JP2010071003A - Structure of step drop section of column base - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a structure of a step drop section of a column base which does not lose proof stress and which can follow a large deformation even when damage is caused in the step drop section. <P>SOLUTION: A first reinforcing means 10 is provided to the step drop section 6 of the column base 1, and the first reinforcing means 10 is constituted by providing a plurality of ring-shaped steel materials 12 which are provided in a state where they surround the outside of the longitudinal reinforcing iron bars 5 at predetermined spacings in the axial direction of the longitudinal reinforcing iron bars 5. Then a second reinforcing means 11 which is formed of spiral steel materials 15 which restraint the concrete inwardly on the inside of the longitudinal reinforcing iron bars is provided to the step drop section 6. Because of this, the structure of the step drop section of the column base does not lose proof stress and can follow large deformation even when damage is caused in the step drop section. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a structure of a stepped portion of a reinforced concrete pedestal having a stepped portion in which an axial reinforcing bar extending in the axial direction of the pedestal is divided.

  In the pier (pillar) that supports the bridge girder, the horizontal force generated in the bridge girder, etc. during an earthquake, etc. is transmitted from the bridge girder to the pier via the falling bridge prevention device (stopper). The bending moment generated in the pier by this horizontal force is , The maximum distribution at the base of the pier, and a triangular distribution with zero at the top. An axial rebar (main rebar) is placed inside the pier to resist this bending moment, but since the bending moment distribution becomes smaller as it goes to the upper part of the pier, the axial rebar at the upper part of the pier is Less than the lower axial rebar. Therefore, in some cases, such a bridge pier is provided with a paragraph portion in which a part of the axial reinforcing bar is fixed at an intermediate height in order to reduce unnecessary axial reinforcing bars in consideration of economy.

By the way, during an earthquake, the pedestal is bent by a load acting on the pedestal, and due to the influence, the axial rebar fixed in the middle of the stepped portion is pulled in the axial direction inside the pedestal. In the paragraph, this pulled axial reinforcing bar generates a force that pushes the concrete covered by the pedestal outward. Further, the axial rebar fixed halfway cannot follow the deflection of the pedestal, and a force is generated so that the tip of the axial rebar protrudes from the pedestal. In addition, since the amount of reinforcing bars in the axial direction reinforcing bars arranged up to the top of the pedestal which is not fixed in the middle is reduced at the stepped portion, it is extended and yielded by the bending moment generated in the pedestal at the stepped portion. When this axial rebar is subjected to a bending moment on the opposite side, this time it compresses and compresses, but it can not shrink to the extent that it yields and is extended greatly, and a protruding force is generated that pushes the covered concrete outward. To do.
And by such a force acting, cracks occur in the concrete around the axial rebar, and the adhesion between the axial rebar and the concrete at the stepped part is lost, and as a result, damage to the pedestal further progresses The phenomenon that it becomes easy to do occurs.

As an example of a technique for dealing with such a phenomenon, a technique described in Patent Document 1 is known.
In this technology, in the structure of a reinforced concrete pedestal that has a stepped part where the axial rebar of the pedestal has been stepped, the position of the intermediate fixing portion of the axial rebar in the stepped part is provided on the outer surface of the pedestal body. A reinforcing member extending in the direction of arrangement of the axial reinforcing bars is fixed.
In such a pedestal structure, the reinforcing member fixed to the outer surface of the pedestal main body presses the outer surface, so that the reinforcing bars are pushed over the concrete and the force that protrudes as described above. Can be countered. Therefore, cracking of the concrete around the axial rebar is suppressed, and loss of adhesion between the axial rebar and the concrete can be suppressed, and as a result, the seismic strength of the pedestal can be improved.
JP 2007-224559 A

By the way, in the current pedestal design system, in the event of a large earthquake, by adjusting the amount of axial rebar that is fixed in the middle of the bending position and in the middle so that the bending portion is not broken with respect to the bending moment distribution. Designed to break at the pedestal base.
However, since the pedestal base is buried in the ground, it is impossible to confirm if the pedestal base has been damaged after the earthquake without digging the soil, and there is also a restoration work when the pedestal base is damaged. There was a problem that it took time and effort to recover because the work was being dug up.
Therefore, in the event of a major earthquake, if damage is generated at the stepped part instead of the base of the pedestal, the subsequent pedestal can be damaged or restored easily. When (cracking, peeling of concrete, buckling of axial reinforcing bars, etc.) occurs, there is a problem that the proof strength is rapidly reduced at the stepped portion and the pedestal cannot follow the large deformation.

  The present invention has been made in view of the above circumstances, and even when damage (cracking, peeling of concrete, buckling of an axial rebar, etc.) occurs at the cut-off portion, the yield strength is not lost and the deformation is large. It is an object to provide a structure for a pedestal that can be followed.

In order to solve the above-mentioned problems, the present invention is a structure of a reinforced concrete pedestal having a stepped portion in which an axial reinforcing bar extending in the axial direction of the pedestal is divided.
A first reinforcing means that reinforces the axial rebar from the outside thereof is provided at the stepped portion and the vicinity thereof, and a second reinforcing means that constrains the concrete inside is provided inside the axial rebar. It is characterized by being.

In such a structure of the stepped part of the pedestal, the first reinforcing means that reinforces the axial rebar from the outside causes the axial rebar to cover the concrete in the stepped part and push the concrete outward. It is possible to counter the force that protrudes, and thus cracking of the concrete around the axial rebar is suppressed, and loss of adhesion between the axial rebar and the concrete can be suppressed.
Moreover, even if damage (cracking, peeling of concrete, buckling of axial rebar, etc.) occurs at the cut-off portion, the inner concrete can be restrained so as not to escape by the second reinforcing means for restraining the concrete inside. Therefore, it is possible to ensure the deformation performance in the paragraphing portion, and the pedestal can follow the large deformation.
In addition, since the deformation performance at the section is secured, the pedestal can be designed to cause damage at the section, not the pedestal base, in the event of a large earthquake, etc. Existence inspection and restoration work can be done easily.

Further, in the structure of the stepped portion of the pedestal according to the present invention, for example, as shown in FIGS. 1 to 3, the first reinforcing means 10 is provided in a ring shape so as to surround the outside of the axial rebar 5. A plurality of steel materials 12 may be provided at predetermined intervals in the axial direction of the axial rebar 5, and a plurality of steel materials 12 are provided so as to surround the outside of the axial rebar 5 as shown in FIGS. 4 to 6. A plurality of steel materials 17 may be provided at predetermined intervals in the axial direction of the axial rebar 5.
Furthermore, as shown in FIGS. 7 to 9, a plurality of steel members 17 provided so as to surround the outside of the axial rebar 5 may be provided so as to constrain the concrete covering from the outside.
Further, as shown in FIGS. 19 to 22, the axial rebar 5 b is divided into a first axial rebar 30 a extending from the lower end portion of the pedestal 1 to the stepped portion 6, and the first axial rebar 30 a. A second axial rebar 30b that is disposed coaxially with the first axial rebar 30a with an interval upward and extends to the upper end of the pedestal 1, and the first axial rebar 30a and the second axial rebar 30b. The lower end is disposed at the same position as the upper end of the first axial rebar 30a, and the upper end is disposed at the same position as the lower end of the second axial rebar 30b. The first reinforcing means 10 (17) may be arranged at the upper end of the first axial rebar 30a and the lower end of the second axial rebar 30b.

  Also, as shown in FIGS. 10 to 16, the first reinforcing means 10 is paired with a pair of reinforcing plates that are in contact with the opposing outer surfaces 3 a and 3 a of the stepped portion 6 and the leg 1 in the vicinity thereof. It is good also as a structure provided with 21 and 21 and the fixing means 22 which fixes these reinforcement boards 21 and 21 to the said outer surface 3a, 3a.

  Further, in the structure of the stepped portion of the pedestal according to the present invention, as shown in FIGS. 1 to 16, the second reinforcing means 11 is placed inside the axial reinforcing bar 5 in the stepped portion 6 and the vicinity thereof. A plurality of rings may be formed by a spiral steel material 15 provided, and as shown in FIG. 17, a plurality of rings provided at predetermined intervals in the axial direction inside the axial rebar 5 in the vicinity of the stepped portion 6 and the vicinity thereof. A plurality of steel materials 27 (see FIG. 18) arranged in a ring shape inside the axial rebar 5 in the vicinity of the stepped portion 6 and in the vicinity thereof may be configured by the reinforced steel material 26. It is good also as a structure provided with two or more by the predetermined interval in the axial direction.

According to the present invention, the first reinforcing means causes the axial rebar to be covered in the stepped portion and pushes the concrete outward, and the axial rebar fixed in the middle cannot follow the deflection of the pedestal, The force that the tip of this axial rebar protrudes from the pedestal, or the force that protrudes outside the covered concrete when the continuous axial rebar to the top of the pedestal yields and receives compressive stress. In addition to being able to counteract, even if damage (cracking, peeling of concrete, buckling of axial rebars, etc.) occurs at the break, the inner concrete is released by the second reinforcing means that restrains the concrete to the inside. Since it can be constrained so as to prevent deformation, it is possible to secure the deformation performance at the paragraphing portion and to follow the large deformation of the pedestal.
In addition, since the deformation performance at the section is secured, the pedestal can be designed to cause damage at the section, not the pedestal base, in the event of a large earthquake, etc. Existence inspection or confirmation and restoration work can be done easily. Therefore, it is possible to shorten the construction period and cost of the restoration work.

Embodiments of the present invention will be described below with reference to the drawings.
(First embodiment)
1 to 3 show a first embodiment. FIG. 1 is a front sectional view of a pedestal, FIG. 2 is a side sectional view of the pedestal, and FIG. 3 is a plan sectional view of a stepped portion of the pedestal. It is.

The pedestal 1 supports the bridge girder of the bridge, and includes a footing portion 2 fixed to the ground and a pedestal main body 3 extending vertically upward from the footing portion 2.
Such a pedestal main body 3 takes into account the load from the bridge girder, and the width in the direction perpendicular to the extending direction of the bridge girder (the left and right width in FIG. 1) is the width in the extending direction of the bridge girder (the left and right in FIG. 2). Wider than the width). That is, as shown in FIG. 3, the pedestal main body 3 has a shape having a rectangular horizontal cross section, and has two pairs of outer surfaces 3a, 3a, 3b, 3b forming a vertical plane. And a pair of outer side surface 3a, 3a respond | corresponds to the long side of the rectangle of the said horizontal cross section, and has a wide horizontal width compared with a pair of outer side surface 3b, 3b corresponding to the short side of a rectangle. Yes.

The pedestal 1 is made of reinforced concrete, and a plurality of axial rebars 5 extending in the axial direction (vertical direction) of the pedestal 1 are arranged in the horizontal direction and embedded in the concrete. As shown in FIG. 3, the large number of axial reinforcing bars 5 are arranged so as to surround the edges of the horizontal section at predetermined intervals along the four sides of the rectangle in the horizontal section of the pedestal main body 3. The outside of the axial rebar 5 is covered concrete. A plurality of rectangular ring-shaped shear reinforcement bars (not shown) are provided at predetermined intervals in the axial direction of the axial reinforcing bars 5 on the axial reinforcing bars 5 arranged so as to surround the edge of the horizontal section of the pedestal main body 3. ing.
As shown in FIG. 1 and FIG. 2, a stepped portion 6 is provided at a height position in the middle of the pedestal main body 3, and about half of the numerous axial reinforcing bars 5 are axial reinforcing bars. 5a, the upper end portion is fixed in the middle of the stepped portion 6, and the remaining half of the axial rebars 5b extend further upward to the upper end portion of the column base body 3. The axial rebars 5 (5a, 5b) are provided with node portions (not shown) at equal intervals in order to reliably adhere to the concrete. Further, the lower end portion of the axial rebar 5 (5a, 5b) extends to the lower portion of the footing portion 2.

When the pedestal main body 3 bends due to the load from the bridge girder at the time of an earthquake in such a stepped portion 6, the axial rebar 5 a fixed in the middle of the stepped portion 6 is pulled by a downward force. And in the paragraph part 6, the axial direction reinforcing bar 5a pulled downward produces the force which pushes and spreads the surrounding concrete, and, thereby, the force which pushes the covering concrete of the pedestal main body 3 outside arises. In addition, the axial rebar 5a cannot follow the deflection of the leg column main body 3, and a force is generated to cause the axial rebar 5a to protrude outward from the leg column main body 3 in the vicinity of the fixing portion on the way. In addition, the axial rebar 5b arranged up to the top of the pedestal that is not fixed halfway is stretched by the bending moment generated in the pedestal 1 at the paragraph 6 because the amount of reinforcement is reduced at the paragraph 6. Surrender. When the axial rebar 5b is subjected to a bending moment on the opposite side, it now contracts with a compressive force, but it cannot shrink to the extent that it yields and is greatly stretched, and the protruding force that pushes the covered concrete outwards appear.
And when the above force acts, a crack generate | occur | produces in the concrete around the axial direction reinforcing bar 5a, and adhesion with the axial direction reinforcing bar 5a and the concrete in the stage part 6 is lost. At this time, the covered concrete may be peeled off from the pedestal main body 3. As a result, a phenomenon occurs in which the damage to the pedestal main body 3 is more likely to proceed.

  Therefore, in the present invention, the first reinforcing means 10 that reinforces the axial rebar 5 from the outside is provided in the stepped portion 6 and its vicinity (near the top and bottom), and concrete is provided inside the axial rebar 5. The 2nd reinforcement means 11 restrained inside is provided.

The first reinforcing means 10 has a configuration in which three rectangular ring-shaped steel materials 12 provided so as to surround the outside of the axial rebar 5 are provided at predetermined intervals in the axial direction of the axial rebar 5. Five first reinforcing means 10 having such a configuration are provided at predetermined intervals on the left and right in the plan sectional view of the stepped portion 6.
The steel material 12 is composed of 6 or 8 axial reinforcing bars 5 as a set, and surrounds the outside of each set of 6 or 8 axial reinforcing bars 5 and has 6 or 8 axial directions. A total of five are provided in the plane section of the section 6 so as to come into contact with the reinforcing bars 5 from the outside. The steel material 12 provided so as to surround the eight axial reinforcing bars 5 is provided at the right end portion of the flat section of the stepped portion 6, and the steel material 12 provided so as to surround the six axial reinforcing bars 5 is: A total of four are provided at the left end of the flat section of the paragraph section 6 and the middle section.

Three sets of six axial rebars 5 surrounded by the steel material 12 are juxtaposed in the width direction of the pedestal main body 3 (long side direction of the flat cross section rectangle in FIG. 3) in the plane cross section of the section 6. The pair of eight axial reinforcing bars 5 arranged opposite to each other in the thickness direction of the pedestal main body 3 (the short side direction of the rectangular plane in FIG. 3) and surrounded by the steel material 12 are In the flat cross section of the ledge 6, four are arranged in parallel in the width direction of the pedestal main body 3 (long side direction of the flat cross section rectangle in FIG. 3), and the thickness direction of the pedestal main body 3 (short in the flat cross section rectangle in FIG. 3). (In the side direction) are arranged opposite to each other.
In addition, among the three steel materials 12 arranged on the upper and lower sides constituting the first reinforcing means 10 (arranged in the axial direction of the axial rebar 5), the steel material 12 located at the uppermost stage is axially fixed in the middle. It arrange | positions at the upper end part of the reinforcing bar 5a, and the remaining two steel materials 12 are arrange | positioned downward from the steel material 12 located in the uppermost stage at fixed intervals.

  In the present embodiment, the steel material 12 is provided so as to surround the outside of each set of 6 or 8 axial rebars 5 with 6 or 8 axial rebars 5 as a set. The number of the axial rebars 5 surrounded by the steel material 12 may be arbitrarily set. Moreover, you may provide so that the outer side of the axial direction reinforcement 5 arrange | positioned so that the edge of the horizontal cross section of the pillar main body 3 may be enclosed like the said shear reinforcement. In this case, the steel material 12 should just be arrange | positioned between the shear reinforcement bars adjacent up and down.

The second reinforcing means 11 is composed of a plurality of spiral steel members 15 provided on the inner side of the axial reinforcing bar 5 in the stepped portion 6 and the vicinity thereof.
As shown in FIG. 3, four spiral steel members 15 are provided on the inner side of the axial reinforcing bars 5... Further, the spiral steel material 15 intersects with the long side of the rectangular ring-shaped steel material 12 in the plane section of the stepped portion 6. In addition, the spiral steel material 15 does not cross | intersect the long side of the outer side of the steel material 12 located in the right-and-left both sides among the five steel materials 12.
Further, as shown in FIGS. 1 and 2, the spiral steel material 15 is provided between the positions separated vertically by a predetermined length from the upper end of the axial reinforcing bar 5a fixed in the middle in the marking portion 6. That is, the spiral steel material 15 is provided over the stepped portion 6 and the vicinity thereof.
In FIGS. 1 and 2, in order to show the steel material 12 on the drawing, a part of the spiral steel material 15 is broken, but the spiral steel material 15 is actually formed continuously up and down.

In such a structure of the stepped portion of the pedestal, the axial reinforcing bar 5 is covered at the stepped portion 6 by the rectangular ring-shaped steel material 12 constituting the first reinforcing means 10 that reinforces the axial reinforcing bar 5 from the outside. The force that pushes the concrete outward, the axial rebar 5a that is fixed in the middle cannot follow the bending of the pedestal 1, and the force that the tip of the axial rebar 5 protrudes from the pedestal, When the axial rebar 5b continuous to the top of the pillar yields and receives compressive stress, it can counteract the force that protrudes outside the covered concrete. Therefore, the crack of the concrete around the axial rebar 5 is suppressed, and loss of adhesion between the axial rebar 5 and the concrete can be suppressed.
Further, even if damage (cracking, peeling of concrete, buckling of the axial rebar 5) occurs in the paragraph 6, the spiral steel material 15 constituting the second reinforcing means 11 that constrains the concrete on the inner side Since the concrete can be constrained so as not to escape, it is possible to ensure the deformation performance at the paragraphing portion 6 and the pedestal 1 can follow a large deformation.
In addition, since the deformation performance at the marking portion 6 can be secured, the pedestal 1 can be designed to cause damage at the marking portion 6 instead of the pedestal base in the event of a large earthquake, and the subsequent pedestal Inspection or confirmation of the presence or absence of damage 1 and restoration work can be easily performed.

(Second Embodiment)
4 to 6 show a second embodiment. FIG. 4 is a front sectional view of a pedestal, FIG. 5 is a side sectional view of the pedestal, and FIG. 6 is a plan sectional view of a stepped portion of the pedestal. It is.
Since the second embodiment shown in these drawings differs from the first embodiment in the configuration of the first reinforcing means 10, the configuration of the first reinforcing means 10 will be described below. The same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

In 2nd Embodiment, the 1st reinforcement means 10 is the structure which provided the two steel materials 17 provided so that the outer side of the axial direction reinforcing bar 5 might be enclosed in the axial direction of the axial direction reinforcing bar 5 at predetermined intervals, and As shown in FIG. 6, five first reinforcing means 10 having such a configuration are provided at predetermined intervals in the left-right direction in the plane cross section of the stepped portion 6.
As shown in FIG. 6, the steel material 17 is formed in a U shape in plan view, and is provided in parallel at a predetermined interval in the long side direction of the flat cross section rectangle in the flat cross section of the stepped portion 6. Two are provided opposite to each other in the short side direction, and a total of ten are provided. In addition, among the five steel materials 17 provided in parallel in the long side direction, the steel material 17 located at the right end has a longer length in the left-right direction than other steel materials.

In the flat cross section of the section 6, the two steel members 17, 17 facing the short side direction of the flat cross section rectangle are composed of 6 or 8 axial reinforcing bars 5 as a set, and each set of axial reinforcing bars 5. And 6 or 8 axial reinforcing bars 5 are provided so as to be in contact with each other from the outside. A predetermined gap is provided between the tip portions of the opposing steel materials 17 and 17.
Moreover, as shown in FIG. 4 and FIG. 5, among the three steel materials 17 arrange | positioned up and down (it arrange | positions in the axial direction of the axial direction reinforcing bar 5) which comprises the 1st reinforcement means 10, it is located in the uppermost stage. The steel material 17 is arrange | positioned at the upper end part of the axial direction reinforcing bar 5a fixed in the middle, and the remaining two steel materials 17 are arrange | positioned downward from the steel material 17 located in the uppermost stage at fixed intervals.

4 and 6, a part of the spiral steel material 15 is broken to show the steel material 17 on the drawing, but the spiral steel material 15 is actually formed continuously up and down.
Further, in the present embodiment, the steel members 17 and 17 are provided so as to surround the outside of each set of six or eight axial reinforcing bars 5 with six or eight axial reinforcing bars 5 as one set. However, the number of the axial reinforcing bars 5 surrounded by the steel materials 17 and 17 may be set arbitrarily. Moreover, you may provide so that the outer side of the axial direction reinforcement 5 arrange | positioned so that the edge of the horizontal cross section of the pillar main body 3 may be enclosed like the said shear reinforcement. In this case, the steel materials 17 and 17 should just be arrange | positioned between the shear reinforcement bars adjacent up and down.

With such a structure of the stepped part of the pedestal, the same effect as in the case of the first embodiment can be obtained.
Moreover, since the steel material 17 which comprises the 1st reinforcement means 10 is formed in the U-shape, material cost can be reduced compared with the rectangular ring-shaped steel material 12 of 1st Embodiment, Since the steel material 17 can be assembled to the axial rebar 5 from the outer surface 3a side of the column base 1, it is easier to assemble than the steel material 12.

(Third embodiment)
7 to 9 show a third embodiment. FIG. 7 is a front sectional view of a pedestal, FIG. 8 is a side sectional view of the pedestal, and FIG. 9 is a plan sectional view of a pedestal. It is.
Since the third embodiment shown in these drawings differs from the second embodiment in the configuration of the first reinforcing means 10, the configuration of the first reinforcing means 10 will be described below. The same components as those in the third embodiment are denoted by the same reference numerals, and description thereof is simplified or omitted.

In 3rd Embodiment, the 1st reinforcement means 10 is the axial direction of the axial reinforcement 5 in the two steel materials 17 provided so that the outer side of the axial reinforcement 5 might be enclosed similarly to 2nd Embodiment. As shown in FIG. 9, the first reinforcing means 10 having such a configuration is provided with three at predetermined intervals. Is provided.
Further, in the flat section of the section 6, the two steel members 17, 17 facing in the short side direction of the flat section rectangle have six or eight axial reinforcing bars 5 as one set, and each set of axial directions. It is provided so as to surround the outside of the reinforcing bar 5. A predetermined gap is provided between the tip portions of the opposing steel materials 17 and 17.
And in 3rd Embodiment, the said steel material 17 is provided so that covering concrete may be restrained from the outside.

  That is, the U-shaped steel material 17 is provided in parallel at a predetermined interval in the long side direction of the flat cross section rectangle in the flat cross section of the stepped portion 6, and is opposed to the short side direction. Although a total of ten steel members 17 are provided, the intermediate steel members 17 a of the steel members 17 are arranged on the long sides along the long sides of the flat section of the section 6. The space between the intermediate steel material 17a and the axial rebar 5 is covered concrete. Further, end steel members 17b, 17b formed at right angles to both ends of the intermediate steel material 17a of the steel material 17 are arranged toward the inside of the flat section of the stepped portion 6 and The axial rebar 5 located at the outer corner is in contact from the outside. That is, the end steel members 17b and 17b of the steel member 17 are divided into four in the case of connecting the axial rebars 5 of 6 or 8 in a rectangular ring shape with a virtual line in the plane cross section of the stepped portion 6. The axial rebar 5 located at the corner is in contact with the outside.

7 and 8, a part of the spiral steel material 15 is broken in order to show the steel material 17 on the drawing, but the spiral steel material 15 is actually formed continuously up and down.
Further, in the present embodiment, the steel members 17 and 17 are provided so as to surround the outside of each set of six or eight axial reinforcing bars 5 with six or eight axial reinforcing bars 5 as one set. However, the number of the axial reinforcing bars 5 surrounded by the steel materials 17 and 17 may be set arbitrarily.

In such a structure of the stepped portion of the pedestal, the same effect as in the case of the second embodiment can be obtained.
Further, since the steel material 17 is provided at the marking portion 6 so as to constrain the covering concrete from the outside, the axial rebar 5 pushes the covering concrete outward, or the axial rebar fixed in the middle. 5a can not follow the bending of the pedestal 1 but can counteract the force that the tip of the axial rebar 5 protrudes from the pedestal by the steel material 17 through the covered concrete. Stripping can be prevented.

(Fourth embodiment)
10 to 13 show a fourth embodiment. FIG. 10 is a front sectional view of a pedestal, FIG. 11 is a side sectional view of the pedestal, and FIG. FIG. 13 is a front view of the pedestal.
Since the fourth embodiment shown in these drawings is different from the first embodiment in the configuration of the first reinforcing means, the configuration of the first reinforcing means will be described below. The same reference numerals are given to the same components as those in the embodiment, and the description thereof will be simplified or omitted.

The first reinforcing means 20 according to the present embodiment includes a pair of reinforcing plates 21 and 21 that are in contact with the opposing outer surfaces 3a and 3a of the stepped portion 6 and the pedestal 1 in the vicinity thereof, and these reinforcing plates 21. , 21 are fixed to the outer side surfaces 3a, 3a.
As shown in FIG. 13, the reinforcing plate 21 is formed of a strip-shaped iron plate, and has a length equal to the width of the pedestal main body 3 of the pedestal 1 (the left-right width in FIG. 13). Yes.

The reinforcing plate 21 extends in the arrangement direction of the axial rebars 5 (5a, 5b) (left and right in FIG. 13) along the position of the fixing portion in the middle of the axial rebar 5a in the stepped portion 6. The outer surface 3a is in contact with the outer surface 3a.
The vertical width of the reinforcing plate 21 is set to 5 to 25 times the diameter of the axial rebar 5, and the upper end of the reinforcing plate 21 is the same height as the intermediate fixing portion at the upper end of the axial rebar 15 a. positioned.

The reinforcing plates 21 and 21 are fixed to the outer surfaces 3 a and 3 a of the pedestal main body 3 by fixing means 22.
That is, first, the fixing means 22 is provided with five PC steel bars 23 provided through the pedestal main body 3 in the thickness direction thereof. Both end portions of each PC steel rod 23 penetrate through the bearing plate 24 and are screwed into the nut 25. Note that male screws are formed at both ends of the PC steel rod 23, and these male screws are screwed into the nut 25. Thus, the fixing means 22 is constituted by the PC steel rod 23, the bearing plates 24 and 24, and the nuts 25 and 25.

  Then, as shown in FIG. 12, five PC steel bars 23 are arranged at predetermined intervals on the left and right in the horizontal section of the section 6, and each is inserted through a hole formed in the section 6. A state in which the reinforcing plates 21 and 21 are pressed against the outer side surfaces 3a and 3a of the columnar body 3 through the bearing plates 24 and 24 by tightening the nuts 25 and 25 that are screwed to the ends of the steel rod 23. It is fixed with. And, by tightening the nuts 25, 25 at both ends, a tensile stress is generated in the PC steel bar 23. As a result, the reinforcing plates 21, 21 on both sides give compressive force to the outer surfaces 3a, 3a, respectively. ing.

In this way, the reinforcing plates 21 and 21 apply a compressive force to the outer surface 3 a, so that the concrete around the axial rebar 5 is pressed against the axial rebar 5. And even when the pedestal main body 3 is bent, this pressing force is applied to the force that the axial rebar 5 covers and pushes the concrete outward in the stepped portion 6, or the axial rebar 5a fixed in the middle. In addition, it is possible to suppress the occurrence of cracks in the concrete around the axial rebar 5a because it can resist the force that the tip of the axial rebar 5 protrudes from the pedestal without being able to follow the deflection of the pedestal 1. As a result, loss of adhesion between the axial rebar 5a and the concrete can be effectively suppressed.
In addition, it is possible to suppress the covering concrete from being peeled off from the pedestal main body 3 by the compressive force of the reinforcing plates 21 and 21.
Similarly to the first embodiment, even if damage (cracking, peeling of concrete, buckling of the axial rebar 5) or the like occurs in the paragraph portion 6, the second reinforcing means for restraining the concrete inside. Since the inner steel concrete can be constrained by the spiral steel material 15 constituting 11, it is possible to ensure the deformation performance at the marking section 6 and the pedestal 1 can follow a large deformation. The
In addition, since the deformation performance at the marking portion 6 can be secured, the pedestal 1 can be designed to cause damage at the marking portion 6 instead of the pedestal base in the event of a large earthquake, and the subsequent pedestal 1 damage can be done and restoration work can be done easily.
In FIG. 11, in order to show the PC steel bar 23 on the drawing, a part of the spiral steel material 15 is broken, but the spiral steel material 15 is actually formed continuously up and down.

(Fifth embodiment)
14 to 16 show a fourth embodiment. FIG. 14 is a front sectional view of a pedestal, FIG. 15 is a side sectional view of the pedestal, and FIG. It is.
The fifth embodiment shown in these drawings is different from the fourth embodiment in that the reinforcing plates 21 and 21 of the first reinforcing means 20 are fixed to the outer side surfaces 3a and 3a of the pedestal main body 3. Since the configuration of the fixing means 22 is described below, the configuration of the fixing means 22 will be described below, and the same components as those in the fourth embodiment are denoted by the same reference numerals, and the description thereof will be simplified or omitted.

As shown in FIG. 15, the fixing means 22 includes an anchor member 26 inserted and fixed to the pedestal main body 3. This anchor member 26 penetrates the covered concrete and is inserted to a position deeper than the axial rebar 5 and is fixed to the concrete with mortar.
As shown in FIGS. 16 and 13, the anchor member 26 is inserted into holes formed in the stepped portion 6 from each of the outer side surfaces 3 a and 3 a at five predetermined intervals on the left and right in the horizontal section of the stepped portion 6. Then, by tightening the nut 25 screwed into the end of each anchor member 26, the reinforcing plate 21 is fixed in a state of being pressed against the outer side surfaces 3a, 3a of the pedestal main body 3 via the bearing plate 24. ing. Then, a tensile stress is generated in the anchor member 26 by tightening the nut 25, and as a result, the reinforcing plates 21 and 21 on both sides apply a compressive force to the outer surfaces 3a and 3a, respectively.

With such a structure of the stepped portion of the pedestal, the same effect as in the case of the fourth embodiment can be obtained.
In FIG. 15, in order to show the anchor member 26 on the drawing, a part of the spiral steel material 15 is broken, but the spiral steel material 15 is actually formed continuously up and down.

In the first to fifth embodiments, the second reinforcing means 11 for constraining the concrete inside the axial rebar 5 is constituted by the spiral steel material 15, but instead of the spiral steel material 15, FIG. As shown in FIG. 17, a plurality of circular ring-shaped steel members 27 provided at predetermined intervals in the axial direction inside the axial rebar 5 may be used. In FIG. 17, in order to show the steel material 12 constituting the first reinforcing means 10, a part of the ring-shaped steel material 27 is omitted, but in reality, the ring-shaped steel material 27 is also axially disposed in the omitted portion. The reinforcing bars 5 are arranged at predetermined intervals in the axial direction.
Further, in place of the ring-shaped steel material 27, as shown in FIG. 18, a plurality of steel materials 28 formed in an arc shape (two in FIG. 18, but the number is arbitrary) are arranged in a ring shape. It is good also as what you did. Bending portions 27a and 27a are formed at both ends of the steel material 28, and the fixing property to the concrete is enhanced.
A plurality of the steel materials 28 are arranged in a ring shape inside the axial rebar 5 at the stage 6, and a plurality of the steel materials 28 are provided at predetermined intervals in the axial direction of the axial rebar 5.

(Sixth embodiment)
19 to 21 show a fourth embodiment. FIG. 19 is a front sectional view of a pedestal, FIG. 20 is a side sectional view of the pedestal, and FIG. 21 is a plan sectional view of a pedestal. It is.
The sixth embodiment shown in these drawings differs from the second embodiment shown in FIGS. 4 to 6 mainly in the configuration of the axial rebar 5b, and hereinafter, this axial rebar 5b will be described. The same components as those in the second embodiment are denoted by the same reference numerals, and the description thereof is simplified or omitted.

In the sixth embodiment, the axial reinforcing bar 5b includes a first axial reinforcing bar 30a, a second axial reinforcing bar 30b, and a connecting axial reinforcing bar 30c.
The first axial reinforcing bar 30 a is a reinforcing bar that extends from the lower end of the pedestal 1 to the section 6. The second axial reinforcing bar 30 b is a reinforcing bar that is arranged coaxially with the first axial reinforcing bar 30 a with an interval upward from the upper end of the first axial reinforcing bar 30 a and extends to the upper end of the pedestal 1.
The connecting axial rebar 30c is disposed inside the first axial rebar 30a and the second axial rebar 30b, the lower end is disposed at the same position as the upper end of the first axial rebar 30a, and the upper end is the same. It is a reinforcing bar arranged at the same position in the vertical direction as the lower end of the second axial reinforcing bar 30b.
The lower end of the connecting axial rebar 30c overlaps the upper end of the first axial rebar 30a in the thickness direction of the pedestal, and the upper end of the lower end of the second axial rebar 30b and the pedestal. It overlaps in the thickness direction. And the U-shaped steel material 17 which comprises the 1st reinforcement means 10 is provided in this overlapped part, Thereby, the 1st axial direction reinforcing bar 30a, the 2nd axial direction reinforcing bar 30b, and the connecting axial direction reinforcing bar 30c are provided. It is integrated.

The steel members 17 are arranged at the upper end of the first axial rebar 30a and the lower end of the second axial rebar 30b, respectively, and the upper end of the first axial rebar 30a and the lower end of the second axial rebar 30b. It is not arranged between.
A spiral steel material 15 constituting the second reinforcing means 11 is provided inside the axial reinforcing bar 5 between the upper end of the first axial reinforcing bar 30 a and the lower end of the second axial reinforcing bar 30 b.

According to the present embodiment, the same effects as those of the second embodiment can be obtained, and the upper end of the first axial rebar 30a and the second axial rebar are not the base of the pedestal in the event of a large earthquake or the like. It is possible to design the pedestal 1 so as to actively generate damage between the lower ends of the 30b, and to obtain an effect that the subsequent inspection or confirmation of the presence or absence of damage to the pedestal 1 and the restoration work can be easily performed. .
In addition, the spiral steel material 15 between the upper end of the first axial rebar 30a and the lower end of the second axial rebar 30b can be constrained so as not to escape the inner concrete, so that the deformation performance at this portion can be ensured. The pedestal 1 can follow a large deformation.

In the present embodiment, as shown in FIG. 22, a rectangular groove-shaped cutout portion 32 may be formed on the side surface of the pedestal 1, and a part of the pedestal 1 may be broken in cross section. The notches 32 are formed on opposite side surfaces of the pillar 1 between the upper end of the first axial rebar 30a and the lower end of the second axial rebar 30b.
In this way, by making the cross section of the pedestal 1 by the notch 32, in the event of a large earthquake or the like, not the pedestal base but the upper end of the first axial rebar 30a and the lower end of the second axial rebar 30b. In the meantime, damage can surely occur.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front sectional view of a pedestal, showing a first embodiment of a structure of a stepped portion of the pedestal according to the present invention. It is a side sectional view of a pedestal. It is a plane sectional view in the paragraph part of a pedestal same as the above. The 2nd Embodiment of the structure of the step part of the pedestal concerning this invention is shown, and is a front sectional view of a pedestal. It is a side sectional view of a pedestal. It is a plane sectional view in the paragraph part of a pedestal same as the above. The 3rd Embodiment of the structure of the step part of the pedestal column concerning this invention is shown, and is a front sectional view of a pedestal column. It is a side sectional view of a pedestal. It is a plane sectional view in the paragraph part of a pedestal same as the above. FIG. 9 is a front sectional view of a pedestal, showing a fourth embodiment of a structure of a stepped portion of the pedestal according to the present invention. It is a side sectional view of a pedestal. It is a plane sectional view in the paragraph part of a pedestal same as the above. It is a front view of a pedestal. FIG. 9 is a front sectional view of a pedestal, showing a fifth embodiment of a structure of a stepped portion of the pedestal according to the present invention. It is a side sectional view of a pedestal. It is a plane sectional view in the paragraph part of a pedestal same as the above. It is a sectional side view of the pedestal which shows the modification of the 2nd reinforcement means in the structure of the step part of the pedestal which concerns on this invention. It is a top view which shows the state which has arrange | positioned steel materials in the ring shape in the modification of the 2nd reinforcement means in the structure of the step part of the pedestal column concerning this invention. FIG. 9 is a front sectional view of a pedestal, showing a sixth embodiment of a structure of a stepped portion of the pedestal according to the present invention. It is a side sectional view of a pedestal. It is a plane sectional view in the paragraph part of a pedestal same as the above. It is the same sectional side view of the pedestal which formed the notch part in the pedestal side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Leg pillar 3 Leg pillar main body 5,5a, 5b Axial reinforcement 6 Paragraph 10,20 1st reinforcement means 11 2nd reinforcement means 12 Ring-shaped steel material 15 Spiral steel material 17 Steel material 21 Reinforcement plate 22 Fixing means 23 PC steel Rod 26 Anchor member 27 Ring-shaped steel 28 Steel 30a First axial rebar 30b Second axial rebar 30c Connecting axial rebar 32 Notch

Claims (9)

In the structure of the pierced part of the reinforced concrete pedestal having the pierced part in which the axial reinforcing bar extending in the axial direction of the pedestal is divided,
A first reinforcing means that reinforces the axial rebar from the outside thereof is provided at the stepped portion and the vicinity thereof, and a second reinforcing means that constrains the concrete inside is provided inside the axial rebar. The structure of the paragraph part of the pedestal characterized by being.   The first reinforcing means has a configuration in which a plurality of ring-shaped steel materials provided so as to surround the outside of the axial rebar are provided at predetermined intervals in the axial direction of the axial rebar. The structure of the step part of the pedestal according to claim 1.   The first reinforcing means has a configuration in which a plurality of steel materials provided so as to surround the outside of the axial rebar are provided at a predetermined interval in the axial direction of the axial rebar. 1. The structure of the paragraph part of the pedestal according to 1.   The said steel material is provided so that covering concrete may be restrained from the outside, The structure of the step part of the pedestal according to claim 3 characterized by the above-mentioned. The axial rebar is arranged coaxially with the first axial rebar with a first axial rebar extending from the lower end of the pedestal to the stepped portion, and spaced upward from the first axial rebar. A second axial rebar extending to the upper end of the pedestal, and the inner side of the first axial rebar and the second axial rebar, the lower end being the same as the upper end of the first axial rebar. It is arranged at a position, and the upper end portion is composed of a lower end portion of the second axial rebar and a connecting axial rebar disposed at the same vertical position,
5. The pedestal column according to claim 3, wherein the first reinforcing means is disposed at an upper end portion of the first axial rebar and a lower end portion of the second axial rebar. 6. Part structure.   The first reinforcing means includes a pair of reinforcing plates that are in contact with the opposing outer surfaces of the stepped portion and the pedestal in the vicinity thereof, and a fixing means that fixes the reinforcing plates to the outer surface. 2. The structure of the step part of the pedestal according to claim 1, wherein   The said 2nd reinforcement means is comprised with the said step part and the spiral steel material provided in the inside of the said axial rebar in the vicinity. The structure of the pedestal paragraph.   The second reinforcing means is composed of a plurality of ring-shaped steel materials provided at predetermined intervals in the axial direction on the inner side of the axial reinforcing bar in the stepped portion and the vicinity thereof. The structure of the step part of the pedestal as described in any one of 6.   The second reinforcing means has a configuration in which a plurality of steel materials arranged in a ring shape are provided at predetermined intervals in the axial direction of the axial rebar inside the axial rebar in the vicinity of the stepped portion and the vicinity thereof. It has become, The structure of the step part of the pedestal as described in any one of Claims 1-6 characterized by the above-mentioned.

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