JP6550611B2 - 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, etc. constructed on the ground, and particularly relates 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 tower for wind turbines, which is a column of wind turbines for wind power generation. At the top of the tower, there are a plurality of propeller blades (blades), and a generator that generates electricity by rotating the windmill, and a nacelle that becomes a heavy object such as a rotating mechanism that aligns the direction of the windmill to the windward are installed. Yes. Further, in order to stably increase the power generation efficiency, it is necessary to receive a stable wind, and it is desirable to place the top at a high position as much as possible. That is, in the tower for windmills , it is necessary to extend a top part to the highest position as much as possible, and to support a heavy article on the top part.

  In a tower-like structure, a large horizontal load is received by the action of the upper wind. Therefore, a bending moment acts as an overturning moment on the base portion of the tower structure. In particular, in the tower for wind turbines, in addition to the horizontal load, a complex load is repeatedly applied by rotating the blades of the wind turbine, changing the direction of the wind turbine by the rotating mechanism, and the combination of these various loads. May cause the windmill tower to tip over. In Japan, the overturning moment due to the seismic load is large, so a foundation structure that can handle earthquakes in addition to wind loads is desired.

  For example, a ground anchor combined pile method disclosed in Patent Document 1, a wind power generation tower disclosed in Patent Document 2, and Patent Document 3 disclosed as a proposal for a basic structure of a high-rise building or a tower-shaped structure. There is an anchor frame of the windmill tower. Further, in Patent Document 4, a column base hardware joined to the lower end of a steel column as a steel column base capable of securing anchor bolt fixing strength without increasing the size of the basic concrete is disclosed as basic concrete. A steel column base is disclosed which is fixed on foundation concrete with anchor bolts and nuts embedded therein.

  In addition, the applicant of the present application is a foundation structure of a tower-like structure such as a column or a tower, and in the foundation structure having a column base portion fixed by using an unbonded anchor that introduces prestress, the occurrence of cracks in the concrete is caused. The basic structure of the tower-like structure which suppresses as much as possible was proposed (refer patent document 5). The basic structure disclosed in Patent Document 5 is a tower-like structure in which at least a tipping moment, a horizontal force, and the like are applied by an external force that acts on the top and the column base, with the top extending to a high position in the sky. In the basic structure of an object, the column base of the tower-like structure is fixed, an unbonded anchor for introducing prestress, a vertical bar arranged in a direction parallel to the unbonded anchor, and the vertical bar A hoop bar having a circumference arranged at an appropriate interval in the longitudinal direction of the vertical bar, and radial horizontal bars arranged in a direction intersecting the unbond anchor and the vertical bar, the unbond anchor and the vertical bar The concrete foundation is formed by driving concrete into the hoop bars and radial horizontal bars around the circumference.

  Further, in Non-Patent Document 1, a method for designing a columnar reinforcing bar of a rising portion (pedestal) of a footing foundation is described. Regarding the design of an anchor bolt, a connecting member joined to a bolt lower end with a nut or the like. Examine whether the stress caused by (anchoring) satisfies the concrete tolerance and the tolerance of the anchoring member itself, and whether the anchor bolt surface adheres to the concrete It is supposed to be.

  Furthermore, in Non-Patent Document 2, the design is made with the smaller of the allowable drawing force determined by the conical fracture of the headed anchor bolt and the allowable value of the anchor bolt member itself.

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

Chimney structure design and construction guidelines (Japanese building center) Various synthetic structural design guidelines (Architectural Society of Japan)

  The support structure by the pile method disclosed in Patent Document 1 is mainly a building, which resists the buoyancy generated in the building by receiving a tipping moment due to a horizontal force caused by wind, earthquake, etc. In the case where a complex overturning moment occurs, the reliability may not be secured. Further, in the wind power generation tower disclosed in Patent Document 2, a tower body formed by stacking hollow cylinders and a prestressed concrete reinforcing member having a T-shaped cross section along the outer periphery on the base side of the tower body. And the reinforcing member is fixedly connected to the base and the tower body. Further, the anchor frame disclosed in Patent Document 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 with a predetermined distance, and the connecting member disposed between the connecting members A plurality of anchor bolts and a plurality of struts connected to the lower surface of the lower anchor plate for positioning the pair of upper and lower anchor plates at a predetermined height on the foundation, the connecting member and the struts Is made of steel pipe.

  In the basic structure disclosed in Patent Document 2 and Patent Document 3, a pedestal that is a base pedestal protruding from the center of the base member is formed, and a tower is fixed to the pedestal. And anchor bolts, and columns. However, since the driven concrete and the anchor bolt are joined with adhesive force, if the falling moment is loaded and this adhesion breaks, the concrete will crack, and if the allowable stress of the concrete is exceeded, There is a risk of damaging the concrete. For this reason, it is desirable that the foundation has a structure that does not have adhesion between the anchor bolt and the concrete, and has a structure using an unbonded anchor that reduces the load on the concrete by changing the load transmission mechanism.

Moreover, in the steel column base disclosed in Patent Document 4, the tensile force of the anchor bolt is transmitted to the reinforcing bar by satisfying the dimensional condition according to the present invention for the load generated in the horizontal direction in the concrete, and the cone It is said that the size of the foundation can be reduced by preventing the destruction of the state. However, the failure mechanism of concrete foundations is not limited to cone-like failure. Especially, in the tower for wind power generation, as mentioned above, heavy objects may be installed at the top of the tower. It is thought that the destruction mechanism works. Therefore, in the invention described in Patent Document 4, there is a possibility that 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 rupture mechanism in the tower for wind power generation cannot secure sufficient proof strength only by the cone-shaped fracture, which is a problem in the steel column base described in Patent Document 4.

  In addition, as disclosed in Non-Patent Document 5 and Non-Patent Document 6, the conventional tower-like structure foundation structure includes anchor bolts attached to concrete with reference to the pointers and the like, and nuts or the like at the lower end thereof. The connecting member (anchor ring) to be joined together is arranged at the rising part (pedestal) of the footing foundation, and is designed on the basis of resisting the overturning moment received from the upper structure by the columnar structure.

  The support structure of a tower-like structure (tower) typified by a chimney is a structure in which a pedestal that is a base pedestal protruding from the center of the base member is formed, and the tower is fixed to this pedestal. The fixing portion is composed of the anchor bolt and the connecting member (anchor ring) in the placed concrete. In addition, it is designed on the assumption that the concrete and the anchor bolt are bonded and joined. When a falling moment is loaded, a tensile force is transmitted through the concrete to the vertical reinforcing bars arranged beside the anchor bolt.

  On the other hand, in a wind turbine tower or the like, the natural period of the upper structure can be determined by fixing the legs. When it is desired to set the position completely or in a state close to this, it is considered that an unbonded anchor is used and a structure in which tension (prestress) is given to the anchor bolt after concrete pouring is considered. In addition, a rotating machine such as a wind turbine may pre-stress bolts in order to prevent fatigue failure in a base bolt that is constantly subjected to load fluctuation.

  When prestress is applied using an unbonded anchor, tensile load acts on the concrete around the unbonded anchor in the vertical direction below the anchoring part (anchor ring) of the unbonded anchor and in the crossing direction (horizontal direction) of the unbonded anchor. Therefore, a stress state different from anchor bolts expected to adhere to concrete that does not apply prestress will occur, and if there is a lack of reinforcing bars necessary for prestressing, immediately after prestressing Even under normal load on the tower structure, cracks occur in the concrete, and when the cracks progress, the concrete may break along the unbonded anchors. The structure that resists the tipping moment of the leg by this structure transmits a tensile force through the concrete to the vertical reinforcing bars arranged in parallel to the anchor bolts, and the radial horizontal bars have a tipping moment. Resist horizontal tension generated on the compression side.

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

  The present invention relates to the improvement of the foundation structure disclosed in Patent Document 5, and in the same manner as the foundation structure, using an unbonded anchor, a foundation structure in which prestress is introduced and concrete is driven into the construction. The object is to provide a foundation structure of a tower-like structure capable of preventing harmful cracks generated in concrete and sufficiently resisting an overturning moment.

As a technical means for achieving the above object, the foundation structure of the tower-like structure according to the present invention is such that the top portion extends to a high position in the sky, and the external force acting on the top portion and the column base portion In the basic structure of the tower- like structure on which at least a falling moment and a horizontal force act, an unbond anchor for fixing the column base of the tower- like structure and introducing prestress is in a direction parallel to the unbond anchor. The inner longitudinal muscles arranged inside the unbond anchor, the outer longitudinal muscles arranged outside, and the unbond anchor, the inner longitudinal muscles, and the outer longitudinal muscles are concentrically arranged at a position sandwiching the unbond anchors. Having a portion in a direction along the direction , hanging on the inner longitudinal bar and the outer longitudinal bar, and having a bending portion, a bending portion or a crossing portion at an appropriate position between both ends, At least both ends The result of an inner longitudinal muscle and either or horizontal rebar indefinite shape obtained by joining the both outer longitudinal muscle, the unbonded anchor and the inner vertical stripe, outer longitudinal muscle, concrete against horizontal rebar irregular shape It is characterized by a concrete foundation formed by driving.

In the state where the tower-like structure is supported by the unbonded anchor introduced with the prestress, there is no adhesion between the unbonded anchor and the concrete, so that the load is not transmitted. However, the concrete surrounded by the unbonded anchor bolt introduced with the prestress and the anchor ring at the lower end is firmly integrated to transmit the load to the unbonded anchor bolt. In this case, while a compressive stress is generated in the vertical direction of the concrete, a tensile force is simultaneously generated which tries to expand the concrete in the horizontal direction intersecting the same. Further, as a reaction force to the foundation due to the external force acting on the top, further compressive stress is added to the compressive stress due to the prestress introduction in the compression side concrete portion due to the overturning moment. Similarly, the tensile stress in the horizontal direction will be further increased. With these tensile stresses to intersect the anchor bolt, horizontal rebar of the irregular shape and arranged over the said inner longitudinal muscle and outer longitudinal muscle to resist. Here, the irregularly shaped horizontal reinforcing bar has a portion in a direction along a direction intersecting the unbonded anchor, the inner vertical bar and the outer vertical bar, and the inner vertical bar and the outer vertical bar. , And has a bending portion, a bending portion or a crossing portion at an appropriate position between both ends, specifically, as shown in FIG. 2, a bending portion , a bending portion or a cross section, and is formed in a planar shape and a portion extending in a direction different from the radial direction of the arcs arranged the longitudinal muscle. For example, it is formed in an L shape, a V shape, an X shape or the like so that at least both ends can be joined to either one or both of the inner vertical stripe and the outer vertical stripe.

The indeterminately shaped horizontal reinforcing bar has a shape arranged at least on the inner vertical bar and the outer vertical bar, for example, a V shape, an L shape, an X shape or the like. In the case of V-shape or L-shape, the bent portion, curved portion, or end portion is joined to the vertical stripe, and in the case of X-shape, each end portion is joined to the vertical stripe.

  Moreover, the foundation structure of the tower-shaped structure which concerns on invention of Claim 2 has arrange | positioned the said unbonded anchor on the leg lower periphery of the tower-shaped structure which should be supported, It is characterized by the above-mentioned.

  In order to arrange unbond anchors efficiently, the structure is arranged on the circumference centered on the column cross-section center position of the tower-like structure, and a pair of unbond anchors are arranged in parallel in the radial direction of the arc. It is arranged. In this case, it is preferable to arrange the longitudinal bars at positions sandwiching the unbond anchor.

In addition, the foundation structure of the tower-like structure according to the invention of claim 3 is formed such that the concrete foundation portion has a footing portion and a pedestal portion raised from the footing portion, and the inner longitudinal bars and the outer longitudinal bars are formed. A streak is made to reach the footing part.

  It does not have a pedestal on the top surface of the footing part, and may be formed on a flat surface or an inclined surface that can drain rainwater, or a shape in which a pedestal part is formed on the top of the footing part. It does not matter if it is. It is sufficient if the pedestal portion is formed to a size that can arrange the horizontal rebar. Concrete is poured into the unbonded anchor and the longitudinal bars and horizontal rebars to form this pedestal. In this case, the lower end of the vertical bar extends to the footing part and is joined to the reinforcing bar arranged in the footing part.

  The foundation structure of the tower-like structure according to the invention of claim 4 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 the column base portion of the tower for wind turbines. As the structure of the foundation to support the chimney and various tower etc. There are various types, a both considering overturning moments and horizontal forces structures, as in the case of the wind turbine, cyclic loading and rotating machine It is not designed to resist fatigue loads due to. The basic structure according to the present invention, by arranging the horizontal rebar, since it is possible to resist the tensile stress of the concrete foundation portion acting in a direction intersecting with Unbonded anchor, towers for wind turbines and the like repeatedly load is applied It will be suitable for the foundation.

According to the basic structure of the tower-like structure according to the present invention, the vertical bars arranged with respect to the unbond anchors and the indefinite shape of the horizontal bars are applied to the stress acting on the concrete even after the prestress is introduced. The reinforcing bar resists, and when the prestress is introduced, the working load due to the external force thereafter and the cracking of the concrete due to the fatigue load due to repetition can be suppressed, and breakage can be prevented.

  Further, according to the basic structure of the tower-like structure according to the invention of claim 2, 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. .

  Moreover, according to the foundation structure of the tower-like structure which concerns on invention of Claim 3, the quantity of the concrete thrown in can be minimized and a 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 shape of the foundation is simplified, so that construction can be facilitated.

  Moreover, according to the basic structure of the tower-like structure according to the invention of claim 4, even when a load from a rotating machine or the like is applied, it is not collapsed, and particularly for wind power generation where a complicated load is applied. It is suitable to adopt for the foundation which supports the column base.

It is a schematic sectional drawing of the foundation provided with the structure which concerns on this invention. It is sectional drawing cut | disconnected along the AA in FIG. It is a general | schematic perspective view explaining the arrangement | positioning state of the unbonded anchor of the foundation structure which concerns on this invention. It is a figure explaining the outline of distribution of the load which acts on the circumference of the unbond anchor which introduced prestress.

  Hereinafter, the basic structure of the tower-like structure according to the present invention will be specifically described based on the illustrated preferred embodiment.

  FIG. 1 schematically shows a foundation provided with the structure according to the present invention, and shows a state of supporting a tower-like structure 1 such as a column base for wind power generation. A foundation 3 is disposed on a pile 2 driven into the ground of 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 FIG. 3, the tower-like structure 1 is fixed to an annular base plate 4 via unbonded anchors 5. The unbonded anchor 5 is stretched over the base plate 4 and the anchor plate 6 so that 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 the radial direction of the circular shape, and these pairs are arranged on the circumference. Are arranged along. The center of the base plate 4 or the like is substantially aligned with the column cross section center C of the tower-like structure 1. Vertical streaks 7 a and 7 b are disposed in parallel to the unbonded anchor 5. The lower end portions of the longitudinal bars 7a and 7b reach the footing portion 3a of the foundation 3, and are joined to the arrangement bars 3c disposed in the footing portion 3a. The longitudinal bars 7a and 7b sandwich the anchor bolt 5, and an outer longitudinal bar 7a is disposed on the outer side, and an inner longitudinal bar 7b is disposed on the inner side.

Then, as shown in FIG. 2, it has an L-shaped, V-shaped, X-shaped, X-shaped, X-shaped or X-shaped cross section so as to have a portion extending in a direction different from the radial direction of the circular base plate 4 in plan view. Horizontal reinforcing bars of irregular shape such as L-shaped reinforcing bars 8L, V-shaped reinforcing bars 8V, X-shaped reinforcing bars 8X, etc., formed in the shape of a letter are arranged. These horizontal reinforcing bars 8L, 8V, 8X are disposed orthogonal to the unbonded anchor 5 and the longitudinal bars 7a, 7b, and are joined to the longitudinal bars 7a, 7b. That is, long end and short end of L-shaped reinforcing bar 8L, both ends and bent parts of V-shaped reinforcing bar 8V, and all ends of X-shaped reinforcing bar 8X are reinforcing bars 7a and 7b, respectively. It is joined. The horizontal reinforcing bars 8L, 8V, 8X are appropriately arranged in the height direction. In addition, other than L-shaped, V-shaped, X-shaped, for example, N-shaped, M-shaped, W-shaped, etc. or any other suitable design can be used for the position of reinforcing bars.

  Concrete is driven into the unbonded anchor 5 and the longitudinal bars 7a and 7b and the horizontal reinforcing bars 8L, 8V and 8X which are stretched over the base plate 4 and the anchor plate 6 in a state where prestress is introduced, and the footing part 3a and the base part 3b And form.

  In the foundation structure configured as described above, for example, the concrete around the unbonded anchor 5 into which prestress is introduced in order to fix the tower for the windmill, the longitudinal direction of the unbonded anchor 5 as shown by the broken line in FIG. A tensile load acts in the direction intersecting the longitudinal direction. For these tensile loads, the horizontal reinforcing bars 8L, 8V, 8X arranged to intersect with the longitudinal direction of the unbond anchor 5 and the longitudinal bars 7a, 7b arranged in parallel to the longitudinal direction of the unbonded anchor 5 are provided. Resist each. Therefore, the occurrence of cracks in the concrete is suppressed as much as possible and breakage is prevented.

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

  Also, when a horizontal load received by wind or earthquake acts as a tipping moment, a load similar to the above is applied, and in addition, a horizontal tensile force is applied to the concrete foundation on the compression side due to the tipping moment. . The horizontal reinforcing bars 8L, 8V, and 8X resist the horizontal tensile stress generated in the surrounding concrete, and the occurrence of cracks in the concrete is suppressed as much as possible, and the breakage is prevented.

  In the embodiment described above, the base plate 4 or the like is described as a circular shape, and the unbond anchor 5 is arranged on the circumference. However, according to the cross-sectional shape of the tower-like structure 1, it is arranged in another shape. You can also. Further, one pair of unbonded anchors 5 is arranged in the radial direction, but one or three or more unbonded anchors may be arranged.

  Further, in the above-described embodiment, the basic structure suitable for the tower of wind power generation has been described. However, the basic structure is not limited to this, and the basic structure of the 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 tower structure according to the present invention, the column base is fixed by using an unbonded anchor introduced with pre-stress, and resists the tensile stress that occurs when the tipping moment is transmitted to the concrete. It becomes a basic structure suitable for a tower for a wind turbine in which a large horizontal load repeatedly acts, can be prevented from collapsing as much as possible, and can contribute to extending the useful life of the tower-like structure.

1 tower-like structure 2 pile 3 foundation
3a Footing part
3b pedestal 4 base plate 5 unbonded anchor 6 anchor plate
7a, 7b longitudinal bars
8L L-shaped rebar (Horizontal rebar with irregular shape )
8 V V-shaped reinforcing bar (horizontal reinforcing bar of irregular shape )
8X X-shaped reinforcing bar (horizontal reinforcing bar of irregular shape )

Claims (4)

In the basic structure of the tower-like structure in which the top part extends to a high position in the sky and at least a falling moment and a horizontal force act on the top part and the column base part by an external force,
An unbond anchor for fixing the column base portion of the tower- like structure and introducing prestress,
In a direction parallel to the unbond anchor, concentrically at a position sandwiching the unbond anchor, an inner vertical line arranged inside the unbond anchor, an outer vertical line arranged outside,
Said inner longitudinal muscle and the Unbonded anchor, a direction along a direction intersecting with the outer longitudinal muscle site, placed over the said inner longitudinal muscle and outer longitudinal muscle, such as appropriate between the ends It consists of an indefinitely shaped horizontal reinforcing bar that has a bent part, a curved part or a crossing part at a position, and at least both ends joined to either one or both of the inner longitudinal bar and the outer longitudinal bar ,
A foundation structure of a tower-like structure, wherein concrete is formed by driving concrete into the unbond anchor, the inner vertical bars, the outer vertical bars, and the horizontal reinforcing bars having an indefinite shape .   The foundation structure of a tower-like structure according to claim 1, wherein the unbonded anchor is disposed on a circumference under a leg portion of the tower-like structure to be supported. The concrete foundation portion is formed into a shape having a footing portion and a pedestal portion raised from the footing portion, and the inner vertical stripe and the outer vertical stripe are made to reach the footing portion. The basic structure of the tower-like structure according to any one of claims 1 and 2.   The foundation structure of the tower-like structure according to any one of claims 1 to 3, wherein the tower-like structure is a column base for wind power generation.

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