Technical Field

This invention relates to a work platform system for multi-storey buildings, and in particular a system which enables temporary access to the perimeter (facade) of a building, for men and materials for example, and for the purpose of maintenance, refurbishment or cladding replacement. pack round Art

Access to the perimeter face of a building is traditionally done with the use of scaffolding assembled from the ground upward, which is time consuming and labour intensive. Scaffolding cantilevered from various levels within the building has also been used, but this intrudes upon tenanted floor space.

Alternatively, swing stage scaffolding, on ropes from overhead davits located on the top of the building, may be used, but these normally have a very limited load capacity. The rope climbing motors used are numerous, small capacity machines and synchronising of the climbing operation also presents a problem.

Disclosure of the Invention

It is the object of the present invention to provide platforms for working access to the perimeter of a building which are of greater capacity than previous suspended systems and are not subject to the problems associated therewith. With the present invention work platforms can be larger and more adequate for their task, and suspension members are less numerous requiring fewer points of control in the lifting process as well as being visually more pleasing on the face of the building during the use of the system. Control of platform level is more positive and precise, and being a suspended system

supported at the top, outside the building, no tenanted floor space need be occupied by the system, and the building perimeter at ground level may also remain available to, or not interfere with movement of, the public as is the case with ground supported scaffolding.

It is also an object of the present invention that access to the perimeter of the building be flexible, both in plan geometry, and in order to accommodate changes in the vertical face alignment of the building.

The present invention envisages a work platform system for the perimeter face of a multi-storey building, including means, in use, to support the system at the top or an upper storey level of the building and extending beyond the perimeter thereof, means to suspend at least one work platform down the face of the perimeter of the building, and jack means selectively coupled between said support means and said suspension means whereby upon increasing or decreasing the length of said suspension means the work platform or platforms can be incrementally lowered down, or raised up, the face of the perimeter of the building.

Preferably the support means is a support frame fixed cantilever style to the top or upper storey level of the building, the suspension means is a series of elongate suspension members, and the jack means are screw jacks, or hydraulic or pneumatic rams.

Preferably the side of the platform or platforms away from the face of the perimeter of the building has enclosure means applied thereto for workman safety. Brief Description of the Drawings

One preferred embodiment of the invention will now be described with reference to the accompanying drawings, in which;

Figure 1 is a plan view of the system extending around the face of the perimeter of a building,

Figure 2 is a cross-sectional view taken along line 2-2 of Figure 1 during one phase of operation of the system,

Figure 3 is a cross-sectional view similar to that of Figure 2 during a subsequent phase of operation of the system, and

Figure 4 is a cross-sectional view once again similar to that of Figures 2 and 3 during a further subsequent phase of operation of the system.

Best Modes for Carrying Out the Invention.

With reference to the drawings, the system of this preferred embodiment of the invention comprises a plurality of support frames 10 positioned and attached via support structures 11 on the roof 12a of the building at spaced apart intervals around the top of the perimeter of a building 12 and extending cantilever style over the building parapet 12b beyond the perimeter of the building. The building is a multi-storey building having a plurality of floor levels 13, and the system is to be used to allow maintenance, refurbishment or cladding replacement of the face of the perimeter of the building. The support frames 10 comprise a pair vertically spaced apart ram or jack support platforms 14 and 15, on the lower one 14 of which the lower end of respective rams or jacks 16 are attached to extend vertically upwardly therefrom and through the upper platform 15. The rams or jacks 16 may be electric motor driven screw jacks of the type described and illustrated in the specification of our

International Patent Application No. PCT/AU90/00042, and carry at their upper ends head frames 17 which are successively raised and lowered during extension and retraction of the jacks.

A plurality of sets of elongate suspension members are suspended from the head frames 17, and are in the form of suspension tubes 18 aligned and attached end to end to extend down the face of the perimeter of the building and to successively lower levels thereof. The lower ends of the aligned sets of suspension tubes carry a plurality of vertically spaced apart work platforms 21 to support workmen maintaining, refurbishing, or replacing cladding on, the face of the building. The platforms 21

extend through and between the sets of suspension tubes to thereby provide continuous platforms extending around the face of the perimeter of the building.

Barriers 22 for the safety of workmen are provided on the sides of the work platforms away from the face of the perimeter of the building, and buffers, slides or rollers 23 are supported by the platform structure to bear against, and space the platform structure from, the face of the perimeter of the building.

The jacks 16, which are controlled to operate in unison by a central controller, together with the head frames 17, are crane lifted into the support frames 10 which are attached to the top of the building. The frames 10 provide access to the jack area for operation, placement and removal of attachments and other components. The frames 10 may be adapted in their support and attachment to the individual building on which they are located.

In the form shown, the platforms are capable of spanning large distances between tubes, and a number of working levels may be supported by the continuous structure, as depicted. Continuity of the working platforms may be about the entire building perimeter, or limited to discrete zones - independent on each building face for instance. Further, this continuity in a multi-level platforms may be staggered vertically at selected locations to accommodate a change in working conditions or a better deployment of labour. The system is flexible and options in continuity of the platforms are numerous, dependent on support and restraint conditions required.

Access to the working platform areas may be by man and material hoists up the outside of the building or via the support structures 11 on the roof of the building. Such hoists outside of the building may readily access/enter the work platform area, being incrementally adjusted in height to match the change in level of the working platforms. Alternatively, access may be by crane externally, or internally by use of the building lifts and

accessing the platforms through a window or from a balcony.

In order to further stabilize and balance the system props 24 and 24 may be respectively coupled between the inner sides of the support frames 10 and the parapet 12b and between the frame 10 and the top of the parapet 12b, whilst frames 25 containing counter weights may be suspended from the inner sides of the support frames.

When the system is in operation the platforms 21 may be either incrementally lifted from the ground up, or lowered incrementally from the top of the building downward.

The operation of the system will be described for the more difficult of the two alternative starting locations, that is, lowering from the top downward.

Sufficient aligned sets of suspension tubes 18 are connected to the head frames 17 to extend to the platform structure incorporating the platforms 21.

The working platforms 21, associated platform levels and barriers 22 are assembled in selected segments at ground level and then raised as completed components with external cranage to the underside of the support frames 10. Here the suspension tubes 18 between the platform structure 21 and the support frame 10 are coupled together in complete safety.

The platform structures are then connected together at the corners of the building.

External cranage is thereafter no longer needed for the incremental lifting or lowering of the system. Sufficient cranage for the supply or removal of materials, if necessary, to and from the work platforms need only be provided during the operation of the system. External cranage will be needed again for dismantling the system.

Dismantling of the lower part of the system will be at ground level, - or even at a constructed level of protection above the ground allowing public access at the base of the building. It then remains to dismantle the rest of the system with external cranage. First the

suspension tubes which must be incrementally dismantled, and then the jacks and their frames at the top of the building.

With reference to Figures 2, 3, and 4 of the drawings, during the work platform lowering operation as shown (Figure 2) shear pins 19 or other attachments are used to couple each of the sets of suspension tubes 18 to structural members of their respective support frames 10 at the lower jack support platform 14, with shear pins 19 or other attachments being used to couple the sets of suspension tubes to the respective head frames 17 at platform 15.

The best means so far devised for the transfer of load from the suspension tubes 18 to supporting frames 10 or head frames 17 is the use of a surrounding support bracket accommodating two shear pins, each in double shear, for the automatic and safe transfer of load to and from the suspension tubes 18 at both jack support platforms 14 and 15.

When the shear pins 19 are removed at platform 15 the jacks 16 can be extended to raise the head frames 17 and reposition platform as shown in Figure 3 whereafter additional suspension tubes 18 are positioned for attachment at their lower ends to the existing sets of tubes 18 and coupled by the shear pins 19 at their upper ends to the head frames 17 at platform 15. The shear pins 19 between the sets of suspension tubes at platform 14 can then be disengaged and the jacks 16 retracted to lower the sets of suspension tubes, and the work platform structure downwardly to a lower position as shown in Figure 4. The sequence of operations is repeated to incrementally lower the work platform structure down the face of the perimeter of the building as maintenance, refurbishment (new cladding 20) or the like proceeds over a period of time.

The operation sequence may be varied in a number of ways, but in each case it involves a means of load transfer from the jacks 16 to the support frames 10 while the jacks are extended and an extra suspension tubes 18 are

added. Then a reversal of the load transfer back from the support frames to the jacks for the incremental downward movement of the work platform structure. The incremental movement in the above operation is equal to the interval between platforms 14 and 15 and is matched to the incremental movement required at working platform structure below.

A variation of the above operation is, for instance, as follows. Again consider the change in system level operation commencing with the shear pins installed at platform 14 and the platform structure suspended from the support frames 10 on top of the building at this level, but still connected via the suspension tubes 18 and head frames 17 to the jacks 16.

The sets of suspension tubes are uncoupled from the top suspension tubes at the coupling just above platform 14.

The jacks 16 are now free to be extended to lift the head frames 17 and top suspension tubes, away from the remaining lower sets of suspension tubes.

The head frames are reconnected to the lower sets of suspension tubes by adding and coupling additional suspension tubes between platforms 14 and 15, the coupling being at just above platform 15, and below just above platform 14.

The jacks are then extended sufficiently to take the weight of the platform structure and sets of suspension tubes. The shear pins in the suspension tubes at platform 14 are removed and the jacks are then retracted to the head level. The support shear pins 19 are recoupled to the suspension tubes at platform 14. The jacks are then slightly retracted to transfer the load to the support frame at platform 14.

The different options in varying this sequence have different advantages and disadvantages, but in each the underlying principle is the same.

The advantages in the operation of this system over the prior art may now be further elaborated upon in

the light of the above description of the system.

As control on the finite and discrete number of suspension lifting points may be quite precise, especially using the motor screw jacks disclosed in the International Patent Application referred to above, and controlled to operate in unison, the entire perimeter work platform structure can be lifted simultaneously. The platform structure on each face of the building can then, as a consequence, be connected together at the building corners throughout the entire operation, which offers mutual stability to the platform string in plan located on each of the building elevations.

It can be seen from the above description of the system that it is readily adapted to various building plan geometries. Similarly, limited changes in vertical alignment of a building face or faces, may be accommodated by a shift of the location of the jack on its supporting frame at the top of the building. This shift can be achieved, as may be required part way through a building maintenance project, with the aid of external cranage and for example the adjustment of the platform string at corner joints.

Furthermore the weight of the platform structure is taken directly by the support frames attached to the building except during the jacking between levels. The system is, in effect, static for the majority of time, and no dynamic loads need be considered on the system. It is only during the jacking shift that dynamic loading and jack capacity reduction involving this dynamic load need be considered - this is a time when the live loads on the system may be reduced by appropriate site control and management.