JP2015175140A - Earthquake-resistance reinforcement method of concrete main girder for bridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an earthquake-resistance reinforcement method and an earthquake-resistance reinforcement structure of a concrete main girder for a bridge capable of easily installing a bearing and an installation member, while improving earthquake-resistance reinforcement performance of the concrete main girder, by maximally restraining a chipping quantity of the concrete main girder.SOLUTION: A hole 1d of the depth within cover concrete is drilled on a side surface of a concrete main girder 1 in response to a position of a plurality of female screw holes formed on a sidewall of an installation member 5, and the tip of a fixing bolt 6 is not projected from the sidewall of the installation member 5, and the installation member 5 is screwed in the female screw hole at an interval between a bottom surface and the side surface of the installation concrete main girder 1, and a form is installed in both side openings of the installation member 5, and concrete mortar 9 is filled in a cavity of the concrete main girder 1 enclosed by the installation member 5 and the form, and the tip of the fixing bolt 6 is inserted into the hole 1d of the concrete main girder 1 by rotating the fixing bolt 6, and the concrete mortar 9 is cured and hardened, and the installation member 5 is integrated with the concrete main girder 1.

Description

  The present invention relates to a seismic reinforcement method for a main girder for a bridge.

  Since the 1999 Hyogoken-Nanbu Earthquake, seismic reinforcement work has been carried out on existing bridges in order to adapt the seismic performance of bridges to Level 2 ground motions.

  However, in the case of reinforced concrete bridges and prestressed concrete bridges, PC cables are installed to introduce reinforcing bars and prestressed concrete, so it is difficult to attach mounting members such as bearings and displacement limiting structures. There was a tendency to lag behind.

  Under such circumstances, Japanese Patent Application Laid-Open No. 2011-252368 discloses a concrete main unit that is easily fixed to a bearing or mounting member by fixing the mounting member integrally to the concrete main girder to improve the seismic capacity of the concrete bridge. Seismic reinforcement methods for girders are presented.

JP 2011-252368 A Road Bridge Specification (V Seismic Design) Japan Road Association, issued April 10, 2002 See 245

  However, the conventional seismic reinforcement method for concrete main girders requires the side of the main girder to be hung until the main girder rebar is exposed. Therefore, when the main girder width is narrow like a pretension T girder, the amount of hanger May increase the strength of the main girder.

  The present invention solves the above-mentioned problems of the prior art, can suppress the amount of suspension of the concrete main girder as much as possible, can improve the seismic compensation performance of the concrete main girder, and can easily mount the support and the mounting member. The purpose is to provide a seismic strengthening method for concrete main girders and a seismic strengthening structure for concrete main girders for bridges.

  In order to solve the above-mentioned problem, the seismic reinforcement method for a concrete main girder for a bridge according to the present invention has a depth within the cover concrete at a position corresponding to a plurality of female screw holes formed on the side wall of the mounting member on the side surface of the concrete main girder. A narrow gap is formed between the bottom surface and side surface of the concrete main girder, and the position of the hole formed on the side surface of the concrete main girder matches the position of the female screw hole formed on the side wall. And a step of arranging a mounting member having a horizontal bottom surface and a vertical side wall screwed so that the front end of the fixing bolt does not protrude from the side wall into the female screw hole, and a step of installing a formwork on both side openings of the mounting member Filling the gap between the mounting member and the concrete main girder surrounded by the formwork with concrete mortar, and the fixing bolt screwed into the female screw hole of the mounting member with the concrete mortar uncured. Rotating the door, the steps of the front end of the fixing bolt is inserted into the hole of the concrete main beam, and cured by curing the concrete, characterized in that it comprises a step of integrally concrete main beam and the mounting member.

  Further, the seismic reinforcement method for a concrete main girder for a bridge according to the present invention is such that the inner diameter of the hole formed in the side surface of the concrete main girder is larger than the outer diameter of the portion of the fixing bolt inserted into the hole, The exhaust gap of the air remaining in the back of the hole when inserting is formed.

  Further, the seismic reinforcement method for a bridge concrete main girder according to the present invention is characterized in that the inner diameter of the hole formed in the side surface of the concrete main girder and the outer diameter of the portion of the fixing bolt inserted into the hole are substantially the same. And

  Further, the seismic reinforcement method for a bridge main girder according to the present invention is characterized by using non-shrinkable concrete mortar or steel fiber reinforced flowable high strength concrete mortar as the concrete mortar.

Moreover, in the concrete main girder seismic reinforcement method for bridges of the present invention, the steel fiber reinforced high-fluidity high-strength concrete is a mixture of cement, limestone filler, and silica fume in a range of 250 to 450 L per 1 m ^{3 of the} mixture. in the cement is added, the limestone filler is added in the range of the mixture 1 m ³ per 150～300L, and silica fume is added in the range of the mixture 1 m ³ per 50～100L, the mixture 1 m ³ per Steel fibers having a diameter of 0.15 to 0.3 mm and a length of about 6 to 25 mm and steel fibers having a diameter of 0.15 to 0.3 mm and a length of 1.0 mm or less are added in a volume ratio of 4 to 12%. And water are kneaded.

  The seismic reinforcement method for a concrete girder for a bridge according to the present invention is characterized in that a water reducing agent and a shrinkage reducing agent are added to the steel fiber reinforced flowable high strength concrete.

Narrow the space between the bottom surface and the side surface of the concrete main girder, and the process of drilling holes with a depth within the cover concrete at positions corresponding to the female screw holes formed on the side wall of the mounting member on the side surface of the concrete main girder The position of the hole formed on the side surface of the concrete main girder and the position of the female screw hole formed on the side wall coincide with each other, and the end of the fixing bolt is screwed into the female screw hole so that it does not protrude from the side wall. Filling the gap between the mounting member and the concrete main girder surrounded by the mold by placing the mounting member with the horizontal bottom and vertical side walls, installing the mold at the opening on both sides of the mounting member, and filling the concrete mortar Rotating the fixing bolt screwed into the female screw hole of the mounting member while the concrete mortar is uncured, inserting the tip of the fixing bolt into the hole of the concrete main girder, Curing and hardening the riet to integrate the concrete main girder and the mounting member into one unit, so that the concrete main girder and the mounting member are firmly integrated with concrete while suppressing the amount of suspension of the concrete main girder as much as possible. By doing so, the seismic performance of the concrete main girder can be improved, and the mounting of the support and the mounting member becomes easy.
The inside diameter of the hole formed in the side surface of the concrete main girder is made larger than the outside diameter of the portion of the fixing bolt inserted into the hole, and the exhaust gap of the air remaining behind the hole when the fixing bolt is inserted into the hole By forming it, it becomes possible to improve the integration of the concrete main girder and the mounting member by eliminating an air reservoir in the concrete filling space.
By making the inner diameter of the hole formed in the side surface of the concrete main girder and the outer diameter of the portion of the fixing bolt inserted into the hole substantially the same, the surface pressure of the fixing bolt can be reduced.

By using non-shrinkable concrete mortar or steel fiber reinforced flowable high strength concrete mortar as concrete mortar, nonshrinkable concrete mortar has good flowability and slow drying, so workability is good and steel fiber reinforced flowable high strength concrete Mortar can improve the concrete strength after curing.
The steel fiber reinforced high fluidity high strength concrete, cement, limestone filler, the mixture comprising silica fume, cement is added in the range of the mixture 1 m ³ per 250～450L, the mixture 1 m ³ per 150 Limestone filler added in the range of 300 L, silica fume added in the range of 50 to 100 L per 1 m ^{3 of the} mixture, and diameter 0 added in the range of 4 to 12% by volume ratio per 1 m ^{3 of the} mixture By kneading a steel fiber having a length of about 15 to 0.3 mm and a length of about 6 to 25 mm, a steel fiber having a diameter of 0.15 to 0.3 mm and a length of 1.0 mm or less, and water, Sufficient dispersion of reinforcing steel fibers in the mortar can be ensured, and the interfacial adhesion strength between the concrete and steel fibers used as a matrix can be ensured, and the reinforcing effect of the steel fibers can be fully demonstrated. , Self-filling that can be filled in a small space, it is possible to secure the fluidity.
By adding a water reducing agent and a shrinkage reducing agent, the steel fiber reinforced flowable high strength concrete can improve the mortar fluidity, separation resistance, strength after hardening and resistance to cracking.

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  Embodiments of the present invention will be described with reference to the drawings.

  FIGS. 1A and 1B are views showing an example of a concrete main girder 1 for a bridge. The concrete main girder 1 has a substantially T-shaped cross section including an upper flange portion 1a, a lower flange portion 1b, and a web portion 1c. The concrete main girder 1 is supported on a bridge pier or abutment 2 via a support 3.

  In the first step of the seismic reinforcement method for the concrete main girder 1, a plurality of holes 1 d having a predetermined inner diameter are drilled on the side surface of the lower flange portion 1 b of the concrete main girder 1 to be seismically reinforced. The drilling position of the hole 1d corresponds to the position of the female screw hole 5a formed in the mounting member 5 described later. The depth of the hole 1d is set so as not to exceed the cover concrete of the reinforcing steel bars 4 of the concrete main girder 1.

  FIGS. 2A and 2B are diagrams showing an example of the attachment member 5. The attachment member 5 is a steel member having a U-shaped cross section from the horizontal bottom 5a and the vertical side wall 5b. The interval L1 between the vertical side wall portions 5c is 20 to 40 mm longer than the width L2 between both side walls of the lower flange portion 1b of the concrete main girder 1. A plurality of female screw holes 5c are formed in the vertical side wall portion 5b at a predetermined interval. A hole 1d is cut in the side surface of the lower flange portion 1b corresponding to the female screw hole 5c formed in the vertical side wall portion 5b. At both ends of the mounting member 5, connecting bolt holes (not shown) for connecting the plurality of mounting members 5 in the bridge axis direction, and the mounting members 5 are arranged at the seismic reinforcement positions of the concrete main girder 1. For this purpose, a wire fixing tool (not shown) for fixing the suspension wire 7a of the lifting tool 7 is attached.

  FIG. 3 is a view showing the fixing bolt 6 screwed into the female screw hole 5 c of the mounting member 5. The fixing bolt 6 is composed of a head portion 6a and a male screw portion 6b. In the embodiment shown in FIG. 8, the outer diameter d of the male screw portion 6 b is 30 to 50 mm smaller than the inner diameter D of the hole 1 d formed in the lower flange portion 1 b of the concrete main girder 1. In the embodiment shown in FIG. 9, the inner diameter D of the hole 1d formed in the lower flange portion 1b of the concrete main girder 1 and the outer diameter d of the male screw portion 6b are made substantially the same. In the embodiment shown in FIG. 10, the inner diameter D of the hole 1d formed in the lower flange portion 1b of the main girder 1 and the outer diameter d of the large diameter portion 6c screwed to the tip of the male screw portion 6b are made substantially the same.

  4A and 4B are views showing a second step of the seismic reinforcement method for the concrete main girder 1. FIG. In this step, the attachment member 5 is disposed at the reinforcing position of the concrete main beam 1. The attachment member 5 is suspended and supported by a suspension wire 7a of a suspension 7 disposed on the upper flange portion 1a of the concrete main girder 1. The distance between the horizontal bottom 5a of the mounting member 5 and the bottom surface of the lower flange 1b of the concrete main girder 1 and the distance between the vertical side wall 5b of the mounting member 5 and the side surface of the lower flange 1b of the concrete main girder 1 are 10 to 20 mm. To be. The hanger 7 arranged on the upper flange portion 1a can be moved, and the work when connecting the plurality of attachment members 5 in the bridge axis direction is facilitated. In the step of disposing the mounting member 5 at a predetermined position, the male screw portion 6b of the fixing bolt 6 is screwed into the female screw hole 5c of the mounting member 5 so that the tip portion does not protrude from the vertical side wall portion 5b. By screwing the fixing bolt 6, the female screw hole 5 c is closed.

  FIG. 5 is a diagram showing a third step of the seismic reinforcement method for the concrete main girder 1. In this step, the mold 8 is installed in the openings on both ends of the mounting member 5. By installing the mold 8 in the opening, the bottom and side surfaces of the lower flange portion 1 b of the concrete main girder 1 are watertightly surrounded by the attachment member 5 and the mold 8.

  FIG. 6 is a diagram illustrating a fourth step of the seismic reinforcement method for the concrete main girder 1. In this step, the concrete mortar 9 is filled into the space between the mounting member 5 and the concrete main girder 1 surrounded by the mold 8.

  As the concrete mortar 9, non-shrinkable concrete mortar or steel fiber reinforced fluidity high strength concrete mortar is used. Non-shrinkable concrete mortar is easy to work because it has good fluidity and slow drying. The steel fiber reinforced flowable high strength concrete mortar has good self-filling even in a narrow space, and can improve the strength after curing.

The steel fiber reinforced flowable high-strength concrete 9 used in the present invention is a mixture made of cement, limestone filler, and silica fume. The cement is added in the range of 250 to 450 L per 1 m ^{3 of the} mixture, and the mixture 1 m. a limestone filler is added in the range of ³ per 150～300L, and silica fume is added in the range of the mixture 1 m ³ per 50～100L, it added in an amount of 4-12% in the mixing body 1 m ³ per volume ratio A steel fiber having a diameter of 0.15 to 0.3 mm and a length of about 6 to 25 mm, a steel fiber having a diameter of 0.15 to 0.3 mm and a length of 1.0 mm or less, and water. To do.

The cement used for the steel fiber reinforced flowable high-strength concrete is preferably normal Portland cement and, if it is intended to improve the early strength of the concrete, early-strength Portland cement is preferably used. Cement is added in the range of 250 to 450 L / m ³ of the mixture. If the added amount of cement is outside the range of 250 to 450 L per 1 m ^{3 of} the mixture, high strength may not be achieved.

The limestone filler used for the steel fiber reinforced flowable high-strength concrete is a limestone powder having a density of about 27 to 28 g / cm ³ and a CaCo ₃ (calcium carbonate) component of 95% or more. Limestone filler is added in the range of 150 to 300 L per 1 m ³ of the mixture. Limestone powder has a good shape and has the effect of improving the fluidity of the cement paste. When the addition amount of the limestone filler is out of the range of 150 to 300 L per 1 m ^{3 of} the mixture, it becomes difficult to ensure adequate fluidity when filling the narrow space.

The silica fume used in the present invention is a glassy silica spherical ultrafine particle powder having a diameter of about 0.1 to 0.2 μm. Silica fume contributes to improving the strength and durability of concrete, and is effective in improving concrete construction (during kneading) by controlling the low water powder ratio. Silica fume is added in the range of 50 to 100 L per 1 m ³ of the mixture. If the amount of silica fume added is outside the range of 50 to 100 L per 1 m ³ of the mixture, the balance of the chemical composition and the particle size distribution of the mixture may be lost, and high strength after curing may not be achieved.

  Steel fiber reinforcement steel fiber for reinforcement used for fluidity high strength concrete is 0.15-0.3 mm in diameter, 6-25 mm in length, 0.15-0.3 mm in diameter, long A steel fiber having a thickness of 1.0 mm or less is combined. The combination of fine steel fibers having a length of 6 to 25 mm and a length of 1.0 mm or less is used when the reinforcing steel fibers are mixed with the mixture, and in the case of only the long steel fibers, Difficult to be evenly dispersed in the mixture. By using a combination of fine steel fibers having a short length, the reinforcing steel fibers are evenly dispersed in the mixture. The reinforcing steel fibers are added in the range of 4 to 12% by volume ratio of the mixture. If the volume ratio of the steel fibers is less than 4%, the reinforcing effect of the steel fibers is reduced, and there is a possibility that good strength cannot be obtained. When the volume ratio of steel fibers is larger than 12%, the fluidity of concrete may be lowered.

  As the water reducing agent, lignin, naphthalenesulfonic acid, melanin, polycarboxylic acid, AE water reducing agent, high performance water reducing agent, and high performance AE water reducing agent can be used. The blending amount of the water reducing agent is preferably 0.5 to 4.0 parts by weight in terms of solid content with respect to 100 parts by weight of cement in consideration of mortar fluidity, separation resistance, and strength after curing.

As the shrinkage reducing agent, a compound mainly composed of a compound represented by the chemical formula R ₁ O (A ₁₀ ) mH may be used. In the chemical formula, R ₁ is hydrogen or a linear or branched alkyl group having 1 to 6 carbon atoms. The blending amount of the shrinkage reducing agent is 0.5 to 10 parts by weight with respect to 100 parts by weight of cement in consideration of workability of mortar, separation resistance, strength after curing and resistance to cracking.

  The water / cement ratio is preferably 10 to 30 parts by weight from the flowability and separation resistance of the mortar and the strength and durability after curing.

By setting the compressive strength after hardening of the steel fiber reinforced flowable high strength concrete 9 to 150 N / mm ² or more, the concrete main girder 1 and the mounting member 5 are firmly integrated with the steel fiber reinforced flowable high strength concrete 9. The seismic strength of the concrete main girder 1 can be dramatically improved.

  FIG. 7 is a diagram showing a fifth step of the seismic reinforcement method for the main concrete girder 1. In this step, the fixing bolt 6 is rotated while the mortar of the steel fiber reinforced flowable high strength concrete 9 filled in the space between the mounting member 5 and the concrete main girder 1 surrounded by the mold 8 is uncured. The male screw portion 6b of the fixing bolt 6 is inserted into the hole 1d. When the mortar of the steel fiber reinforced flowable high-strength concrete 9 is filled in the gap between the mounting member 5 and the concrete main beam 1, an air pocket is formed at the bottom of the hole 1d which is a non-through hole.

  FIG. 8 is an enlarged view of the embodiment showing a state in which the male screw portion 6b of the fixing bolt 6 is inserted into the hole 1d. The inner diameter D of the hole 1d is formed 30 to 50 mm larger than the outer diameter of the external thread portion 6b of the fixing bolt 6. As the external thread portion of the fixing bolt 6, it is preferable to use an outer diameter of MD24 or more. When the fixing bolt 6 is rotated and the male screw portion 5b is inserted into the hole 1d, the air in the air reservoir at the bottom of the hole 1d is pushed out, and the air is discharged to the outside from the gap between the hole 1d and the male screw portion 8b. . If the difference between the inner diameter D of the hole 1d and the outer diameter d of the male screw portion 6b is too large, the effect of pushing out the air in the hole 1d due to the insertion of the male screw portion 6b is reduced, and the inner diameter D of the hole 1d and the outer diameter of the male screw portion 6b are reduced. If the difference in d is too small, the extruded air cannot be discharged smoothly.

  FIG. 9 is an enlarged view of the embodiment showing a state in which the male screw portion 6b of the fixing bolt 6 is inserted into the hole 1d. The inner diameter D of the hole 1d and the outer diameter of the portion of the fixing bolt 6 inserted into the hole 1d are made substantially the same. As shown in FIG. 10, a large-diameter portion 6c having an outer diameter d may be screwed to the tip of the male screw portion 6b in substantially the same manner as the inner diameter D of the hole 1d. By making the inner diameter D of the hole 1d and the portion of the fixing bolt 6 inserted into the hole 1d substantially the same, the surface pressure of the fixing bolt 6 can be reduced, and even non-shrinkable concrete mortar with good fluidity and slow drying can be fixed. Bolts can be fixed and cost reduction can be expected.

  The sixth step of the seismic reinforcement method for the concrete main girder 1 is a step of curing and curing the uncured concrete mortar 9 in the state shown in FIG. After confirming that the concrete mortar 9 is sufficiently cured, the mold 8 is removed. In this process, the seismic reinforcement method for one section of the concrete main girder 1 is completed. The first to sixth steps described above are sequentially performed along the bridge axis direction of the concrete main girder 1.

  As described above, according to the seismic strengthening method for a bridge concrete main girder and the seismic reinforcement structure for a bridge concrete main girder according to the present invention, mortar filling into a narrow space can be smoothly performed while suppressing the amount of suspension of the concrete main girder as much as possible. The seismic performance of the concrete main girder can be improved by firmly integrating the concrete main girder and the mounting member with concrete, and mounting of the support and the mounting member is facilitated.

  1: concrete main girder, 1a: upper flange portion, 1b: lower flange portion, 1c: web portion, 1d: hole, 2: bridge pier or abutment, 3: support, 4: reinforcing steel, 5: mounting member, 5a: horizontal Bottom part, 5b: Vertical side wall part, 5c: Female screw hole, 6: Fixing bolt, 6a: Head part, 6b: Male screw part, 6c: Large diameter part, 7: Lifting tool, 7a: Hanging wire, 8: Formwork, 9 : Concrete mortar

Claims (6)

Drilling a hole having a depth within the cover concrete at a position corresponding to a plurality of female screw holes formed on the side wall of the mounting member on the side surface of the concrete main beam,
A narrow space is provided between the bottom surface and the side surface of the concrete main girder so that the position of the hole formed on the side surface of the concrete main girder matches the position of the female screw hole formed on the side wall. Disposing a mounting member having a horizontal bottom surface and a vertical side wall screwed so that the tip of the side wall does not protrude from the side wall;
Installing a formwork on both side openings of the mounting member;
Filling the gap between the mounting member and the concrete main girder surrounded by the formwork with concrete mortar,
In a state in which the concrete mortar is uncured, rotating the fixing bolt screwed into the female screw hole of the mounting member, and inserting the tip of the fixing bolt into the hole of the concrete main beam,
Curing and hardening the concrete, and integrating the concrete main girder and the mounting member;
A seismic reinforcement method for bridge concrete main girders, characterized by comprising:   The inside diameter of the hole formed in the side surface of the concrete main girder is made larger than the outside diameter of the portion of the fixing bolt inserted into the hole, and the exhaust gap of the air remaining behind the hole when the fixing bolt is inserted into the hole The seismic reinforcement method for a concrete main girder for bridges according to claim 1, wherein the method is formed.   2. The seismic reinforcement of a concrete main girder for bridges according to claim 1, wherein an inner diameter of a hole formed on a side surface of the concrete main girder is substantially the same as an outer diameter of a portion of the fixing bolt inserted into the hole. Construction method.   The seismic reinforcement method for a concrete main girder for bridges according to any one of claims 1 to 3, wherein as the concrete mortar, non-shrinkable concrete mortar or steel fiber reinforced fluidity high strength concrete mortar is used. The steel fiber reinforced high fluidity high strength concrete, cement, limestone filler, the mixture comprising silica fume, cement is added in the range of the mixture 1 m ³ per 250～450L, the mixture 1 m ³ per 150 Limestone filler added in the range of 300 L, silica fume added in the range of 50 to 100 L per 1 m ^{3 of the} mixture, and diameter 0 added in the range of 4 to 12% by volume ratio per 1 m ^{3 of the} mixture A steel fiber having a length of about 15 to 0.3 mm and a length of about 6 to 25 mm, a steel fiber having a diameter of 0.15 to 0.3 mm and a length of 1.0 mm or less, and water are kneaded and formed. The seismic reinforcement method for a concrete main girder for bridges according to claim 4.   6. The seismic reinforcement method for a bridge concrete main girder according to claim 5, wherein the steel fiber reinforced flowable high strength concrete is added with a water reducing agent and a shrinkage reducing agent.

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