U.S. patent application number 12/224810 was filed with the patent office on 2009-07-02 for placing device building system and method of constructing a multi-storey building.
Invention is credited to Thomas Axelsson, Hakan Camper, Rikard Espling, Mikael Fritzon, Jonas Graslund, Pertt Johansson, Carl Jonsson, Per-Ola Jonsson, Sven Junkers, Roland Kindberg, Ove Lagerqvist, Jorgen Larsson, Andreas Simfors, Per Tureson.
Application Number | 20090169339 12/224810 |
Document ID | / |
Family ID | 38475144 |
Filed Date | 2009-07-02 |
United States Patent
Application |
20090169339 |
Kind Code |
A1 |
Simfors; Andreas ; et
al. |
July 2, 2009 |
Placing Device Building System and Method of Constructing a
Multi-Storey Building
Abstract
A placing device (1) for placing building elements (2) in
constructing a multi-storey building comprises a lifting means (4)
for lifting a prefabricated building element (2), a moving means
(7) for moving the placing device (1) into and out of a lower
storey of the multi-storey building, the lower storey being
arranged under an upper storey, a rotary means (8) for rotating the
building element (2) about a normal to a floor plane of the lower
storey, a vertical adjustment means (20) for vertically adjusting
the building element (2), and a control means (14) for controlling
the placing device (1) for placing the building element (2)
according to a predetermined pattern. A building system and a
method of constructing a multi-storey building are also
disclosed.
Inventors: |
Simfors; Andreas; (Goteborg,
SE) ; Lagerqvist; Ove; (Lulea, SE) ; Jonsson;
Carl; (Limhamn, SE) ; Camper; Hakan; (Bjarred,
SE) ; Graslund; Jonas; (Hasselby, SE) ;
Larsson; Jorgen; (Timmele, SE) ; Fritzon; Mikael;
(Hesingborg, SE) ; Tureson; Per; (Lerum, SE)
; Jonsson; Per-Ola; (Vaxjo, SE) ; Johansson;
Pertt; (Goteborg, SE) ; Espling; Rikard;
(Stockholm, SE) ; Kindberg; Roland; (Kalmar,
SE) ; Junkers; Sven; (Vastra Frolunda, SE) ;
Axelsson; Thomas; (Stockholm, SE) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 8910
RESTON
VA
20195
US
|
Family ID: |
38475144 |
Appl. No.: |
12/224810 |
Filed: |
March 8, 2007 |
PCT Filed: |
March 8, 2007 |
PCT NO: |
PCT/SE2007/000220 |
371 Date: |
January 27, 2009 |
Current U.S.
Class: |
414/10 ;
414/800 |
Current CPC
Class: |
E04G 21/167 20130101;
E04B 1/3522 20130101; E04B 1/04 20130101; E04G 21/16 20130101 |
Class at
Publication: |
414/10 ;
414/800 |
International
Class: |
E04G 21/14 20060101
E04G021/14 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 8, 2006 |
SE |
0600503-7 |
Oct 12, 2006 |
SE |
0602140-6 |
Claims
1. A placing device for placing building elements in constructing a
multi-storey building wherein it comprises: a lifting means for
lifting a prefabricated building element, a moving means for moving
the placing device into and out of a lower storey of the
multi-storey building, the lower storey being arranged under an
upper storey, a rotary means for rotating the building element
about a normal to a floor plane of the lower storey, a vertical
adjustment means for vertically adjusting the building element, and
a control means for controlling the placing device for placing the
building element according to a predetermined pattern.
2. A placing device as claimed in claim 1, in which the moving
means comprises wheels for movement along rails arranged in the
floor plane of the lower storey.
3. A placing device as claimed in claim 1, in which the moving
means comprises caterpillar tracks.
4. A placing device as claimed in claim 1, further comprising a
lateral displacement means for displacing the building element
parallel to the floor plane.
5. A placing device as claimed in claim 1, further comprising a
longitudinal displacement means for displacing the building element
in a plane parallel to the floor plane.
6. A placing device as claimed in claim 1, further comprising a
rotating means for rotating the building element about a normal to
the floor plane.
7. A placing device as claimed in claim 1, further comprising a
pivot means for turning the building element in a plane
perpendicular to the floor plane.
8. A placing device as claimed in claim 1, further comprising a
tilting means for turning the building element in a plane
perpendicular to the floor plane.
9. A placing device as claimed in claim 1, further comprising a
transverse displacement means for displacing the wall element
parallel to the floor plane.
10. A placing device as claimed in claim 1, in which the control
means comprises a programmable control unit for controlling the
placing device according to a predetermined coordinate system.
11. A placing device as claimed in claim 1, in which the lifting
means Comprises suction cups for holding the building element.
12. A placing device as claimed in claim 1, in which the lifting
means comprises at least one mandrel for engagement in a recess at
an underside of the building element.
13. A placing device as claimed in claim 1, in which the lifting
means comprises lowerable arms for lifting floor structure
elements.
14. A placing device as claimed in claim 5, in which the
longitudinal displacement means and the pivot means comprise a
common bearing.
15. A building system for constructing a multi-storey building,
comprising a placing device as claimed in claim 1 and at least two
lifting devices for lifting the building element when it is placed
according to the predetermined pattern.
16. A building system as claimed in claim 15, further comprising
lifting towers arranged along an outside of the multi-storey
building.
17. A building system as claimed in claim 16, further comprising
tie rods which interconnect two lifting towers arranged on opposite
sides of the multi-storey building.
18. A method of constructing a multi-storey building, in which an
upper storey is constructed and raised before a lower storey is
constructed under the raised upper storey wherein a placing device
lifts by a lifting means a prefabricated building element from a
storage place, that the placing device moves the building element
to a placement position in the lower storey according to a
predetermined pattern by moving itself inside the lower storey
and/or rotating the lifting means about a normal to a floor plane
of the lower storey, and that the placing device places the
building element in the placement position.
19. A method as claimed in claim 18, in which the storage place is
outside the multi-storey building.
20. A method as claimed in claim 18, in which the building element
is a wall element or a floor structure element.
21. A method as claimed in claim 18, in which the building element
is selected from the group consisting of a bathroom module, a
kitchen module, a stair module and an elevator module.
22. A method as claimed in claim 18, in which the placing device
finely adjusts the position of the building element by lateral
displacement of the building element parallel to the floor
plane.
23. A method as claimed in claim 18, in which the placing device
finely adjusts the position of the building element by longitudinal
displacement of the building element parallel to the floor
plane.
24. A method as claimed in claim 18, in which the placing device
finely adjusts the position of the building element by rotating the
building element about a normal to the floor plane.
25. A method as claimed in claim 18, in which the placing device
finely adjusts the position of the building element by turning the
building element in a plane perpendicular to the floor plane.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a placing device for
placing building elements in constructing a multi-storey building.
The invention also relates to a building system for constructing a
multi-storey building. The invention further relates to a method of
constructing a multi-storey building, in which an upper storey is
constructed and raised before a lower storey is constructed under
the raised upper storey.
TECHNICAL BACKGROUND
[0002] Multi-storey buildings are traditionally constructed from
the bottom to the top, and one of the first steps is usually to
perform the foundation work. The foundation can, for example, be a
slab on the ground or a basement foundation, on which the first
storey (i.e. the ground floor) of the multi-storey building is
constructed. Then, on top of the first storey, a second storey is
built which is supported by structural concrete elements belonging
to the first storey.
[0003] Concrete elements are subsequently placed or cast on the
underlying elements until a desired number of storeys is obtained,
and as the building grows higher building elements are lifted
increasingly higher up by means of conventional cranes. In many
cases interior fittings are also lifted up and placed on the floor
level where they are to be mounted.
[0004] Scaffolding and other security details are often mounted at
the outside of the building, which is time-consuming and expensive
but necessary to obtain a safe working environment.
[0005] A general problem of prior-art building methods is that it
is often relatively time-consuming and thus expensive to construct
a multi-storey building. Furthermore, much nonproductive work is
performed in the form of scaffold erecting, material handling,
crane lifting and also rework due to erroneously performed working
operations.
[0006] Building elements which are lifted into the building by
crane have to be exactly positioned by hand. This increases the
labour costs and also constitutes a source of risk for the
erectors.
[0007] Another problem is that both the building and the building
workers are exposed to weather, which in turn results in a number
of problems.
[0008] Prior-art building methods also suffer from drawbacks such
as the danger of people or objects falling from a high place, which
may cause both material damage and personal injury to workers who
either fall or are hit by falling objects.
[0009] A further drawback of prior-art methods of constructing
multi-storey buildings is the increased risk of accidents involved
in working with cranes.
[0010] Another problem of prior-art building methods is that
perishable materials cannot be mounted until the building is
covered and initial moisture dried out. This leads to long
construction times and high costs.
[0011] Therefore building methods are developed in which the
storeys are built in reverse order. According to such a method, the
construction starts with the foundation work. Then, on the
foundation, the uppermost storey and the roof are built. The
uppermost storey is subsequently raised by one floor, after which
the construction of the second uppermost storey is initiated below
the uppermost storey. The construction then proceeds in this manner
until a desired number of storeys is obtained and is completed by
the building of the ground floor. The walls and the floor
structures are cast in situ. A method of this type is disclosed,
for instance, in U.S. Pat. No. 3,828,513.
[0012] One drawback of these "reverse" building methods is that
they use in-situ concrete, which demands a great deal of work on
the work site. In addition, casting concrete in situ requires much
equipment, for instance, in the form of pumps and forms. There is
also a risk of casting errors leading to rework. Another problem of
casting in situ is that the concrete must dry, which increases the
construction time. Prefabricated building elements cannot be used,
since the "reverse" building process makes it impossible for cranes
to lift building elements into the storey which is currently being
constructed as it is hidden under the storeys that are already
built.
SUMMARY OF THE INVENTION
[0013] One object of the present invention is to remedy or at least
mitigate the above-described problems.
[0014] A particular object is to provide a device which makes it
possible to construct multi-storey buildings more effectively.
[0015] Another object is to provide an improved building system,
which makes it possible to construct multi-storey buildings more
effectively.
[0016] Yet another object of the invention is to indicate an
improved method of constructing multi-storey buildings.
[0017] These objects are achieved by a placing device according to
claim 1. Preferred embodiments are defined in dependent claims
2-14.
[0018] The objects are also achieved by a building system according
to claim 15 and preferred embodiments thereof defined in dependent
claims 16 and 17.
[0019] The objects are further achieved by a method according to
claim 18. Preferred variants of the method are defined in dependent
claims 19-25.
[0020] The placing device according to the invention comprises:
[0021] a lifting means for lifting a prefabricated building
element,
[0022] a moving means for moving the placing device into and out of
a lower storey of the multi-storey building, the lower storey being
arranged under an upper storey,
[0023] a rotary means for rotating the building element about a
normal to a floor plane of the lower storey,
[0024] a vertical adjustment means for vertically adjusting the
building element, and
[0025] a control means for controlling the placing device for
placing the building element according to a predetermined pattern.
By this device, it is possible to place in an efficient manner
prefabricated building elements for constructing a multi-storey
building, in which a lower storey is constructed under a finished
upper storey.
[0026] The moving means of the placing device can comprise wheels
for movement along rails arranged in the floor plane of the lower
storey. It is thus possible to easily provide safe movement of the
placing device.
[0027] Alternatively, the moving means can comprise caterpillar
tracks, which allow free movement of the placing device.
[0028] According to preferred embodiments of the invention, the
placing device comprises various means for moving and turning the
building element, such as a lateral displacement means for
displacing the building element parallel to the floor plane, a
longitudinal displacement means for displacing the building element
in a plane parallel to the floor plane, a rotating means for
rotating the building element about a normal to the floor plane, a
pivot means for turning the building element in a plane
perpendicular to the floor plane, a tilting means for turning the
building element in a plane perpendicular to the floor plane, or a
transverse displacement means for displacing the wall element
parallel to the floor plane. With the aid of these means, it is
possible to finely adjust the position of the building element in
various directions.
[0029] The control means of the placing device can comprise a
programmable control unit for controlling the placing device
according to a predetermined coordinate system. Owing to this, the
placing can be automated for increased precision and safety.
[0030] The lifting means advantageously comprises suction cups for
holding the building element. The building elements can thus be
held in a very safe manner.
[0031] The lifting means can comprise at least one mandrel for
engagement in a recess at an underside of the building element.
This further increases the holding safety.
[0032] According to an embodiment, the lifting means comprises
lowerable arms for lifting floor structure elements. Owing to this,
the lifting means can be specially adjusted for safe movement of
floor structure elements.
[0033] The longitudinal displacement means and the pivot means
advantageously comprise a common bearing. The construction of the
placing device can thus be very compact.
[0034] The inventive building system comprises a placing device
according to the invention and at least two lifting devices for
lifting the building element when it is placed according to the
predetermined pattern. With such a building system, it is possible
to effectively position and hold building elements which are to be
mounted.
[0035] Lifting towers are advantageously arranged along an outside
of the multi-storey building. By means of the lifting towers, the
finished storeys can be raised before the construction of the next
storey begins, without the need of any entrances in the storeys for
lifting devices. In addition, their location at the outside of the
building allows free space inside the building, which means that
all the building elements required can be lifted into position from
the inside of the storey currently being built, without being
obstructed by lifting devices passing through the building.
[0036] The building system can further comprise tie rods which
interconnect two lifting towers arranged on opposite sides of the
multi-storey building. Owing to this, the horizontal forces
occurring when raising the finished storeys can be absorbed.
[0037] The inventive method of constructing a multi-storey building
is characterised in
[0038] that a placing device lifts by a lifting means a
prefabricated building element from a storage place,
[0039] that the placing device moves the building element to a
placement position in the lower storey according to a predetermined
pattern by moving itself inside the lower storey and/or rotating
the lifting means about a normal to a floor plane of the lower
storey, and
[0040] that the placing device places the building element in the
placement position. This method makes it possible to construct a
multi-storey building in an efficient and safe manner with reduced
manual labour input. As the building elements are prefabricated,
the construction time is reduced and better manufacturing
tolerances are possible.
[0041] The storage place of the building elements is advantageously
outside the multi-storey building, which makes it easier to select
a suitable unloading place and which allows the work site to be
more accessible.
[0042] The building element can be a wall element or a floor
structure element, which allows efficient construction of a
storey.
[0043] The building element can also be selected from the group
consisting of a bathroom module, a kitchen module, a stair module
and an elevator module, for increased prefabrication of the
multi-storey building.
[0044] Advantageously, the placing device finely adjusts the
position of the building element by lateral displacement of the
building element parallel to the floor plane and/or longitudinal
displacement of the building element parallel to the floor plane
and/or rotating the building element about a normal to the floor
plane and/or turning the building element in two planes
perpendicular to the floor plane. By these motions the position of
the building element can be precisely adjusted.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] In the following, the invention will be described in more
detail with reference to the accompanying schematic drawings which
for the purpose of exemplification show presently preferred
embodiments of the invention.
[0046] FIG. 1 is a perspective view, seen obliquely from the rear,
of a placing device according to the invention.
[0047] FIG. 2 is a front elevational view of the placing
device.
[0048] FIG. 3 is a perspective view, seen obliquely from the front,
of the placing device.
[0049] FIG. 4 is an elevational view, seen from the side, of the
placing device.
[0050] FIG. 5 is an outline diagram which illustrates the various
motions of the placing device.
[0051] FIG. 6 is a perspective view showing parts of a building
system according to the invention.
[0052] FIG. 7 is a sectional view showing parts of the building
system.
DESCRIPTION OF PREFERRED EMBODIMENTS
[0053] The placing device 1 shown in FIG. 1 is adapted for
positioning prefabricated building elements of reinforced concrete,
such as floor structure elements 2, in constructing a multi-storey
building 3 (see FIG. 7). The placing device 1 is essentially
composed of a lifting means 4 supported by a rotary arm 5, which is
mounted on a carriage 6.
[0054] The carriage 6 has wheels 7 for moving the placing device 1
along rails (not shown) in a floor plane G of the multi-storey
building 3. The arm 5 is rotatably connected to the carriage 6 via
a bearing 8, so that the arm 5 and the lifting means 4 supported by
the arm 5 can be rotated about a normal N to the floor plane G.
[0055] The lifting means 4 has two lifting forks 10, which each are
provided with a mandrel 11 for engagement with a hole or a groove
at the underside of the wall element 9. For as precise engagement
as possible, the wall element should be formed with a hole at each
end of its underside, but in view of the manufacturing tolerances
of the wall elements it is suitable to have instead a hole at one
end of the wall element and a groove at the other end. One of the
mandrels 11 can thus be engaged in the groove, so that the wall
element 9 can be held in a safe manner, in spite of any dimensional
deviations. To hold the wall element 9 in a safe manner, the
lifting means 4 also has suction cups 12 which can retain the wall
element 9 by suction.
[0056] The lifting means 4 is in the position shown in FIG. 1 which
is adapted for lifting and moving wall elements 9 (see FIG. 6), but
by lowering two lowerable arms 13 the lifting means can be adapted
for lifting and moving floor structure elements 2. In that case,
the floor structure element 2 rests on the lowered arms 13.
[0057] The placing device 1 has a control unit 14, which makes it
possible to remote-control the motions of the placing device 1, for
instance by means of a hand control, for placing the building
element 2, 9 according to a predetermined pattern, which is laid
down in a construction drawing.
[0058] The placing device 1 has several degrees of freedom in the
motion pattern of the lifting means 4 and the building element 2
supported by the lifting means 4. The motion pattern is seen more
clearly in FIG. 5. Besides the fact that the placing device 1 can
execute a movement (arrow a) into and out of the storey C in
question with the aid of the moving means consisting of the wheels
7 and the rails (not shown) in the floor plane G, and that the arm
5 can be rotated via the bearing 8 in a rotary motion (arrow b)
about the normal N to the floor plane G, the lifting means 4 and
the building element 2 supported by the lifting means 4 can be
moved and rotated in a number of different ways.
[0059] Using a lateral displacement means in the form of a rack 15,
the arm 5 can be displaced laterally (arrow g), perpendicularly to
the motion into and out of the storey C provided by the wheels 7.
Furthermore, the arm 5 can be lengthened and shortened in a
longitudinal displacement motion (arrow c) by means of a bearing 16
and two hydraulic cylinders 17, so that the lifting means 4 is
moved in a direction parallel to the movement of the placing device
1 into and out of the storey C. In this manner, it is possible to
obtain a finer adjustment of the position of the building element 2
in this direction compared to what is possible using the wheels
7.
[0060] The same bearing 16 as that used for lengthening and
shortening the arm 5 is used as a pivot means 18 for turning (arrow
d) the lifting means 4 in a plane perpendicular to the floor plane
G.
[0061] It is possible to provide a rotation (arrow e) of the
lifting means about the normal N to the floor plane G by a rotating
means in the form of a bearing 19. The same bearing 19 can be used
together with hydraulic cylinders 20 as vertical adjustment means
for vertically adjusting (arrow f) the lifting means 4.
[0062] A transverse displacement means 21 can displace the building
element 2 on the lifting means 4 in a direction (arrow h) parallel
to the floor plane G for fine adjustment of the position of the
building element 2 on the floor plane G.
[0063] A tilting means in the form of a bearing 22 allows tilting
of the lifting means 4 and the building element 2 supported by the
lifting means 4 in a turning motion (arrow i) in a plane
perpendicular to the floor plane G and perpendicular to the plane
in which the above-mentioned pivoting motion (arrow d) of the arm 5
takes place.
[0064] Owing to the various motions of the placing device 1, the
placement of the heavy concrete element 2 can be controlled both
roughly and finely.
[0065] Besides the placing device 1, the inventive building system
also includes lifting devices in the form of two jacks 23 per wall
and a number of lifting towers 24. The lifting towers 24 are placed
along the outside of the multi-storey building 3. The lifting
devices 23 are placed on the floor plane G for receiving a wall
element 9, one at each end of the wall element 9. The lifting
devices 23 temporarily raise the wall element 9 placed by the
placing device 1 so that the lifting towers 24 can engage the lower
edge of the wall element 9.
[0066] The inventive building method according to which the
building system is intended to operate will now be described. The
building method is based on the principle of building the storeys
of the multi-storey building 3 in reverse order. As seen in FIG. 7,
the finished storeys A and B are raised to make room for the
construction of the next storey C under the two upper storeys A and
B.
[0067] The placing device 1 can be moved by means of the wheels 7
into and out of the lower storey C (see FIG. 7) which is being
constructed under a raised, previously built upper storey B. The
placing device 1 fetches a building element, such as a floor
structure element 2, from a storage place outside the multi-storey
building 3. The placing device 1 is then moved into the lower
storey C. The arm 5 is rotated by the rotary means 8 about the
normal N to the floor plane G so that the floor structure element 2
attains approximately the position in which it is to be placed. The
position of the floor structure element 2 is then finely adjusted
by the various possibilities of movement of the placing device 1,
as described above, and the floor structure element is lowered down
to its position. When the floor structure element 2 is placed, the
placing device 1 is moved out of the storey C to fetch more floor
structure elements 2 and wall elements 9. The placing device 1 can,
of course, also be used for placing other building elements, such
as kitchen modules, bathroom modules, stair modules and elevator
modules (not shown). When the wall element 9 has reached its place,
it is raised by the placing device 1 towards the already built
upper storey B. When all the building elements 2, 9 of the storey C
are placed, they are interconnected and cast together while being
lifted by the lifting devices 23. The building elements 2, 9 of the
lower storey C are also interconnected and cast together with the
previously constructed upper storey B. The lifting towers 24 are
then connected to the lower edge of the placed wall elements 9 to
stepwise raise, by repeated engagement, all the finished storeys A,
B, C by a bit more than one storey H to make room for the
construction of the next storey. While the next storey is being
constructed, the work in the lowermost C of the finished storeys
can be completed, for instance electrical work, heating,
ventilation and sanitary installations and paint work.
[0068] By this method and the inventive placing device, it is
possible to construct a multi-storey building in a very efficient
way. Moreover, very good precision of the positioning of the
building elements 2, 9 can be achieved.
[0069] The construction of the placing device 1 is particularly
compact, among other things because the lengthening/shortening of
the arm 5 can be provided by the same bearing as the pivoting
motion of the arm 5.
[0070] The location of the lifting towers 24 at the outside of the
building 3 allows the space inside the building 3 in the storey C
just being built to be free and not being disturbed by lifting
devices passing therethrough. This makes it possible to place, by
means of the placing device 1, all the building elements required,
wall elements 9 and floor structure elements 2 as well as
prefabricated modules, such as kitchens, bathrooms and elevators.
If instead the lifting device had been placed inside the building
3, with entrances through the floor structures of the storeys, it
would have been possible to place the wall elements 3 by means of
the placing device but it would have been necessary to place the
floor structure elements in some other way. At the same time, the
placing device 1 facilitates the use of exterior lifting towers 24,
since it can work inside the storey C which is currently being
built and place the building elements 2, 9 required without being
obstructed by the lifting towers 24.
[0071] It can be noted that the method of operation of the placing
device 1 differs in principle from that of conventional cranes in
that the building elements 2, 9 are placed starting from the inside
of the storey C and working out to the place where the walls are to
be raised, whereas conventional cranes are placed outside the
building and lift the building elements from the outside in.
Conventional cranes cannot be used in building methods in which the
storeys are built in reverse order, since the crane has not got
access to the storey which is under construction as it is located
under already built storeys. In addition, conventional cranes lift
the building element at one point only, which means that the
building element can rotate freely and tip. In the final placement
of the building element, the erectors have to guide the lifted
building element by hand, which involves working environment risks,
in particular when handling heavy concrete elements.
[0072] In summary, it can be concluded that by using the invention
it is possible to provide a building, which during construction, is
protected from weather, which results in shorter construction times
due to less need of drying out and the possibility to mount
moisture-sensitive materials earlier, to automate the construction
of the building with exact positioning of the building elements and
to mount both the structural building elements and prefabricated
modules, such as bathrooms and kitchens, by means of the same
device.
[0073] It will be understood that a number of modifications of the
inventive embodiments described herein are possible within the
scope of the invention, which is defined by the appended
claims.
[0074] For example, instead of wheels 7, the placing device 1 can
have caterpillar tracks (not shown). Then there is no need for
rails in the floor plane G and the placing device 1 can move
freely. The lateral displacement of the arm 5 can, of course, be
provided by other means than by racks 15, for instance by wheels
and rails.
[0075] The controlling of the placing device can be automated. In
that case, the control unit 14 can be programmable for controlling
the placing device 1 in a predetermined coordinate system. This
control could be based directly on suitably designed drawings.
[0076] The suction cups 12 can be connected to lights (not shown)
which are lit when a sufficient negative pressure is attained to
indicate when the wall element 9 is secured.
[0077] In FIG. 7, only two lifting towers 24 are shown but
naturally more lifting towers can be used, suitably at least four.
If four lifting towers 24 are used, they can, for instance, be
placed in the centre at each side of a four-sided multi-storey
building 3.
[0078] When two opposite lifting towers 24 are raising the finished
storeys, they can be interconnected by tie rods to absorb the
horizontal forces occurring in the lifting, since the lifting takes
place from the outside of the building, i.e. eccentrically.
Alternatively, each lifting tower can be anchored to the
ground.
* * * * *