JP2016169493A - Structure and method for reinforcing existing concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reinforcing structure for reinforcing an existing concrete structure by a concrete lining method, the reinforcing structure enabling a reinforcing bar in an axial direction to be anchored to a footing or other foundation body without interfering with existing reinforcing bars.SOLUTION: An existing concrete structure (2) having a footing or other foundation body (4) and a bridge pier or other structural body (6) extending from the foundation body is reinforced by a concrete lining method. A reinforcing bar (12) in an axial direction for reinforcement is placed on an outer surface of the bridge pier, and is anchored to the footing at a lower edge side through root lining concrete (14) and a connecting member (16), thereby enhancing bending strength. The remaining part of the reinforcing bar in the axial direction is embedded in lining concrete (20) that covers the bridge pier. The connecting member fixes the lining concrete on the footing. Since a degree of freedom of layout of the connecting member is higher than the reinforcing bar in the axial direction, an erection hole (22) for erecting the connecting member may be formed at a location that does not require cutting of an existing reinforcing bar (8c) in the footing.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a reinforcing structure and a reinforcing method for an existing concrete structure. In particular, the present invention relates to a reinforcing structure and a reinforcing method against a bending load of an abutment or an abutment.

  As a seismic reinforcement method for bridge piers, a steel plate winding method is known (for example, Patent Document 1). This construction method improves the shear strength and toughness of the pier by winding the steel plate around the existing pier, and improves the bending strength by fixing the steel plate to the footing. A continuous fiber sheet such as carbon fiber or aramid fiber may be used instead of the steel plate (for example, Patent Document 2).

  Moreover, the construction method which winds up concrete instead of a steel plate or a continuous fiber sheet is also known. 5 and 6 show a schematic longitudinal sectional view and a transverse sectional view of a bridge pier reinforced by a conventional concrete winding method. The existing bridge substructure 102 includes a footing 104 fixed on the ground and a bridge pier 106 extending from the footing 104 in a columnar shape. Seismic reinforcement for the substructure 102 is performed as follows. That is, the footing 104 and the pier 106 include the existing reinforcing bars 108 inside. A plurality of erection holes 110 are provided in the footing 104, a resin anchor is inserted into the erection hole 110, and further, the lower end side of the reinforcing axial rebar 112 is erected in the erection hole 110, The axial rebar 112 is fixed to the footing 104. After that, the strip reinforcing bar 114 is disposed, and the wound concrete 116 is placed on the outer periphery of the bridge pier 106 so as to embed the axial reinforcing bar 112 and the band reinforcing bar 114.

JP-A-9-158127 Japanese Patent No. 2994365

  In many cases, the concrete winding method has an advantage that the cost can be reduced as compared with the winding method of a steel plate or a continuous fiber sheet. In the reinforcement of the base of the pier by the concrete winding method, if a large residual displacement occurs in the pier with toughness reinforcement alone, the bending strength can be improved by fixing the axial rebar to the footing. However, in the conventional concrete winding method, since the axial rebar is directly inserted and fixed in the erection hole provided in the footing, the positional relationship between the footing and the existing reinforcing bar has been a problem. When the newly installed axial rebar for reinforcement is placed at a position where it interferes with the existing reinforcing bar of the footing, or when the position of the existing reinforcing bar deviates from the design position, the footing will occur when the existing reinforcing bar is cut. There was a risk that the yield strength of the steel would decrease. On the other hand, if the position of the interfering axial reinforcing bar is shifted, or if the interfering axial reinforcing bar is not fixed in the footing without being put into the erection hole provided in the footing, there is a possibility that a sufficient reinforcing effect cannot be obtained. .

  In view of such a problem, the present invention provides a reinforcing structure for an existing concrete structure capable of fixing an axial reinforcing bar for reinforcement to a base such as a footing without causing a problem of a positional relationship with the existing reinforcing bar. With the goal.

  One aspect of the present invention is a reinforcing structure of an existing concrete structure (2) including a base body (4) and a structure main body (6, 32, 52) extending from the base body. An axial rebar (12, 38, 58) extending in the extending direction and disposed along the outer surface of the structure body, and a plurality of erection holes (22) provided in the base body. A connecting member (16, 40, 60) having an extending portion (16a) attached and extending from the erection hole, and including the extending portion of the connecting member, and the structure A root wound concrete (14, 34, 54) placed over an outer surface of a portion of the main body adjacent to the base body and a surface of the base body adjacent thereto, the axial rebar embedded therein, and the root wound concrete; The outer surface of the structure body so as to be integrated And a pouring has been wound fresh concrete (20,35,55), one end of the axial reinforcing bar, characterized in that embedded in the neck wrapping concrete.

  According to this configuration, the axial rebar can be fixed to the base body through the root-wrapped concrete and the coupling member without being built directly into the hole provided in the base body, and the bending strength of the structure body can be improved. . The connecting member fixes the root-wrapped concrete to the base, but since the degree of freedom of arrangement is higher than that of the axial reinforcing bar, the erection hole for installing the connecting member is the existing reinforcing bar included in the base. It can be provided at a position where it does not need to be cut, and the strength of the existing part of the concrete structure is maintained.

  Another aspect of the present invention is characterized in that, in the above configuration, the coupling member is made of a PC tendon.

  According to this configuration, the root-wrapped concrete can be firmly fixed to the base body by pressing the root-wrapped concrete against the base body by prestress. Since one end of the axial rebar is embedded in the root-wrapped concrete, the axial rebar is firmly fixed to the base via the root-wrap concrete and the connecting member, and the bending strength can be improved.

  According to another aspect of the present invention, in the above configuration, a laterally tightened PC tension member (18, 42, 62) disposed in the root wound concrete and provided with a tension force for pressing the root wound concrete against the structure body. Is further provided.

  According to this configuration, since prestress is applied to the root-wrapped concrete by the laterally tightened PC tendon, the bending strength and shear strength of the root-wrapped concrete can be improved. Therefore, it is suitable when the root-wrapped concrete can be made small, and there are restrictions such as minimum soil covering and river inhibition rate.

  Another aspect of the present invention is characterized in that, in the above configuration, the base body is a footing, and the structure main body is a bridge pier.

  According to this structure, the reinforcement of the bridge substructure that receives a large load from the superstructure can be performed at low cost.

  One aspect of the present invention is a method for reinforcing an existing concrete structure (2) including a base body (4) and a structure main body (6, 32, 52) extending from the base body. And providing a plurality of mounting holes (22), and connecting members (16, 40, 60) including extending portions (16a) extending from the base body in the mounting holes. Disposing an axial rebar (12, 38, 58) along an outer surface of the structure body so as to extend in an extending direction of the structure body; and extending the coupling member. Placing a wound concrete (14, 34, 54) over the outer surface of the portion adjacent to the base of the structure body and the surface of the base adjacent thereto so as to include the protruding portion; Embedded axial rebar and the root Placing the rolled concrete (20, 35, 55) on the outer surface of the structure body so as to be integrated with the concrete, and in the step of arranging the axial rebar, One end side is arranged so as to be embedded in the root-wrapped concrete.

  Another aspect of the present invention is characterized in that, in the above configuration, the coupling member is made of a PC tendon material, and further includes a step of applying a tension force after the root-wrapped concrete is placed.

  In addition, according to another aspect of the present invention, in the above-described configuration, a step of placing a laterally tightened PC tendon (18, 42, 62) at a position where the root wound concrete is placed; And a step of applying a tension to the laterally tightened PC tendon so as to press the root-wrapped concrete against the structure body after being provided.

  According to another aspect of the present invention, in the above configuration, the base body is a footing, and the structure main body is a bridge pier.

  According to the method provided with these configurations, it is possible to provide a reinforcing structure having the above-described corresponding structure and its operation effect.

  According to the present invention, the axial rebar can be fixed to the base via the root-wrapped concrete and the coupling member without being built directly into the hole provided in the base, and the bending strength of the structure body can be improved. . The connecting member fixes the root-wrapped concrete to the base, but since the degree of freedom of arrangement is higher than that of the axial reinforcing bar, the erection hole for installing the connecting member is the existing reinforcing bar included in the base. It can be provided at a position where it does not need to be cut, and the strength of the existing part of the concrete structure is maintained.

Schematic longitudinal cross-sectional view (II cross section of FIG. 2) of the reinforcement structure which concerns on embodiment Schematic cross-sectional view of the II-II cross section of FIG. Schematic cross-sectional view of a cross section passing through a pier base of a reinforcing structure according to a modified embodiment Schematic cross-sectional view of a cross section passing through a pier base of a reinforcing structure according to another modified embodiment Schematic longitudinal sectional view of a conventional reinforcing structure (VV cross section in FIG. 6) Schematic cross-sectional view of section VI-VI in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show an embodiment in which the present invention is applied to a bridge substructure 2.

  The bridge substructure 2 that is an existing concrete structure includes a footing 4 that becomes a base fixed to the ground, and a columnar bridge pier 6 that extends upward from the upper surface of the footing 4 and becomes a structure main body. The footing 4 may be fixed to the ground via a foundation pile (not shown). The bridge pier 6 may be formed with a beam (not shown) extending laterally at an upper portion thereof, and supports the superstructure of the bridge via a support. The footing 4 and the pier 6 include an existing reinforcing bar 8. The existing reinforcing bar 8 extends in the vertical direction from the footing 4 to the pier 6 and extends in the horizontal direction at right angles to the existing axial reinforcing bar 8a and the existing axial reinforcing bar 8a whose lower end is bent in the horizontal direction. The existing band reinforcing bar 8b and the existing footing reinforcing bar 8c including the main reinforcing bar and stirrup of the footing 4 are included.

  The reinforcing structure 10 includes an axial rebar 12 newly installed for reinforcement, a root concrete 14 embedded in the lower end side of the axial rebar 12 and placed so as to surround the outer surface of the base of the bridge pier 6. The joint member 16 made of a PC steel rod for fixing the root winding concrete 14 to the footing 4, the laterally tightened PC tension member 18 made of PC steel wire for reinforcing the root winding concrete 14, and the root winding concrete 14 are integrated. A wound concrete 20 embedded in the remaining portion of the axial rebar 12 and placed so as to surround the outer surface of the pier 6. In FIG. 2, the outline of the rolled concrete 20 provided above the cross section of the figure is indicated by an imaginary line (two-dot chain line). Hereinafter, the reinforcing structure 10 will be described along the construction procedure.

  After earth retaining or temporary closing is performed as necessary, the ground is excavated so that the upper surface of the footing 4 is exposed, and a scaffold is constructed. In order to ensure the integrity with the concrete that is newly placed for reinforcement, the surfaces of the existing footing 4 and the pier 6 are provided by blasting or chipping.

  Next, the upper surface of the footing 4 in the vicinity of the base portion of the pier 6 is drilled, and a plurality of erection holes 22 for erected anchor members are provided. The plurality of building holes 22 are arranged so as to form a double ring shape along the outer periphery of the base portion of the pier 6. The plurality of erection holes 22 forming each ring shape are arranged at substantially equal intervals. The plurality of mounting holes 22 may form a single or triple or more ring shape. When the drilling position overlaps with the existing footing reinforcing bar 8c by the preliminary survey or actual drilling, the drilling position is shifted so as not to overlap with the existing footing reinforcing bar 8c, and the building hole 22 is formed. The erection holes 22 in which the drilling positions are shifted in this way are not equidistant from the adjacent erection holes 22 and may deviate from an annular arrangement, but the deviation is allowed.

  Next, an anchor member for coupling the root-wrapped concrete 14 to the footing 4, that is, a coupling member 16 made of a PC steel rod is built in the erection hole 22. The coupling member 16 is installed such that the lower side is received in the erection hole 22 and the upper extension part 16 a extends from the footing 4. Thereafter, the filler is injected into the erection hole 22, and the coupling member 16 is fixed to the footing 4. As the filler, a resin such as an epoxy resin, mortar, or the like can be used. However, it is preferable to use a non-shrink mortar that is not affected by creep.

  Next, a sheath for anchor (not shown, disposed coaxially with the coupling member 16), a sheath for laterally tightening PC tendon (not illustrated, disposed coaxially with the laterally tightened PC tendon 18), shaft Directional reinforcing bars 12 and belt reinforcing bars 24 are arranged. The anchor sheath is disposed so that the extending portion 16a of the coupling member 16 passes therethrough, and prevents the root wound concrete 14 to be placed later from adhering directly to the coupling member 16. The sheath for the laterally tightened PC tendon is arranged so as to surround the pier 6 within the planned placement range of the root-wrapped concrete 14, and extends in a substantially horizontal direction. As shown in FIG. 2, when the root-wrapped concrete 14 is placed in a substantially rectangular shape in plan view, four laterally tightening PC tendon sheaths are arranged along the four sides of the rectangular shape. The

  The main part of the axial rebar 12 extends in the axial direction of the pier 6 that is substantially parallel to the existing axial rebar 8 a, that is, in the substantially vertical direction, and is disposed along the outer surface of the pier 6. A plurality of the axial reinforcing bars 12 are arranged, but are arranged closer to the pier 6 than the coupling member 16 at substantially equal intervals so as to surround the outer periphery of the pier 6 as a whole. The lower end side of the axial rebar 12 is refracted substantially at a right angle, and is arranged so that the end portion faces the outside with respect to the pier 6. The lower end side of the axial rebar 12 and its vicinity are located within the planned placement range of the root-wrapped concrete 14, and the remaining portion is located within the planned placement range of the rolled concrete 20. The band reinforcing bar 24 abuts on the plurality of axial reinforcing bars 12 so as to be substantially orthogonal to each other and is disposed so as to surround the pier 6. A plurality of band reinforcing bars 24 are arranged, and are arranged at substantially equal intervals at positions shifted in the vertical direction.

  Next, the formwork for the root winding concrete 14 is installed, and the root winding concrete 14 is cast. The root-wrapped concrete 14 is placed in a predetermined range on the upper surface of the footing 4 so as to cover the base of the pier 6, that is, the outer periphery of the end on the footing 4 side, and adheres to the base of the pier 6 and the upper surface of the footing 4. ing. The root-wrapped concrete 14 has a predetermined thickness from the outer surface of the base portion of the pier 6 toward the outside, and in this embodiment, the inner side adheres to the pier 6 with respect to the rectangular pier 6 in plan view, It has a rectangular shape whose outer side widens the pier 6. The root-wrapped concrete 14 is embedded with a lower end side of the axial rebar 12, a band rebar 24 wound around the lower end side of the axial rebar 12, an anchor sheath, and a laterally tightened PC tendon sheath. After the root-wrapped concrete 14 has hardened, the formwork is removed. Here, the upper end of the anchor sheath and both ends of the laterally tightened PC tendon sheath were driven so that the tensioning operation of the coupling member 16 and the insertion and tensioning of the laterally tightened PC tendon 18 could be performed. It is not buried in the root winding concrete 14.

  Next, the laterally tightened PC tendon 18 is inserted into the laterally tightened PC tendon sheath, and tension is applied. Further, tension is also applied to the coupling member 16. The laterally tightened PC tendon 18 is made of PC steel wire. The laterally tightening PC tension member 18 and the coupling member 16 are fixed in a state where tension is applied by a known fixing tool such as a wedge method or a screw method. After the tension is applied, the grout is injected between the laterally tightened PC tendon sheath and the laterally tightened PC tendon 18 and between the anchor sheath and the coupling member 16. Further, the fixing tool for the lateral fastening PC tendon 18 and the connecting member 16 is buried with concrete or mortar.

  Next, a formwork for the rolled concrete 20 is installed, and the rolled concrete 20 is placed. The wound concrete 20 adheres to the outer surface of the pier 6 so as to cover the outer periphery of the pier 6 and is in contact with and integrated with the root-wrapped concrete 14 at the lower end. In the direction from the outer surface of the pier 6 toward the outside, the wound concrete 20 is thinner than the root-wrapped concrete 14. In this embodiment, the rolled concrete 20 has a rectangular shape in which the inner side adheres to the pier 6 and the outer side widens the pier 6 with respect to the rectangular pier 6 in a plan view. In the wound concrete 20, the portions other than the portion embedded in the root-wrapped concrete 14 among the axial direction reinforcing bars 12 and the band reinforcing bars 24 are embedded. After the rolled concrete 20 is cured, the formwork is removed.

  After that, if the scaffolding is removed, the footing 4 is backfilled, and the earth retaining work or temporary closing work is carried out, these are removed.

  The effect of this embodiment is demonstrated.

  Since the rolled concrete 20 integrated with the axial rebar 12 is attached to the pier 6, the toughness and shear strength of the pier 6 are improved. Furthermore, since the axial rebar 12 is fixed to the footing 4 via the root concrete 14 and the connecting member 16, the bending strength of the pier 6 is improved.

  The number of the coupling members 16 is smaller than that of the axial rebar 12 and the interval between the coupling members 16 can be widened. Therefore, the number of holes drilled in the footing 4 is reduced, and the load on the existing substructure 2 can be reduced.

  Moreover, since the coupling member 16 should just be arrange | positioned in the root winding concrete 14, the freedom degree of the arrangement | positioning is high. Therefore, the construction is easy even if the number of the coupling members 16 is large, and the erection hole 22 can be provided so as not to cut the existing footing reinforcing bar 8c, and the proof stress of the existing part of the footing 4 is not reduced. Can do. Since the embedment hole 22 can be provided independently in the axial rebar 12, the reinforcing structure 10 is used when a large reinforcing strength is required, that is, when the number of the axial rebar 12 is large and the diameter is large. Is preferred.

  Further, by introducing a tension force to the coupling member 16, even if the number of the coupling members 16 is reduced, the root-wrapped concrete 14 can be reliably fixed to the footing 4. Therefore, the axial rebar 12 fixed to the footing 4 via the root winding concrete 14 and the connecting member 16 is reliably fixed to the footing 4 and improves the bending strength of the pier 6.

  Moreover, since the bending strength and shear strength of the base of the existing bridge pier 6 and the root winding concrete 14 are improved by reinforcing the root winding concrete 14 with the laterally tightened PC tension member 18, the height and thickness of the root winding concrete 14 are increased. Therefore, the root-wrapped concrete 14 can be reduced in size. In particular, in the bridge substructure 2 provided in the river, when there is a minimum covering over the footing 4 and a restriction on the river obstruction rate of the pier 6, it is preferable to apply tension by the laterally tightening PC tendon 18.

  Next, a modified embodiment of the present invention will be described with reference to FIG. In the description, the description of the configuration common to the above-described embodiment is omitted, and the same reference numerals are given. FIG. 3 is a schematic cross-sectional view of a portion of the root-wrapped concrete 34 of the bridge pier 32 having a circular cross-sectional shape. In FIG. 3, the outline of the rolled concrete 35 provided above the cross section is indicated by an imaginary line (two-dot chain line). The existing pier 36 a is embedded in the pier 32. The inner surface of the concrete core 34 is attached to the pier 32 and the outer surface has a circular ring shape in plan view. The reinforcing reinforcing axial member 38 and the connecting member 40 have the same configuration as that of the above embodiment except that they are arranged on the circumference along the outer surface of the pier 32 at substantially equal intervals. Two semicircular transversely tightened PC tendon members 42 are combined and arranged inside the annular root-wrapped concrete 34 along the outer periphery thereof. The wound concrete 35 has an inner surface attached to the pier 32 and an outer surface having a circular ring shape in plan view, and its radial thickness is smaller than that of the rooted concrete 34.

  FIG. 4 shows another variant embodiment. FIG. 4 is a schematic cross-sectional view of a portion of the root-wrapped concrete 54 of the bridge pier 52 having an oval cross-sectional shape. In FIG. 4, the outline of the rolled concrete 55 provided above this cross section is indicated by an imaginary line (two-dot chain line). The existing pier 56a is embedded in the pier 52. The inner surface of the cored concrete 54 adheres to the pier 52, and the outer surface has an oval ring shape in plan view. The reinforcing reinforcing bar 58 and the connecting member 60 have the same configuration as that of the above embodiment except that the reinforcing bars 58 and the connecting member 60 are arranged on the oval ring shape along the outer surface of the bridge pier 52 at approximately equal intervals. Two oval semi-circular transversely tightening PC tendons 62 are combined and arranged inside the oval-shaped annular root-wrapped concrete 54 along the outer periphery thereof. The wound concrete 55 has an inner surface attached to the bridge pier 52, an outer surface having an oval annular shape in plan view, and a radial thickness smaller than that of the root-wrapped concrete 54.

  Although the description of the specific embodiment is finished as described above, the present invention is not limited to the above embodiment and can be widely modified. The structural body to which the reinforcing structure of the present invention is applied may be an abutment. In addition, for example, the existing concrete structure may be a concrete structure including a column, a wall, a beam, or the like as a structure main body, such as a shroud (dong) or a water tank. Further, the reinforcing structure may not cover the entire circumference of the structure main body, and may be provided only along a part of the wall surface of the structure main body. The connecting member may be replaced with another PC tendon instead of the PC steel rod. For example, a PC steel strand or fiber reinforced plastic such as carbon fiber or glass fiber may be used. Further, a reinforcing bar such as a deformed steel bar may be used as the connecting member instead of the PC tendon material. In this case, the anchor sheath is not installed, and the extending portion of the reinforcing bar as the connecting member is directly rooted concrete. Adhere to. The laterally tightened PC tendon may be a PC steel rod or a fiber reinforced plastic such as carbon fiber or aramid fiber instead of the PC steel strand. Also, the laterally tightened PC tendon members in FIGS. 3 and 4 may be one or three or more in a circular or oval shape instead of two. Moreover, the winding concrete may be placed before the tension of the laterally tightened PC tension member or the coupling member, and either of the tensioning operations of the laterally tightened PC tension member and the coupling member may be performed first. . Each of the axial rebars may be a joint of a plurality of rebars, and the lower end side of the axial rebar may change the direction of the refracted direction as appropriate, or change its shape. .

2 ... substructure (concrete structure), 4 ... footing (base), 6, 32, 52 ... pier (structure body), 12, 38, 58 ... axial rebar, 14, 34, 54 ... root-wrapped concrete, 16, 40, 60 ... coupling members, 18, 42, 62 ... side-tensioned PC tendon, 20, 35, 55 ... rolled up concrete, 22. .. Built-in hole

Claims (8)

A reinforcing structure of an existing concrete structure provided with a base body and a structure body extending from the base body,
An axial rebar extending in the extending direction of the structure body and disposed along the outer surface of the structure body;
A coupling member that is engaged with a plurality of mounting holes provided in the base body and has an extending portion extending from the mounting hole;
A root-wrapped concrete containing the extending portion of the coupling member and being placed over the outer surface of the structure main body adjacent to the base and the surface of the base adjacent thereto;
The coiled concrete is embedded in the axial rebar, and is wound on the outer surface of the structure body so as to be integrated with the root-wrapped concrete.
One end side of the axial rebar is embedded in the root concrete, The reinforcement structure characterized by the above-mentioned.   The reinforcing structure according to claim 1, wherein the coupling member is made of a PC tendon.   The reinforcing structure according to claim 1, further comprising a laterally tightened PC tension member disposed in the root wound concrete and provided with a tension force that presses the root wound concrete against the structure main body.   The reinforcing structure according to claim 1, wherein the base body is a footing, and the structure main body is a bridge pier. A method for reinforcing an existing concrete structure including a base body and a structure body extending from the base body,
Drilling the base to provide a plurality of holes for building;
Building a coupling member including an extending portion extending from the base body into the building hole;
Placing an axial rebar along the outer surface of the structure body so as to extend in the extending direction of the structure body;
Placing root-wrapped concrete over the outer surface of the portion of the structure body adjacent to the base and the surface of the base adjacent thereto so as to include the extended portion of the coupling member;
Placing the wound concrete on the outer surface of the structure body so as to embed the axial rebar and to be integrated with the rooted concrete,
In the step of arranging the axial rebar, the reinforcing method is characterized in that one end side of the axial rebar is arranged so as to be embedded in the root-wrapped concrete.   The reinforcing method according to claim 5, further comprising a step of applying a tension force after the connecting member is made of a PC tendon and the root-wrapped concrete is placed. Placing a laterally tightening PC tendon at the position where the root wrapped concrete is placed;
6. The method of claim 5, further comprising a step of applying a tension force to the laterally tightened PC tendon so as to press the root wound concrete against the structure body after the root wound concrete has been placed. Or the reinforcement method of 6.   The reinforcing method according to claim 5, wherein the base body is a footing, and the structure main body is a bridge pier.

Images