JP6638140B2 - Basic structure of tower structure - Google Patents

Description

  The present invention relates to a foundation structure of a tower-like structure constructed up to a high position in the sky such as a pillar, a tower, a monument, and the like constructed on the ground, and particularly to a foundation structure using an unbonded anchor for introducing prestress. .

There are various tower-like structures constructed on the ground, such as various towers, monuments, and chimneys. One of them is a windmill tower, which is a support for a windmill for wind power generation. At the top of the tower, a plurality of propeller blades (blades) are installed, and a generator that generates electricity by the rotation of the windmill, and a nacelle that is a heavy object such as a rotating mechanism that adjusts the direction of the windmill to the windward are installed. I have. In addition, in order to stably increase the power generation efficiency, it is necessary to receive a stable wind, and it is desirable that the top is located as high as possible. That is, in a tower for a windmill , it is necessary to extend a top portion as high as possible to support a heavy object on the top portion.

  The tower-like structure receives a large load in the horizontal direction due to the wind acting on the tower. For this reason, the bending moment acts on the foundation portion of the tower-like structure as a falling moment. In particular, in the tower for a windmill, in addition to the horizontal load, the rotation of the blade of the windmill, the change in the orientation of the windmill by the rotation mechanism, and the like, and furthermore, a complicated load is repeatedly applied due to a combination of these various loads. This may cause the wind turbine tower to fall. Also, in Japan, since the overturning moment due to the seismic load is large, a foundation structure that can cope with an earthquake in addition to the load due to the wind is desired.

  As proposals for the foundation structure of a high-rise building or a tower-like building, for example, a ground anchor / pile method disclosed in Patent Literature 1, a wind power tower disclosed in Patent Literature 2, and disclosed in Patent Literature 3 There is an anchor frame for the windmill tower. Patent Literature 4 discloses, as a steel column base capable of securing anchoring strength of anchor bolts without excessively increasing the dimensions of the base concrete, a column base metal joined to the lower end of the steel column, A steel column base fixed on a foundation concrete with anchor bolts and nuts embedded therein is disclosed.

  In addition, the applicant of the present application has found that in a foundation structure of a tower-like structure such as a column or a tower, the occurrence of concrete cracking in a foundation structure having a column base fixed by using an unbond anchor for introducing a prestress. A basic structure of a tower-like structure to be suppressed as much as possible has been proposed (see Patent Document 5). The basic structure disclosed in Patent Document 5 has a tower-like structure in which a top portion extends to a high position in the sky, and at least a tipping moment, a horizontal force, and the like are applied by an external force acting on the top portion and the column base. In the basic structure of the object, the column base of the tower-shaped structure is fixed, an unbonded anchor for introducing a prestress, a vertical bar arranged in a direction parallel to the unbonded anchor, and bonded to each of the vertical bar. The hoop streaks forming a circumference arranged at appropriate intervals in the longitudinal direction of the longitudinal streaks, and radial horizontal streaks arranged in a direction intersecting the unbonded anchors and the streaks. , Concrete is driven into the circumferential hoop and radial horizontal streaks to form a concrete foundation.

  In addition, Non-Patent Document 1 describes a method of designing a columnar reinforcing bar at a rising portion (pedestal) of a footing foundation. Regarding the design of an anchor bolt, a connecting member joined to a lower end of the bolt by a nut or the like is described. Investigating whether the various stresses caused by (anchor ring) satisfy the allowable value of concrete and the allowable value of the anchoring member itself, and whether the adhesion of anchor bolt surface to concrete satisfies the allowable value. It is supposed to.

  Further, in Non-Patent Document 2, the design is made with the smaller of the allowable pulling force determined by the cone-shaped fracture of the headed anchor bolt and the allowable value of the anchor bolt member itself.

Japanese Patent Publication No. 5-59219 JP 2002-122066 A JP-A-2004-278400 JP-A-5-25832 Japanese Patent No. 4242445

Chimney structure design and construction guidelines (Nihon Architectural Center) Various composite structural design guidelines (Architectural Institute of Japan)

  The supporting structure by the pile method disclosed in Patent Literature 1 is mainly a building, which resists buoyancy generated in the building by receiving a falling moment due to a horizontal force due to a wind, an earthquake, or the like. When such a complicated overturning moment occurs, there is a possibility that the reliability cannot be ensured. Further, in the wind power generation tower disclosed in Patent Document 2, a tower main body formed by stacking hollow cylindrical bodies and a prestressed concrete reinforcing member having a T-shaped cross section are provided along the outer periphery of the tower main body on the base side. And the reinforcing member is fixedly connected to the foundation and the tower body. Further, the anchor frame disclosed in Patent Literature 3 includes a pair of upper and lower ring-shaped anchor plates, a plurality of connecting members for connecting the pair of upper and lower anchor plates at a predetermined interval, and an arrangement between the connecting members. A plurality of anchor bolts, and a plurality of pillars connected to the lower surface of the lower anchor plate to position the pair of upper and lower anchor plates at a predetermined height on the foundation, the connection member and the pillar Is composed of a steel pipe.

  The basic structure disclosed in Patent Document 2 or Patent Document 3 is a structure in which a pedestal that is a base pedestal protruding from a central portion of a base member is formed, and a tower is fixed to the pedestal. And anchor bolts and columns. However, since the concrete and the anchor bolts are bonded by adhesive force, if this adhesion is broken due to the loading of the overturning moment, cracks will occur in the concrete, and if the allowable stress of concrete is exceeded, Concrete may be damaged. For this reason, it is desirable that the foundation be of a type that does not have the adhesion between the anchor bolt and the concrete, and that it be a structure using an unbonded anchor that reduces the load on the concrete by changing the load transmission mechanism.

Further, in the steel column base disclosed in Patent Document 4, with respect to the load generated in the concrete in the horizontal direction, the tensile force of the anchor bolt is transmitted to the reinforcing bar by satisfying the dimensional conditions according to the present invention, and the cone It is said that the size of the foundation can be reduced by suppressing the state fracture. However, the destruction mechanism of concrete foundation is not limited to cone-shaped destruction, especially for towers for wind power, as described above, because heavy objects are installed on the top of the tower. It is thought that the destruction mechanism works. Therefore, in the invention described in Patent Literature 4, there is a possibility that a sufficient durability cannot be provided as a base structure of a tower-like structure whose top is extended to a high position in the sky like a tower for a windmill. In particular, it can be said that the fracture mechanism of a tower for wind power generation in particular cannot sufficiently secure the proof strength only by the cone-shaped fracture which is a problem with the steel column base described in Patent Document 4.

  Further, as disclosed in Non-Patent Document 5 and Non-Patent Document 6, the conventional basic structure of the tower-like structure includes an anchor bolt attached to concrete and a nut at the lower end thereof attached to concrete with reference to the above-mentioned guideline and the like. A connecting member (anchor ring) to be joined is disposed on a rising portion (pedestal) of the footing foundation, and is designed on the basis that a columnar structure resists a falling moment received from an upper structure.

  The supporting structure of a tower-like structure (tower) represented by a chimney or the like is a structure in which a pedestal, which is a base pedestal protruding from the center of a base member, is fixed to the pedestal, The anchoring section is composed of the anchor bolt and the connecting member (anchor ring) in the concrete cast. In addition, the concrete and the anchor bolt are designed on the assumption that they are adhered and joined together, and when a falling moment is loaded, the tensile force is transmitted to the vertical reinforcing bars arranged beside the anchor bolt through the concrete.

  On the other hand, in a tower for a windmill or the like, the natural period of the upper structure can be determined by fixing the legs. When it is desired to completely fix or close to this state, it is conceivable to use an unbonded anchor and to provide a structure in which tension (prestress) is applied to the anchor bolt after concrete is driven. Further, a rotating machine such as a windmill may put prestress on a bolt for the purpose of not causing fatigue failure of the foundation bolt which is constantly subjected to load fluctuation.

  When prestress is applied using an unbonded anchor, a tensile load acts on the concrete around the unbonded anchor in a vertical direction below a lower end anchoring portion (anchor ring) of the unbonded anchor and in a cross direction (horizontal direction) of the unbonded anchor. Therefore, a stress state different from the anchor bolt expected to adhere to concrete without prestressing will occur, and if the rebar required at the time of prestress introduction is insufficient, immediately after the introduction of prestress Also, even under normal load on the tower-like structure, cracks occur in the concrete, and if the cracks progress, the concrete may break along the unbond anchor. In addition, the structure that resists the overturning moment of the legs by this structure transmits tensile force via concrete to the vertical reinforcing bars arranged in parallel with the anchor bolt, and the radial horizontal streaks reduce the overturning moment. Resists horizontal tensile forces generated on the compression side.

  Therefore, as disclosed in Patent Document 5, even when prestress is introduced using an unbonded anchor, harmful cracks are not generated in concrete, and the foundation can sufficiently resist overturning moment. The above-mentioned problem was solved by forming the foundation structure of the tower-like structure in consideration of the shape and the arrangement of the reinforcing bars.

  The present invention relates to the improvement of the foundation structure disclosed in Patent Document 5, and for example, when the reinforcement is overcrowded when constructing the foundation structure according to Patent Document 5, the same effect is obtained. It is desired to simplify the construction using another promising method.

  Therefore, the present invention is a foundation structure in which prestress is introduced and concrete is driven in using an unbond anchor, and construction is simplified, and harmful cracks generated in concrete are prevented by simplifying the construction, and a falling moment is obtained. An object of the present invention is to provide a basic structure of a tower-like structure that can sufficiently withstand the above.

As a technical means for achieving the above object, the basic structure of the tower-like structure according to the present invention is such that the top is extended to a high position in the sky, and an external force acting on the top and the column base is used. At least in the basic structure of the tower-like structure on which the overturning moment and the horizontal force act, the circular pillar-like part of the tower-like structure is fixed, and is arranged in a circular shape along the pillar-like part for introducing prestress . An unbonded anchor, a vertical line parallel to the unbonded anchor, and arranged concentrically at a position sandwiching the unbonded anchor, a width direction parallel to the vertical direction, and a longitudinal direction to an inner longitudinal line and an outer longitudinal line. In a position crossing the streaks, in a direction intersecting the unbonded anchors and the longitudinal streaks, such as a crack-preventing net radially arranged in a circular radial direction in which the unbonded anchors are arranged. The concrete base is formed by driving concrete into the unbonded anchor, the vertical streaks, and the crack preventing net.

  In the state where the tower-like structure is supported by the unbonded anchor into which the prestress has been introduced, there is no adhesion between the unbonded anchor and the concrete, so that no load is transmitted. However, the concrete surrounded by the unstressed anchor bolts into which the prestress has been introduced and the anchor ring at the lower end is strongly integrated to transmit the load to the anchor ring. In this case, while compressive stress is generated in the vertical direction of the concrete, tensile stress that attempts to expand the concrete in a horizontal direction crossing the compressive stress is simultaneously generated. Further, as a reaction force to the foundation due to the external force acting on the top portion, further vertical compressive stress is applied to the compressive side concrete portion by the overturning moment to the compressive stress due to the introduction of the prestress. Similarly, the horizontal tensile stress will be further increased. These tensile stresses are resisted by a crack preventing net arranged crossing the anchor bolts and the vertical streaks, thereby preventing cracks from occurring in concrete.

The crack preventing net is formed in a substantially rectangular shape, and its longitudinal direction is arranged at a position where the inner vertical streaks and the outer vertical streaks have passed, and the width direction is a direction parallel to the vertical direction. For this reason, the crack prevention net is arranged in the vertical plane, and is in a state of radially extending from the center of the circle where the vertical streaks are arranged.

Further, in the foundation structure of the tower-like structure according to the invention of claim 2, the crack preventing net has a top portion extending to a high position in the sky, and an external force acting on the top portion and the column base portion is provided by: At least in the basic structure of the tower-like structure on which the overturning moment and the horizontal force act, the circular pillar-like part of the tower-like structure is fixed, and is arranged in a circular shape along the pillar-like part for introducing prestress. An unbonded anchor, a direction parallel to the unbonded anchor, a vertical streak arranged concentrically at a position sandwiching the unbonded anchor, and a direction intersecting the unbonded anchor and the vertical streak, the longitudinal direction being a position having passed through the inner longitudinal muscle and outer longitudinal muscle, sector part in forming, the circumferential direction parallel to arranging the horizontal direction, the unbonded anchor and longitudinal muscle and cracking prevention nets passed through the Made, the unbonded anchor and vertical stripe, is characterized in that is formed with a concrete foundation by implanting concrete against cracking prevention nets.

  The crack preventing net is arranged in a horizontal plane. In this case, the crack preventing net may be arranged in a donut shape. However, for ease of construction, a part of a fan shape is formed, and these are arranged in a ring shape to form a donut shape as a whole. It is arranged in.

Further, the basic structure of the tower-like structure according to the invention of claim 3 is characterized in that the unbonded anchor is arranged on the circumference of the lower leg of the tower-like structure to be supported.

  In order to efficiently arrange the unbond anchors, the structure is arranged on the circumference centered on the column cross-section center position of the tower-like structure, and furthermore, a pair of unbond anchors are juxtaposed in the radial direction of this arc. Have been placed. In this case, it is preferable to dispose the vertical streak at a position sandwiching the unbond anchor.

Further, in the foundation structure of the tower-like structure according to the invention of claim 4, the concrete foundation portion is formed in a shape having a footing portion and a pedestal portion rising from the footing portion, and the vertical streak is formed by the footing portion. It is characterized by having reached.

  The footing portion may not have a pedestal portion on the upper surface, and may be formed on a plane or an inclined surface which is inclined to drain rainwater, or a shape having a pedestal portion formed on an upper portion of the footing portion. May be used. It is sufficient that the pedestal portion is formed in a size capable of disposing the crack preventing net. Concrete is driven into the unbond anchor, the vertical streaks, and the crack preventing net to form the pedestal portion. In this case, the lower end portion of the vertical streak is extended to the footing portion, and is joined to a reinforcing bar arranged in the footing portion.

Further, the basic structure of the tower-like structure according to the invention of claim 5 is characterized in that the tower-like structure is a column base for wind power generation.

The foundation structure according to the present invention is particularly suitable for supporting a column base of a tower for a windmill. There are various types of foundation structures that support chimneys and various towers, but all of them are structures that take into account the overturning moment and the horizontal force. It is not designed to resist fatigue loads due to In the foundation structure according to the present invention, by arranging the net for preventing cracks, it is possible to withstand the tensile stress of the concrete foundation acting in the direction intersecting with the unbond anchor, so that the wind turbine is subjected to repeated loads and the like . It is suitable for the foundation of the tower.

  According to the foundation structure of the tower-like structure according to the present invention, even after the prestress has been introduced, the stress acting on the concrete, the vertical streaks and the crack preventing net disposed with respect to the unbond anchor. When the prestress is introduced, cracking of the concrete due to the applied load due to the external force thereafter and the fatigue load due to repetition is suppressed, and it is possible to prevent the concrete from breaking.

Further, according to the basic structure of the tower-like structure according to the third aspect of the present invention, it is possible to reliably resist the load acting in any direction regardless of the direction due to the external force acting on the tower-like structure. .

Further, according to the foundation structure of the tower-like structure according to the invention of claim 4 , the amount of concrete to be poured is minimized, and the construction cost can be reduced. In addition, when the upper surface is a flat surface or an inclined surface without forming the pedestal portion, the construction of the foundation becomes simple, so that the construction can be facilitated.

Further, according to the basic structure of the tower-like structure according to the invention of claim 5 , even when a load from a rotating machine or the like is applied, the tower does not collapse, and especially for a wind power generation where a complicated load is applied. It is suitable to be used as a foundation supporting column bases.

1 is a schematic sectional view of a foundation having a structure according to a first embodiment of the present invention. It is sectional drawing cut | disconnected along the AA in FIG. FIG. 2 is a schematic perspective view of a main part of the basic structure according to the embodiment shown in FIG. 1. It is an outline sectional view of the foundation provided with the structure concerning a 2nd embodiment of this invention. FIG. 5 is a cross-sectional view taken along line AA in FIG. 4. FIG. 5 is a schematic perspective view of a main part of the basic structure according to the embodiment shown in FIG. 4. It is a schematic perspective view explaining the arrangement state of the unbonded anchor of the foundation structure concerning this invention. It is a figure explaining the outline of distribution of the load which acts around the unbonded anchor which introduced the prestress.

  Hereinafter, the basic structure of the tower-like structure according to the present invention will be specifically described based on the illustrated preferred embodiments. 1 to 3 show a first embodiment, and FIGS. 4 to 6 show a second embodiment.

  FIG. 1 shows a state in which a tower-like structure 1 such as a pillar for wind power generation is supported. A foundation 3 is placed on a pile 2 driven into the ground at the construction site of the tower-like structure 1. In this embodiment, the foundation 3 is formed in a shape including a footing portion 3a and a pedestal portion 3b.

  As shown in FIGS. 3 and 7, the tower-like structure 1 is fixed to an annular base plate 4 via an unbond anchor 5. The unbonded anchor 5 is bridged between the base plate 4 and the anchor plate 6 so that a prestress is introduced. The base plate 4 and the anchor plate 6 are formed in a circular shape as shown in FIGS. 2 and 3, and a pair of unbonded anchors 5 are arranged in a radial direction of the circular shape, and these pairs are formed around the circumference. Are arranged along. Note that the center of the base plate 4 and the like is substantially coincident with the center C of the column section of the tower-shaped structure 1. Vertical streaks 7 a and 7 b are arranged in parallel with the unbond anchor 5. The lower ends of the vertical streaks 7a and 7b reach the footing portion 3a of the foundation 3, and are joined to the reinforcing bars 3c arranged in the footing portion 3a. The vertical bars 7a and 7b are provided with an outer vertical bar 7a on the outside and an inner vertical bar 7b on the inside with the anchor bolt 5 interposed therebetween.

  As shown in FIGS. 1 to 3, the crack preventing net 8 formed in a substantially rectangular shape is extended from the outside of the vertical streak 7 a to the inside of the vertical streak 7 b with the width direction being the vertical direction. Have been. That is, as shown in FIG. 1, the crack preventing nets 8 are arranged in a vertical plane and extend radially from the center of the base plate 4.

  Concrete is driven into the unbonded anchor 5 and the vertical bars 7a, 7b and the net 8 for preventing cracks, which are stretched over the base plate 4 and the anchor plate 6 in a state where prestress is introduced, so that the footing portion 3a and the pedestal portion 3b are connected. Form. It should be noted that the crack preventing net 8 is tied to the vertical streak 7 before driving concrete. In addition, the pedestal portion 3b only needs to be formed to have an outer diameter dimension in which the crack preventing net 8 can be arranged.

  In the foundation structure configured as described above, for example, the concrete around the unbonded anchor 5 into which the prestress has been introduced for fixing the tower for wind turbines, as shown by the broken line in FIG. A tensile load acts in a direction intersecting the longitudinal direction. The net 8 for preventing cracks, which is disposed to intersect with the longitudinal direction of the unbonded anchor 5, and the longitudinal bars 7a, 7b, which are disposed parallel to the longitudinal direction of the unbonded anchor 5, respectively, resist these tensile loads. . Therefore, the occurrence of cracks in the concrete is suppressed as much as possible, and the breakage of the concrete is prevented.

  In addition, when a horizontal load received by a wind, an earthquake, or the like acts as a falling moment, in addition to the same load as described above, a horizontal tensile force is applied to the concrete foundation on the compression side due to the falling moment. . The crack prevention net 8 resists the tensile stress in the horizontal direction generated in the surrounding concrete, so that the occurrence of cracks in the concrete is suppressed as much as possible, and the concrete is prevented from breaking.

  Next, the basic structure according to the second embodiment shown in FIGS. 4 to 6 will be described. The same parts as those in the first embodiment are denoted by the same reference numerals.

  In the basic structure according to the second embodiment, the crack prevention net 9 is annularly arranged in a horizontal plane. As long as it is arranged in a horizontal plane, it may be annular, but in order to simplify the construction, an appropriate number of crack preventing nets 9 formed in a part of a sector are annularly arranged. . As shown in FIG. 5, in this embodiment, ten crack preventing nets 9 formed in a part of a sector are arranged in a ring shape. The crack preventing net 9 is extended from the outside of the outer longitudinal streaks 7a to the inner side of the inner longitudinal streaks 7b so as to extend. The outer longitudinal streaks 7a, the inner longitudinal streaks 7b, and the unbonded anchor 5 are connected to the cracks. The prevention net 9 is penetrated. As shown in FIGS. 4 and 6, the crack preventing nets 9 are arranged in a plurality of stages at appropriate intervals in the vertical direction.

  Concrete is driven into the unbonded anchor 5 and the vertical bars 7a, 7b and the net 9 for preventing cracks, which are stretched over the base plate 4 and the anchor plate 6 in a state where the prestress is introduced, so that the footing portion 3a and the pedestal portion 3b are connected. Form. It should be noted that the crack preventing net 8 is tied to the vertical streak 7 before driving concrete. In addition, the pedestal portion 3b only needs to be formed to have an outer diameter dimension in which the crack preventing net 9 can be arranged.

  In the basic structure configured as described above, the crack preventing net 9 and the unbonded anchor, which are arranged to intersect with the longitudinal direction of the unbonded anchor 5, against the tensile load generated in the concrete as in the first embodiment. The longitudinal streaks 7a and 7b arranged in parallel to the longitudinal direction of No. 5 respectively resist. Therefore, the occurrence of cracks in the concrete is suppressed as much as possible, and the breakage of the concrete is prevented.

  Further, even when a horizontal load caused by wind, earthquake, or the like acts as a falling moment, the crack preventing net 9 resists the horizontal tensile stress generated in the surrounding concrete, thereby minimizing the occurrence of cracks in the concrete. And breakage is prevented.

  In the embodiment described above, so-called fiber concrete in which short fibers such as synthetic fibers and steel fibers are mixed in the concrete to be poured can be used, and the occurrence of cracks against the tensile force applied to the concrete can be used. It can be more suppressed.

  In the above-described embodiment, the base plate 4 and the like are circular, and the unbonded anchors 5 are arranged on the circumference. However, the unbonded anchors 5 are arranged in other shapes according to the cross-sectional shape of the tower-like structure 1. You can also. Although one pair of unbonded anchors 5 is arranged in the radial direction, one or three or more unbonded anchors 5 may be arranged.

  In the above-described embodiment, the basic structure suitable for a tower for wind power generation has been described. However, the present invention is not limited to this. As a basic structure for a tower-like structure extended to a high position in the sky such as a monument or a chimney. It can also be used.

  According to the foundation structure of the tower-like structure according to the present invention, the column base is fixed by using the unbonded anchor that introduces the prestress, and resists the tensile stress generated when the overturning moment is transmitted to the concrete. Thus, the foundation structure suitable for a tower for a windmill in which a large horizontal load repeatedly acts can be prevented, and the collapse can be prevented as much as possible, which can contribute to prolonging the service life of the tower-like structure.

1 tower-like structure 2 pile 3 foundation
3a Footing section
3b Base 4 Base plate 5 Unbonded anchor 6 Anchor plate
7a, 7b Vertical streaks 8 Net for preventing crack 9 Net for preventing crack

Claims (5)

In the basic structure of a tower-like structure in which the top portion extends to a high position in the sky and an external force acting on the top portion and the column base portion, at least a falling moment and a horizontal force are applied,
Fixing a circular column base of the tower-shaped structure, unbonded anchors arranged circularly along the column base to introduce prestress,
A vertical line arranged in a direction parallel to the unbonded anchor and concentrically at a position sandwiching the unbonded anchor,
The width in the vertical direction and parallel to a position where the longitudinal direction is passed through the inner longitudinal muscle and outer longitudinal muscle, a direction crossing the unbonded anchor and the longitudinal muscle, distribution of the unbonded anchor And a crack prevention net arranged radially in the radial direction of
A foundation structure for a tower-like structure, wherein concrete is driven into the unbonded anchor, the vertical streaks, and the crack prevention net to form a concrete foundation. In the basic structure of a tower-like structure in which the top portion extends to a high position in the sky and an external force acting on the top portion and the column base portion, at least a falling moment and a horizontal force are applied,
Fixing a circular column base of the tower-shaped structure, unbonded anchors arranged circularly along the column base to introduce prestress,
A vertical line arranged in a direction parallel to the unbonded anchor and concentrically at a position sandwiching the unbonded anchor,
In the direction intersecting the unbond anchor and the longitudinal streaks, the longitudinal direction is formed at a position where the inner longitudinal streaks and the outer longitudinal streaks pass, and is formed as a part of a sector, and its circumferential direction is parallel to the horizontal direction. And a crack-preventing net that penetrates the unbonded anchor and the vertical streaks ,
A foundation structure for a tower-like structure, wherein concrete is driven into the unbonded anchor, the vertical streaks, and the crack prevention net to form a concrete foundation.   The basic structure of a tower-like structure according to claim 1 or 2, wherein the unbond anchor is arranged on a circumference below a leg of the tower-like structure to be supported. Forming the concrete base portion into a shape having a footing portion and a pedestal portion raised from the footing portion,
The basic structure of a tower-like structure according to any one of claims 1 to 3, wherein the vertical streaks reach the footing portion.   The basic structure of a tower-like structure according to any one of claims 1 to 4, wherein the tower-like structure is a column base for wind power generation.

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