JP4711850B2 - Structure of the pedestal - Google Patents

Description

  The present invention relates to the structure of a reinforced concrete pedestal.

Conventionally, the bridge pier of the following patent document 1 is known as a technique of such a field. In such a pedestal, the bending moment acting on the pedestal main body due to the horizontal force at the time of the earthquake becomes smaller as it goes up, so the upper reinforcing bars of the pedestal main body can be made smaller than the lower reinforcing bars. . Therefore, such a pedestal 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 reinforcing bars in consideration of economy. Is common.
JP-A-9-209580

  However, in such a pedestal, the strength at the stepped portion tends to be weak, and therefore the seismic strength of the pedestal tends to be weakened due to the stepped portion. Therefore, in this type of pedestal having a paragraph portion, improvement of seismic strength is a problem.

  Then, an object of this invention is to provide the structure of the pedestal which can improve seismic strength in the pedestal provided with a paragraph part.

  The inventors of the present invention have completed the present invention by paying attention to the following phenomenon that occurs in the stepped part of the pedestal during an earthquake. That is, in the event of an earthquake, the pedestal main body is bent by a load acting on the pedestal, and as a result, the reinforcing bars fixed in the middle of the stepped portion are pulled in the axial direction inside the pedestal main body. In the paragraphing section, the pulled reinforcing bars generate a force that pushes the cover concrete of the pedestal body outward. In addition, the reinforcing bar that has been fixed in the middle cannot follow the bending of the pedestal body, and a force is generated so that the tip of the reinforcing bar protrudes from the pedestal body. And when such a force works, cracks occur in the concrete around the reinforcing bars, and the adhesion between the reinforcing bars and the concrete at the stepped portion is lost, and as a result, the damage to the pedestal main body is more likely to proceed. The phenomenon that occurs.

On the other hand, the structure of the pedestal according to the present invention is the structure of a reinforced concrete pedestal having a stepped portion in which a reinforcing bar extending in the axial direction of the pedestal main body is divided. The reinforcing member extending in the reinforcing bar arrangement direction is fixed along the position of the fixing portion of the reinforcing bar in the stepped portion, and the width of the reinforcing member measured in the extending direction of the reinforcing bar is It is characterized by being 5 to 25 times the diameter .

  In this pedestal structure, the reinforcing member fixed to the outer surface of the pedestal body resists the force that the rebar pushes the cover concrete outward and the above-mentioned force that protrudes by pressing the outer surface. Can do. Accordingly, cracks in the concrete around the reinforcing bars are suppressed, and loss of adhesion between the reinforcing bars and the concrete can be suppressed. As a result, the seismic strength of the pedestal can be improved.

  Further, in the structure of the pedestal according to the present invention, the pedestal main body has a cross-sectional shape formed by the long side and the short side, and the reinforcing member is fixed to the outer surface corresponding to the long side in the cross-sectional shape. It may be. In the pedestal main body having a cross-sectional shape as described above, the bending in the direction orthogonal to the long side is the largest, and thus the above phenomenon occurs most on the outer surface corresponding to the long side due to such bending. easy. Therefore, in this pedestal main body, the outer surface corresponding to the long side is pressed by the reinforcing member, so that the loss of adhesion between the reinforcing bars and the concrete on the outer surface is suppressed. Can be improved.

  Further, the reinforcing member may be fixed by an anchor member inserted to a position deeper than the position of the reinforcing bar of the pedestal main body. According to such a configuration, the reinforcing member can be pressed against the outer surface by applying a tensile stress to the anchor member. Therefore, the concrete around the reinforcing bars can be pressed against the reinforcing bars by the reinforcing member, and as a result, loss of adhesion between the reinforcing bars and the concrete can be effectively suppressed.

In this case, the reinforcing members are provided as a pair on the outer surfaces facing each other, and the reinforcing members may be connected by a penetrating member that penetrates the pedestal main body. According to such a configuration, since the tensile stress of the connecting member can be applied to the reinforcing members on the outer side surfaces facing each other, the reinforcing members can be effectively pressed against both outer side surfaces. .
Further, the reinforcing member extends horizontally, and the upper end of the reinforcing member may be located at the same height as the upper end of the reinforcing bar fixed in the middle of the section.
Further, the pedestal is an existing pedestal, the reinforcing member is a member that is attached to the outer surface of the existing pedestal and reinforces the existing pedestal, and the reinforcing member has a pressing surface that presses the outer surface. The pressing surface may be a flat surface that extends continuously along the outer surface over the entire outer surface.
In addition, the pedestal is an existing pedestal, the reinforcing member is a member that is attached to the outer surface of the existing pedestal and reinforces the existing pedestal, and the reinforcing member extends horizontally, Of the outer surface of the pedestal, a portion above the reinforcing member and a portion below the reinforcing member may be exposed.

Further, the structure of the pedestal according to the present invention is a reinforced concrete pedestal structure having a stepped portion in which a reinforcing bar extending in the axial direction of the pedestal main body is divided. A reinforcing member extending in the reinforcing bar arrangement direction is fixed along the position of the fixing part in the middle of the reinforcing bar in the stepped portion, and further provided with a biasing means for biasing the reinforcing member to press against the outer surface. It is characterized by that. The reinforcing member can be effectively pressed against the outer surface by the biasing force of the biasing means.

Moreover, in the structure of the pedestal according to the present invention, in the structure of the reinforced concrete pedestal having a stepped portion in which the reinforcing bars extending in the axial direction of the pedestal main body are divided, The reinforcing member extending in the reinforcing bar arrangement direction is fixed along the position of the fixing part in the middle of the reinforcing bar in the section, and the reinforcing member is curved so that the center in the extending direction is directed to the pedestal main body side. It is pressed against the outer surface from the state and is in close contact with the outer surface. According to such a configuration, the pressing force is effectively applied even at the center of the reinforcing member by the elastic force of the reinforcing member itself, and an equal pressing force can be applied to the outer surface.

  According to the structure of the pedestal of the present invention, the seismic strength can be improved in the pedestal having a paragraphed portion.

  Hereinafter, preferred embodiments of a structure of a pedestal according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
As shown in FIGS. 1 and 2, the bridge 100 includes a plurality of reinforced concrete piers (leg columns) 1 and a bridge girder 3 that is supported by the piers 1 and extends in the horizontal direction. The pier 1 includes a footing 7 fixed to the ground 5 and a pier body (pedestal body) 9 extending vertically upward from the footing 7. Further, the pier 1 includes a support portion 11 that is provided above the pier body 9 and supports the bridge girder 3.

  In consideration of the load from the bridge girder 3, the bridge pier body 9 is formed so that the width in the direction perpendicular to the extending direction of the bridge girder 3 is wider than the width of the bridge girder 3 in the extending direction. That is, the pier main body 9 has a shape having a rectangular horizontal cross section, and has two pairs of outer side surfaces 9a and 9b forming a vertical plane. The pair of outer surfaces 9a correspond to the long sides of the rectangle of the horizontal cross section, and have a wider horizontal width than the pair of outer surfaces 9b corresponding to the short sides of the rectangle.

  As shown in FIGS. 3 to 5, in the pier main body 9, a plurality of reinforcing bars 15 extending in the vertical direction are arranged in the horizontal direction and embedded in the concrete portion 13. In the middle of the pier main body 9, there is a stepped portion 17, and about half of the reinforcing bars 15, about half of the reinforcing bars 15 a are fixed at the upper end at the stepped portion 17. The remaining approximately half of the reinforcing bars 15b extend further upward to the support portion 11. The reinforcing bars 15 are provided with node portions 15c at equal intervals in order to reliably adhere to the concrete portion 13.

  When the bridge pier body 9 bends due to a load from the bridge girder 3 at the time of the earthquake in such a section 17, the reinforcing bar 15 a fixed in the middle of the section 17 is pulled with a downward force F <b> 1. And in the paragraph part 17, the node part 15c of the reinforcing bar 15a stretched downward generates a force that pushes and spreads the surrounding concrete, and thereby the force F2 that pushes the cover concrete 13a of the pier body 9 outward. Occurs. Further, as shown in FIG. 6, the reinforcing bar 15a cannot follow the bending of the pier body 9, and a force F3 is generated in the vicinity of the fixing portion 15d in the middle so that the reinforcing bar 15a protrudes outward from the pier body 9. Then, when the forces F2 and F3 as described above are applied, cracks occur in the concrete around the reinforcing bars 15a, and adhesion between the reinforcing bars 15a and the concrete part 13 at the stage 17 is lost. At this time, the cover concrete 13a may be peeled off from the pier body 9. As a result, a phenomenon occurs in which the breakage of the pier body 9 is further facilitated.

  Moreover, according to the cross-sectional shape of the pier main body 9 in the pier 1, since the pier main body 9 has a large bending | flexion to the extending direction of the bridge girder 3, especially the above-mentioned reinforcing bar 15a and concrete part 13 in the outer surface 9a, The phenomenon of loss of adhesion is likely to occur. Therefore, in order to improve the seismic strength of the pier 1 as a whole, it is particularly effective to reinforce the outer surface 9a in order to suppress the above phenomenon on the outer surface 9a.

  Therefore, as shown in FIGS. 2 to 4 and 7, the outer surfaces 9 a and 9 a on both sides of the pier body 9 are horizontally extended to a position corresponding to the intermediate fixing portion 15 d of the reinforcing bar 15 a in the marking portion 17. Existing reinforcing plates (reinforcing members) 21 are respectively attached. This reinforcing plate 21 is a U-shaped steel material having the same length as the horizontal width of the outer surface 9a, and has a pressing surface 21a that forms a flat surface. The vertical width of the reinforcing plate 21 is set to 5 to 25 times the diameter of the reinforcing bar 15a, and the upper end of the reinforcing plate 21 is positioned at the same height as the midway fixing portion d at the upper end of the reinforcing bar 15a. is doing. The reinforcing plate 21 is attached to the outer surface 9a by three anchor members 25 and nuts 29 so that the pressing surface 21a is in close contact with the outer surface 9a via the rubber plate 23.

  The anchor member 25 passes through the cover concrete 13a and is inserted to a position deeper than the reinforcing bar 15a, and is fixed to the concrete portion 13 by a mortar 26. As a result of the tightening of the nut 29, a tensile stress is generated in the anchor member 25. As a result, the pressing surface 21a of the reinforcing plate 21 is pressed against the outer surface 9a to apply the compressive force F4. As the anchor member 25, a rod rope such as a PC rope having a thread groove and a screw rebar can be employed.

  Since the reinforcing plate 21 has a U-shaped cross section, the bending of the reinforcing plate 21 itself due to the tightening of the nut 29 is very small, and the reinforcing plate 21 applies an equal compressive force F4 to the outer surface 9a. can do. Further, since the bearing plate 27 is sandwiched between the nut 29 and the reinforcing plate 21, the tightening force of the nut 29 is efficiently transmitted to the reinforcing plate 21, and further, between the pressing surface 21a and the outer surface 9a. Since the rubber plate 23 is sandwiched between them, an equal compressive force F4 is applied to the outer surface 9a.

  Thus, since the reinforcement board 21 provides the compressive force F4 to the outer surface 9a, the concrete around the reinforcing bar 15a is pressed against the reinforcing bar 15a. And even when the pier body 9 bends, this pressing force opposes the above-mentioned forces F2 and F3, so that the occurrence of cracks in the concrete around the reinforcing bar 15a can be suppressed. Loss of adhesion with the concrete portion 13 can be effectively suppressed. Further, it is possible to prevent the covering concrete 13a from being separated from the pier body 9 by the compressive force F4 by the reinforcing plate 21. Therefore, according to the structure of the pier 1 described above, the seismic strength of the pier body 9 can be improved by reinforcing the stepped portion 17, and as a result, the seismic strength of the pier 1 as a whole can be improved. it can. Moreover, in such a reinforcement structure of the pier 1, the amount of reinforcing bars and the amount of concrete can be saved as compared with a general reinforcement structure that increases the cross-sectional dimension of the pier body 9.

  In the pier 1, the reinforcing plate 21 applies a compressive force to the outer surface 9 a in advance by the tightening force of the nut 29, but the nut 29 may be tightened only to the extent that the reinforcing plate 21 can be fixed. Even if it does in this way, when bending of the pier main body 9 generate | occur | produces, since the said force F2, F3 can be suppressed with the reinforcement board 21, the loss of adhesion with the reinforcing bar 15a and the concrete part 13 is suppressed. Is possible.

(Second Embodiment)
With reference to FIG. 8, the pier 51 which concerns on 2nd Embodiment of this invention is demonstrated. In the stepped portion 53 of the pier 51, instead of the anchor member 25 in the pier 1, three penetration steel members (penetrating members) 55 that penetrate the pier main body from the outer surface 9a to the other outer surface 9a are provided. Yes. As the penetrating steel material 55, a bar rope such as a PC rope having a thread groove and a screw rebar can be employed. The three penetrating steel members 55 are respectively inserted into three penetrating holes penetrating the pier main body 9, and nuts 29 are attached to both ends of each penetrating steel member 55.

  The pair of reinforcing plates 21 attached to both sides of the pier body 9 are fixed to the opposite outer surfaces 9a and 9a at three locations by the through steel members 55 and the nuts 29, respectively. And the tension | tensile_strength has arisen in the penetration steel material 55 by clamping | tightening the nut 29 of both ends, As a result, the reinforcement board 21 of both sides has provided the compressive force with respect to the outer surface 9a, respectively. As described above, also by the bridge pier 51 having such a configuration, a compressive force can be applied to the outer side surface 9a, and the same effects as the above-described bridge pier 1 can be achieved. In addition, in this pier 51, about the structure same or equivalent to the pier 1, the same code | symbol is attached | subjected to drawing, and the description is abbreviate | omitted.

(Third embodiment)
A pier 61 according to a third embodiment of the present invention will be described with reference to FIGS. In the stepped portion 63 of the bridge pier 61, a second reinforcing plate 65 having a configuration equivalent to that of the reinforcing plate 21 is provided on the outer side along the reinforcing plate 21 of the outer side surfaces 9a on both sides. The two second reinforcing plates 65 are formed slightly longer than the horizontal width of the outer surface 9a, and both ends of the second reinforcing plate 65 extend along the outer surface 9b and a connecting steel material 67 and a nut 68. Are connected by As the connecting steel material 67, a bar rope such as a PC rope having a thread groove and a screw rebar can be adopted.

  Between the reinforcing plate 21 and the second reinforcing plate 65, three coil springs (biasing means) 69 arranged at equal intervals are sandwiched and attached so as to be stretchable, and each coil spring is tightened by tightening a nut 68. 69 is compressed. As a result, the reinforcing plates 21 on both sides are separated by the compressive force from the coil spring 69 to sandwich the portion 63, and apply compressive force to the outer surface 9a. As described above, even with the bridge pier 61 having such a configuration, a compressive force can be applied to the outer surface 9a, and the same effects as the above-described pier 1 can be achieved. Moreover, according to such a structure, since the process of forming the hole for anchor members in the pier main body 9 becomes unnecessary, workability | operativity improves.

  Further, since the tightening force of the nut 68 is applied to both ends of the second reinforcing plate, the second reinforcing plate 65 is slightly curved so that the center is separated from the outer surface 9a. However, since the compressive force from the second reinforcing plate 65 is transmitted to each part of the reinforcing plate 21 through the plurality of coil springs 69 at equal intervals, the reinforcing plate 21 has an even compressive force with respect to the outer surface 9a. Therefore, the reinforcement of the pier body 9 can be evenly performed. Since the second reinforcing plate 65 is formed in a U-shaped cross section like the reinforcing plate 21, the bending of the second reinforcing plate 65 itself due to the tightening of the nut 68 is extremely small, and the second reinforcing plate 65 is equal to the reinforcing plate 21. Can provide a good compression force. In addition, in this pier 61, about the structure same or equivalent to the pier 1, the same code | symbol is attached | subjected to drawing, and the description is abbreviate | omitted.

(Fourth embodiment)
A pier 71 according to a fourth embodiment of the present invention will be described with reference to FIG. In the paragraph 73 of the pier 71, instead of the reinforcing plate 21 in the pier 1, reinforcing plates 75 are attached to the outer side surfaces 9a on both sides. Each reinforcing plate 75 has a U-shaped cross section, and is a steel material that is curved so that the center in the extending direction is directed to the outer surface 9a. Each of these reinforcing plates 75 is elastically deformed linearly along the outer surface 9a by being pressed against the outer surface 9a from a curved state, and the pressing surface 75a of each reinforcing plate 75 is interposed via the rubber plate 23. In close contact with the outer surface 9a. And in the state which elastically deformed in this way, the mutual both ends of the reinforcement board 75 of both sides are connected by the connection steel material 77 and the nut 78 which extend along the outer surface 9b. As this connecting steel material 77, it is possible to adopt a bar rope such as a PC rope having a thread groove and a screw rebar.

  In this way, the reinforcing plates 75 on both sides that are curved in advance so as to be convex toward the outer surface 9a are pressed against the outer surface 9a so as to be elastically deformed linearly, and are connected to each other. Thus, the two reinforcing plates 75 sandwich the stepped portion 73 of the pier main body 9 and apply a compressive force to the outer side surface 9a. As described above, also by the bridge pier 71 having such a configuration, a compressive force can be applied to the outer side surface 9a, and the same effects as the above-described bridge pier 1 can be achieved.

  Further, since the tightening force of the nut 78 is applied to both ends of the reinforcing plate 75, the reinforcing plate 75 receives a force that curves so that the center is separated from the outer surface 9a. Although it is conceivable that the compression force to the outer surface 9a is not sufficient at the center of the reinforcing plate 75 due to this bending, according to the structure of the bridge pier 71, the reinforcing plate 75 is caused by the residual stress of the reinforcing plate 75 due to elastic deformation. Even in the central portion, a sufficient compressive force is applied to the outer surface 9a. Therefore, the compressive force to the outer surface 9a in the length direction of the reinforcing plate 75 is made uniform, and the pier body 9 can be evenly reinforced. In order to achieve a more uniform compression force, the rigidity and curved shape of the reinforcing plate 75 may be appropriately designed. Moreover, in this pier 71, about the structure same or equivalent to the pier 1, the same code | symbol is attached | subjected to drawing, and the description is abbreviate | omitted.

  The present invention is not limited to the embodiment described above. For example, the structure of the above-mentioned piers 1, 51, 61, 71 can be suitably applied particularly to an existing pier's seismic reinforcement structure, but may be applied to the structure of a new pier.

  Moreover, although the cross-sectional shape of the pier main body 9 in the said embodiment was a rectangle formed by a pair of long side and a short side, the number of the long side and short side of a cross-sectional shape is not limited. Further, the long side and the short side are not limited to a straight line, and both or one of them may be a curved line. Examples of such cross-sectional shapes include shapes shown in FIGS. 13 (a), (b), and (c). All of these shapes are formed by long sides A1, A2, A3 and short sides A9, and the bridge pier body 9 having such a cross-sectional shape corresponds to the long sides A1, A2, A3, respectively. It is preferable that the reinforcing member is fixed to the outer side surface.

  Moreover, you may employ | adopt combining suitably each structure of each pier 1,51,61,71 in the above-mentioned 1st-4th embodiment.

It is a figure which shows the bridge in which the structure of the pedestal concerning this invention is used. It is a perspective view which shows 1st Embodiment of the structure of the pillar based on this invention. It is sectional drawing in alignment with the III-III line in the pier of FIG. It is sectional drawing along the IV-IV line in the bridge pier of FIG.2 and FIG.3. It is the vertical sectional view which expanded the middle fixing part vicinity of the reinforcing bar. It is a figure which shows the state which the pier of FIG. 2 bent. It is sectional drawing along the VII-VII line in FIG. It is sectional drawing which shows 2nd Embodiment of the structure of the pillar based on this invention. It is sectional drawing which shows 3rd Embodiment of the structure of the pillar based on this invention. FIG. 10 is an end view taken along line XX in FIG. 9. FIG. 10 is an end view taken along line XI-XI in FIG. 9. It is sectional drawing which shows 4th Embodiment of the structure of the pillar based on this invention. (A), (b), (c) is a figure which shows the example of the cross-sectional shape of a pier main body.

Explanation of symbols

  1, 51, 61, 71: Pier (leg post), 9a, 9a ... Outer surface, 9 ... Pier main body (pillar main body), 15a ... Reinforcing bar, 15d ... Middle fixing part, 17, 53, 63, 73 ... Paragraph Shim, 21, 75 ... reinforcing plate (reinforcing member), 25 ... anchor member, 55 ... penetrating steel material (penetrating member), 69 ... coil spring (biasing means).

Claims (9)

In the structure of the pedestal made of reinforced concrete having a stepped part in which the reinforcing bars extending in the axial direction of the pedestal main body are divided,
Wherein the outer surface of the pillar body, Ri Contact the paragraph and the reinforcing member extending in the arrangement direction of the reinforcing bar along the position of the middle fixing portions of the reinforcing bars in the section is fixed,
The width of the reinforcing member measured in the extending direction of the reinforcing bar is 5 to 25 times the diameter of the reinforcing bar. The pedestal main body has a cross-sectional shape formed by a long side and a short side,
The structure of the pedestal according to claim 1, wherein the reinforcing member is fixed to an outer surface corresponding to the long side in the cross-sectional shape.   The structure of the pedestal according to claim 1 or 2, wherein the reinforcing member is fixed by an anchor member inserted to a position deeper than the position of the reinforcing bar of the pedestal main body.   The said reinforcement member is provided as a pair in the said outer surface which mutually opposes, The said reinforcement members are connected by the penetration member which penetrates the said pedestal main body, The Claims 1-3 characterized by the above-mentioned. The structure of the pedestal according to any one of the above items. The reinforcing member extends horizontally,
5. The pedestal according to claim 1, wherein an upper end of the reinforcing member is positioned at the same height as an upper end of the reinforcing bar fixed on the way at the stepped portion. Construction. The pedestal is an existing pedestal, and the reinforcing member is a member attached to an outer surface of the existing pedestal to reinforce the existing pedestal,
The reinforcing member includes a steel material having a pressing surface that presses the outer surface,
The pedestal structure according to any one of claims 1 to 5, wherein the pressing surface forms a flat surface that continuously extends along the outer surface over the entire outer surface. . The pedestal is an existing pedestal, and the reinforcing member is a member attached to an outer surface of the existing pedestal to reinforce the existing pedestal,
The reinforcing member extends horizontally,
7. The pedestal according to claim 1, wherein, of the outer side surface of the existing pedestal, a portion above the reinforcing member and a portion below the reinforcing member are exposed. Structure. In the structure of the pedestal made of reinforced concrete having a stepped part in which the reinforcing bars extending in the axial direction of the pedestal main body are divided,
A reinforcing member is fixed to the outer side surface of the pedestal main body, extending in the arrangement direction of the reinforcing bars along the position of the fixing portion of the reinforcing bars in the stepped portion,
A structure of a pedestal, further comprising urging means for urging the reinforcing member to press against the outer surface. In the structure of the pedestal made of reinforced concrete having a stepped part in which the reinforcing bars extending in the axial direction of the pedestal main body are divided,
A reinforcing member is fixed to the outer side surface of the pedestal main body, extending in the arrangement direction of the reinforcing bars along the position of the fixing portion of the reinforcing bars in the stepped portion,
A structure of a pedestal, wherein the reinforcing member is pressed against the outer surface from a curved state so that a center in an extending direction is directed toward the pedestal main body, and is in close contact with the outer surface.

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