EP1144062B1

EP1144062B1 - Method for constructing a vertical ring-shaped structure

Info

Publication number: EP1144062B1
Application number: EP99959555A
Authority: EP
Inventors: Faramand Jahanpour
Original assignee: BUILDING DESIGN PARTNERSHIP LT; Building Design Partnership Ltd
Current assignee: Building Design Partnership Ltd
Priority date: 1999-01-13
Filing date: 1999-12-09
Publication date: 2004-11-10
Anticipated expiration: 2019-12-09
Also published as: DE69921854T2; ES2230906T3; WO2000041789A1; ATE281875T1; DE69921854D1; EP1144062A1; CZ20012490A3; AU1669500A

Abstract

A method for constructing a vertically ring structure from a plurality of pre-fabricated arced segments. Each of the segments has at least one face arranged to engage with a face on an adjacent segment when in position. The method comprises a step of connecting two adjacent segments. A force is then provided tangential to the ring structure with pre-stressed cables in order to pull the two adjacent segments together and the procedure repeated for each of the segments of the structure. The structure is thereby held in position and resisting the tendency for collapse of the segments caused by their dead weight, throughout the construction process. The structure may be a Ferris wheel.

Description

The present invention relates to the construction of large vertical ring structures, for example the construction of a Ferris wheel.
Small ring structures can be constructed flat on the ground and be subsequently erected in one piece. However, as the ring structure becomes larger, the forces exerted on joints within the structure when lifting it in one piece become much greater than the forces that need to be withstood by the joints once it is upright. Providing the considerable extra strength to the structure that is required when lifting in one piece can make it bulky and can be very expensive. Therefore, for larger ring structures, it is usually necessary to carry out construction in the vertical plane from the outset. The problem arising from vertical construction of any ring structure is that the upper section of the arch collapses under its own weight, unless otherwise supported. The current philosophy for vertical construction requires large temporary trusses which act as compression struts bracing the structure. These trusses are expensive and their erection involves major site works, costing time and money.
The present invention seeks to overcome the above problems and to provide a method for constructing vertically ring structures, which is both quicker and less expensive than the previously used, and above mentioned, methods. GB-A-16588 and US-A-1987004 both disclose ferris wheels and discuss how to construct them.
In order to achieve the above object there is provided a method for constructing a vertical ring structure from a plurality of pre-fabricated arced segments, each of the segments having at least one face arranged to engage with a face on an adjacent segment when in position, the method comprising the steps of :
connecting two adjacent segments,
providing a force tangential to the ring structure with pre-stressed cables in order to pull the two adjacent segments together and
repeating this procedure for each of the segments of the structure, thereby holding the structure in position and resisting the tendency for inward collapse of the segments caused by their dead weight, throughout the construction process.
In a preferred embodiment of the present invention the pre-stressed cables are provided around the outer surface of the structure.
It is preferred that the pre-stressed cables are attached to both of the adjacent segments. It is also preferred that tensioned cables are used to restrain the structure laterally as erection of the structure progresses.
It is further preferred that the segments be lifted into position by a cradle that moves around the outside of, and is supported by, the previously erected segments.
It is still further preferred that the pre-stressed cables are removed once the final segment is in place.
It is also preferred that the final segment to be put into the structure is the uppermost segment.
It is preferred that the vertical ring structure is a Ferris wheel. In this embodiment it is further preferred that each segment is attached to a central supporting bobbin by permanent radial cables in order to hold the wheel together.
This sequence of construction has several benefits in time and cost. All segments will be pre-fabricated in the factory and will be connected together on site. Therefore, major site work is eliminated and construction is speeded up.
The large temporary trusses which are costly and involve major site work are no longer needed.
The pre-stressed cables are lightweight temporary elements which can be reused when dismantling the object in future.
One further problem that occurs with the operation of ferris wheels is that imbalances in the weight loading of the wheel occur due to differing passenger numbers and weight in each carriage. This imbalance leads to uneven loading of the drive mechanism for the ferris wheel, and increases the power and torque requirements of the drive mechanism, making the wheel expensive to install and costly to run and maintain.
The method of construction for a preferred embodiment of the present invention is described below with reference to the accompanying drawings, in which:
Figure 1 shows completion of a first stage in a construction method according to the invention.
Figure 2 shows completion of a second stage in construction method of figure 1;
Figure 3 shows a cradle, employed in the present invention in operation;
Figure 4 shows completion of a third stage in construction method of figure 1;
Figure 5 shows a fourth stage in the construction method of figure 1;
Figure 6 shows a final stage in the construction method of figure 1;
Figure 7 shows a cross section of a cradle carrying a wheel segment;
Figure 8 shows a ferris wheel; and
Figure 9 shows a section of the ferris wheel of figure 8.
Referring to the figures a Ferris wheel is to be constructed from a plurality of identical segments. These segments are pre-fabricated in a factory and are assembled on site. As shown in figure 1, each segment 4 consists of a steel framework, of triangular cross section, forming an arced section of the circumference of the wheel. The wheel circumference consists of an inner rail and two parallel outer rails, the rails being interconnected by struts, to form a framework.
The first stage in the construction process is shown in figure 1, in which a main supporting tripod and a supporting bobbin 2 are erected. Then a base platform 3 is constructed onto which the first pre-fabricated arced segment 4 is fixed. Permanent radial cables 6 are connected from the arced segment 4 to the bobbin 2.
The second stage in the construction process is shown in figure 2. Segments 8,10 adjacent to the first segment 4 are connected and bolted to the first segment 4. Radial cables 6 are then connected from the segments 8,10 to the central bobbin 2. This stage is then repeated to position the next two segments on the free ends of the segments 8,10.
Two cradles 12,13 then need to be made. These cradles 12, 13 are temporary works structures, both of which can carry, and are approximately twice the length of, each of the pre-fabricated wheel segments. Each cradle 12,13 consists of a steel frame, rollers which slide around the outer rings of the erected wheel segments, a winch to hoist the segments into position, and a platform for access. Figure 7 shows a cross-sectional view of a cradle carrying an arced segment 22. The cradle has a rectangular section for carrying a segment 22 and a substantially triangular section 21 for engaging with the erected structure, thereby obtaining support. The engaging section also helps to align segments correctly just prior to connection to the structure.
In the third stage of the construction process the cradles 12,13 are installed on each side of the base 3, on the outer ring of the erected wheel segments. The cradles 12,13 are used for lifting the new segments of the wheel into position whilst being supported by the previously erected wheel segments, this is shown in figure 3. Each cradle 12,13 is pushed along until it projects approximately half of its length beyond the structure, from where the new wheel segment is lifted and bolted into position. Radial cables 6 are then connected from the new segment to the central bobbin 2. This third stage is then repeated until the semi-circle of the wheel is completed, with an equal number of segments each side of the base 3, as shown in figure 4.
The fourth stage of the construction process is the installation of the upper segments. This is done in the same way as the installation of the lower segments, but before the segments are released from the winch pre-stressed cables are attached from the new segment around the outer surface of the wheel to a lower, previously erected, segment of the wheel. This cable resists the tendency towards inward collapse caused by the dead weight of the segment.
This fourth stage is repeated, building the wheel up, as shown in figure 5, using pre-stressed cables (not shown) to tension the segments back to the lower part of the wheel. Anchor cables 25 are used to restrain the wheel laterally as erection progresses.
The final stage in the construction process is the installation of the final segment, the uppermost or 'key' segment, and subsequent release of the pre-stressed cables. The final segment is compressed by the adjacent segments and thereby resists the inward collapse of the wheel. The completed wheel is shown in figure 6. When making wheels or arches from a plurality of segments it is often found that the final segment is either larger or smaller than the remaining space. This is can be due to a change in size of the segments owing to atmospheric conditions or deformation of the structure owing to the supports used. The pre-stressed cables used in the above method can be tensioned in order to leave the correct space, to within the small tolerances required.
Referring to figures 8 and 9 a ferris wheel has a plurality of carriages 30 disclosed around the circumference of its central wheel. Figure 9 shows an section of a ferris wheel with one carriage attached. Each of the carriages 30 has in its base, a fluid reservoir 31. Associated with each carriage 30 is a carriage weight detector (not shown) which operates to determine the weight of a carriage 30 once loaded with the passengers (not shown). The output of the base detector is fed to a controller 33 associated with a main fluid reservoir 34. The controller 33 compares the measured weight of particular carriage 30 to a reference, and determines whether a fluid should be added to or removed from the fluid reservoir 31 associated with that carriage. A pump 35 is then operated to add or remove fluid from the reservoir 31 to adjust the weight of the carriage 30 to the reference weight. Each of the carriages can then be provided with the same weight, leading to a smooth operation of the rotation of the ferris wheel.

Claims

A method for constructing a vertical ring structure from a plurality of pre-fabricated arced segments (4), each of the segments having at least one face arranged to engage with a face on an adjacent segment when in position, the method comprising the steps of : connecting two adjacent segments, repeating this procedure for each of the segments of the structure and providing a force tangential to the ring structure with pre-stressed cables in order to pull the two adjacent segments together for each of the segments of the upper semicircle of the structure, thereby holding the structure in position and resisting the tendency for inward collapse of the segments caused by their dead weight, throughout the construction process.
A method according to claim 1, wherein the pre-stressed cables are provided around the outer surface of the structure.
A method according to claim 1 or 2, wherein the pre-stressed cables are attached to both of the adjacent segments (4).
A method according to any of the preceding claims, wherein tensioned cables are used to restrain the structure laterally as construction of the structure progresses.
A method according to any of the preceding claims, wherein the segments (4) are lifted into position by a cradle (12,13) that is moved around the outside of, and is supported by, the previously erected segments.
A method according to any of the preceding claims, wherein the pre-stressed cables are removed once the final segment (4) is in place.
A method according to any of the preceding claims, wherein the final segment (4) to be put into the structure is the uppermost segment.
A method according to any of the preceding claims, wherein the vertical ring structure is a Ferris wheel.
A method according to claim 8, wherein each segment (4) is attached to a central supporting bobbin (2) by permanent radial cables (6) in order to hold the wheel together.