Anchor bolt installation method and bracket mounting structure for existing bridge pier

Abstract

To provide an anchor bolt installation method that can sufficiently ensure pull-out resistance of anchor bolts fixed to existing bridge piers while suppressing an increase in the weight of the existing bridge piers.SOLUTION: An anchor bolt 20 installation method for an existing concrete pier 2 includes a process of removing a portion of the side end 2c of the existing pier 2, a process of casting fiber-reinforced concrete into the cut-finished surface 2d formed on the side end 2c of the existing pier 2 to form a replacement section 10, and a process of fixing the anchor bolts 20 to the replacement section 10.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a method for installing anchor bolts in existing bridge piers and a bracket mounting structure. [Background technology]

[0002] In seismic reinforcement of an existing bridge, when replacing the bearings between the piers and the bridge girder, multiple anchor bolts are fixed to the side ends of the upper part of the pier, and brackets are attached to each anchor bolt, thereby installing the brackets on the outer surface of the upper part of the pier. Then, a jack is installed on the top surface of the bracket, and the bearing is replaced while supporting the bridge girder with the jack (see, for example, Patent Document 1). In addition, if a horizontal force distribution structure is installed on the top surface of the bracket after replacing the bearings, the seismic performance of the bridge can be improved. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-212916 Summary of the Invention [Problem to be solved by the invention]

[0004] If the distance from the side end face of the pier to the anchor bolt is small, it may not be possible to ensure sufficient pull-out strength of the anchor bolt. In this case, concrete is added to the side end face of the pier to increase the cross section of the pier in the bridge width direction, thereby ensuring the pull-out strength of the anchor bolt. With this configuration, the weight of the pier increases, so it may be necessary to reinforce the base of the pier.

[0005] An object of the present invention is to solve the above-mentioned problems and to provide an anchor bolt installation method and bracket mounting structure that can sufficiently ensure the pull-out strength of anchor bolts fixed to existing piers while suppressing an increase in the weight of the existing piers. [Means for solving the problem]

[0006] In order to solve the above-mentioned problems, the first invention is a method for installing anchor bolts in existing concrete piers, which includes a concrete removal step of removing a portion of the side end of the existing pier, a fiber-reinforced concrete pouring step of pouring fiber-reinforced concrete into the machined finished surface formed on the side end of the existing pier in the concrete removal step to form a replacement portion, and an anchor bolt fixing step of fixing an anchor bolt in the replacement portion.

[0007] In order to solve the above-mentioned problems, the second invention is a method for installing anchor bolts in existing concrete piers, comprising: a concrete removal step of removing a portion of the side end of the existing pier; an anchor bolt placement step of placing an anchor bolt to the side of a machined finished surface formed on the side end of the existing pier in the concrete removal step; and a fiber-reinforced concrete pouring step of pouring fiber-reinforced concrete into the machined finished surface to form a replacement section, and fixing the anchor bolt to the replacement section.

[0008] The type of fiber that can be incorporated into the fiber-reinforced concrete of the present invention is not limited. For example, metal fibers (such as steel fibers), synthetic fibers (such as carbon fibers, PVA (polyvinyl alcohol) fibers, and aramid fibers), and inorganic fibers (such as silica fibers and basalt fibers) can be incorporated into the concrete.

[0009] In this invention, a portion of the side end of an existing bridge pier is replaced with fiber-reinforced concrete, and an anchor bolt is fixed to the replaced portion. Since the pull-out strength of an anchor bolt is correlated with the compressive strength of concrete, fixing the anchor bolt to fiber-reinforced concrete, which has high compressive strength and tensile properties, can ensure sufficient pull-out strength of the anchor bolt. In the present invention, a portion of the side end of the existing pier is removed, and then fiber-reinforced concrete is poured onto the machined finished surface of the side end. This reduces the increase in weight of the existing pier compared to when additional concrete is added without removing a portion of the side end of the existing pier.

[0010] In the fiber-reinforced concrete pouring step in the anchor bolt installation method described above, it is preferable to form the replacement portion by pouring the fiber-reinforced concrete onto the cut-finished surface within the range of the side end portion of the existing pier before removing a portion of the side end portion of the existing pier. This configuration reduces the size of the replacement section, suppressing the increase in weight of the existing pier and preventing the existing pier from exceeding its construction limit.

[0011] In the above-described anchor bolt installation method, if the existing pier is made of reinforced concrete, it is preferable that the concrete at the side end of the existing pier is removed to expose the reinforcing bars in the concrete removal step. Then, by burying the existing reinforcing bars in the replacement parts, it is possible to reduce construction costs and shorten the construction period.

[0012] In order to solve the above problem, the third invention is a bracket mounting structure for an existing concrete pier, which comprises a replacement section formed by replacing part of the concrete at the side end of the existing pier with fiber-reinforced concrete, an anchor bolt fixed to the replacement section, and a bracket attached to the anchor bolt.

[0013] In this configuration, by fixing the anchor bolt to the replaced part made of fiber-reinforced concrete, the weight increase of the existing pier is suppressed while the pull-out strength of the anchor bolt is sufficiently ensured, allowing the bracket to be stably installed on the existing pier. [Effects of the Invention]

[0014] In the anchor bolt installation method and bracket mounting structure for existing bridge piers of the present invention, by fixing the anchor bolt to the replaced part made of fiber-reinforced concrete, it is possible to suppress an increase in the weight of the existing bridge pier while ensuring sufficient pull-out strength of the anchor bolt. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a front view showing an existing bridge pier to which the bracket mounting structure according to the first embodiment is applied. FIG. [Figure 2] FIG. 10 is a front view showing a concrete removing step in the anchor bolt installation method according to the first embodiment. [Figure 3] FIG. 2 is a front view showing a fiber-reinforced concrete pouring step in the anchor bolt installation method according to the first embodiment. [Figure 4] FIG. 2 is a front view showing an anchor bolt fixing step in the anchor bolt installation method according to the first embodiment. [Figure 5] 5 is a VV cross-sectional view of FIG. 4 illustrating the anchor bolt fixing step in the anchor bolt installation method according to the first embodiment. [Figure 6] 1 is a side cross-sectional view showing a state in which a jack is installed on a bracket in a bracket mounting structure according to a first embodiment. FIG. [Figure 7] FIG. 3 is a side cross-sectional view showing a state in which a horizontal force distributing structure is installed on a bracket in the bracket mounting structure according to the first embodiment. [Figure 8] FIG. 10 is a front view showing an anchor bolt placement step in the anchor bolt installation method according to the second embodiment. [Figure 9] FIG. 10 is a front view showing a fiber-reinforced concrete pouring step in the anchor bolt installation method according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the description of each embodiment, the same components are denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0017] [First embodiment] FIG. 1 is a front view showing an existing bridge pier to which a bracket mounting structure according to a first embodiment is applied. As shown in Figure 1, the mounting structure 1 for the bracket 30 of the first embodiment comprises a replacement portion 10 formed in the protruding portion 2b of the existing pier 2, a plurality of anchor bolts 20 fixed to the replacement portion 10, and a bracket 30 attached to each anchor bolt 20. The existing bridge pier 2 is made of reinforced concrete and consists of a column 2a erected on a foundation structure 3 buried in the ground, and overhangs 2b extending from the top of the column 2a on both sides in the direction of the bridge width. A bridge girder 4 is placed on the top surface of the overhang 2b via a bearing 5. The mounting structures 1, 1 of this embodiment are provided at both end portions 2c, 2c of the overhanging portion 2b in the pier width direction.

[0018] Fig. 2 is a front view showing a concrete removing step in the anchor bolt installation method according to the first embodiment. Fig. 3 is a front view showing a fiber-reinforced concrete pouring step in the anchor bolt installation method according to the first embodiment. As shown in Figure 2, a machined surface 2d is formed on the end face of the overhanging portion 2b in the bridge width direction (the horizontal direction perpendicular to the bridge axis direction). The machined surface 2d is a processed surface formed by chipping off the end of the existing side end portion 2c of the overhanging portion 2b in the bridge width direction.

[0019] As shown in Figure 3, the replacement section 10 is a section formed by pouring fiber-reinforced concrete onto the machined surface 2d formed on the side end 2c of the overhanging section 2b. In other words, the replacement section 10 is a section where part of the concrete of the existing overhanging section 2b has been replaced with fiber-reinforced concrete.

[0020] The replacement section 10 is formed within the range of the side end 2c of the existing overhanging section 2b before the end is removed (within the range indicated by the two-dot chain line in FIG. 2). The weight of the replacement section 10 is approximately the same as the weight of the concrete removed from the side end 2c of the existing overhanging section 2b.

[0021] The fiber-reinforced concrete in the replacement section 10 is made by mixing fibers such as metal fibers, synthetic fibers, and inorganic fibers into the concrete. Note that there are no limitations on the type, size, and mixing ratio of the fibers mixed into the concrete. The fiber reinforced concrete of the replacement part 10 is configured to have a greater compressive strength than the concrete that constitutes the existing protruding part 2b. For example, the fiber reinforced concrete of the first embodiment is made by mixing fibers with a diameter of 0.01 to 1.00 mm and a length of 60 mm or less into the concrete at a mixing rate of 0.05 to 5.00 vol%, and has a compressive strength of 30 N / mm 2 It is set to above.

[0022] FIG. 5 is a VV cross-sectional view of FIG. 4, illustrating the anchor bolt fixing step in the anchor bolt installation method according to the first embodiment. The anchor bolt 20 is provided on the surface of the overhanging portion 2b in the bridge axis direction. As shown in Figure 5, the base of the anchor bolt 20 is fixed in a state where it is embedded in the overhanging portion 2b, and the tip of the anchor bolt 20 protrudes from the surface of the overhanging portion 2b in the bridge axis direction.

[0023] FIG. 4 is a front view showing the anchor bolt fixing step in the anchor bolt installation method according to the first embodiment. In the first embodiment, multiple anchor bolts 20 are arranged at intervals in the vertical and horizontal directions, as shown in Fig. 4. Of the multiple anchor bolts 20, each of the anchor bolts 20 in a vertical row arranged on the side furthest to the side edge in the bridge axis direction of the overhanging portion 2b is fixed to the replacement portion 10.

[0024] The bracket 30 comprises a flat plate 31 abutted against the bridge axis direction surface of the protruding portion 2b, a plurality of vertical ribs 32 extending from the flat plate 31 in the bridge axis direction, and an upper plate 33 extending from the upper edge of the flat plate 31 in the bridge axis direction (see Figure 5). As shown in Fig. 5, the tip of each anchor bolt 20 is inserted into a plurality of mounting holes formed in the flat plate 31 of the bracket 30. Then, nuts are screwed onto the tip of the anchor bolt 20, thereby fixing the bracket 30 to the surface of the overhanging portion 2b in the bridge axis direction.

[0025] Next, a method for installing the anchor bolt 20 of the first embodiment will be described. (Concrete removal process) In the concrete removal process, as shown in Figure 2, the end of the side end 2c of the overhanging portion 2b of the existing pier 2 is chipped off and removed. One method for removing the end of the side end 2c of the overhanging portion 2b is, for example, the water jet method, which involves spraying high-pressure water onto the concrete to scrape it off. With the water jet method, only the concrete at the end of the side end 2c of the overhanging portion 2b is removed, exposing the existing reinforcing bars 2e that were buried at the end of the side end 2c of the overhanging portion 2b. Furthermore, when the end of the side end 2c of the overhanging portion 2b is removed, a machined surface 2d is formed on the side end 2c. Fine irregularities are formed on the machined surface 2d. Reinforcing bars 2e protrude from the machined surface 2d in the bridge width direction.

[0026] (Fiber reinforced concrete pouring process) In the fiber-reinforced concrete pouring step, as shown in Fig. 3, fiber-reinforced concrete is poured onto the machined finished surface 2d formed on the side end 2c of the overhanging portion 2b to form the replaced portion 10. As a result, the concrete at the end of the side end 2c of the overhanging portion 2b is replaced with fiber-reinforced concrete. In this case, since fine irregularities are formed on the machined surface 2d of the side end 2c of the protrusion 2b when the concrete is removed, there is no need to roughen the machined surface 2d when pouring the fiber-reinforced concrete. As shown in FIG. 3, reinforcing bars 2e are embedded in the replacing portion 10, protruding from the machined surface 2d.

[0027] The replacement portion 10 is formed by pouring fiber reinforced concrete onto the cut-finished surface 2d within the range of the side end portion 2c of the protruding portion 2b before the concrete removal step (the range indicated by the two-dot chain line in FIG. 2). Specifically, formwork (not shown) is installed to fit the underside of the side end 2c before the concrete removal process, the side surface in the bridge width direction, and the side surface in the bridge axis direction (front and back), and then fiber-reinforced concrete is poured into the formwork. In this embodiment, the underside and side surface in the bridge axis direction of the replacement part 10 are flush with the underside of the side end 2c and the side surface in the bridge axis direction. In the first embodiment, the replacement section 10 is formed in an area substantially the same as the area of ​​the side end 2c of the overhanging section 2b before the end of the side end 2c of the overhanging section 2b is removed, but the size is not limited thereto. The replacement section 10 may be large enough to fix a plurality of anchor bolts 20 in a vertical row, as shown in Figure 4.

[0028] (Anchor bolt fixing process) In the anchor bolt fixing process, a plurality of anchor bolts 20 are fixed to the surface of the overhanging portion 2b in the bridge axis direction. At this time, each of the anchor bolts 20 in a row arranged on the side edge side of the overhanging portion 2b in the bridge axis direction is fixed to the replacement portion 10.

[0029] After fixing the anchor bolts 20 to the overhanging portion 2b in the above manner, as shown in Fig. 5, the flat plate 31 of the bracket 30 is placed on the surface of the overhanging portion 2b in the bridge axis direction, and the tip of each anchor bolt 20 is inserted into each mounting hole of the flat plate 31. Furthermore, nuts are screwed onto the tip of the anchor bolt 20 to fix the bracket 30 to the overhanging portion 2b.

[0030] Next, a method for replacing the bearing 5 using the bracket 30 of the first embodiment will be described. FIG. 6 is a side cross-sectional view showing a state in which a jack is installed on a bracket in the bracket mounting structure according to the first embodiment of the present invention. As shown in Figure 6, a jack 6 is placed on the upper surface of the upper plate 33 of the bracket 30, and the jack 6 is extended to remove the existing bearing 5 while supporting the bridge girder 4 with the jack 6. Then, after a new bearing 5 is placed on the upper surface of the overhanging portion 2b, the jack 6 is contracted to support the bridge girder 4 with the bearing 5.

[0031] Next, a method for installing the horizontal force distributing structure 7 using the bracket 30 of the first embodiment will be described. FIG. 7 is a side cross-sectional view showing a state in which a horizontal force distributing structure is installed on a bracket in the bracket mounting structure according to the first embodiment of the present invention. 7, the upper part 7b is connected to the lower part 7a so as to be displaceable laterally. The lower part 7a of the horizontal force distributing structure 7 is fixed to the upper surface of the bracket 30, and the upper part 7b is fixed to the underside of the bridge girder 4. As a result, the horizontal force generated on the upper part of the bridge during an earthquake or strong wind is shared and borne by the support 5 and the horizontal force distribution structure 7, thereby improving the earthquake resistance of the bridge.

[0032] In the above-described construction method of the anchor bolt 20 and mounting structure 1 of the bracket 30, as shown in FIG. 4, the concrete at the end of the side end 2c of the protruding portion 2b of the existing pier 2 is replaced with fiber-reinforced concrete, and the anchor bolt 20 is fixed to the replaced portion 10. The pull-out strength of the anchor bolt 20 is correlated with the compressive strength of the concrete, so by fixing the anchor bolt 20 to fiber-reinforced concrete, which has high compressive strength and tensile properties, the pull-out strength of the anchor bolt 20 can be sufficiently ensured.

[0033] 3, in the first embodiment, after removing a portion of the side end 2c of the overhanging portion 2b of the existing pier 2, fiber-reinforced concrete is poured onto the machined surface 2d of the side end 2c. Therefore, compared to adding concrete without removing a portion of the side end 2c of the existing pier 2, it is possible to suppress an increase in weight of the upper part of the existing pier 2.

[0034] In addition, in the first embodiment, fiber-reinforced concrete is poured onto the cutting-finished surface 2d within the range of the side end 2c of the protrusion 2b before the end of the side end 2c is removed, thereby preventing the protrusion 2b from exceeding the building limit.

[0035] In addition, in the first embodiment, as shown in Figure 2, the concrete at the side end of the bridge is removed to expose the existing reinforcing bars 2e, and the reinforcing bars 2e are buried in the replacement sections 10, thereby reducing construction costs and shortening the construction period.

[0036] Although the first embodiment of the present invention has been described above, the present invention is not limited to the first embodiment and can be modified as appropriate within the scope of the invention. In the first embodiment, as shown in Fig. 4, the replacement portion 10 is formed at the end of the side end portion 2c in the bridge width direction of the overhanging portion 2b of the existing pier 2, but the location where the replacement portion is formed on the existing pier 2 is not limited, and the replacement portion is formed corresponding to the location where the anchor bolt 20 is to be installed. For example, the replacement portion may be formed by replacing part of the concrete on the face of the existing pier 2 in the bridge axis direction with fiber-reinforced concrete.

[0037] The bracket 30 in the first embodiment is a member for supporting the jack 6 shown in Figure 6 and the horizontal force distribution structure 7 shown in Figure 7, but the purpose of use and structure of the bracket attached to the existing pier 2 in the present invention are not limited.

[0038] [Second embodiment] Next, a method for installing the anchor bolt 20 according to the second embodiment will be described. Fig. 8 is a front view showing an anchor bolt placement step in the anchor bolt installation method according to the second embodiment. Fig. 9 is a front view showing a fiber-reinforced concrete pouring step in the anchor bolt installation method according to the second embodiment. The method of installing the anchor bolt 20 of the second embodiment differs from the method of installing the anchor bolt 20 of the first embodiment in that, as shown in FIG. 8, the anchor bolt 20 is placed on the side of the machined surface 2d of the protruding portion 2b, and then, as shown in FIG. 9, a replacement portion 10 is formed.

[0039] In the method for installing the anchor bolts 20 of the second embodiment, as shown in FIG. 8, after the concrete removal step, a plurality of anchor bolts 20 are arranged in a vertical line on the side of the machined finished surface 2d formed on the side end 2c of the protruding portion 2b (anchor bolt arrangement step). Thereafter, as shown in FIG. 9, fiber reinforced concrete is poured onto the machined finished surface 2d to form a replacement portion 10, and an anchor bolt 20 is fixed to the replacement portion 10 (fiber reinforced concrete pouring step). With this configuration, after forming the replacement portion 10, there is no need to form a hole in the replacement portion 10 for inserting the base of the anchor bolt 20, thereby shortening the construction period.

[0040] The second embodiment of the present invention has been described above, but the present invention is not limited to the second embodiment, and similar to the first embodiment, it can be modified as appropriate within the scope of the spirit thereof. [Explanation of symbols]

[0041] 1 Mounting structure 2 Existing piers 2a Pillar 2b Overhang 2c side end 2D cutting finish surface 2e Reinforced concrete 3 Basic structure 4 Bridge girders 5 Bearing 6. Jack 7 Horizontal force sharing structure 7a bottom 7b top 10 Replacement Department 20 anchor bolts 30 Bracket 31 flat plate 32 Vertical ribs 33 Upper Plate

Claims

1. A method for installing anchor bolts in an existing concrete pier, a concrete removal process of removing a portion of the side end of the existing pier; a fiber-reinforced concrete pouring step of pouring fiber-reinforced concrete onto the cut-finished surface formed on the side end of the existing pier in the concrete removal step to form a replacement portion; and an anchor bolt fixing step of fixing the anchor bolt in the replaced portion.

2. A method for installing anchor bolts in an existing concrete pier, a concrete removal process of removing a portion of the side end of the existing pier; an anchor bolt placement step of placing anchor bolts on the sides of the machined finished surfaces formed on the side ends of the existing piers in the concrete removal step; and a fiber-reinforced concrete pouring step of pouring fiber-reinforced concrete onto the machined finished surface to form a replacement portion, and fixing the anchor bolt to the replacement portion.

3. In the fiber reinforced concrete pouring step, 3. The method for installing anchor bolts in an existing pier according to claim 1, wherein the fiber-reinforced concrete is poured onto the cutting-finished surface within the range of the side end of the existing pier before removing a portion of the side end of the existing pier to form the replacement portion.

4. The existing bridge pier is made of reinforced concrete, In the concrete removal step, 3. The method for installing anchor bolts in an existing pier according to claim 1, wherein concrete at a side end of the existing pier is removed to expose reinforcing bars.

5. A bracket mounting structure for an existing concrete pier, A replacement portion formed by replacing a portion of the concrete at the side end of the existing pier with fiber-reinforced concrete; An anchor bolt fixed to the replacement portion; A bracket attached to the anchor bolt.

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