TECHNICAL FIELD

The present invention relates to climbing formwork assemblies and associated methods. Embodiments of the present invention find application, though not exclusively, in the fields of constructing walled structures such as the cores of high-rise buildings, lift wells, stairwells, towers, etc.

BACKGROUND ART

Any discussion of documents, acts, materials, devices, articles or the like which has been included in this specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed in Australia or elsewhere before the priority date of this application.

It is known to make use of climbing formwork assemblies that typically include upper and lower decks and formwork shutters to construct tall structures such as the cores of high- rise buildings, lift wells, stairwells, towers, etc. Such prior art climbing formwork assemblies typically make use of posts or columns that are positioned atop the vertical concrete walls of the structure. The posts or columns are acted upon by jacks when it is necessary to raise the entire climbing formwork assembly. During lifting, the lifting force is transferred down the posts or columns and onto the top of the concrete walls that were formed from the previous concrete pouring. Whilst in use, the posts or columns of such climbing formwork assemblies will typically protrude by up to several meters above the working platform surface. Hence, the posts or columns typically constitute obstructions to the working platform surface and can present safety issues, such as a potential to be impacted by crane-hoisted loads, for example.

When it is necessary to execute a lift, the prior art arrangements typically hoist the platform at a rate of approximately 40 mm per minute. This slow rate, combined with a substantial time requirement for plumbing to ensure the correct alignment of the platform once it has been raised, means that the prior art arrangements are typically operated with an approximate 7 day pour cycle. It has been appreciated by the inventor of the present application that the abovedescribed prior art arrangements can suffer from a lack of stability, for example due to movements allowed by the posts or columns. This lack of stability has negative ramifications in relation to the amount of plumbing required to properly level the climbing formwork assembly between each successive lift-and-pour cycle to ensure ongoing wall verticality. Additionally, a lack of stability contributes to a lowering of the maximum allowable wind limit during lifting.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome, or substantially ameliorate, one or more of the disadvantages of the prior art, or to provide a useful alternative.

In one aspect of the present invention there is provided a climbing formwork assembly for construction of a walled structure having at least one wall defining a wall top surface, the climbing formwork assembly being operable to construct the wall in a series of pour-and- climb cycles, the climbing formwork assembly including: a lower wall engagement member configured, in use, to engage formations disposed in the wall, the formations being spaced below the wall top surface; an upper wall engagement member disposed intermediate said lower wall engagement member and the wall top surface; a platform structure having an upper platform supporting a plurality of downwardly extending formwork shutters, the upper platform also supporting a lower platform via at least one support member; and a ram disposed intermediate the lower wall engagement member and the upper platform, the ram being operable to lift the platform structure relative to the wall, wherein, in use during lifting of the platform structure, a load path of lifting forces extends between the lower wall engagement member, the ram, and the upper platform.

In an embodiment the upper wall engagement member defines a collar through which the ram is extendable, the ram being slidably retained by the collar.

Preferably substantially no lifting hardware associated with the climbing formwork assembly protrudes above the upper platform.

Preferably a vertical distance between the upper platform and the lower wall engagement member (whilst the platform structure is in use in a fully lowered configuration) is greater than any one of the following: 4.5 meters; 5 meters; 5.5 meters; 6 meters or 6.5 meters.

In an embodiment the lower wall engagement member is an elongate shear key configured to extend between two adjacent walls, the elongate shear key defining two opposed ends, each end having an outwardly resiliently biased retractable engagement lug and wherein each of the walls have formations in the form of recesses shaped to receive an engagement lug. Preferably the recesses and engagement lugs cooperate so as to resist downward movement of the elongate shear key relative to the walls and to allow upward movement of the elongate shear key relative to the walls, the shear key being freed for said upward movement by inward retraction of the engagement lugs.

In one embodiment the recesses define an inclined upper surface shaped to promote inward retraction of the engagement lugs in response to upward movement of the lower wall engagement member. In this embodiment the recesses also define a flat or inclined lower surface shaped to oppose inward retraction of the engagement lugs in response to downward movement of the lower wall engagement member.

In one embodiment the upper wall engagement member is an elongate shear key configured to extend between two adjacent walls, the elongate shear key defining two opposed ends, each end having an outwardly resiliently biased retractable engagement lug and wherein each of the walls have formations in the form of recesses shaped to receive an engagement lug.

Preferably at least one of the formwork shutters is fixedly disposed on the upper platform and at least one of the formwork shutters is moveably disposed on the upper platform such that a separation distance between the formwork shutters is adjustable.

Typically, at least two adjacent formwork shutters have proximal ends that are respectively fixedly disposed on the platform and the upper wall engagement member is attached to, and extends between, respective distal ends of the at least two adjacent formwork shutters.

In one embodiment at least a portion of the lower platform is supported by via support members depending from the upper wall engagement member. In one embodiment an upper end of the ram is attached to the upper platform via a spherical bearing.

According to another aspect of the invention there is provided a method of operating a climbing formwork assembly as described above, the method including: engaging the lower wall engagement member with formations disposed in the wall; extending the ram so as to raise the platform structure relative to the wall from a lowered configuration to a raised configuration until the upper wall engagement member engages with further formations disposed in the wall; and retracting the ram so as to raise the lower wall engagement member until the lower wall engagement member engages with further formations disposed in the wall.

Preferably at least one of the formwork shutters is fixedly disposed on the platform and said at least one fixed formwork shutter remains in sliding face-to-face contact with the wall whilst the platform structure is being raised.

Preferably the method further includes using a hydraulic fluid pumping system configured to individually control a pressure at which hydraulic fluid is pumped to each of the rams. This may involve calculating a fluid pumping pressure for each of the rams based upon load distribution across the platform structure and pre-setting a pressure for each of the rams to a maximum calculated pressure prior to initiating a lift.

The features and advantages of the present invention will become further apparent from the following detailed description of preferred embodiments, provided by way of example only, together with the accompanying drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1 is a sectional side view of an embodiment of a climbing formwork assembly being used for the construction of a wall, with the climbing formwork assembly being in a lowered configuration;

Figure 2 is a sectional side view of the embodiment of figure 1, with the climbing formwork assembly being in a raised configuration;

Figure 3 is a side view of an embodiment of a ram. Figure 4 is a plan view of an example wall layout that could be constructed using the embodiment of a climbing formwork assembly as illustrated in figure 1;

Figure 5 is a plan view of an example layout of wall engagement members as applied to the example wall layout of figure 3;

Figure 6 is a plan view of an example formwork layout as applied to the example wall layout of figure 3;

Figure 7 depicts cross sectional views of a spherical bearing that is used for connection of the ram;

Figure 8 depicts a side view and a cross sectional view of a housing for the spherical bearing shown in figure 7;

Figure 9 is a plan view of an embodiment of a lower wall engagement member;

Figure 10 is an end view of the embodiment of a lower wall engagement member of figure 9;

Figures 11 & 12 are side and plan views respectively of components that may be assembled to form part of an embodiment of a collar for use on an upper wall engagement member;

Figure 13 is a plan view of another component that may be assembled to form part of an embodiment of the collar for use on the upper wall engagement member;

Figure 14 is a plan view of an embodiment of an upper wall engagement member; and

Figure 15 is a perspective view of an embodiment of a hydraulic fluid pumping control system for control of the rams of the climbing formwork assembly.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

The climbing formwork assembly 1 as illustrated in figures 1 and 2 is typically used for construction of walled structures such as the cores of high-rise buildings, lift wells, stairwells, towers, etc. When construction of the walls commences at the foundation or ground level, formwork shutters are used without any of the self-climbing equipment. This allows the construction of the walls up to a height at which the climbing formwork assembly 1 may be positioned by crane onto the walls, which is typically approximately 3 meters. The climbing formwork assembly 1 is then operable to construct the walls in a series of pour-and-climb cycles. For example, as shown in figure 1, the climbing formwork assembly 1 is in a fully lowered configuration. Whilst in this configuration, the operators ensure that the formwork shutters 2, 3 are positioned as required to define the outer surfaces of the walls and then concrete is poured in between the formwork shutters 2, 3 at a rate that preferably does not exceed 1.2 meters per hour. Once the concrete has dried sufficiently to provide the requisite strength, which is approximately 8 MPa, the climbing formwork assembly 1 is operable to climb the walls in a manner that will be described in more detail below.

In the embodiment illustrated in figures 1 and 2 a pair of lower wall engagement members 4 are configured, in use, to engage formations 5 disposed in the walls 6 spaced below the wall top surface 7. These lower wall engagement members 4 remain fixed in position relative to the walls 6 whilst the climbing formwork assembly 1 is being raised. This provides the support needed to oppose the raising forces generated by extension of the ram 9 during raising of the climbing formwork assembly 1. Once the platform structure 10 has been raised, the climbing formwork assembly 1 is in the raised configuration as illustrated in figure 2.

A pair of upper wall engagement members 8 are disposed intermediate the lower wall engagement members 4 and the wall top surface 7. These upper wall engagement members 8 remain in a fixed position relative to the walls 6 whilst the ram 9 is being retracted. This retraction is necessary to lift the lower wall engagement members 4 up to allow them to engage with the next higher set of formations 5 disposed in the walls 6. This completes the raising process and, once the platform structure 10 has been plumbed, the next concrete pour cycle may commence. This repeats as required until the desired building height has been reached.

Hence, it follows from the preceding two paragraphs that climbing is a two-step process. Firstly, the lower wall engagement members 4 remain fixed whilst the ram 9 is extended, which raises the entire platform structure 10. Secondly, the platform structure 10, along with the upper wall engagement members 8, remain fixed whilst the ram 9 is retracted, which raises the lower wall engagement members 4 up until they engage with the next higher set of formations 5.

The platform structure 10 has an upper platform 11. This is constructed from an array of beams and must be engineered to provide high strength properties due to the loadings to which the upper platform 11 is subject. The upper side of the upper platform 11 supports the construction workers. Cladding 12 is disposed around the perimeter of the upper platform 11 for safety.

At a very high level of generality, an aspect of the embodiment of the invention is that the lifting hardware associated with the climbing formwork assembly 1 (such as the rams 9 and the upper and lower engagement members 4 and 8) is positioned lower relative to the upper platform 11 as compared to the lifting hardware used in the prior art (such as posts or columns). More specifically, the vertical distance between the lower side of the upper platform 11 and the upper side of the lower wall engagement members 4 (whilst the platform structure 11 is in use in a fully lowered configuration) is approx. 6.6 meters. In other embodiments, this dimension is preferably greater than any one of 4.5 meters; 5 meters; 5.5 meters; 6 meters or 6.5 meters. This enhances safety in the embodiment because substantially none of the lifting hardware of the climbing formwork assembly 1 protrudes above the upper platform 1, which avoids the obstructions caused by the posts or columns of the prior art. This also improves the ease and safety of the operation of cranes in the vicinity of the upper platform 11 because the lack of protruding posts or columns relieves the crane operator of the need to avoid impacting crane loads against them.

The formwork shutters 2, 3 extend downwardly from the lower side of the upper platform 11. Some pairs of adjacent formwork shutters 2 have proximal ends that are fixedly disposed on the upper platform 11 and some of the formwork shutters 3 have proximal ends that are moveably disposed on the upper platform 11. More specifically, the moveable formwork shutters 3 are supported by wheeled trolleys that run along the lower horizontal portion of an I-beam that supports the upper platform 11. This moveability allows the separation distance between the formwork shutters 2, 3 to be adjusted to suit the desired width of the concrete wall that is to be formed between the formwork shutters 2, 3. When the moveable formwork shutters 3 have been adjusted to the desired separation from the fixed formwork shutters 2, the moveable formwork shutters 3 are temporarily locked in place, allowing the concrete to be poured between the formwork shutters 2, 3.

Once the concrete has sufficiently hardened (i.e., when the concrete has an approximate strength of at least 5 MPa), the moveable formwork shutters 3 are unlocked and moved away from the wall 6 in preparation for the raising of the platform structure 10, which can occur once the concrete has a strength of at least 8 MPa. During the raising, the fixed shutters 2 are in sliding face-to-face contact with the sides of the walls 6, which acts as a guide to help maintain the desired alignment of the platform structure 10 with the walls 6. This helps to reduce the amount of plumbing that is required after the raise to ensure that the platform structure 10 is properly aligned with the walls 6, which saves valuable time in the construction process. Additionally, this also helps to improve the overall stability of the climbing formwork assembly 1 whilst it is being raised, which helps to increase the maximum wind limit above which raising may not occur. For the illustrated embodiment the maximum wind limit for raising of the platform structure 10 is 15 kph, although this may vary depending upon a desired factor of safety.

The upper platform 11 also supports a lower platform 14 via a plurality of support members 13 which extend downwardly from the upper platform 11. On the perimeter of the platform structure 10 the cladding 12 functions as the support member 13 to support the outer portions of the lower platform 14. Towards the middle of the upper platform 11, a support member 13 supports another portion of the lower platform 14. The lower platform 14 is also used by the construction workers during construction of the walls 6.

As shown in figures 1 and 2, rams 9 are disposed intermediate, and extend respectively between, the lower wall engagement members 4 and the upper platform 11. The rams 9 are telescopic and are hydraulically operable to lift the platform structure 10 relative to the walls 6. During lifting of the platform structure 10, the load path of lifting forces extends between the lower wall engagement members 4, the rams 9 and the upper platform 11. The load path also extends across the upper platform 11, down the formwork shutters 2, 3 and the support members 13, and into the lower platform 14. The upper wall engagement members 8 are disposed at the distal ends of the adjacent pairs of fixed formwork shutters 2 and extend therebetween. Support members 15 extend down from the upper wall engagement members 8 to support portions of the lower platform 14 and hence the load path also extends down these components.

In the embodiment, each ram 9 is a single stroke ram design with a maximum range of 4500 mm and having the following properties:

I. Double acting cylinder with dual counterbalance cartridges mounted in the base;

II. Single stroke ram with capacity to lift at 1.7mm/sec;

III. Cylinder maximum operating pressure 2500 PSI / 170 Bar;

IV. Maximum operating extension force at 2500 psi = 30,000 Kg / 294 KN;

V. Maximum operating retraction force at 2500 psi = 17,000 Kg / 166 KN;

VI. Counterbalance cartridges pre-set at 1.3 times the maximum load induced pressure - 3250 PSI 1224 Bar; and

VII. Approximate 30 Tonne maximum capacity.

As best shown in figure 14, the upper wall engagement members 8 each define a collar 16 through which the ram 9 extends. During extension or retraction, the ram 9 is slidably retained by the collar 16. Hence, the lateral support offered by the collar 16 reduces deflection of the ram 9 during lifting of the platform structure 10. When installing the rams 9 into climbing formwork assembly 1, the upper wall engagement members 8 each have an opening sized to accept the barrel of a ram 9. The items nos. 1, 2 and 3 illustrated in figures 11, 1 and 13 are then installed onto the upper wall engagement members 8 to form the collar 16, which slidably retains the rams 9 respectively within the upper wall engagement members 8. A bleeder valve 17 runs down the outside of the barrel of each ram 9 and item no. 3 shown in figure 13 includes a cut out sized to accommodate the bleeder valve 17.

Another feature of the embodiment that helps to minimise deflection of the rams 9 is mounting of the top of the rams 9 via spherical bearings 24. That is, the upper ends of the rams 9 are each attached to the upper platform 11 via a spherical bearing 24. Cross sectional views of an example of a suitable spherical bearing 24 are illustrated in figure 7. Through experimentation, it has been determined by the inventor that a spherical bearing that is commercially available from Universal Bearing Company, 7 Toohey Rd, Wetherill Park NSW 2164, Australia, and that is known as Part No. GEG50ET-2RS is suitable for use in the embodiment. Each spherical bearing 24 is housed in the housing 25 shown in figure 8, which is connected to the top end of each ram 9. The use of spherical bearings 24 helps eradicate rotational forces that could otherwise be imparted to the rams 9 and thereby cause deflection. Testing of prototypes of the embodiment has confirmed that the rams 9 exhibit minimal deflection. The lower ends of the rams 9 are each attached to the lower wall engagement members 4 via a simple pin connection. The spherical bearings 24 are not required to form this lower connection because the lower wall engagement members 4 are not susceptible to the potential for twisting or movement to the same extent as the upper platform 11.

As best shown in figures 9 and 10, the lower wall engagement member may take the form of elongate lower shear key 18 configured to extend between two adjacent walls 6. The elongate lower shear key 18 defines two opposed ends, each of which has an outwardly resiliently biased retractable engagement lug 19. More specifically, the lugs 19 are rotatably mounted at each of the ends of the lower shear key 18 and are resiliently biased to rotate outwardly from the ends. The shapes of the lugs 19 correspond to the shapes of the formations 5 in the walls 6 with which they engage. More specifically, the formations 5 are in the form of recesses 20, each shaped to receive an engagement lug 19. The recesses 20 and engagement lugs 19 cooperate with each other so as to resist downward movement of the elongate shear key 18 relative to the walls 6. The recesses 20 define a flat or inclined lower surface 21 shaped to oppose inward retraction of the engagement lugs 19 in response to the exertion of a downwardly directed force on the lower shear key 18. That is, the lugs 19 effectively key into the recesses 20 in response to extension of the ram 9 generating a force attempting to push the shear key 18 downwards.

The recesses 20 and engagement lugs 19 also cooperate with each other so as to allow upward movement of the elongate shear key 18 relative to the walls 6. This is because the recesses 20 define an inclined upper surface 22 shaped to promote inward retraction of the engagement lugs 19 in response to upward movement of the elongate shear key 18. Hence, retraction of the rams 9 creates enough force to allow the upper surfaces of the lugs 19 to slide against the inclined upper surfaces 22 of the recesses 20, which allows for inward retraction of the engagement lugs 19 against the resilient biassing, thereby freeing the lower shear key 18 for upward movement.

As best shown in figure 14, the upper wall engagement member 8 is also in the form of an elongate upper shear key 23 that is similar to lower shear key 18 except with provision for the above-mentioned collar 16. The upper shear key 23 also makes use of the lug 19 and recess 20 arrangement described above to allow for the upper shear key 23 to be displaced upwardly out of the recesses 20, but not downwardly.

Figure 4 is a plan view of an example wall layout that could be constructed with the embodiment illustrated in figures 1 and 2. Figure 5 is a plan view of an example layout for the placement of the shear keys 19, 23, which avoids the penetrations in the walls. Figure 6 is a plan view of an example layout for the formwork shutters 2, 3 required to construct the example wall layout of figure 3. The designation RF in figure 6 is a reference to a rolling or moveable formwork shutter 3 and the designation FF in figure 6 is a reference to a fixed formwork shutter 2.

The embodiment of the method of operating a climbing formwork assembly 1 includes engaging the lower wall engagement members 4 with the formations 5 disposed in the walls 6. The embodiment of the method also includes extending the rams 9 so as to raise the platform structure 10 relative to the walls 6 from a lowered configuration (as shown for example in figure 1) to a raised configuration (as shown for example in figure 2) until the upper wall engagement members 8 engage with further formations 5 disposed higher up in the wall 6. During this raising of the platform structure 10, the fixed formwork shutters 2 remain in sliding face-to-face contact with the walls 6. The embodiment of the method also includes retracting the rams 9 so as to raise the lower wall engagement members 4 until the lower wall engagement members 4 engage with further formations disposed higher up in the wall 6.

The embodiment of the method also includes using a hydraulic fluid pumping system 26, as illustrated in figure 15 to individually control a pressure at which hydraulic fluid is pumped to each of the rams 9. This may involve calculating a fluid pumping pressure for each of the rams 9 based upon the load as distributed across the platform structure 10. The pressure for each of the rams 9 connected to the hydraulic fluid pumping system 26 is pre-set to the calculated pressure for the maximally loaded ram 9 prior to initiating a lift. The hydraulic fluid pumping system 26 used in the embodiment has the following properties:

I. 14 individual outlet radial piston pump;

II. Single 14 station manifold to supply individual pump flows. Each station has its own pressure relief pre-set at the maximum operating pressure 2500 PSI / 170 Bar. Manifold station is numbered 1 to 14; III. Each station is operated by 4 way/3 positional detented manual lever directional control valve (DCV);

IV. 14 station pressure gauge manifold to monitor individual pressure reading of each cylinder when in use during ram extension and retraction. Each gauge is numbered 1 to 14 to correspond with the DCV numbers;

V. Pump theoretical flow per outlet is 1.9 litres per minute;

VI. Theoretical cylinder rod retraction speed is 3.12mm per second (i.e., 3 metres in

16 minutes and 4.5 metres in 24 minutes);

VII. Theoretical cylinder ram extension speed isl.7mm per second (i.e., 3 metres in 29 minutes and 7.5 metres in 43 minutes);

VIII. WOOL capacity for the hydraulic oil required to engage the rams; and

IX. All ports can be engaged to provide an initial up take of 500psi per ram.

Any dimensions that may be depicted in any of the figures are provided purely by way of non-limiting example. It will be appreciated that other embodiments of the invention may have various components having differing dimensions.

Testing of the embodiment of the invention advantageously exhibited efficiency and accuracy compared to the prior art during and subsequent to the climbing process. As a result, the time taken to complete the climbing process is typically substantially reduced, which leads to a safer and more productive system. In particular, the embodiment exhibited:

• Smoother climbing;

• Substantially shorter post climb plumbing durations;

• Improved stability and wind resistance;

• Climbs executed at approximately 1.7mm per sec (compared to a typical climb speed of approximately 0.7 mm per sec for the prior art);

• Load paths directed through the formwork shutters 2, 3 as well as rams 9 in lieu of obstructive posts or columns used with prior art systems;

• Less obstructions on the upper platform 11 ;

• Pre-setting of the pressure gauges on each of the ram outlets at the hydraulic fluid pumping system 26 to help ensure a consistent and level climb for the whole system, especially when the climb begins;

• The use of spherical bearings 24, which reduce the incidence of deflection of the rams 9 as they extend to their maximum capacity under load; • The use of the collars 16 at the upper shear keys 23 ;

• Improved pre-assembly of units, which has the potential to improve site productivity; and

• In some circumstances, the embodiment may allow for a 3 to 4 day pour cycle (compared to a typical 7 day pour cycle for the prior art systems).

While a number of preferred embodiments have been described, it will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.