Building construction system

A building construction system for progressively forming a plurality of vertical superimposed concrete segments. A plurality of screw jacks form support columns and carry at their upper ends sub-frames upon which an overlying main frame is positioned. Formworks are suspended from the main frame and are moveable into position for pouring concrete to form the segments. The screw jacks are supported on a horizontal building element preceding a previously constructed horizontal building element and are retractable. The main frame is supported on adjustable struts for repositioning the screw jacks prior to extension to a subsequent segment forming position.

TECHNICAL FIELD 
This invention relates to an improved self-climbing system for the 
incremental construction of walls, and in particular the construction of 
vertical walls of concrete in the building and construction industry. The 
invention also relates to the construction of other concrete members in 
building structures, such as perimeter and band beams, although in its 
broadest form the invention relates primarily to the construction of 
vertical concrete elements, such as vertical walls forming the central 
service core of the building structure and/or the perimeter of the 
building structure. 
More particularly the invention relates to a complete highrise construction 
system which involves a method and apparatus for the incremental in-situ 
construction of the vertical concrete elements (perimeter walls and 
service cores), perimeter and band beams, and to a limited extent the 
floor slabs, in office towers, highrise condominiums and tall civil 
structures. 
BACKGROUND ART 
Existing self-climbing systems, such as those disclosed in Australian 
Patent No. 490759, and our co-pending Australian Patent Application No. 
18541/88, have limitations with regards to the flexibility of the systems. 
It is the object of the present invention to provide a system which is 
self-climbing and after the initial assembly requires no external cranage 
for lifting from one level to another. The system preferably carries with 
it all formwork components, safety decks, work platforms and perimeter 
safety screening, that is, all that is necessary for the safe working of 
personnel in and about the apparatus at all times to the completion of the 
structure. Upon building completion the system becomes redundant and is 
dismantled by external means. 
A further object of the invention is to provide a system which is capable 
of constructing structures of any size, shape or height; and although 
primarily concern with the construction of vertical walls, can have the 
versatility to construct the following groups of concrete elements. 
(a) Perimeter walls, beams and columns, together with internal columns, 
beams, shear walls and all central core walls concurrently 
(b) Half the relevant building elements cast by the system at one level, 
and the other half at one level advanced in a construction, conveniently 
split to suit the geometry and/or construction of the building. 
(c) Perimeter walls, beams and columns only. 
(d) Perimeter walls, beams and columns together with internal columns and 
beams and shear walls only. In this case the central core walls could be 
constructed ahead of the main floor areas by employing a conventional slip 
or jump form system. 
(e) Perimeter walls, beams and columns at one level and the central core 
walls at an advanced level in a split system. 
(f) All central core walls only. 
None of the existing self-climbing systems, including those of the patent 
and patent application referred to previously, can achieve such 
versatility of operation which are the objectives of the present 
invention. 
Since the introduction of central core climbing systems (slip or jump form 
systems the subject of the aforementioned Patent and Patent applications), 
and the introduction of fast cycle table-form systems for horizontal 
elements such as floor slabs, the construction of the perimeter of a 
building has been critical to floor to floor cycle times in the 
construction of multi-storey buildings. This is due largely to site crane 
dependence, the concentration of elements around the perimeter, and the 
safety requirements for personnel around the edge of the building in the 
formation of the perimeter. 
The preferred object of the present invention is to speed up the 
construction of perimeter, and like elements, in the construction of 
multi-storey buildings. 
DISCLOSURE OF THE INVENTION 
The present invention envisages a building construction system for 
progressively forming a plurality of vertical superimposed concrete 
segments in a building construction, said system comprising a plurality of 
jacking devices forming support columns and each carrying at their upper 
ends sub-frames for the system onto which a main frame overlying the 
positions at which the segments are to be formed is adapted to be 
positioned, and from which the form works are suspended to be movable to 
positions to define spaces within which concrete is poured to form said 
segments, said jacking devices being adapted to be supported on a lower 
previously constructed level of said building preceding a previously 
constructed level of said building and retractable while said main frame 
is supported on temporary supports to reposition said jack means for 
support on the previously constructed level of said building structure. 
With the system of the present invention, external cranes or other lifting 
machines are limited to the initial assembly and the final dismantling of 
the system, and to the supply of building materials, such as concrete, 
reinforcing steel and structural steel. The system after assembly is self 
sufficient in climbing from one level to another. 
The system carries all the formwork components necessary to form the groups 
of concrete elements according to any one of the schedules. 
The system can carry with it all the necessary access platforms for 
tradesmen and workmen, and forming an integral part of the system, 
together with safety screens at the perimeter or atriums of buildings and 
protecting two or more levels below. 
A typical construction cycle employing the system might be as follows: 
(1) Form the lifts/central core region with a conventional self-climbing 
core forming system or a system in accordance with the present invention. 
Advance the core construction together with any necessary associated floor 
area sufficiently ahead of the general floor levels being formed leaving 
construction joints about the core to receive main floor slabs and floor 
beams. 
(ii) As soon as the perimeter walls, or columns and beams, are at a level 
which is sufficiently typical of the structure and are clear of any 
surrounding ground, the system can be employed. First the perimeter 
elements are poured--walls, or columns and beams. Such elements have 
construction joints to receive horizontal elements such as beams and 
slabs. 
(iii) The system is advanced to clear the next floor level and this floor 
can then be poured, including into the receiving perimeter construction 
joints. 
(iv) As the immediately formed level is available to stabilize the system, 
the next level of perimeter elements can be poured, and so on. 
Preferably, the positions of the sub-frames relative to the jacking devices 
and also as a consequence the pouring chutes are adjustable, whereby the 
sub-frames and the main frame supported thereon will extend further beyond 
or close to the jacking devices, for example, to progressively shift the 
perimeter wall inwardly of the building as the building construction 
continues whereby to form a progressively inwardly stepped perimeter wall. 
Preferably the perimeter safety screens extend several floors below that 
from which a particular wall section is being formed at any time, whereby 
workman situated on platforms suspended from the safety screen structure 
can carry out finishing work at the floors below, such as surface 
finishing and glazing, within the relative safety of the safety screen 
suspended from the overhead framework, and which safety screen will rise 
progressively with the framework. 
Preferably also in relation to the assembly of the safety screen, 
prefabricated screen sections of standardized width are provided and have 
arrangements of holes or slots adjacent their edges and extending in 
lines, inwardly of the edges of each screen section, whereby with varying 
lengths of perimeter wall, gaps between screen sections during assembly of 
the safety screen which are less than the width of the screen sections 
themselves, can be filled by overlapping adjacent edges of the screen 
sections whereby a selected pair of holes or slots in the sections align 
to receive attachment means such as bolts or other fastening devices. 
Preferably the main frame is formed from prefabricated frame sections which 
are brought to the site and positioned onto the pre-positioned jacking 
devices and sub-frames, whereafter the frame sections are connected 
together to form a unitary main frame, or some may be left unconnected 
whereby individual lengths of the main frame can be raised independently 
of each other to allow vertical concrete walls or components to be formed 
at differing heights in accordance with a predetermined building schedule 
to provide some versatility in utilization of building workers. 
Preferably, for safety reasons, mesh covers are provided over the pouring 
chutes between formworks whereby concrete can be poured through the mesh 
and reinforcement can pass therethrough, whilst at the same time 
preventing building workers from falling into and through the pouring 
chutes. Preferably the mesh covers are hinged to adjacent working 
platforms whereby they can be swung upwardly out of the way when accessed 
to the pouring chutes might be required. 
Preferably means are provided to allow fine adjustment of the formworks at 
their points of suspension from the overhead main frame.

BEST MODES FOR CARRYING OUT THE INVENTION 
Referring to FIGS. 1 to 11 of the drawings, the first preferred embodiment 
of the invention comprises a plurality of jacking devices in the form of 
extendable jacks or hydraulic rams 20, strategically positioned having 
regard to the shape of the building to be constructed and positioned where 
vertical concrete walls and beams are to be constructed. The uppermost 
ends of each of the jacks or hydraulic rams carry sub-frames 21 formed 
from a series of longitudinal frame members 21a, lateral frame members 
21b, and vertical frame members 21c, collectively affixed to the upper 
most ends of the rams via connecting plates 22 between the upper and lower 
pairs of frame members 21a. 
The sub-frames 21 in turn support a main frame 23 for the system and 
overlying the walls, columns and other vertical elements 24 of the 
building construction to be formed, and consisting of longitudinal frame 
members 23a, lateral frame members 23b, vertical frame members (not 
visible) and diagonals 23d. The longitudinal frame members 23a are adapted 
to overlie support members 21d carried by the sub-frames 21. 
In addition, each of the sub-frames 21 at the perimeter wall receives a 
counterweight frame 25, including longitudinal frame members 25a received 
within the longitudinal frame members 21a of the sub-frames, which members 
21a may be in the form of channel sections or hollow-sections within which 
the frame members 25a are received. The counterweight frames 25 also 
include vertical members 25b, and the outermost ends of the counterweight 
frames support counterweights 26 the weight of which is calculated to 
off-set the weight of the system on the opposite side of the axes of the 
rams at the positions of the rams, to thereby provide a stable balanced 
structure for the system. 
FIGS. 2 to 5 of the drawings show the various stages during the assembly of 
the system. Prior to assembly of the system a first building level is 
formed using conventional wall and slab casting procedures, to provide the 
vertical walls 27, and any other vertical components of the building 
structure, and the first level floor slab 28. With reference to FIG. 2 of 
the drawings, the lower ends of the rams 20 are positioned through 
apertures in the floor slab 28 and support brackets 29 connect the rams 20 
to the floor slab, with adjustable struts 30 being utilized to further 
support and vertically align the rams between anchor points 29a on the 
rams and anchor points 29b on the floor slab 28. With reference to FIGS. 3 
and 5, the main frame 23 is then assembled on top of the sub-frames 21 
with the longitudinal frame members 23a engaging the support members 21d 
of the sub-frames whereby the whole of the main frame, or independent 
sections thereof, are supported on jacks or rams 20 via their sub-frames 
21. The counterweight frames 25 are thereafter inserted into the 
sub-frames and as formworks 31 (as shown in FIG. 6 of the drawings) are 
placed in position on the main frame, the counterweights 26 are positioned 
and adjusted to balance the system on either side of the axes of the rams 
20. 
To complete the system, various working decks 32 for workmen and tradesmen 
are position within and suspended from the main frame, whilst members 23e 
extending vertically downwardly from the main frame carry safety screens 
32a which extend to at least the level below, if not several levels below, 
the level being constructed. In addition, chutes 33 are provided through 
the deckings 32 on the main frame to communicate with the spaces between 
the formworks 31 when the formworks are moved to the wall segment casting 
positions, and/or positions for the casting of other vertical components 
of the building structure. Formworks 31 are in turn suspended from the 
sub-frames or the main frame on rollers 34 which allow the form works to 
be rolled into and away from the required concrete casting positions. 
The progressive casting of vertical building components, such as vertical 
perimeter walls and the vertical walls of the building service core, and 
any vertical building columns, is now described with reference to FIG. 6 
to 11 of the drawings. 
After the system has been assembled on the previously formed first level of 
the building construction as shown in FIG. 6 of the drawings, the 
formworks 31 are moved into position, and with reference to FIG. 13 of the 
drawings, are held in position by tie bars 35 extending through the 
combination of vertical and horizontal members 31a and 31b forming the 
main structural members for the formworks. 
As shown in FIG. 7 of the drawings, the wall segment 27a, and other 
vertical components for the second level of the building are cast and 
allowed to cure, whereafter the formworks are detached from the tie bars 
and separated, whereafter the jacks rams 20 are extended to the position 
shown in FIG. 8. The floor slab 28b for the next level is also cast using 
conventional floor slab casting techniques with its edges cast into 
ledgers 27b on the inner upper edges of the adjacent wall segments, and 
with reference to FIG. 8 of the drawings, the floor slabs are cast with 
apertures through which the jacks 20 extend. 
As shown in FIG. 9 of the drawings, at the next building level, the 
formworks 31 are repositioned and tied together to define spaces for the 
next wall segment and other vertical building components at that level, 
and once again a concrete pour is made. 
As shown in FIG. 10 of the drawings, temporary vertical adjustable struts 
36 are positioned between the main frame or sub-frames of the system and 
the underlying floor slab 28b to support the system whilst the jacks 20 
are retracted to draw their lower sections upwardly through the apertures 
in the floor slab 28b to be thereafter supported by the brackets 29 and by 
the struts 30 in the manner shown in FIG. 2. The procedure as per FIGS. 7 
to 10 is thereafter repeated for subsequent levels. 
Generally at strategic times during the operation of the system the 
sub-frames are braced to the builing structure below to provide rigidity. 
In the embodiments of FIGS. 1 to 10, any openings, such as windows through 
the perimeter walls of the building, are formed by providing suitable 
block-outs between the opposing wall forming formworks 31, whilst in the 
alternative embodiment of FIG. 12, openings, such as perimeter window 
openings as shown in FIG. 12, are formed by casting horizontal separating 
wall segments 37 between adjacent levels of the building utilizing short 
formworks 31a with lower formworks 31b being provided to define the bottom 
of the concrete casting cavity and held into position by adjustable 
vertical struts 38. In other respects the components of the system are 
identical to those of the first embodiment and the same identifying 
reference numerals have been utilized. 
FIG. 14 of the drawings illustrates how the system of the preferred 
embodiments of the invention may also be adapted to form horizontal beams 
39 within the building structure with interconnecting floor slabs 40, with 
provision to allow the beam casting formworks to be moved from below one 
beam casting level and upwardly to the next. 
As shown to the left of FIG. 14, when a structural beam 39 is to be cast, 
the formwork 41, appropriately shaped, is suspended from the system by 
rollers 44 received and movable along structural members 42 of the main 
frame 23 and/or sub-frames 21, and pivots thereabout. During casting of 
the beam the formwork 41 is supported and held in position by vertical 
adjustable struts 43. After casting and curing of the concrete beam 39, 
and as shown to the right hand side of FIG. 14, the struts 43 are removed, 
the formworks 41 swung or allowed to swing downwardly about the axis of 
the rollers 44, whereafter extension of the jacks 20 allows the formworks 
41 carried by the overhead frame work to move upwardly through the space 
between adjacent beams 39 and to the next level. 
Referring to the embodiment of FIGS. 15 to 21 of the drawings, as with the 
previous embodiments, this embodiment of the invention comprises a 
plurality of jacking devices in this case in the form of extendable jacks. 
The extendable jacks are electric motor driven screw jacks 20 also 
strategically positioned having regard to the shape of the building to be 
constructed and positioned where vertical concrete walls and beams are to 
be constructed. The uppermost ends of each of the jacks or hydraulic rams 
carry the sub-frames 21 formed from the series of longitudinal frame 
members 21a, the lateral frame members (not visible), and the vertical 
frame members 21c, collectively affixed to the upper most ends of the rams 
via the connecting plates 22 on the upper and lower pairs of frame members 
21a. 
The sub-frames 21 in turn support the main frame 23 for the system and 
overlying the walls, columns and other vertical elements 24 of the 
building construction to be formed, and consisting of the longitudinal 
frame members, lateral frame members, vertical frame members and 
diagonals, with the longitudinal frame members being adapted to overlie 
the support members carried by the sub-frames 21 as in the previous 
embodiments. 
In addition, each of the sub-frames 21 at the perimeter wall receives the 
counterweight frame 25, including longitudinal the frame members 25a 
received within the longitudinal frame members 21a of the sub-frames, 
which members 21a may be in the form of channel sections or 
hollow-sections within which the frame members 25a are received. The 
counterweight frames 25 also include the vertical members 25b, and the 
outermost ends of the counterweight frames support the counterweights 26 
the weight of which is calculated to off-set the weight of the system on 
the opposite side of the axes of the rams at the positions of the rams, to 
thereby provide the stable balanced structure required for the system. 
The lower ends of the rams 20 are positioned through the apertures in the 
floor slabs 28 and the support brackets 29 connect the rams 20 to the 
lowermost floor slabs, with the adjustable struts 30 being utilized to 
further support and vertically align the rams between the anchor points 
29a on the jacks and the anchor points 29b on the floor slab 28. The main 
frame 23 is assembled on top of the sub-frames 21 with the longitudinal 
frame members 23a engaging the support members 21d of the sub-frames 
whereby the whole of the main frame, or independent sections thereof, are 
supported on the jacks 20 via their sub-frames 21. 
To complete the system, the various working decks 32 for workmen and 
tradesmen are position within and suspended from the main frame, whilst 
the members 23e extending vertically downwardly from the main frame carry 
safety screens 32a which in this embodiment extend to two additional lower 
levels. In addition, the chutes 33 are provided through the deckings 32 on 
the main frame to communicate with the spaces between formworks 31 when 
the formworks are moved to the wall segment casting positions, and/or 
positions for the casting of other vertical components of the building 
structure. The formworks 31 are in turn suspended from the sub-frames or 
the main frame on the rollers 34 which allow the form works to be rolled 
into and away from the required concrete casting positions. 
The progressive casting of vertical building components, such as vertical 
perimeter walls and the vertical walls of the building service core, and 
any vertical building columns, is as described in detail in connection 
with the previous embodiments. 
In accordance with one of the modifications, the subject of this 
embodiment, the sub-frame 21 and the pouring chutes 33 are adjusted 
relative to the jacks 20, whereby to provide a greater amount of overhang 
beyond the perimeter of the building, and as such greater space between 
the perimeter of the building and the suspended safety screen 32a, for 
comfort and safety of workman situated on the platform 32 carried by the 
safety screen construction. 
In accordance with another of the modifications, the subject of this 
embodiment, and with particular reference to FIG. 16 of the drawings, the 
pouring chutes 33 are covered by mesh covers 100 through which concrete 
can be poured into the pouring slots between the tops of the formworks 31 
and thereafter into the cavity between the formworks, and the mesh covers 
may be hinged (not shown) to an adjacent working platform 32 so that they 
can be swung out of the way if access to the pouring chutes and slots is 
required. 
A still further modification, the subject of this embodiment, lies with the 
provision of attachments between the formworks 31 and the rollers to allow 
for fine adjustment of the positions of the formworks relative to the main 
frame 23, both upwardly and downwardly, as well as in the case of the 
outermost formwork, adjustment inwardly and outwardly of the building 
structure as well as along the building structure. 
In the case of the innermost formworks 31 shown on the left in FIG. 16, the 
upper ends of the vertical frame members 31a of the formworks, to which 
timber panels 31b are attached, are coupled via horizontal frame members 
101 and bolts 102 to a bracket 103 having a hole through one end, through 
which is received a threaded suspension member 104, carrying a nut 105 on 
the end thereof beneath the bracket. The upper end of the suspension 
member is connected to an axle about which the roller 34 rotates as it 
rolls along the flange of the structural member forming part of the main 
frame 23. By adjusting the nut 105 along the end of the suspension member 
104, the association formwork is raised or lowered relative to the 
overhead main frame. 
In the case of the outermost formwork 31 shown on the right in FIG. 16, and 
with reference to FIGS. 17 to 19, the upper ends of the vertical frame 
member 31a are also coupled with bolts 108, via a horizontal frame member 
106 and spacers 107, to a bracket 109 in the form of an inverted channel 
section, through which a threaded suspension member 110 carrying a nut 111 
extends for vertical adjustment similar to that for the inner formwork. An 
adjustment housing 112 is received within the bracket 109, and the 
housing, in turn, receives an adjustment member 113 through which the 
suspension member 110 passes to be attached thereto by a nut 114. The 
suspension member also passes through an aperture 115 in the bracket 109 
aligned with apertures 116 in the adjustment housing 112, all of which 
apertures are larger than the diameter of the suspension member 110 to 
accommodate relative movement thereto. The adjustment member 113 carries 
an elongate threaded horizontally disposed adjustment member 117 which 
extends through a hole 118 in the end wall of the adjustment housing 112, 
and carries a nut 119 externally of the housing, which, when adjusted 
along the member 117, causes the associated formwork 31 to move toward and 
away from the other formwork. The adjustment housing 112 also carries an 
elongate threaded horizontally disposed adjustment member 120 which 
extends through a hole 121 in one of the flanges of the inverted channel 
section forming the bracket 109, and also has a nut 122 associated 
therewith which, when adjusted along the member 120, will cause the 
bracket 109 and the formwork associated therewith to move backwards and 
forwards along the length of the building structure. It will be apparent 
from the above that adjustment of the outer formwork can be facilitated in 
three directions, namely, upwardly and downwardly, inwardly and outwardly, 
and back and forth along, the main frame 23 to allow for fine adjustment 
of the formwork position relative to the building being constructed. 
With reference again to FIG. 16 of the drawings, the axle for the rollers 
34 for the outermost formwork 31 carries a strap 123 which, in turn, is 
bolted to a convenient location through the flange of the associated 
member of the main frame 23 to hold the roller in position when the 
associated formwork 31 is at the correct casting position. 
Referring to FIG. 20 of the drawings, each jack 20 is an electric motor 
driven screw jack, and the operation of each jack may be controlled to 
operate simultaneously with the other jacks whereby all will be extended 
or retracted in unison to keep the construction system as a whole level. 
Each jack comprises a tubular motor housing 125 closed at the top and 
bottom by end walls 126 and 127 respectively. The upper end of the housing 
contains an electric motor 128 which drives a threaded power screw 129 via 
an electromagnetic clutch 130, a gear box 131, a torque limiting coupling 
132, and a bearing arrangement 133. A tubular fixed jack rod 134 forming 
an inner jack column is provided attached within the housing adjacent the 
bearing arrangement 133 and extends from within, and downwardly from, the 
housing into a co-axial outer column 137 for telescopic movement in 
relation thereto. A support tube 135 is received within the inner jack 
column 134 to be axially telescopingly movable therein and through a hole 
134a in the end of the column 134, and has its lower end connected at 136 
to the bottom of the interior of the outer column 137. The upper end of 
the support tube 135 carries a collar 138 internally threaded to engage 
with the externally threaded power screw 129. 
When the power screw 129 is rotated in one direction the motor housing 125, 
and the sub-frame and main frame supported thereon, will be driven 
(raised) upwardly whilst the support tube 135 attached to the outer column 
137 remains fixed to the lower building structure as shown in FIG. 8 of 
the first embodiment of the invention. When the power screw 129 is rotated 
in the opposite direction, with the outer column 137 detached from the 
lower building structure, and the main frame 23, sub-frames 21, and 
accordingly the housing 125, fixed at an elevated position, the outer 
column 137 and the support tube 135 will be drawn respectively upwardly 
around and within the inner jack column 134 as shown in FIG. 10 of the 
first embodiment of the invention. 
As discussed previously, in a preferred embodiment of the present invention 
the safety screen construction 32a is one in which prefabricated screen 
sections of standardized width are provided with arrangements of holes or 
slots adjacent their edges in lines extending inwardly thereof, whereby 
the varying lengths of perimeter walls, gaps between screen sections 
during assembly of the safety screen which are less than the width of the 
screen sections themselves, can be filled by overlapping adjacent edges of 
the screen sections with a selected pair of holes or slots in the sections 
aligned to receive attachment means such as bolts or other fastening 
devices. 
In addition, and also in accordance with a preferred embodiment of the 
invention, the main frame 23 may be formed from prefabricated frame 
sections, which frame sections are brought to the site and positioned onto 
the pre-positioned jacking devices 20 and sub-frames 21, whereafter the 
prefabricated frame sections are connected together to form a unitary main 
frame, or some may be left unconnected whereby individual lengths of the 
main frame can be raised independently of each other to allow vertical 
concrete walls or components to be formed at differing heights in 
accordance with a predetermined building schedule to provide some 
versatility in the utilization of building workers. 
Turning to FIGS. 22 to 27 of the drawings, the construction system of this 
fourth embodiment of the invention, as particularly utilized for 
constructing service cores in multi-storey buildings, comprises upper or 
head frames 200 forming part of the sub-frames and main frame and 
supporting the tubular motor housings 125 of screw jacks 20 similar to 
that of FIGS. 20 and 21, and downwardly from which the remainder of the 
screw jacks 20 extend. In this case, two screw jacks for the particular 
core shaft under construction are provided. The head frames 200 are, in 
turn, supported on an underlying grid of longitudinally and transversely 
extending main frame members 201 and 202 from which various formworks 203, 
and screens 205 carrying working platforms 204, are suspended. In this 
embodiment working platforms 206 with perimeter safety barriers 207 are 
provided on top of the grid of main frame members. 
In addition, the formworks themselves support internal working platforms 
208 with hand rails 208a at the inner formworks and bolted thereto, and 
external working platforms 209 with hand rails 209a which are hooked over 
the upper edges of the external formworks when the external formworks are 
moved to their outermost positions as shown in FIGS. 24 and 25 of the 
drawings and to allow access by workmen for cleaning of the formwork 
surfaces. The lower ends of the inner formworks have a further internal 
working platform 210 suspended therefrom. 
The lower ends of the screw jacks 20 carry retractable shear keys 211 
which, at various times, engage in pockets 212 formed in the inner side of 
the walls of the vertically superimposed wall segments 213 of the core as 
it is constructed. A still further and lowermost working platform 214 is, 
in turn, suspended from the shear keys by means of hangers 215 to allow 
access to the inside surfaces of previously cast wall segments for 
cleaning and finishing operations. 
As with the previous embodiments, the upper ends of the formworks are 
suspended from the overhead frame members via rollers 216 with adjustment 
of the formworks in three directions being achieved by adjustment 
mechanisms of the type previously described and illustrated with reference 
to FIGS. 17 to 19 of the drawings. 
The system of this fourth embodiment of the invention includes a number of 
feet assemblies 217 for supporting the system on an underlying previously 
cast wall segment 213, and comprise vertically adjustable screw members 
218 within large support heads 219 for engaging in sockets 222 formed in 
the top edge of the underlying wall segment by the heads 219 as the 
segment is cast. Concrete pouring chutes 220 are provided in line with the 
wall segments to be constructed and with mesh covers 221. In this fourth 
embodiment of the invention the wall construction system is alternately 
supported on a previous cast wall segment by the retractable shear keys 
211 or the feet assemblies 217. 
FIGS. 25 to 28 show the first four stages in casting a wall segment, and 
particularly the first wall segment 213 on a floor slab 223 at ground 
level. The floor slab 223 has an opening 224 therethrough communicating 
with a space or cavity beneath the slab and into which the lower ends of 
the screw jacks 20 can extend. A series of short starting walls 225 are 
firstly poured and allowed to solidify. 
The majority of the wall construction system is then assembled by locating 
the screw jacks 20 through the openings 224 and supported by a temporary 
bottom support frame 226 spanning between the starting walls 225. The 
screw jacks 20 are then temporarily braced to each other and/or the bottom 
support frame 226. The head frames 200 are then positioned on the screw 
jacks, if not already attached, the grid of main frame members 201 and 202 
is then assembled complete with the working platform 206 and safety 
barriers 207, and the inner and outer formworks 203 then placed in their 
suspended positions, together with the feet assemblies 217, chutes 220 and 
mesh covers 221. 
The formworks are then moved to their wall casting positions and the first 
wall segment 213 is then cast to extend upwardly from the starting walls 
225, and the wall segments then allowed to solidify. Prior to casting the 
wall segments, any reinforcement, block-outs for wall openings and shear 
key pocket forming means, such as 227, are positioned. 
After solidification of the wall segments 213 the formworks are separated 
and the system is raised on the screw jacks 20 to the position shown in 
FIG. 26 where the lower inner and external platforms 210 and 204 are 
attached whereafter, the screw jacks are extended to raise the whole 
system to the next wall segment casting level as shown in FIG. 27. 
The feet assemblies 217 are then lowered to a position between the 
formworks such that when the formworks are again moved to their casting 
positions, and the necessary reinforcements and block-outs positioned, the 
pouring of concrete will produce second wall segments 213 vertically 
superimposed on the first wall segments and extending up to, and around, 
the support heads 219 of the feet assemblies 217. 
After solidification of the second level of wall segments 213, and with the 
system supported on top of the second wall segments via the feet 
assemblies 217, the screw jacks are braced by temporary bracings 226a the 
temporary support frame 226 can then be removed and replaced with the 
retractable shear keys 211. The temporary bracings 226a can then be 
removed. The screw jacks are then reversed such as to retract, and in 
effect lift the shear keys 211 to the position shown in FIG. 28 whereby 
the engaging noses 211a which are biased outwardly of the shear keys will 
engage with the pockets 212 cast in the first level of the wall segments 
213. The lowermost working platform 214, with its hangers 215, is then 
positioned and assembly of the whole of the wall construction system is 
completed. 
The raising of the system to construct subsequent higher wall segments is 
achieved by extending and retracting the screw jacks 20 with the system 
being alternately supported by the shear keys 211 when the screw jacks are 
extended to raise the system to the next casting position, or suspended by 
the feet assemblies 217 when the screw jacks are retracted to raise the 
shear keys to their next support position. 
The service core construction system of this fourth embodiment of the 
invention may be combined with peripheral wall and beam construction 
systems of the type the subject of the preceding embodiments to allow both 
service core and building construction at the same time, and generally in 
advance of the construction of perimeter walls, beams and floor slabs. 
As well as reinforced concrete structures, the system of the present 
invention is designed to construct concrete encased steel structures. 
Floor to floor heights (levels) in commercial buildings are in the range 
2.7 m to 4.0 m. In the case of concrete encased steel structures, the rams 
20 and associated bracing may advance the placement of perimeter steel 
elements two levels in advance in order to satisfy steel alignment 
specifications in advance of concrete encasement. It will be appreciated 
that the rams 20 and the associated bracing will need to extend an 
additional floor level and the size and the extent of this additional 
supporting structure will be considerable. 
The system of the present invention has considered all relevant trades, and 
as such, the platforms provided for pouring concrete and working decks for 
carpenters and other tradesmen at the appropriate levels and locations. 
These platforms are constantly provided and require no manual shifting 
from one level to another as they are carried along with the advancing of 
the system. 
The safety screens added about the perimeter of a building, are also 
carried with the system. The screens can be carried down several floors to 
protect perimeter trades below. The entire perimeter may be clad to add 
psychological security to work undertaken in this area of the building 
construction. 
The continuing presence of working platforms and safety screens, and their 
automatic advance with the system, reduces the amount of work and 
facilitates the ease and speed with which the construction operations are 
completed. 
The majority if not all of the structural components of the system can be 
manufactured off-site and shipped thereto for subsequent assembly with 
other components on-site.