Reinforcement method of hollow cross section reinforced concrete bridge pier and reinforcement structure thereof

Abstract

To provide reinforcement technology of a hollow cross section reinforced concrete bridge pier that can intend to reduce worker's workload, contract a work period, and cut a work cost.SOLUTION: A reinforcement method of a hollow cross section reinforced concrete bridge pier includes drilling a concrete injecting hole 125 led into a building frame inside 121 on an outer wall 126 above a plastic hinge region 120 of a bridge pier body 12 (a first drilling process S1), filling concrete 123 to the building frame inside 121 of the plastic hinge region 120 by injecting the concrete 123 from the concrete injecting hole 125 into the building frame inside 121 (a concrete filling process S30), drilling slip stopper steel material holes 128 arriving to an inside of the concrete 123 on the outer wall 126 of the plastic hinge region 120 of the bridge pier body 12 after hardening the concrete 123 (a second drilling process S33), and fixing the concrete 123 to the bridge pier body 12 by driving slip stopper steel materials 124 into the slip stopper steel material holes 128 (a slip stopper steel material construction process S34).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a reinforcing technique for hollow cross-section reinforced concrete piers, the structure of which is hollow in order to reduce the effect of the pier's own weight. [Background technology]

[0002] Expressways and the like built in mountainous regions and the like often use bridges with high piers of 30 to 40 m or more in height. Generally, such high piers are made of hollow cross-section reinforced concrete with a hollow body in order to reduce the effect of the pier's own weight (see, for example, Patent Documents 1 and 2).

[0003] When alternating horizontal positive and negative loads are applied to a bridge pier due to an earthquake or other event, a large bending moment may occur at the base of the pier. The plastic region that may occur at the base of the pier as a result of this is generally called the plastic hinge region. Some existing hollow cross-section reinforced concrete piers have hollow bodies in the plastic hinge region. For such existing hollow cross-section reinforced concrete piers, seismic reinforcement work is being carried out by placing reinforcement bars inside the body and filling it with concrete in the plastic hinge region. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2001-342711 A [Patent Document 2] JP 2013-2238 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional seismic reinforcement work for existing hollow section reinforced concrete piers requires workers to perform rebar arrangement work inside the structure, which requires cutting the rebar of the pier to create an opening large enough for workers to enter inside the structure. In addition, rebar arrangement work inside the narrow structure places a burden on the workers. Furthermore, this work extends the construction period and increases the work costs.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and its purpose is to provide a reinforcement technology for hollow cross-section reinforced concrete piers that can reduce the workload on workers, shorten construction time, and reduce work costs. [Means for solving the problem]

[0007] In order to solve the above problems, in the present invention, first, a concrete injection hole that leads to the inside of the structure is drilled in the outer wall above the plastic hinge region of the hollow cross-section reinforced concrete pier. Next, concrete is injected through the concrete injection hole to fill the inside of the structure in the plastic hinge region. Then, after the filled concrete hardens, a hole for a shear stopper steel material that reaches the concrete filled inside the structure is drilled in the outer wall of the plastic hinge region, and a shear stopper steel material is driven into the hole for the shear stopper steel material to fix the concrete filled inside the structure to the structure.

[0008] Here, prior to pouring concrete into the skeleton, a camera may be inserted into the concrete pouring hole to check the condition of the inside of the skeleton in the plastic hinge region. If the inside of the skeleton is dry and the inner wall is rough (uneven), and it is expected that the concrete to be filled inside the skeleton in the plastic hinge region will adhere to the inner wall, the process of drilling holes for the anti-slip steel material in the outer wall of the plastic hinge region and driving in the anti-slip steel material after the concrete has hardened may be omitted.

[0009] For example, the present invention provides A method for reinforcing a hollow cross-section reinforced concrete pier, comprising the steps of: A first drilling step of drilling a concrete injection hole leading to the inside of the hollow cross-section reinforced concrete pier in an outer wall above a plastic hinge region of the hollow cross-section reinforced concrete pier; A concrete filling step of pouring concrete through the concrete pouring hole to fill the interior of the skeleton in the plastic hinge region with concrete; A second drilling step of drilling holes for anti-slip steel members in an outer wall of the plastic hinge region of the skeleton of the hollow cross-section reinforced concrete pier after the concrete filled inside the skeleton in the plastic hinge region has hardened, the holes reaching the concrete filled inside the skeleton; and a shear-stop steel installation process for driving shear-stop steel into the shear-stop steel hole to fix the concrete filled inside the structure to the structure of the hollow cross-section reinforced concrete pier.

[0010] Further, for example, the present invention provides A reinforcement structure for a hollow section reinforced concrete pier, Concrete is filled inside the skeleton of the hollow section reinforced concrete pier in a plastic hinge region of the skeleton; and anti-slip steel members that fix the concrete filled inside the structure to the outer walls of the plastic hinge regions of the structure. Effect of the Invention

[0011] In the present invention, in a hollow cross-section reinforced concrete pier, a concrete injection hole leading to the inside of the skeleton is drilled in the outer wall above the plastic hinge region, and concrete is injected into the inside of the skeleton from this concrete injection hole to fill the inside of the skeleton in the plastic hinge region. Also, a hole for a shear stopper steel material is drilled in the outer wall of the plastic hinge region, and a shear stopper steel material is driven into this hole for the shear stopper steel material to fix the concrete filled inside the skeleton to the skeleton, so that the hollow cross-section reinforced concrete pier can be effectively reinforced.

[0012] In this way, according to the present invention, workers can efficiently perform all work outside the skeleton of the structure without entering the narrow interior of the skeleton. In addition, there is no need to create an opening in the skeleton for workers to enter inside the skeleton. Therefore, it is possible to provide a reinforcement technology for hollow cross-section reinforced concrete piers that can reduce the workload of workers, shorten the construction period, and reduce work costs. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a partial cross-sectional view of an existing hollow section reinforced concrete pier 1a to which a reinforcing structure for a hollow section reinforced concrete pier according to one embodiment of the present invention is applied. [Diagram 2] FIG. 2 is a flow diagram for explaining a construction method (reinforcing method) of a reinforced structure for a hollow cross-section reinforced concrete pier according to one embodiment of the present invention. [Diagram 3] FIG. 3 is a flow diagram for explaining the concrete filling step (with slip-stop construction) S3 shown in FIG. [Figure 4] FIG. 4 is a flow diagram for explaining the concrete filling step (without slip-stop construction) S4 shown in FIG. [Diagram 5] FIG. 5 is a partial cross-sectional view of a modified example 1b of an existing hollow section reinforced concrete pier to which a reinforcing structure for a hollow section reinforced concrete pier according to one embodiment of the present invention is applied. [Figure 6] FIG. 6 is a partial cross-sectional view of an existing hollow section reinforced concrete pier 1 which is to be reinforced by the reinforcing structure of a hollow section reinforced concrete pier according to this embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] FIG. 6 is a partial cross-sectional view of an existing hollow section reinforced concrete pier 1 which is to be reinforced by the reinforcing structure of a hollow section reinforced concrete pier according to this embodiment.

[0016] The hollow cross-section reinforced concrete pier 1 is used for the purpose of reducing the bridge weight in high bridges, for example, 30 to 40 m or more in height, and as shown in the figure, is composed of a foundation footing 10 with at least the lower end embedded in the ground, a bridge seat 11 supporting a bridge (not shown), and a bridge leg body 12 arranged between the foundation footing 10 and the bridge seat 11 to connect and secure them together. The bridge leg body 12 is a hollow cylindrical reinforced concrete structure in which reinforcing bars 122 are arranged. In the existing hollow cross-section reinforced concrete pier 1, which is an example of the reinforcement target in this embodiment, the inside 121 of the bridge leg body 12 is hollow even in the plastic hinge region 120.

[0017] Fig. 1 is a partial cross-sectional view of an existing hollow section reinforced concrete pier 1a to which a hollow section reinforced concrete pier reinforcing structure according to the present embodiment is applied. In the hollow section reinforced concrete pier 1a shown in Fig. 1, components having the same functions as those of the hollow section reinforced concrete pier 1 shown in Fig. 6 are given the same reference numerals.

[0018] As shown in the figure, in an existing hollow cross-section reinforced concrete pier 1a to which this embodiment is applied, concrete 123 is filled into a skeleton interior 121 in a plastic hinge region 120 of the bridge leg body 12. Also, in the plastic hinge region 120 of the bridge leg body 12, a plurality of shear stop steel members 124 are arranged, which reach from an outer wall 126 to the concrete 123 in the skeleton interior 121. The shear stop steel members 124 are preferably formed of a high-strength material such as PC (Prestressed Concrete) steel.

[0019] 1, reference numeral 125 denotes a concrete injection hole provided at a position higher than the plastic hinge region 120 in order to fill the interior 121 of the skeleton with concrete 123, and is sealed with grout after completion of the reinforcement process according to the reinforcing method for a hollow cross-section reinforced concrete pier according to this embodiment. Reference numeral 128 denotes a shear stop steel hole provided in the plastic hinge region 120 in order to drive in the shear stop steel 124, and reaches from the outer wall 126 to the inside of the concrete 123 in the interior 121 of the skeleton.

[0020] FIG. 2 is a flow diagram for explaining a construction method (reinforcing method) of a reinforced structure of a hollow cross-section reinforced concrete pier according to this embodiment.

[0021] [First drilling process S1] At least one concrete injection hole 125 that leads from the outside to the inside 121 of the bridge body is drilled in the outer wall 126 of the bridge leg body 12 above the plastic hinge region 120. Here, the concrete injection hole 125 is drilled so as to pass between the reinforcing bars 122 of the bridge leg body 12. In this way, the reinforcing bars 122 are not cut to make way for the concrete injection hole 125, so the impact on the strength of the bridge leg body 12 can be reduced.

[0022] [Internal condition confirmation process S2] A camera is inserted into the interior 121 of the structure through the concrete injection hole 125 drilled in the first drilling step S1, and the condition of the interior 121 of the structure in the plastic hinge region 120 is confirmed.

[0023] For example, it is confirmed that no foreign objects (formwork, wastewater, etc.) remain inside the structure 121, and that the space inside the structure 121 is in a state in which filling the structure 121 with concrete 123 is expected to improve the earthquake resistance, etc. of the entire bridge.

[0024] If the space inside the structure 121 is in such a state, the surface state of the inner wall 127 inside the structure 121 is observed. If the surface of the inner wall 127 inside the structure 121 has almost no roughness (unevenness) and adhesion between the concrete 123 and the inner wall 127 cannot be expected (S2: "Fair"), proceed to the concrete filling step (with anti-slip construction) S3. If the inner wall 127 inside the structure 121 has moderate roughness (unevenness) and adhesion between the concrete 123 and the inner wall 127 can be expected (S2: "Good"), proceed to the concrete filling step (without anti-slip construction) S4.

[0025] On the other hand, if foreign objects (formwork, wastewater, etc.) remain in the skeleton interior 121, and it is determined that filling the skeleton interior 121 with concrete 123 while leaving these foreign objects will not significantly improve the earthquake resistance performance of the entire bridge (S2: "Not possible"), the existing earthquake reinforcement process S5 is carried out. That is, first, an opening large enough for a worker to enter the skeleton interior 121 is provided in the bridge body 12. Next, a worker enters the skeleton interior 121 from this opening and removes foreign objects from the skeleton interior 121, thereby preparing the skeleton interior 121 in an appropriate state. Then, reinforcement is arranged in the skeleton interior 121 in the plastic hinge region 120, concrete is filled in, and the concrete is allowed to harden.

[0026] FIG. 3 is a flow diagram for explaining the concrete filling step (with slip-stop construction) S3 shown in FIG.

[0027] [Concrete filling process S30] Concrete 123 is poured through the concrete pouring hole 125 to fill the interior 121 of the body in the plastic hinge region 120 with the concrete 123.

[0028] [Gap confirmation process S31] After the concrete 123 filled inside the structure 121 of the plastic hinge region 120 has hardened, a camera is inserted into the structure 121 through the concrete injection hole 125 to check whether there is a gap between the concrete 123 and the inner wall 127 of the structure 121.

[0029] If a gap is confirmed between the concrete 123 and the inner wall 127 (S31: Yes), the process proceeds to the grout injection step S32. On the other hand, if no gap is confirmed between the concrete 123 and the inner wall 127 and the two are in close contact (S31: No), the grout injection step S32 is omitted and the process proceeds to the second hole drilling step S33.

[0030] [Grout injection process S32] Grout is injected from the concrete injection hole 125 into the gap between the concrete 123 filled in the interior 121 of the skeleton in the plastic hinge region 120 and the inner wall 127 of the interior 121 of the skeleton, and then hardened.

[0031] [Second drilling process S33] In the plastic hinge region 120 of the bridge leg body 12, a plurality of holes 128 for the anti-slip steel are drilled, which reach from the outer wall 126 to the inside of the concrete 123 filled in the interior 121 of the frame. Here, the holes 128 for the anti-slip steel are drilled at positions passing between the reinforcing bars 122 of the bridge leg body 12. In this way, the reinforcing bars 122 are not cut, so that the influence on the strength of the bridge leg body 12 can be reduced. In addition, it is preferable to drill a plurality of holes 128 for the anti-slip steel at a predetermined interval so that they are evenly arranged in the circumferential direction and the axial direction of the bridge leg body 12. In this way, the anti-slip steel 124 driven in the anti-slip steel construction step S34 described later is evenly arranged in the circumferential direction and the axial direction of the bridge leg body 12 in the plastic hinge region 120. Therefore, when alternating positive and negative horizontal loads due to an earthquake or the like are applied to the hollow cross-section reinforced concrete pier 1a, the load transmitted from the bridge body 12 to the concrete 123 via the anti-slip steel 124 can be distributed more evenly.

[0032] [Slip-stop steel construction process S34] After injecting binder into each of the steel shear stopper holes 128, the steel shear stoppers 124 are driven into the concrete 123 until they reach the inside of the concrete 123. This fixes the concrete 123 to the bridge leg body 12.

[0033] [Hole sealing for concrete injection S35] The concrete injection hole 125 is sealed with grout, completing the concrete filling step (with anti-slip construction) S3.

[0034] FIG. 4 is a flow diagram for explaining the concrete filling step (without slip-stop construction) S4 shown in FIG.

[0035] [Concrete filling process S40] Concrete 123 is poured through the concrete pouring hole 125 to fill the interior 121 of the body in the plastic hinge region 120 with the concrete 123.

[0036] [Gap confirmation process S41] After the concrete 123 filled inside the structure 121 of the plastic hinge region 120 has hardened, a camera is inserted into the structure 121 through the concrete injection hole 125 to check whether there is a gap between the concrete 123 and the inner wall 127 of the structure 121.

[0037] If a gap is confirmed between the concrete 123 and the inner wall 127 (S41: Yes), the process proceeds to the grout injection step S42. On the other hand, if it is confirmed that there is no gap between the concrete 123 and the inner wall 127 and that the two are in close contact (S41: No), the process skips the grout injection step S42 and proceeds to the concrete injection hole sealing step S43.

[0038] [Grout injection process S42] Grout is injected from the concrete injection hole 125 into the gap between the concrete 123 filled in the interior 121 of the skeleton in the plastic hinge region 120 and the inner wall 127 of the interior 121 of the skeleton, and then hardened.

[0039] [Hole sealing for concrete injection S43] The concrete injection hole 125 is sealed with grout, completing the concrete filling step (without slip-stop construction) S4.

[0040] One embodiment of the present invention has been described above.

[0041] In this embodiment, a concrete injection hole 125 leading to the skeleton interior 121 is drilled in an outer wall 126 above the plastic hinge region 120 of the bridge leg body 12 of the hollow cross-section reinforced concrete pier 1a, and concrete 123 is injected from this concrete injection hole 125 into the skeleton interior 121 to fill the skeleton interior 121 of the plastic hinge region 120 with the concrete 123. Also, a shear stopper steel hole 128 is drilled in the outer wall 126 of the plastic hinge region 120, and shear stopper steel 124 is driven into this shear stopper steel hole 128 to fix the concrete 123 filled in the skeleton interior 121 to the bridge leg body 12, so that the hollow cross-section reinforced concrete pier 1a can be effectively reinforced.

[0042] In this way, according to this embodiment, workers can efficiently perform all work outside the bridge footing body 12, without entering the narrow interior of the body 121. In addition, there is no need to provide an opening in the bridge footing body 12 for workers to enter the interior of the body 121. This reduces the workload of workers, shortens the construction period, and reduces work costs.

[0043] In this embodiment, a concrete injection hole 125 is drilled in the outer wall 126 of the bridge leg body 12 above the plastic hinge region 120 so as to pass through the unreinforced portion, i.e., between the reinforcing bars 122 of the bridge leg body 12. As a result, the reinforcing bars 122 are not cut to make way for the concrete injection hole 125, which reduces the effect on the strength of the bridge leg body C.

[0044] In this embodiment, in the plastic hinge region 120, holes 128 for shear stop steel are drilled in the bridge leg body 12 so as to penetrate the unreinforced portion, i.e., between the reinforcing bars 122 of the bridge leg body 12. By doing so, the reinforcing bars 122 are not cut to make way for the holes 128 for shear stop steel, so the effect on the strength of the bridge leg body 12 can be further reduced.

[0045] In this embodiment, a binder is injected into each of the shear-stopping steel holes 128 before the shear-stopping steel materials 124 are driven in. As a result, the shear-stopping steel materials 124 are fixed to the bridge foot structure 12 and the concrete 123 with the binder, so that the concrete 123 can be more firmly fixed to the bridge foot structure 12.

[0046] In this embodiment, prior to the concrete filling steps S30 and S40, a camera is inserted into the skeleton interior 121 through the concrete injection hole 125 to check the state of the skeleton interior 121 of the plastic hinge region 120. If no foreign matter (formwork, wastewater, etc.) remains in the skeleton interior 121, and the concrete 123 filled into the skeleton interior 121 of the plastic hinge region 120 can be expected to provide a sufficient reinforcing effect for the plastic hinge region 120, and if the inner wall 127 of the skeleton interior 121 has a suitable roughness (unevenness) and can be expected to bond the concrete 123 to the inner wall 127, the second drilling step of drilling the anti-slip steel hole 128 in the outer wall 126 of the plastic hinge region 120 and the anti-slip steel construction step of driving the anti-slip steel 124 are omitted (concrete filling step (without anti-slip construction) S4). Therefore, according to this embodiment, the process is simplified, the construction period is further shortened, and the work costs can be reduced.

[0047] In this embodiment, after the concrete 123 filled in the skeleton interior 121 of the plastic hinge region 120 hardens, a camera is inserted into the skeleton interior 121 through the concrete injection hole 125 to check for the presence or absence of a gap between the concrete 123 and the inner wall 127 of the skeleton interior 121 of the plastic hinge region 120. If a gap is confirmed, grout is injected into the gap through the concrete injection hole 125. This improves the bond strength between the concrete 123 filled in the skeleton interior 121 of the plastic hinge region 120 and the bridge footing 12, and makes it possible to more effectively reinforce the hollow cross-section reinforced concrete pier 1a.

[0048] The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the present invention.

[0049] For example, in this embodiment, in the concrete filling step (with slip-stop construction) S3 shown in FIG. 3, the second hole drilling step S33 and the slip-stop steel construction step S34 are carried out after the concrete filling step S30. However, the present invention is not limited to this. The second hole drilling step S33 and the slip-stop steel construction step S34 may be carried out prior to the concrete filling step S30. In this case, the slip-stop steel hole 128 drilled in the second hole drilling step S33 may be a hole that penetrates the plastic hinge region 120 of the bridge leg main body 12. In addition, the slip-stop steel 124 may be driven so as to reach a predetermined position from the outer wall 126 of the bridge leg main body 12 to a predetermined position inside the skeleton 121.

[0050] 5, anti-slip steel material 124a with a plate 129 attached to its head may be driven into anti-slip steel hole 128. By using anti-slip steel material 124a with a plate 129 attached to its head, it is possible to reduce the possibility of damaging the outer wall 126 of the bridge foot structure 12 when driving the anti-slip steel material 124a.

[0051] In addition, the present invention can be applied in the same manner as this embodiment to existing hollow cross-section reinforced concrete piers that have been seismically reinforced using the RC lining method, so long as the inside of the structure in the plastic hinge area is hollow. [Explanation of symbols]

[0052] 1, 1a, 1b: Hollow section reinforced concrete pier 10: Foundation footing 11: Bridge seat 12: Bridge leg body 120: Plastic hinge area 121: Inside the structure 122: Steel bars 123: Concrete 124: Anti-slip steel 125: Hole for pouring concrete 126: Outer wall of bridge leg body 12 127: Inner wall of bridge leg body 12 128: Hole for anti-slip steel 129: Plate

Claims

1. A method for reinforcing a hollow cross-section reinforced concrete pier, comprising the steps of: A first drilling step of drilling a concrete injection hole leading from the outside to the inside of the hollow cross-section reinforced concrete pier in an outer wall above a plastic hinge region of the hollow cross-section reinforced concrete pier; A concrete filling step of pouring concrete through the concrete pouring hole to fill the interior of the skeleton in the plastic hinge region with concrete; A second drilling step of drilling holes for anti-slip steel members in the outer wall of the plastic hinge region of the skeleton of the hollow cross-section reinforced concrete pier after the concrete filled inside the skeleton in the plastic hinge region has hardened, the holes reaching the concrete filled inside the skeleton; and a shear-stop steel construction process for driving a shear-stop steel into the shear-stop steel hole to fix the concrete filled inside the structure to the structure of the hollow cross-section reinforced concrete pier. A method for reinforcing a hollow cross-section reinforced concrete bridge pier.

2. A method for reinforcing a hollow cross-section reinforced concrete pier according to claim 1, In the first drilling step, The concrete injection hole is drilled in an unreinforced portion of the exterior wall above the plastic hinge region. A method for reinforcing a hollow cross-section reinforced concrete bridge pier.

3. A method for reinforcing a hollow cross-section reinforced concrete pier according to claim 1, In the second drilling step, The holes for the anti-slip steel material are drilled in the unreinforced portion of the outer wall of the plastic hinge region. A method for reinforcing a hollow cross-section reinforced concrete bridge pier.

4. A method for reinforcing a hollow cross-section reinforced concrete pier according to claim 1, In the shear stop steel construction process, A binder is injected into the hole for the shear-stop steel material, and then the shear-stop steel material is driven into the hole for the shear-stop steel material. A method for reinforcing a hollow cross-section reinforced concrete bridge pier.

5. A method for reinforcing a hollow cross-section reinforced concrete pier according to claim 1, The anti-slip steel has a plate connected to the head A method for reinforcing a hollow cross-section reinforced concrete bridge pier.

6. A method for reinforcing a hollow cross-section reinforced concrete pier according to any one of claims 1 to 5, Prior to the concrete filling step, a camera is inserted into the skeleton through the concrete injection hole drilled in the first drilling step to check the state of the inside of the skeleton in the plastic hinge region. If the state confirmed by the internal state confirmation step is a predetermined state in which the concrete filled by the concrete filling step and the inner wall inside the skeleton of the plastic hinge region can be fixed, the second hole drilling step and the anti-slip steel construction step are omitted. A method for reinforcing a hollow cross-section reinforced concrete bridge pier.

7. A method for reinforcing a hollow cross-section reinforced concrete pier according to any one of claims 1 to 5, a gap confirmation step of, prior to the second drilling step, inserting a camera into the structure through the concrete injection hole drilled in the first drilling step after the concrete filled in the plastic hinge region of the structure has hardened, and confirming whether or not there is a gap between the concrete filled in the concrete filling step and an inner wall of the structure in the plastic hinge region; When a gap between the hardened concrete and the inner wall of the skeleton in the plastic hinge region is confirmed by the gap confirmation step, a grout injection step of injecting grout into the gap from the concrete injection hole prior to the second drilling step is further provided. When the grout injection step is performed, the second drilling step is performed after the grout injected into the gap has hardened. A method for reinforcing a hollow cross-section reinforced concrete bridge pier.

8. A method for reinforcing a hollow cross-section reinforced concrete pier according to claim 6, A gap confirmation process, which is a process prior to the second drilling process, includes inserting a camera into the structure through the concrete injection hole drilled in the first drilling process after the concrete filled in the concrete filling process has hardened, and confirming whether or not there is a gap between the concrete and an inner wall of the structure in the plastic hinge region. When a gap between the hardened concrete and the inner wall of the skeleton in the plastic hinge region is confirmed by the gap confirmation step, a grout injection step of injecting grout into the gap from the concrete injection hole prior to the second drilling step is further provided. When the grout injection step is performed, the second drilling step is performed after the grout injected into the gap has hardened. A method for reinforcing a hollow cross-section reinforced concrete bridge pier.

9. A reinforcement structure for a hollow section reinforced concrete pier, Concrete is filled inside the skeleton of the hollow section reinforced concrete pier in a plastic hinge region of the skeleton; and a shear-stop steel member that fixes the concrete filled inside the skeleton to the outer wall of the skeleton in the plastic hinge region. A reinforcement structure for hollow cross-section reinforced concrete piers.

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