Figure 1 connect to a first modular staircase unit 22. The first modular staircase unit 22 includes a rectangular bottom connector 24 which connects at its corners to four uprights 26. The bottom connector 24 further includes supporting or strengthening beams 28 and 30 that provide rigidity to the bottom connector 24 and thus impart rigidity to the posts 14 of the base frame 12, while the beams 28 and 30 can also support components of the staircase unit 22.

[0041] The staircase unit 22 includes a staircase that has a bottom landing 32, a top landing 34 and stairs 36. The stairs 36 extend between the bottom and top landings 32 and 34, while access stairs 38 extend at an angle (see Figure 2) from the same floor or ground surface on which the feet 18 of the base frame 12 rest up to the bottom landing 32. The access stairs 38 connect to the staircase unit 22 at the bottom landing 32 by a connection interface 40 that allows the access stairs 38 to pivot relative to the base frame 12, so that the foot 42 of the access stairs 38 can remain grounded as the staircase unit 22 is lifted or lowered and the angle a (see Figure 2) changes.

[0042] The top landing 34 is formed as a platform which is of a size that can accommodate multiple personnel. Moreover, the top landing 34 has opposite cantilevered ends 42 that extends beyond the rectangular area defined by the four posts 14 to increase the surface area of the top landing 34. The cantilevered ends 42 of the top landing 34 are supported by bracing arms 44.

[0043] The staircase unit 22 includes a railing 46 about the bottom landing 32, the top landing 34 and the stairs 36. In addition, a railing extends about the recess formed in the floor of the top landing 34 which permits access via the stairs 36. The railings 46 and 48 are provided in accordance with normal safety requirements relating to staircases used in construction sites. In order to access or egress the top landing 34, the railing 46 includes a gate 50.

[0044] The uprights 26 of the staircase unit 22 can be permanently attached to the sleeves 20 or can be releasably attached. The adjustment sleeves 20 can thus be attached to the staircase unit 22 when the staircase unit 22 is connected to the base frame 12, or the adjustment sleeves 20 can be formed as part of the stair case unit 22, ie they can be fixed to the uprights 26 such as by bolting or welding.

[0045] In order to assemble the staircase assembly 10, the staircase unit 22 can be craned into position relative to the base frame 12 and for this, the staircase unit 22 can include lifting lugs 52 for connection to a crane by rope or chain. If the adjustment sleeves 20 have already been attached to the staircase unit 22, either permanently or releasably, the sleeves 20 and the staircase unit 22 can be lowered together onto the posts 14. Alternatively, if the adjustment sleeves 20 have been applied to the posts 14 prior to introduction of the staircase unit 22, the staircase unit 22 can be craned into position relative to the sleeves 20 for attachment to the sleeves 20.

[0046] With the adjustment sleeves 20 installed on the posts 14 and with the staircase unit 22 connected to the sleeves 20, the crane can lift the staircase unit 22 to the desired vertical position and with the respective openings in the posts 14 and adjustment sleeves 20 aligned, locking pins can be inserted into the openings to secure the relative position of the staircase unit 22 relative to the base frame 12. Personnel can then access the staircase assembly 10 as required until such time as the assembly 10 is to be disassembled, or the height of the staircase unit 22 on the base frame 12 is to be adjusted. For adjustment, a crane can reconnect to the staircase unit 22, to bear the weight of the unit 22 so that pins can be removed from connecting the adjustment sleeves 20 to the posts 14 and the staircase unit 22 can thereafter be lifted or lowered to a new vertical position. Once the new vertical position has been reached, the pins can be reinserted and the staircase assembly 10 is again ready for use.

[0047] Figure 3 illustrates a second aspect of the present invention in which first and second modular staircase units are provided in a modular staircase assembly 60. In Figure 3, the first modular staircase unit 62 is located beneath the second modular staircase unit 64, so that the top landing 66 of the second modular staircase unit 64 is elevated to a greater vertical height than compared to the top landing 34 of the staircase assembly 10. Thus, the height of the top landing 34 in one example, could be at 4.3m from the floor or ground surface on which the staircase assembly 10 rests, while the height of the top landing 66 could be at about 7.8m above the floor or ground surface.

[0048] The modular staircase unit 64 of Figure 3 is identical to the first modular staircase unit 22 of Figures 1 and 2. What changes between the Figures 1 and 3 arrangements, is that the first modular staircase unit 62 in Figure 3 is an additional and different staircase unit to that of the respective units 22 and 64 of Figures 1 and 3. Accordingly, concentrating on the staircase unit 62 of Figures 3 and 4, this includes a bottom landing 68 and an intermediate landing 70. A first stair portion 72 extends upwardly from the bottom landing 68 to the intermediate landing 70. A second stair portion 74 extends to the bottom landing 76 of the staircase unit 64. The respective stair portions 72 and 74 are connected either by welding or bolt connection at the opposite ends to the respective bottom and intermediate landings 68 and 70 and the further bottom landing 76.

[0049] Many of the features of the staircase assembly 60 are the same as the staircase assembly 10. Thus, the base frame 78 of the assembly 60 has the same construction as the base frame 12 of the assembly 10, so that it includes four posts 80 and four sleeves 82. The sleeves connect to a bottom connector 84 of the staircase unit 62 and that bottom connector includes the same beam arrangement as the bottom connector 24 of Figure 1 and supports a similar landing 68 to the bottom landing 32 shown in Figure 1.

[0050] The staircase unit 62 further includes an upper connector 86 that is rectangular and which connects to the four uprights 88 that extend between the bottom and upper connectors 84 and 86. The bottom and upper connectors 84 and 86 and the uprights 88 form a cubic structure that connects to the sleeves 82.

[0051] The upper connector 86 connects to the bottom connector 90 of the staircase unit 64 to connect the modular staircase units 62 and 64 together. The bottom connector 90 is equivalent to the bottom connector 24 of the staircase assembly 10 of Figure 1. The upper connector 86 connects to the bottom connector 90 by lugs 92 that are shown in more detail in Figure 5. The lugs 92 include bolt openings so that the respective lugs can be bolted together to secure the modular staircase units 62 and 64 together.

[0052] It will be appreciated from Figures 3 and 4, that the staircase unit 62 is attached to the sleeves 82, while the staircase unit 64 is attached to the staircase unit

62. Thus, the height of the top landing 66 of the staircase unit 64 can be raised and lowered by raising and lowering the sleeves 82, which consequently raise both the staircase unit 62 and 64 together. The same arrangement that is described above in relation to the modular staircase assembly 10 can be employed to raise and lower the staircase units 62 and 64.

[0053] It is to be noted that other arrangements to lift and lower the staircase units 62 and 64 include jacking arrangements that can for example, push upwardly from a floor or ground surface against the bottom connectors 24 or 84, or that act directly on the sleeves 20 and 82.

[0054] It will be appreciated from the transition between Figures 1 and 3, that further staircase units can be added to further increase the height to which the staircase unit 64 can reach. Moreover, the construction of the staircase units can vary from a single flight arrangement of the staircase units 22 and 64 of Figures 1 and 3, to the two-flight staircase unit 62. Accordingly, the invention extends to staircase units that include a greater number of flights and a greater number of landings.

[0055] Figure 6 illustrates the staircase assembly 60 of Figure 3, but using rollers 94 on the base frame 78, rather than stationary feet 18 as shown in Figures 1 and 3. The rollers 94 preferably include braking arrangements so that the rollers can be locked against rolling movement when the assembly 60 is in position.

[0056] Otherwise, the arrangement of Figure 6 is identical to the arrangement of Figure 3 and 4.

[0057] The modular staircase assemblies of the present invention provide a relatively simple and convenient stair assembly that is height adjustable. Adjustability is provided by the use of sleeves attached to upstanding posts, while further height adjustment of a more significant nature can be achieved by adding multiple modular staircase units to a base frame.

[0058] Where any or all of the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other features, integers, steps or components.

[0059] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations and modifications which fall within the spirit and scope of the present invention.

[0060] Future patent applications may be filed in Australia or overseas on the basis of or claiming priority from the present application. It is to be understood that the following provisional claims are provided by way of example only, and are not intended to limit the scope of what may be claimed in any such future application. Features may be added to or omitted from the provisional claims at a later date so as to further define or re-define the invention or inventions.

Claims (23)

The claims defining the invention are as follows:

1. A modular staircase assembly, including:

a base frame having a base for resting on a floor surface and four vertically upstanding posts arranged in a square or rectangular configuration,

a first modular staircase unit being connected to the posts by four adjustment sleeves that are slidable relative to the posts for movement up and down the posts, the sleeves being fixable to the posts at a selected vertical position, the first modular staircase unit further including a staircase,

the first modular staircase unit being shiftable vertically by altering the selected vertical position at which the adjustment sleeves of the first modular staircase unit are fixed to the posts of the base frame.

2. A modular staircase assembly according to claim 1, the base frame having feet for engaging the floor surface on which the base frame rests.

3. A modular staircase assembly according to claim 2, the feet being height adjustable for levelling the modular staircase assembly on the floor surface.

4. A modular staircase assembly according to claim 1, the base frame having rollers or castors for rolling along the floor surface on which the base frame rests.

5. A modular staircase assembly according to anyone of claims 1 to 4, the staircase of the first modular staircase unit having a lower and upper ends and the first modular staircase unit being connected to access stairs that extend at an acute angle from the floor surface on which the base frame rests up to the lower end of the staircase.

6. A modular staircase assembly according to claim 5, the access stairs having a floor surface engagement end and a first modular staircase unit connection end and the access stairs being pivotably connected to the first modular staircase unit at the connection end so that the access stairs pivot relative to the first modular staircase unit to a greater acute angle as the first modular staircase unit is shifted upward relative to the posts of the base frame.

7. A modular staircase assembly according to anyone of claims 1 to 6, the staircase of the first modular staircase unit having a bottom landing from which a first stair portion of the first modular staircase unit staircase extends upwardly.

8. A modular staircase assembly according to anyone of claims 1 to 7, the staircase of the first modular staircase unit having a top landing to which a second stair portion of the first modular staircase unit staircase extends.

9. A modular staircase assembly according to claim 8, the staircase of the first modular staircase unit having an intermediate landing between the top and bottom landings and the first stair portion of the first modular staircase unit staircase extends upwardly in a first direction to the intermediate landing and the second stair portion of the first modular staircase unit staircase extends from the intermediate landing upwardly in a second direction, opposite the first direction, to the top landing.

10. A modular staircase assembly according to anyone of claims 1 to 9, the first modular staircase unit including a square or rectangular bottom connector which connects at or adjacent its corners to the four adjustment sleeves and the bottom connector supporting a bottom section of the staircase of the first modular staircase unit.

11. A modular staircase assembly according to anyone of claims 1 to 10, the first modular staircase unit including a square or rectangular top connector which connects at or adjacent its corners to the four adjustment sleeves and the top connector connecting to a top section of the staircase of the first modular staircase unit.

12. A modular staircase assembly according to claim 10 or 11, the first modular staircase unit having four uprights that are releasably connected to the respective adjustment sleeves, so that the first modular staircase unit can be released from the base frame by disconnecting the four uprights from the respective adjustment sleeves, the bottom connector connecting to a bottom section of the uprights and the top connector connecting to a top section of the uprights.

13. A modular staircase assembly according to anyone of claims 1 to 12, an upper end of the first modular staircase unit being releasably connected to a second modular staircase unit, the second modular staircase unit including a staircase, each of the first and second modular staircase units being shiftable vertically by altering the selected vertical position at which the adjustment sleeves of the first modular staircase unit are fixed to the posts of the base frame.

14. A modular staircase assembly according to claim 13, the staircase of the second modular staircase unit having a bottom landing from which a first stair portion of the second modular staircase unit staircase extends upwardly.

15. A modular staircase assembly according to claim 13 or 14, the staircase of the second modular staircase unit having a top landing to which a second stair portion of the second modular staircase unit staircase extends.

16. A modular staircase assembly according to claim 15, the first and second stair portions being coextensive.

17. A modular staircase assembly according to claim 15 or 16, the top landing being a platform allowing multiple personnel to work from the top landing, the top landing being fenced by a railing.

18. A modular staircase assembly according to claim 17, the railing including a gate for accessing the top landing.

19. A modular staircase assembly according to any one of claims 15 to 18, the top landing having a cantilever portion that extends out beyond the periphery of the four posts of the base frame.

20. A modular staircase assembly according to any one of claims 13 to 19, the second modular staircase unit having four uprights to which the staircase of the second modular staircase unit is attached, bottom ends of the four uprights being releasably connected to the upper end of the first modular staircase unit.

21. A modular staircase assembly according to claim 13 when dependent on claim 12, the second modular staircase unit having four uprights to which the staircase of the second modular staircase unit is attached, bottom ends of the four uprights being releasably connected to upper ends of the four uprights of the first modular staircase unit.

22. A modular staircase assembly according to any one of claims 13 to 21, an upper end of the second modular staircase unit being releasably connected to a third modular staircase unit, the third modular staircase unit including a staircase, the third modular staircase unit being shiftable vertically with the first and second modular staircase units by altering the selected vertical position at which the adjustment sleeves to are fixed to the posts of the base frame.

23. A modular staircase assembly according to any one of claims 1 to 22, the adjustment sleeves being fixable to the posts at a selected vertical position by the posts and the adjustment sleeves each having openings that can be brought into registration for receipt of a pin.