Patent Publication Number: US-8973309-B2

Title: Tower structure

Description:
REFERENCE TO RELATED APPLICATIONS 
     Reference is hereby made to U.S. Provisional Patent Application Ser. No. 61/465,628, filed Mar. 23, 2011 and entitled “Slender Mast-Levitating Ring-Tower Structure,” the disclosure of which is hereby incorporated by reference in its entirety and priority of which is hereby claimed pursuant to 37 CFR 1.78(a) (4) and (5)(i). 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to building structures generally and more particularly to tower structures employing tensioned structural elements. 
     BACKGROUND OF THE INVENTION 
     The following publications are believed to represent the current state of the art: 
     U.S. Pat. Nos. 3,922,827 and 4,473,976; 
     Japanese Patent Publication Nos. 04189986, 06346634 and 2003027768; 
     German Patent Publication No. 10316405; 
     E. Heinle and F. Leonhardt, Towers: A Historical Survey, Butterworth Architecture, English translation, 1989, pp 98-99; and 
     Hyperboloid Structure, downloaded from http://en.wikipedia.org/wiki/Hyperboloid_structure on Jan. 27, 2012. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to provide an improved tower structure employing tensioned structural elements. 
     There is thus provided in accordance with a preferred embodiment of the present invention a tower structure including a central, vertical mast and a plurality of tensioned elongate elements arranged to support the mast against buckling, the plurality of tensioned elements together defining a generally hyperboloid structure and including a first plurality of elongate elements which define a multiplicity of junctions therebetween, a second plurality of junction-to-mast joining elongate elements which join at least some of the multiplicity of junctions to the central, vertical mast; and a third plurality of junction-to-junction joining elongate elements which are connected at a plurality of mutually spaced fixed locations therealong to the at least some of the multiplicity of junctions. 
     Preferably, the first plurality of tensioned elongate elements are at least generally straight. Additionally or alternatively, the third plurality of tensioned elongate elements are generally parabolic. 
     In accordance with a preferred embodiment of the present invention the tower structure also includes a multiplicity of connectors operative to interconnect the first plurality of tensioned elongate elements with the second plurality of elongate elements and the third plurality of tensioned elongate elements at the multiplicity plurality of junctions. 
     In accordance with a preferred embodiment of the present invention the tower structure also includes a ring truss structure. Additionally the ring truss structure preferably houses a restaurant facility, the restaurant facility having a ring configuration and extending generally in a circle through 360 degrees in a plane perpendicular to the mast, the ring configuration providing both interior facing and exterior facing views. 
     Preferably, the restaurant facility includes multiple seating levels. 
     In accordance with a preferred embodiment of the present invention the interior facing views include views of substantially the entire restaurant facility and the ring truss structure as well as of tensioned elements of the tower structure. 
     In accordance with a preferred embodiment of the present invention the tower structure also includes multiple 360 degree ring platforms at least one of which is stationary and at least part of at least another of which is driven in 360 degree motion in a horizontal plane about the mast. 
     There is also provided in accordance with a preferred embodiment of the present invention a restaurant facility mounted on a ring truss structure forming part of a tower structure having a mast, the restaurant facility having a ring configuration and extending generally in a circle through 360 degrees in a plane perpendicular to the mast, the ring configuration providing both interior facing and exterior facing views. 
     Preferably, the restaurant facility includes multiple seating levels. 
     In accordance with a preferred embodiment of the present invention the the interior facing views include views of substantially the entire restaurant facility and the ring truss structure as well as of tensioned elements of the tower structure. 
     Preferably, the restaurant facility includes multiple 360 degree ring platforms at least one of which is stationary and at least part of at least another of which is driven in 360 degree motion in a horizontal plane about the mast. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which: 
         FIGS. 1A and 1B  are simplified respective pictorial and side view illustrations of a tower structure constructed and operative in accordance with a preferred embodiment of the present invention; 
         FIG. 2  is a simplified pictorial view of the mast and hyperbolic structure elements and the junction-to-mast joining elements in an incomplete rendering of the tower structure of  FIGS. 1A and 1B ; 
         FIG. 3  is a simplified pictorial view of the mast and hyperbolic structure elements, the junction-to-mast joining elements and the junction-to-junction joining elements of the tower structure of  FIGS. 1A &amp; 1B ; 
         FIGS. 4A and 4B  are simplified pictorial illustrations of part of the tower structure of  FIGS. 1A &amp; 1B  including a multi-story restaurant facility in the shape of a ring; 
         FIG. 5  is a composite illustration of a multi-element connector useful in the tower structure of  FIGS. 1A-4B ; and 
       FIGS.  6 A- 6 PP are simplified pictorial illustrations of multiple stages in construction of the tower structure of  FIGS. 1A-4B . 
     
    
    
     DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT 
     Reference is now made to  FIGS. 1A and 1B , which are simplified respective pictorial and side view illustrations of a tower structure constructed and operative in accordance with a preferred embodiment of the present invention, to  FIG. 2 , which is a simplified pictorial view illustration of the mast and hyperbolic structure elements and the junction-to-mast joining elements of the tower structure of  FIGS. 1A and 1B , and to  FIG. 3 , which is a simplified pictorial view illustration of the mast and hyperbolic structure elements, the junction-to-mast joining elements and the junction-to-junction joining elements of the tower structure of  FIGS. 1A &amp; 1B . 
     As seen in  FIGS. 1A and 1B , the tower structure preferably comprises a vertically oriented central mast  100 , preferably a steel pipe of diameter five meters, wall thickness 10 centimeters and height 600 meters. As will be described hereinbelow, the central mast  100  is maintained under compression. 
     In accordance with a preferred embodiment of the present invention, a plurality of tensioned elongate elements, generally designated by reference numeral  102 , are arranged to support the mast  100  against horizontal forces, such as wind forces and earthquake forces, and buckling. The plurality of tensioned elements  102  together define a generally hyperboloid structure  104 . 
     The plurality of tension elongate elements  102  preferably include a first plurality of tensioned elongate elements  106 , which are generally straight and define a multiplicity of junctions  108  therebetween. The plurality of tensioned elongate elements  106  are each anchored at a lower end thereof, preferably onto a structurally secure anchoring foundation and are attached at an upper portion thereof to a ring truss structure  110 . Typically about 48 tensioned elongate elements  106  are provided and are anchored in pairs at 24 anchoring foundation locations  111  distributed along a horizontal circle  112  centered about mast  100  and having a radius of approximately 50 meters. It is appreciated that for the sake of clarity, the drawings show a lesser number of tensioned elongate elements  102 . 
     Each pair of tensioned elongate elements  106  includes a left tensioned elongate element  106  which extends upwardly and to the left of mast  100  and a right tensioned elongate element  106  which extends upwardly and to the right of mast  100 . The azimuth of the anchoring foundation location  111  in a plane perpendicular to mast  100  and centered on mast  100  preferably differs from the azimuth of the attachment location on ring truss structure  110  in a parallel plane thereto by 120 degrees. 
     It is a particular feature of the present invention that a plurality of junction-to-mast joining tensioned elongate elements  120  join at least some of the multiplicity of junctions  108  to the central, vertical mast  100 . Preferably multiple, azimuthally distributed junction-to-mast joining tensioned elongate elements  120  extend in the same plane at a plurality of vertical locations  122  along mast  100 . Preferably tensioned elongate elements  120  extend generally, but not precisely, radially outwardly from mast  100 . 
     It is a particular feature of the present invention that the plurality of tension elongate elements  102  includes a third plurality of junction-to-junction joining tensioned elongate elements  130 , which are connected at a plurality of mutually spaced fixed locations therealong to a corresponding plurality of junctions  108 , typically less than all of junctions  108  and preferably one-half of all junctions  108 . Preferably, each of junction-to-junction joining tensioned elongate elements  130  extends upwardly in a vertical plane, in which extends mast  100 , from an anchoring foundation location  111  at least to an attachment location at ring truss structure  110  and is connected to a pair of intersecting tensioned elongate elements  106  at each of a plurality of junctions  108  lying along its path. The azimuth of the anchoring location  111  of each of junction-to-junction joining tensioned elongate elements  130  preferably is the same as the azimuth of the attachment location thereof on ring truss structure  110 . 
     As seen in  FIGS. 1A &amp; 1B , the plurality of tensioned elongate elements  102 , including tensioned elongate elements  106  and  130  or extensions thereof, also extend from ring truss structure  110  to a higher ring structure  140 , on which may be mounted a spherical structure  142  or other suitable structure. The arrangement of the tensioned elongate elements  106  and  130  between ring truss structure  110  and ring structure  140  may be similar in all relevant respects to the arrangement of elongate elements  106  and  130  between the base and the ring truss structure  110 . 
     Junction-to-mast joining tensioned elongate elements  120  are preferably provided at ring truss structure  110  and ring structure  140  and at locations therebetween. It is appreciated that additional ring structures (not shown) may also be provided. 
     In the illustrated embodiment, a plurality of cables  146  extend upwardly from the ring truss structure  110 , to the mast  100  at a location  148  vertically spaced above ring truss structure  110 , but below the top of the mast  100 . Cables  146  preferably together define an overall conical configuration centered on mast  100 . 
     In the illustrated embodiment, a plurality of cables  150  extend upwardly from the uppermost ring structure, here ring structure  140 , to the mast  100  at a location  160  vertically spaced above ring structure  140 , but typically below the top of the mast  100 . Cables  150  preferably together define an overall conical configuration centered on mast  100 . 
     Reference is now made to  FIGS. 4A and 4B , which are simplified pictorial illustrations of part of the tower structure of  FIGS. 1A &amp; 1B , including a multi-storey restaurant facility  200  having a ring configuration. 
     As seen in  FIGS. 4A and 4B , which illustrate the restaurant facility  200  with respective lesser and greater amounts of detail, the restaurant facility  200  is preferably surrounded by the ring truss structure  110  and extends generally in a circle through 360 degrees in a plane perpendicular to mast  100 . The ring configuration of the restaurant facility provides both interior facing and exterior facing views for a very large number of diners and may include seating at multiple levels, as shown. The interior views include views of substantially the entire restaurant facility and the ring truss structure  110  as well as of the various tensioned elements  106 , 120  and  130 . The restaurant facility may be accessed via elevators  220  riding along tracks formed on outside surfaces of mast  100  and by stairways  240  which wind around the mast  100 . Radial passageways  260  preferably interconnect an elevator and stairway lobby  270  with the restaurant facility  200 . 
     In the illustrated embodiment, four 360 degree ring platforms, respectively designated by reference numerals  280 ,  290 ,  300  and  320  are provided. Preferably, platform  280  is stationary and at least part of each of the remaining platforms  290 ,  300  and  320  are driven in 360 degree motion in a horizontal plane about mast  100 . 
     Reference is now made to FIGS.  6 A- 6 PP, which are simplified illustrations of a preferred manner of construction of a preferred embodiment of the present invention. 
     Turning initially to  FIG. 6A , there is seen a first internal section  600  of mast  100  which is arranged in an upstanding arrangement and supported onto a suitable foundation  602  onto which is formed a steel plate  604  which is anchored onto the foundation  602 . A bottom circumferential edge  606  of first internal section  600  is preferably welded to the steel plate  604 . Section  600  of mast  100  is preferably made of FE-52 steel and preferably has a thickness of 10 cm, an outer diameter of 250 cm and a height of 7.5 meters. 
     Turning to  FIG. 6B , it is seen that a second internal section  610  of mast  100 , preferably made of FE-52 steel and having a thickness of 10 cm, an outer diameter of 250 cm and a height of 15 meters is positioned, as by a crane  612 , such as a Terex HC275 crane, onto a top edge  614  of section  600  and is welded thereto at a bottom edge  616  of the second internal section  610 . 
       FIG. 6C  shows a first external section  620  of mast  100 , which is positioned, as by crane  612 , over the first and second internal sections  600  and  610  of mast  100 . As seen in  FIG. 6C , the first external section  620 , as seen in section, preferably includes three generally identical concave portions  622  which are mutually separated by three generally identical convex portions  624 . The configuration and size of the concave portions  622  define inwardmost vertical axes  626  which lie along an imaginary cylinder having an inner diameter which is just slightly larger than the outer diameter of first and second internal sections  600  and  610 . The first external section  620  of mast  100  is welded to the first and second internal sections  600  and  610  of mast  100  preferably along vertical axes  626 . 
     First external section  620  is preferably welded at a lower edge  628  thereof to steel plate  604  and is formed with apertured connectors  632  at each junction between a concave portion  622  and a convex portion  624 . Each concave portion  622  is preferably formed with a pair of parallel vertically extending tracks  634  and each convex portion  624  is preferably formed with a pair of parallel vertically extending tracks  636 . Preferably first external section  620  is formed with a plurality of human access apertures  638 . 
     Turning now to  FIG. 6D , it is seen that three vertical track climbing cranes  640  are positioned along tracks  634  formed on concave portions  622  and are employed to position a second external section  650  onto first external portion  620 . Cranes  640  are preferably suitably modified Terex HC275 cranes. Second external section  650  may be identical in all relevant respects to first external section  620  and is preferably welded at a lower edge  652  to upper edge  630  of first external section  620  and along vertical axes  626  to plural internal sections of the mast. 
     The addition and welding of further internal and external mast sections as shown and described hereinabove is repeated until a mast height of about 75 meters is reached. At this point, which is illustrated in  FIG. 6E , temporary stabilizing cables  660  are preferably preattached to some of apertured connectors  632  formed on the current topmost external section of the mast, prior to attachment of outer ends  662  thereof to attachment foundations  664 . 
       FIG. 6F  shows stabilizing cables  660  attached at the outer ends  662  to corresponding attachment foundations  664  and tensioned, thereby to temporary stabilize the partially constructed mast.  FIG. 6G  shows further construction of the mast, up to a height of approximately 400 meters, and employing additional temporary stabilizing cables  660 , which are attached to the partially constructed mast, typically at heights of 75 meters, 150 meters, 250 meters and 350 meters. 
     Turning now to  FIG. 6H , there is seen further construction of mast  100  in generally the same manner as described hereinabove, followed by simultaneous positioning of three truss sections of ring structure  110  ( FIGS. 1A &amp; 1B ), which are preferably joined together as shown in  FIG. 6I  to define ring truss structure  110 . 
       FIG. 6J  shows attachment of a plurality of radial tension elements  670 , such as rods or cables, between multiple connection locations  672  on ring truss structure  110  and apertured connectors  632  on mast  100  located generally in the same horizontal plane as locations  672 . It is appreciated that the plurality of radial tension elements  670  are all preferably equally tensioned and all preferably lie in a single horizontal plane. 
       FIG. 6K  shows a plurality of ring truss support elements  146  ( FIGS. 1A &amp; 1B ) such as rods or cables, which are connected typically between connection locations  672  on ring truss structure  110  and apertured connectors  632  at a location  148  ( FIGS. 1A &amp; 1B ) on mast  100 , which location is approximately 75 meters above the horizontal plane of radial tension elements  670 . At this stage, the ring truss structure  110  is supported by the mast  100  via ring truss support elements  146 . 
     Turning now to  FIG. 6L , there is seen preparation of tensioned elongate elements  106  ( FIGS. 1A &amp; 1B ), which are preferably fabricated on site as bundles of parallel wires. It is seen that tensioned elongate elements  106  are preferably laid out on the ground and the bundles of wires are covered with a protective layer  690  other than at the intended locations  692  of junctions  108  ( FIGS. 1A &amp; 1B ). 
     Multi-element connectors  700  are preferably threaded along each elongate element  106  and positioned therealong at the intended locations of junctions  108  and permanently fixed thereto. 
     Preferably, connectors  700  are permanently fixed to the tensioned elements  106  by pouring a bonding agent, preferably an alloy of tin and lead, into the interior spaces of connectors  700  which surround the tensioned elements  106 . Hardening of the bonding agent bonds the tensioned elements  106  to connectors  700  and prevents relative motion therebetween. 
     Reference is now made to  FIG. 5 , which illustrates a preferred embodiment of a connector  700 . Connector  700  is preferably made of FE-52 steel and is formed with first and second bores  702  and  704  which are non-intersecting and which extend along respective bore axes  712  and  714  which are angularly separated from each other in two dimensions, such that bore axes  712  and  714  are not coplanar. Bores  702  and  704  are designed to accommodate tensioned elongate elements  106 . 
     In accordance with a preferred embodiment of the present invention, a non-cylindrical passageway  720  is also formed in connector  700  and extends along an axis  722  and is designed to accommodate a tensioned elongate element  130 . As seen clearly in  FIG. 5 , the cross section of non-cylindrical passageway  720  preferably has a generally curved hour-glass configuration. It is appreciated that the angular relationships between bores  702  and  704  and passageway  720  may vary for connectors  700  employed at different levels of the tower structure, in view of the different angular relationships between tensioned elements  106  and  130  thereat. 
     Further in accordance with a preferred embodiment of the present invention each connector  700  is provided with an apertured connector  724 , which preferably lies in a vertical plane and is employed for attachment of a junction-to-mast joining tensioned elongate element  120  thereto, thereby to enable joining of the junctions  108 , at which connectors  700  are provided, to the central, vertical mast  100 . 
     Reference is now made to  FIG. 6M , which is simplified for clarity by eliminating most of the stabilizing cables  660 , which continue to be present, from the drawing. As seen in  FIG. 6M , each tensioned elongate element  106 , having fixed thereto connectors  700  at each of locations  108 , is attached at one end thereof to a foundation  802  at an anchoring location  111  ( FIGS. 1A &amp; 1B ) and is attached at an opposite end thereof to an apertured connector  804  formed on ring truss structure  110  ( FIGS. 1A &amp; 1B ).  FIG. 6M  shows positioning and attachment of a first left tensioned elongate element  106  and  FIG. 6N  shows positioning and attachment of a second left tensioned elongate element  106 .  FIG. 6O  shows positioning and attachment of all of the left tensioned elongate elements  106 , typically 24 in number. For clarity, only 12 are shown. The connectors  700  are shown on each illustrated left tensioned elongate element. 
     Turning now to  FIG. 6P , there is seen a first step in positioning a first right tensioned elongate element  106 . This is preferably done by lowering a first right tensioned elongate element lead wire  810  by means of crane  640  to a top most connector  700  on one of left tensioned elongate elements  106 , which was already positioned and connected but preferably not yet tensioned. A human operator is preferably lowered on a platform  820  by another crane in order to thread the first right tensioned elongate element lead wire  810  initially through a topmost connector  700  on one of the left tensioned elongate elements  106  and thereafter through sequentially lower connectors  700  on other left tensioned elongate elements  110 , as shown in  FIG. 6Q . 
     As shown in  FIG. 6R , once the lead wire  810  has been threaded through all of the connectors  700  through which the right tensioned elongate element  106  is intended to extend, the lower end of the lead wire  810  is attached to a first end of a first right tensioned elongate element  106  preferably, using a bonding agent, preferably an alloy of tin and lead. Hardening of the bonding agent bonds the tensioned element  106  to the lead wire  810 . It is appreciated that the opposite end of right tensioned elongate element  106  may be mounted onto a foundation at an anchoring location  111 . 
     The lead wire  810  is then pulled upwardly so as to thread the first right tensioned elongate element  106  through the various connectors  700  through which the lead wire  810  was earlier threaded, possibly with the assistance of a human operator, as seen in  FIGS. 6S ,  6 T and  6 U. The upper end of the first right tensioned elongate element  106  is then attached to an apertured connector  804  formed on ring truss structure  110  ( FIGS. 1A &amp; 1B ), as seen in  FIG. 6V . 
       FIG. 6W  shows positioning and attachment of all of the right and left tensioned elongate elements  106 , typically 48 in number. For clarity, only 24 are shown. The connectors  700  are shown each threaded onto both a right tensioned elongate element  106  and a left tensioned elongate element  106 . 
     Turning now to  FIG. 6X , there is seen a first step in positioning a first junction-to-junction joining tensioned elongate element  130  ( FIGS. 1A &amp; 1B ). This is preferably done by lowering a first junction-to-junction joining tensioned elongate element lead wire  830  by means of crane  640  to a top most connector  700  which is already threaded by both left and right tensioned elongate elements  106 , which are already positioned and connected but preferably not yet tensioned. A human operator is preferably lowered on a platform  820  by another crane in order to thread the first junction-to-junction joining tensioned elongate element lead wire  830  initially through a topmost connector  700  and thereafter through sequentially lower connectors  700 , as shown in  FIG. 6Y . 
     As shown in  FIG. 6Z , once the lead wire  830  has been threaded through all of the connectors  700  through which the junction-to-junction joining tensioned elongate element  130  is intended to extend, the lower end of the lead wire  830  is attached to a first end of a first junction-to-junction joining tensioned elongate element  130 , preferably, using a bonding agent, preferably an alloy of tin and lead. Hardening of the bonding agent bonds the tensioned element  106  to the lead wire  810 . It is appreciated that the opposite end of the first junction-to-junction joining tensioned elongate element  130  may be mounted onto a foundation at an anchoring location  111 . 
     The lead wire  830  is then pulled upwardly so as to thread the first junction-to-junction joining tensioned elongate element  130  through the various connectors  700  through which the lead wire  830  was earlier threaded, possibly with the assistance of a human operator, as seen in FIGS.  6 AA,  6 BB and  6 CC. The upper end of the first junction-to-junction joining tensioned elongate element  130  is then attached to an apertured connector  804  formed on ring truss structure  110  ( FIGS. 1A &amp; 1B ), as seen in FIG.  6 DD. 
     FIG.  6 EE shows positioning and attachment of junction-to-junction joining tensioned elongate elements  130 , typically 24 in number. For clarity, only 12 are shown. The connectors  700  are shown each threaded onto a right tensioned elongate element  106  and a left tensioned elongate element  106  and to a junction-to-junction joining tensioned elongate element  130 . 
     It is appreciated that connectors  700  are arranged in a plurality of horizontal planes, perpendicular to mast  100 . Preferably all of the connectors  700  which lie in a given horizontal plane are each connected to mast  100  at a location in that plane by means of a tensioned element  120 , here designated by reference numeral  850 , such as a cable or rod which extends from each connector  700  to a corresponding apertured connector  632  on mast  100 . Typically four tensioned elements  850  are attached to each apertured connector  632 , although for simplicity only two are shown in the drawings. FIG.  6 FF shows the tensioned elements  850  connected in one plane, here designated by reference numeral  860  and FIG.  6 GG shows tensioned elements  850  connected in multiple planes, here designated by reference numerals  860 ,  862  and  864 , it being appreciated that typically 6 or more planes may be provided. 
     The azimuth of the anchoring location of each junction-to-mast joining tensioned elongate element  850  on the mast  100  in a plane perpendicular to the mast  100  and centered thereon preferably differs from the azimuth of the attachment location of the same junction-to-mast joining tensioned elongate element  850  at a junction  108  by up to about 28 degrees. 
     Reference is now made to FIG.  6 HH, which illustrates additional tensioning of tensioned elements  106  and  130 , which is effected utilizing tensioners  865  mounted onto tensioned elements  106  and  130 . This tensioning can be realized, for example, by employing equipment or services provided by Daversteels of South Yorkshire, UK or by Macalloy Ltd. of Sheffield, UK. It is appreciated that elements  106 ,  120  and  130  are always maintained under tension, even in the absence of side forces resulting from wind and earthquakes. Preferably elements  106  and  130  are each maintained under tension of approximately 600 tons. Elements  120  are each preferably maintained under tension of approximately 100 tons. As a result, elements  146  are each maintained under tension of approximately 1800 tons. 
     Thereafter, as seen in FIG.  6 II, the connectors  700  are permanently fixed to the right tensioned elements  106  and tensioned elements  130 . The permanent fixing is preferably carried out by pouring a bonding agent, preferably an alloy of tin and lead, into the interior spaces of connectors  700  which surround the right tensioned elements  106  and tensioned elements  130 . Hardening of the bonding agent bonds the right tensioned elements  106  and tensioned elements  130  to the connectors and prevents relative motion therebetween. 
     At this stage the arrangement of tensioned elements  106  and  130  and connectors  700  with respect to the mast  100  is preferably such that side forces on the tower structure are transferred via tensioned elements  106 ,  130  and  120  to anchoring foundations at locations  111  and accordingly, the temporary stabilizing cables  660  may be removed, as shown in FIG.  6 JJ. 
     Typically following removal of the temporary stabilizing cables  660 , further sections  870  are added to the mast  100 , using cranes  640 , as shown in FIG.  6 KK, generally in the same manner as described hereinabove with reference to  FIGS. 6B-6E . FIG.  6 KK also shows raising a temporary support element  880 . 
     FIG.  6 LL shows plural temporary support elements  880  in place for providing support to the additional sections  870  against side forces. In this case, the ring structure  110  provides anchoring foundations for the temporary support elements  880 . 
     FIG.  6 MM shows provision of right and left tensioned elements  890 , junction-to-junction joining tensioned elongate elements  892 , connected thereto by connectors  894 , and radially extending tensioned elements  896  joining ring structure  140  and ring truss structure  110 . These elements are then suitably tensioned. Realization of the additional structure of FIG.  6 MM is generally in accordance with that described hereinabove with reference to FIGS.  6 H- 6 II. At this stage the arrangement of tensioned elements  890  and  892  and connectors  894  with respect to the additional sections  870  of the mast  100  is preferably such that side forces on the additional structures  870  and ring structure  140  are transferred via tensioned elements  890  and  892  to anchoring foundations defined by ring truss structure  110  and accordingly, the temporary stabilizing cables  880  may be removed, as shown in FIG.  6 NN. 
     Thereafter, as seen in FIG.  6 OO, spherical structure  142  is mounted onto upper ring structure  140  as by cranes  640 . A final structure is shown in FIG.  6 PP. 
     It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and subcombinations of features recited in the claims as well as modifications thereof which would occur to a person of ordinary skill in the art upon reading the foregoing and which are not in the prior art.