JP6845456B1 - How to replace concrete bridges with precast floor slabs - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for replacing a concrete bridge with a precast slab, which can effectively fix a tensile resistance material such as a stirrup of a main girder and replace it with a precast slab. SOLUTION: In a method of replacing an RC slab of a concrete bridge with a precast slab of a concrete bridge, the upper part of a main girder to be joined to the RC slab of a concrete bridge is scraped off and a stirrup or the like is used. The upper part of the tensile resistance material was exposed, and the exposed tensile resistance material was cut in the middle and effectively fixed by mechanical fixing means to reduce the effective concrete of the main girder and the effective concrete. Place the precast floor slab on the girder. [Selection diagram] FIG. 9

Description

The present invention relates to a replacement method for replacing a cast-in-place RC slab of a concrete bridge with a precast slab.

In bridges such as road bridges, concrete slabs are damaged by repeated wheel loads due to vehicle traffic, so after a certain period of time, the damaged old RC slabs are removed from the bridge girders and replaced with new slabs. It is being replaced and updated. In recent years, new floor slabs have been updated to precast floor slabs. This is because the precast floor slab is manufactured in a factory or the like where the surrounding environment is prepared, so that a high-quality product can be stably supplied and the renewal work period can be shortened.

For example, Patent Document 1 discloses a method for replacing a precast floor slab for a PC synthetic girder, which replaces a cast-in-place RC floor slab of a concrete bridge of a T-type synthetic girder with a precast floor slab for a PC synthetic girder (Patent Document 1). 1), paragraphs [0034] to [0041] of the specification, FIGS. 5 to 14 of the drawings, and the like).

However, in the method for replacing the precast water slab for PC synthetic girder described in Patent Document 1, the slip-preventing reinforcing bar 12 and the stirrup 13 of the main girder 3 are used at the joint portion of the integrated synthetic girder with the RC water slab. Since it is necessary to leave it, a large amount of concrete must be scraped with ultra-high pressure water such as a breaker or a water jet, which causes a problem that it takes a long time to work.

Further, in the method of replacing the precast floor slab for PC composite girder described in Patent Document 1, in order to leave the anti-slip reinforcing bar 12 and the stirrup 13 arranged on the main girder, the steel plate embedded in the precast floor slab is used. There is a problem that it is difficult to install the precast floor slab at an appropriate position because the reinforcing bars interfere with each other, or it takes time to install the precast floor slab.

In addition, in the method for replacing the precast floor slab for PC synthetic girders described in Patent Document 1, a space for fixing the anti-slip reinforcing bars 12 and the stirrup 13 under the precast floor slab for PC synthetic girders and the upper part of the space. Since the floor slab thickness for arranging the horizontal tightening PC steel material is required, the thickness of the floor slab after renewal becomes thicker than before renewal, and there is a problem that the remaining main girder and substructure are burdened. There was also.

In order to solve such a problem, it is conceivable to cut the anti-slip reinforcing bar or the stirrup in the middle. However, according to the idea of the road specification, the stirrup, which is a tensile resistance material for synthetic girders, must be designed based on the truss theory, and the load-bearing mechanism cannot be established unless it is fixed to the compressed chord material, and the main girder. There is a problem that the web part of is not functioning effectively. Therefore, when such a problem is solved and the RC floor slab of a concrete bridge made of synthetic girders is replaced with a precast floor slab, the cut stirrup is effectively fixed and the RC floor slab is replaced with a precast floor slab. There was a longing for a way to update to.

Japanese Unexamined Patent Publication No. 2019-132070

Therefore, the present invention has been devised in view of the above-mentioned problems, and the purpose of the present invention is to effectively fix a tensile resistance material such as a stirrup of a main girder and replace it with a precast floor slab. The purpose is to provide a possible replacement method for precast slabs of concrete bridges.

The method of replacing the RC slab of a concrete bridge with a precast slab according to the first invention is a method of replacing the RC slab of a concrete bridge with a precast slab of a concrete bridge, and is a method of replacing the RC floor of a concrete bridge with a precast slab. The upper part of the main girder to be joined to the plate is scraped off to expose the upper part of the tensile resistance material made of reinforced concrete , and the exposed tensile resistance material is cut in the middle to cut the mechanical fixing means into the tensile resistance material. It is characterized in that the precast floor slab is placed on the main girder after being fixed so that the tensile resistance material is fixed so as not to shift in the material axial direction.

The method for replacing a concrete bridge with a precast slab according to the second invention is that in the first invention, the mechanical fixing means is a steel pipe crimping type in which a steel pipe is crimped to the tensile resistance material, and the main girder. It is characterized by having a tensile resistance material fixing step of crimping a steel pipe to the tension resistance material exposed above and fixing the steel pipe.

The method for replacing a concrete bridge with a precast floor slab according to the third invention is the wedge fixing type in which the mechanical fixing means is a wedge fixing type in which a steel pipe is externally fitted to the tensile resistance material and fixed with a wedge. It is characterized by having a tensile resistance material fixing step in which a steel pipe is externally fitted to the tensile resistance material exposed on the main girder and fixed with a wedge to fix the tension resistance material.

The method for replacing a concrete bridge with a precast floor slab according to the fourth invention is that in the first invention, the mechanical fixing means is a screw in which a nut is screwed into a screw formed on the outer peripheral surface of the tensile resistance material. It is a fixing type, and after forming a screw groove on the outer peripheral surface of the tensile resistance material exposed on the main girder, the nut is screwed into the screw groove of the tensile resistance material to fix the tensile resistance material. It is characterized by having a process.

In the method of replacing the concrete bridge with the precast slab according to the fifth invention, in any one of the first to fourth inventions, the upper surface of the main girder around the exposed tensile resistance material is adjusted to be non-landing. It is characterized in that the mechanical fixing means is attached to the tensile resistance material after the non-landing adjustment is performed so that the material becomes smooth.

According to the first to fifth inventions, a high-quality precast slab is newly installed to replace an old and damaged existing RC slab by effectively fixing a tensile resistance material such as a stirrup of a main girder of a concrete bridge. Can be replaced with. Therefore, the existing concrete bridge can be renewed at low cost and in a short period of time, and the existing concrete bridge can be appropriately maintained to achieve a long life.

In particular, according to the second to fourth inventions, it is not necessary to bring a large device to the site, and it is possible to easily and easily fix a tensile resistance material such as a stirrup at a floor slab renewal site of a concrete bridge.

In particular, according to the fifth invention, the tensile resistance material such as stirrup can be more appropriately fixed, and the life of the existing concrete bridge can be extended.

FIG. 1 is a vertical cross-sectional view showing a state in which a bridge to which a method for replacing a concrete bridge according to an embodiment of the present invention is replaced with a precast slab is vertically cut in a direction perpendicular to the bridge axis. FIG. 2 is an enlarged view of part A of FIG. FIG. 3 is a process explanatory view showing the step of removing the floor slab of the method of replacing the concrete bridge with the precast floor slab according to the embodiment of the present invention in an overall cross-sectional view cut along the direction Y perpendicular to the bridge axis. FIG. 4 is a process explanatory view showing an enlarged cross-sectional view of the main girder upper chipping step of the method of replacing the concrete bridge with the precast floor slab according to the embodiment of the present invention. It shows before the main girder upper chipping process, and (b) shows after the main girder upper chipping process. FIG. 5 is a process explanatory view showing an enlarged cross-sectional view of a portion B of FIG. 4 showing a non-landing adjustment step of a method of replacing a concrete bridge with a precast slab according to an embodiment of the present invention. FIG. 6 is an enlarged cross-sectional view showing a tensile resistance material fixing step of a method for replacing a concrete bridge with a precast floor slab according to an embodiment of the present invention. FIG. 7 is a process explanatory view showing a case where the tensile resistance material fixing step is performed by using the mechanical fixing means according to the second embodiment. FIG. 8 is a process explanatory view showing a case where the tensile resistance material fixing step is performed by using the mechanical fixing means according to the third embodiment. FIG. 9 is a process explanatory view showing an overall cross-sectional view of the precast slab mounting step of the method for replacing the concrete bridge with the precast slab according to the embodiment of the present invention, cut along the direction Y perpendicular to the bridge axis. is there. 10A and 10B are process explanatory views when the present invention is applied to a box girder bridge, in which FIG. 10A shows before updating, FIG. 10B shows when the floor slab is removed, and FIG. 10C shows after updating. FIG. 11 is a process explanatory view when the present invention is applied to a floor slab bridge of a hollow floor slab (hollow slab), where (a) is before renewal, (b) is when the floor slab is removed, and (c) is after renewal. Is shown.

Hereinafter, an embodiment for implementing a method for replacing a concrete bridge according to the present invention with a precast slab will be described in detail with reference to the drawings.

A method of replacing a concrete bridge with a precast slab according to an embodiment of the present invention will be described with reference to FIGS. 1 to 11. A T-girder bridge will be described as an example of a bridge to which the method of replacing the concrete bridge according to the embodiment of the present invention with a precast slab is applied.

<Bridge>
First, with reference to FIGS. 1 and 2, a bridge to which the method of replacing the concrete bridge according to the embodiment of the present invention with a precast slab is applied will be briefly described. FIG. 1 is a vertical cross-sectional view showing a state in which a bridge to which the method for replacing a concrete bridge according to an embodiment of the present invention is replaced with a precast slab is vertically cut in a direction perpendicular to the bridge axis, and FIG. 2 is a vertical cross-sectional view. It is an enlarged view of the part A of FIG.

The bridge B1 to which the present invention is applied is a reinforced concrete (RC) bridge used as a road bridge, and includes four reinforced concrete (prestressed concrete PC girders) as shown in FIGS. 1 and 2. It is composed of T girders G1 to G4, which are the main girders of (the same applies hereinafter), and a cast-in-place RC slab F1 which is a synthetic slab joined to the upper parts of these T girders G1 to G4. Further, along the edges on both sides of the RC floor slab F1, a wall balustrade W1 and a ground covering portion W2 are formed as a bollard. However, facilities and asphalt pavement installed above the wall balustrade W1 and the ground cover W2 are not necessarily installed, so they are omitted.

The X direction in the figure refers to the bridge axis direction along the axial directions of the T girders G1 to G4 of the bridge B1, and the Y direction is the horizontal direction perpendicular to the bridge axis direction X of the bridge B1. Is pointing to. Further, the Z direction refers to the vertical direction, which is the vertical direction.

Further, as shown in FIG. 2, the stirrup Sr, which is a tensile resistance material of the main girder T girder G2 (G1, G3, G4), has an upper portion extending to the RC floor slab F1 and has a fixing length with a hook. It is secured and fixed in the upper part F1a of the main girder of the RC floor slab F1. Further, a U-shaped slip-preventing reinforcing bar S1 is arranged on the upper part F1a of the main girder to be joined to the T girder G2 of the bridge B1. Then, oblique streaks S2 continuous up to the T girder G2 are arranged on the haunch portion of the RC floor slab F1. In this way, the bridge B1 is a site-made synthetic girder bridge in which the T girder G2 and the RC floor slab F1 are integrated to counter external forces.

Next, a specific procedure of the method of replacing the concrete bridge with the precast slab according to the embodiment of the present invention will be described with reference to FIGS. 3 to 9.

(Floor slab removal process)
FIG. 3 is a process explanatory view showing the step of removing the floor slab of the method of replacing the concrete bridge with the precast floor slab according to the embodiment of the present invention in an overall cross-sectional view cut along the direction Y perpendicular to the bridge axis. First, in the method of replacing the concrete bridge with the precast floor slab according to the present embodiment, as shown in FIG. 3, a floor slab removing step of cutting and removing the RC floor slab F1 is performed.

Specifically, using a large rotary cutting device called a wall saw or a diamond cutter, the RC slab F1 beside the T girders G1 to G4 indicated by ▽ in the figure is cut along the bridge axis direction X. , RC floor slab F1 is cut along the direction Y perpendicular to the bridge axis, and RC floor slab F1 is subdivided. After that, the RC floor slab F1 that has been lifted by a lifting machine such as a crane and divided into small pieces is carried out, and concrete is crushed and dismantled and removed using a breaker or the like at another place.

(Main girder upper part chipping process)
FIG. 4 is a process explanatory view showing an enlarged cross-sectional view of the main girder upper chipping step of the method of replacing the concrete bridge with the precast floor slab according to the embodiment of the present invention. It shows before the main girder upper chipping process, and (b) shows after the main girder upper chipping process. Next, in the method of replacing the concrete bridge with the precast floor slab according to the present embodiment, as shown in FIG. 4, the main girder upper part scraping step of scraping the main girder upper part F1a of the RC floor slab F1 of the bridge B1. I do.

Specifically, using a chipping device such as a water jet, the concrete of the upper part F1a of the main girder, which is the remainder of the RC floor slab F1 removed in the front floor slab removal process other than the T girders G1 to G4, is scraped off. , Also cut and remove the internal reinforcing bars. However, as shown in FIG. 4, the stirrup Sr is exposed by leaving the upper portion for a predetermined length (about 50 mm to 100 mm in the embodiment) required for attaching the mechanical fixing means described later, and the rest is removed. Remove it together with other internal reinforcing bars that interfere with the replacement work.

The end faces exposed to the outside after cutting of the slip prevention reinforcing bars S1 and the oblique bars S2 are subjected to rust preventive end face treatment such as applying a rust preventive resin.

(Non-land adjustment process)
FIG. 5 is a process explanatory view showing an enlarged cross-sectional view of a portion B of FIG. 4 showing a non-landing adjustment step of a method of replacing a concrete bridge with a precast slab according to an embodiment of the present invention. Next, in the method of replacing the concrete bridge with the precast slab according to the present embodiment, as shown in FIG. 5, the upper surface of the T girders G1 to G4 is smoothed by the non-landing adjusting material P. Perform a non-land adjustment process.

Specifically, the upper surface of the T-girder G2, which has been scraped off in the upper part of the front main girder to form irregularities, is cleaned, a primer for concrete is applied, and at least around the exposed stirrup Sr. A putty-like non-landing adjusting material P is applied to the upper surfaces of the T-girders G1 to G4 to adjust the non-landing so as to be smooth.

Examples of the primer include an epoxy-based primer, an acrylic-based primer, and a urethane-based primer. Further, examples of the non-landing adjusting material P include inorganic type, organic type (for example, epoxy type, acrylic type, urea type, urethane type), resin mortar and the like. However, the non-landing adjusting material used in the present invention can be applied as long as it has a predetermined viscosity and is in the form of a putty that can be adhered to concrete via a primer.

Further, in this step, not only the periphery of the stirrup Sr but also the entire upper surface of the T girders G1 to G4 may be smoothed. This is because the precast floor slab installation process, which is a post-process, can be easily executed. However, this step may not be carried out, and the next step may be carried out suddenly. This is because the stirrup Sr can be fixed if the next step is executed without performing the non-landing adjustment.

(Tensile resistance material fixing process)
FIG. 6 is an enlarged cross-sectional view showing a tensile resistance material fixing step of a method for replacing a concrete bridge with a precast floor slab according to an embodiment of the present invention. Next, in the method of replacing the concrete bridge with the precast floor slab according to the present embodiment, the mechanical fixing means 1 according to the first embodiment shown in FIG. 6 is fixed to the stirrup Sr which is a tensile resistance material. A tensile resistance material fixing step is performed in which the tensile resistance material is fixed so as not to shift in the material axial direction.

Specifically, as shown in FIG. 6, a cylindrical steel material P1 is externally fitted to the exposed portion on the main girder of the T girders G1 to G4 of the stirrup Sr left in the upper cutting process of the front main girder, and a hydraulic device or the like is used. Crimping. That is, the mechanical fixing means 1 according to the first embodiment is a steel pipe crimping type reinforcing bar fixing means for crimping a cylindrical steel material P1 to a deformed steel rod (reinforcing bar) which is a tensile resistance material. Of course, the steel material to be crimped is not limited to a cylindrical shape, and may be a polygonal tubular body such as a nut or a square tubular steel material.

Next, a case where the tensile resistance material fixing step is performed by using the mechanical fixing means 2 according to the second embodiment different from the embodiment of FIG. 6 will be described. FIG. 7 is a process explanatory view showing a case where the tensile resistance material fixing step is performed by using the mechanical fixing means according to the second embodiment. As shown in FIG. 7, in this step, the cylindrical steel material P2 is externally fitted to the exposed portion on the main girder of the T girders G1 to G4 of the stirrup Sr left in the front main girder upper part scraping step to form the cylindrical steel material P2. Drive the wedge K1 into the gap between the stirrup Sr and fix it. That is, the mechanical fixing means 2 according to the second embodiment is a wedge fixing type reinforcing bar fixing means for fixing a cylindrical steel material P2 to a deformed steel rod (reinforcing bar) which is a tensile resistance material by using a wedge K1.

Next, a case where the tensile resistance material fixing step is performed by using the mechanical fixing means 3 according to the third embodiment will be described. FIG. 8 is a process explanatory view showing a case where the tensile resistance material fixing step is performed by using the mechanical fixing means according to the third embodiment. As shown in FIG. 8, in this step, a screw groove is cut on the outer peripheral surface of the exposed portion on the main girder of the T girders G1 to G4 of the stirrup Sr left in the upper cutting step of the front main girder, and the screw groove is formed. Screw the long nut P3 to be screwed. That is, the mechanical fixing means 3 according to the third embodiment is a screw fixing type reinforcing bar fixing means for screwing a long nut P3 into a deformed steel rod (reinforcing bar) which is a tensile resistance material. Of course, the shape of the long nut is not particularly limited, and a tubular body having a thread thread to be screwed with the thread groove cut on the inner peripheral surface can be formed.

Although the mechanical fixing means 1 to 3 according to the first to third embodiments have been exemplified and described above as the fixing means of the stirrup Sr which is a tensile resistance material, other mechanical fixing means applicable to the present invention have been described above. As the means, a mechanical fixing means in which a tubular steel material is externally fitted into a stirrup and a filler made of a time-curing material is filled and cured in the meantime to be fixed, or these mechanical fixing means 1 to 3 and a filler are used. It can also be used as a mechanical fixing means in combination with the above. As the filler made of the time-curing material, an inorganic type, an organic type (for example, an epoxy type, an acrylic type, a urea type, a urethane type), a resin mortar, or the like is adopted as in the case of the non-landing adjusting material P described above. can do.

In short, the mechanical fixing means applicable to the present invention has a portion larger than the diameter of the steel material, and the fixing body that enhances the adhesive force with the concrete against the tensile force acting in the axial direction of the steel material is firmly formed. Any fixed mechanical fixing may be used.

(Precast floor slab placement process)
FIG. 9 is a process explanatory view showing an overall cross-sectional view of the precast slab mounting step of the method for replacing the concrete bridge with the precast slab according to the embodiment of the present invention, cut along the direction Y perpendicular to the bridge axis. is there. Next, in the method of replacing the concrete bridge with the precast floor slab according to the present embodiment, the precast floor slab placing step of placing the precast floor slab on the main girder is performed.

Specifically, the precast floor slab 5 is placed on the T girders G1 to G4 using a lifting machine such as a crane, and the precast floor slab 5 is fixed on the upper surface of the T girders G1 to G4 in the front tensile resistance material fixing process. A filler M such as non-shrink mortar is filled around the means 1 to 3 and between the precast floor slab 5 and the T girders G1 to G4 and cured. Then, by the completion of this step, the work of updating the concrete bridge to the precast floor slab according to the method of replacing the concrete bridge with the precast floor slab according to the present embodiment is completed.

According to the method for replacing the concrete bridge with the precast floor slab according to the embodiment of the present invention described above, the stirrup Sr of the T girders G1 to G4, which are the main girders of the bridge B1, is mechanically fixed to the means 1 to 3 and the like. The old and damaged RC floor slab F1 can be replaced with a new high-quality precast floor slab 5. Therefore, the floor slab of the existing concrete bridge B1 can be renewed at low cost and in a short period of time, and appropriate maintenance can be achieved to extend the life of the bridge B1.

Further, according to the method of replacing the concrete bridge with the precast floor slab according to the present embodiment, the upper surface of the T girders G1 to G4 is smoothed before being fixed to the stirrup Sr by the mechanical fixing means 1 to 3 and the like. Since the non-land adjustment step for adjusting the non-land is performed, the tensile resistance material such as stirrup can be more appropriately fixed, and the life of the existing concrete bridge can be extended. Further, in the non-landing adjustment step, by smoothing the entire upper surface of the T girders G1 to G4, the precast floor slab installation step can be easily executed in a short time.

The method of replacing the concrete bridge with the precast floor slab according to the embodiment of the present invention has been described in detail above, but any of the above-mentioned or illustrated embodiments is one embodiment embodied in carrying out the present invention. It is just an indication of. Therefore, the technical scope of the present invention should not be construed in a limited manner by these.

In particular, the T-girder bridge has been described as an example of a bridge to which the present invention is applied, but the bridge is not limited to the T-girder bridge. For example, as shown in FIG. 10, the present invention can also be applied to updating a concrete slab of a box girder bridge to a precast slab. Further, as shown in FIG. 11, the present invention can also be applied to updating a concrete slab of a slab bridge having a hollow slab (hollow slab) to a precast slab. In short, the present invention can be applied when replacing the RC slab of a concrete bridge with a precast slab.

1,2,3: Mechanical fixing means P1: Cylindrical steel material P2: Cylindrical steel material K1: Wedge P3: Long nut M: Filler P: Non-landing adjustment material 5: Precast floor slab B1: Bridge G1 to G4: T girder ( Main girder)
S1: Anti-slip rebar S2: Oblique rebar Sr: Stirrup (tensile resistance material)
F1: RC floor slab F1a: Main girder upper part W1: Wall railing W2: Ground covering part P1: Pavement W1, W2: Ground covering part X: Bridge axis direction Y: Bridge axis perpendicular direction Z: Vertical direction

Claims (5)

Replacing the RC slab of a concrete bridge with a precast slab This is a method of replacing a concrete bridge with a precast slab.
The upper part of the main girder to be joined to the RC slab of the concrete bridge was scraped off to expose the upper part of the tensile resistance material made of reinforcing bars , and the exposed tensile resistance material was cut in the middle to cut the mechanical fixing means . On a precast slab of a concrete bridge, which is fixed to the tensile resistance material and fixed so that the tensile resistance material does not shift in the material axial direction, and a precast slab is placed on the main girder. Replacement method. The mechanical fixing means is a steel pipe crimping type in which a steel pipe is crimped to the tensile resistance material.
The method for replacing a concrete bridge with a precast slab according to claim 1, further comprising a tensile resistance material fixing step of crimping and fixing a steel pipe to the tensile resistance material exposed on the main girder. The mechanical fixing means is a wedge fixing type in which a steel pipe is fitted onto the tensile resistance material and fixed with a wedge.
The precast slab of a concrete bridge according to claim 1, further comprising a tensile resistance material fixing step of externally fitting a steel pipe to the tensile resistance material exposed on the main girder and fixing and fixing the steel pipe with a wedge. How to replace with. The mechanical fixing means is a screw fixing type in which a nut is screwed into a screw formed on the outer peripheral surface of the tensile resistance material.
Having a tensile resistance material fixing step of forming a screw groove on the outer peripheral surface of the tensile resistance material exposed on the main girder and then screwing the nut into the screw groove of the tensile resistance material to fix the tension material. The method for replacing a concrete bridge according to claim 1 with a precast slab. The feature is that the mechanical fixing means is attached to the tensile resistance material after the non-land adjustment is performed so that the upper surface of the main girder around the exposed tensile resistance material is smoothed by the non-land adjustment material. The method for replacing a concrete bridge with a precast slab according to any one of claims 1 to 4.

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