Precast wall parapet and joint structure for precast wall parapet

Abstract

To provide a precast wall railing capable of ensuring many installation points for wiring conduits while reducing the labor required for construction, and a joint structure of a precast wall railing.SOLUTION: A joint structure 1 of a precast wall railing 2 is a structure for joining a precast floor slab 3 and a precast wall railing 2 placed on the top of the precast floor slab 3. The joint structure includes: a recess 5 formed to open on the lower surface of the precast wall railing 2; a joint floor slab reinforcing bar 4 protruding from the top surface of the precast floor slab 3 and inserted into the recess 5; and a filler 7 filled in the recess 5. In the precast wall railing 2, a diagonal reinforcement 21 is arranged upward from the front of the recess 5. The joint floor slab reinforcing bar 4 has a reinforcing bar diameter larger than that of a main bar 22 of the precast wall railing 2, and a fixing body 8 is formed at the tip.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a precast wall railing and a joining structure of precast wall railings.

Background Art

[0002] In some road bridges and the like, there are wall railings provided to prevent users from falling. Wall railings are generally made of reinforced concrete. By using precast members (precast wall railings) as such wall railings, the workability can be improved. In addition, in the wall railing, a pipe for wiring (for example, wiring of communication equipment) may be formed along the axial direction. As a method of installing a precast wall railing on a floor slab, loop bars may be exposed from the lower surface of the precast wall railing, and bars may be projected from the upper surface of the floor slab, and they may be joined through mortar cast in a state where these bars are wound in (see, for example, Patent Document 1). In the joining structure of the precast wall railing of Patent Document 1, a jig for connecting to another adjacent precast wall railing is provided at the end face of the precast wall railing.

[0003] Patent Document 2 discloses a joining structure of a precast wall railing in which a knockout is formed at the leg portion of the precast wall railing, an insertion hole communicating with the knockout is formed from the lower surface of the precast wall railing, an anchor bolt projecting from the upper surface of the floor slab is inserted into this insertion hole, and a nut is screwed onto the head of the anchor bolt in the knockout. Patent Document 2 also discloses a structure in which adjacent precast wall railings are connected by a connecting bolt disposed across both wall railings. The connecting bolt is fastened to a nut in a knockout formed in the wall surface of the precast wall railing. Furthermore, Patent Document 3 discloses a joining structure for precast wall parapets, in which reinforcing bars protruding from the lower surface of the precast wall parapet are inserted into insertion holes formed in the floor slab, and mortar is filled into the gap between the insertion holes and the reinforcing bars. In the joining structure of Patent Document 3, when connecting adjacent precast wall parapets, connecting bars protruding from the end face of one precast wall parapet are inserted into slits formed on the end face of the other precast wall parapet, and mortar is filled into the slits.

[0004] In the joint structure of Patent Document 1, formwork must be installed on the side of the joint with the floor slab, making the formwork installation work time-consuming. Furthermore, when installing a wall parapet on a road that is in use, formwork must also be installed on the road side, requiring traffic restrictions. In addition, because a jig for joining to other precast wall parapets is provided on the end face of the precast wall parapet, it is not possible to form conduits for wiring. Furthermore, the joint structure described in Patent Document 2 requires the formation of a box-shaped opening facing the outer surface, and there are concerns about a reduction in load-bearing capacity due to this opening. In addition, the presence of connecting bolts limits the locations where wiring conduits can be formed. Furthermore, in the joint structure described in Patent Document 3, if there is a misalignment between the reinforcing bars of the precast wall parapet and the insertion holes in the floor slab, installation becomes impossible, which increases the effort required for quality control during manufacturing, as well as handling during transportation and construction. In addition, if slits or connecting bars are placed to join adjacent precast wall parapets, the locations for forming conduits for wiring are limited. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-036205 [Patent Document 2] Japanese Patent Publication No. 2018-066141 [Patent Document 3] Japanese Patent Publication No. 2021-147840 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention aims to propose a precast wall parapet and a joint structure for precast wall parapets that can reduce the effort required during construction and secure more locations for installing wiring conduits. [Means for solving the problem]

[0007] To solve these problems, the precast wall parapet of the present invention is attached to the upper part of a precast floor slab, and has an opening on its lower surface and a recess formed therein into which connecting floor slab reinforcement bars erected on the upper surface of the precast floor slab can be inserted, and diagonal reinforcement bars are arranged from the front upward of the recess. Furthermore, the joint structure for a precast wall parapet of the present invention is used to join a precast floor slab and a precast wall parapet placed on the upper surface of the precast floor slab, and comprises a recess formed to open on the lower surface of the precast wall parapet, a joint floor slab reinforcing bar protruding from the upper surface of the precast floor slab and inserted into the recess, and a filling material filled into the recess, wherein diagonal reinforcement bars are arranged in the precast wall parapet from the front to the top of the recess, and the joint floor slab reinforcing bar has a larger diameter than the main reinforcement bars of the precast wall parapet and has an anchoring body formed at its tip. This precast wall parapet and precast wall parapet joint structure eliminates the need for formwork at the joint, thus reducing construction time. Furthermore, since anchoring bodies are formed at the ends of the jointing floor slab reinforcement, the anchoring length can be shortened, minimizing the height of the recess and maximizing piping space. Additionally, by joining the precast wall parapet to the precast floor slab using the jointing floor slab reinforcement with anchoring bodies, the necessary load-bearing capacity can be ensured without the need to join adjacent precast wall parapets with jigs or other fixtures. Therefore, jigs for joining precast wall parapets can be omitted, allowing for the formation of continuous pipelines across multiple precast wall parapets. Moreover, since the recess (box-out) is not exposed on the outer surface, the recess does not become a weak point. Furthermore, the front side of the recess is reinforced with diagonal reinforcement, ensuring the necessary load-bearing capacity against bending stress.

[0008] Furthermore, if the cross-sectional shape of the recess is an inverted trapezoid where the width of the upper end is greater than the width of the lower end, it is possible to prevent the hardened filler material from coming out of the recess, and the jointing performance is further improved. It is even more effective if irregularities (for example, roughening or shear keys) are formed on the inner surface of the recess. It is also desirable that reinforcing bars for preventing widening are placed horizontally inside the recess from the front to the back. Furthermore, if the upper end of the recess is sloped with a gradient greater than or equal to the transverse gradient of the road, a reverse slope is prevented, and air can be released from the highest point when filling with the filler material. Furthermore, it is desirable that the embedding length of the reinforcing steel for the connecting slab into the recess be 5.0 times or more the diameter of the reinforcing steel. Furthermore, the filler material has a design standard strength of 70 N / mm². 2 In summary, the adhesion strength to concrete is 2.6 N / mm². 2 It is desirable to use the high-strength mortar described above. [Effects of the Invention]

[0009] According to the precast wall parapet and precast wall parapet joining structure of the present invention, it is possible to reduce the effort required during construction and to secure a location for installing wiring conduits. [Brief explanation of the drawing]

[0010] [Figure 1] This is a front view showing the joint structure of the precast floor slab. [Figure 2] This is a cross-sectional view showing the joint structure of precast floor slabs. [Figure 3] This is an enlarged cross-sectional view showing the joint between the precast floor slab and the precast wall parapet. [Figure 4] This graph shows the results of the extraction experiment. [Modes for carrying out the invention]

[0011] In this embodiment, a joint structure 1 between a precast deck slab 3 and a precast wall parapet 2 that is connected to the precast deck slab 3 in the bridge axis direction of the bridge will be described. Figure 1 shows the joint structure 1 between the precast wall parapet 2 and the precast deck slab 3. The joint structure 1 consists of a joint floor slab reinforcement 4 having an anchoring body 6 protruding from the upper surface of the precast floor slab 3, a recess 5 formed to open into the lower surface of the precast wall parapet 2, and a filler material 7 filled into the recess 5.

[0012] The precast wall railing 2 is mounted and attached on the upper part (upper surface) of the precast floor slab 3. As shown in FIG. 1, it is a precast reinforced concrete member in which main reinforcement bars 22 and distribution reinforcement bars 23 are arranged, and a plurality (four in this embodiment) of recesses 5 opening on the lower surface are formed. The plurality of recesses 5 are formed at predetermined intervals in the axial direction (bridge axis direction). FIG. 2 shows a cross-sectional view of the joint structure 1. As shown in FIG. 2, the recess 5 can insert the joint floor slab reinforcement 4 erected on the upper surface of the precast floor slab 3. That is, the recess 5 is formed according to the arrangement of the joint floor slab reinforcement 4. FIG. 3 shows the joint portion between the precast wall railing 2 and the precast floor slab 3. As shown in FIG. 3, the cross-sectional shape of the recess 5 is a reverse trapezoidal shape in which the width Wt at the upper end is larger than the width Wb at the lower end. Also, the upper surface of the recess 5 has an inclination considering the cross slope of the road so that the road side or the opposite side is the highest in the state where the precast wall railing 2 is placed on the precast floor slab 3. Further, an air vent hole 51 extending laterally from the upper end portion of the recess 5 is formed in the recess 5. The air vent hole 51 opens on the side surface of the concrete portion 21.

[0013] At the position of the recess 5, the precast wall railing 2 increases the amount of reinforcement compared to the portion other than the recess 5 (general portion). The method of increasing the amount of reinforcement is not limited, but for example, the reinforcement pitch corresponding to the position of the recess 5 is made denser than that of the general portion, or the reinforcement diameter is made larger than that of the general portion. As shown in FIG. 2, a plurality (six in this embodiment) of pipelines 24 are formed along the axial direction in the precast wall railing 2. The pipeline 24 is a hole for inserting wiring for communication and the like, and penetrates the precast wall railing 2 in the axial direction inside the main reinforcement bar 22. The pipeline 24 is formed by piping a pipe material. The pipe material constituting the pipeline 24 has an inner diameter sufficiently large for the wiring inserted into the pipeline 24. The inner diameter of the pipeline 24 has a margin greater than or equal to the designed maximum displacement amount at the boundary between the precast wall railings for the wiring.

[0014] In addition, in the present embodiment, in the leg portion of the precast wall railing 2, diagonal bars 21 are arranged obliquely upward from the front of the recess 5. The diagonal bars 21 are arranged between the front surface of the precast wall railing 2 and the recess 5. In the present embodiment, as the diagonal bars 21, reinforcing bars with a bar diameter D13 are used. In the leg portions of the precast wall railing 2 other than the recess 5, D13 is used as the diagonal bars 21. Furthermore, as shown in FIG. 3, in the recess 5, anti-width-expansion reinforcing bars 25 horizontally spanned from the front surface side to the back surface side are arranged.

[0015] The precast floor slab 3 is made of reinforced concrete. Inside the precast floor slab 3, as shown in FIG. 1, floor slab longitudinal bars 31 in two upper and lower stages are arranged along the bridge axis direction (left - right direction in the drawing), and floor slab transverse bars 32 intersecting with the floor slab longitudinal bars 31 are arranged. Also, on the upper surface of the end portion of the precast floor slab 3, joint floor slab reinforcing bars 4 are protruding corresponding to the position of the recess 5 of the precast wall railing 2. When the precast wall railing 2 is placed on the upper surface of the precast floor slab 3, the joint floor slab reinforcing bars 4 are inserted into the recess 5 of the precast wall railing 2. The joint floor slab reinforcing bars 4 of the present embodiment are extension portions of the floor slab transverse bars 32 arranged on the lower surface side of the precast floor slab 3, and are bent upward at the end portion of the precast floor slab 3 and protrude from the upper surface of the precast floor slab 3.

[0016] The joint floor slab reinforcing bars 4 protrude from the upper surface of the precast floor slab 3. The embedding length of the joint floor slab reinforcing bars 4 into the recess 5 is a length that can ensure 7.5 times or more of the bar diameter. The joint floor slab reinforcing bars 4 of the present embodiment are SD390 or less, and the bar diameter is D22. Although the bar diameter of the joint floor slab reinforcing bars 4 is not limited, it is desirable to make it larger than the bar diameter of the main bars 22 of the precast wall railing 2.

[0017] The fixing body 6 is made of a steel plate (in the present embodiment, width 40 mm × length 70 mm × thickness 16 mm) having an outer shape larger than the cross - section of the joint floor slab reinforcing bars 4, and is fixed to the tip portion of the joint floor slab reinforcing bars 4. The fixing body 6The method of fixing the connecting floor slab reinforcement 4 is not limited; for example, it may be welded, or fixed by friction welding or gas welding. Also, if the connecting floor slab reinforcement 4 is threaded, the anchoring body 6 Nuts may be used as fasteners, or steel plates with bolt holes may be used. 6 This is not limited to being formed by fixing a separate component (steel plate), but may also be, for example, an enlarged diameter portion (a so-called bump) formed by forging the end.

[0018] The precast wall parapet 2 and the precast floor slab 3 are joined by placing the precast wall parapet 2 on the upper surface of the precast floor slab 3 and filling the recess 5 with filler material 7. The filler material 7 has a design strength of 70 N / mm². 2 The above-mentioned high-strength mortar has an adhesion strength of 2.6 N / mm² to the concrete (inner surface of recess 5). 2 This concludes the explanation. When the filler material 7 filled into the recess 5 solidifies, the adhesive force between the filler material 7 and the reinforcing steel 4 for the connecting floor slab fixes the reinforcing steel 4 and the solidified filler material 7 together. Furthermore, the solidified filler material 7 is fixed together to the inner surface of the recess 5. As a result, the precast wall parapet 2 and the precast floor slab 3 are fixed together.

[0019] Next, the construction procedure for the joint structure 1 will be explained. First, the precast floor slab 3 is laid. After the precast floor slab 3 is laid, the precast wall parapet 2 is installed on top of the precast floor slab 3 so that the joint floor slab reinforcement 4 is inserted into the recess 5. As shown in Figure 3, a filler material 61 is interposed between the precast wall parapet 2 and the precast floor slab 3. The material that makes up the filler material 61 is not limited, but in this embodiment, elastic sponge is used. Next, the filler material 7 is filled into the recess 5. The filler material 7 is injected from the front side (road side) of the precast wall parapet 2. In this embodiment, injection holes or gaps are formed in the filler material 61, and the filler material 7 is injected from these parts. As the filler material 7 is filled, the air in the recess 5 is exhausted from the air vent hole 51 (see Figure 1). Note that adjacent precast wall parapets 2 are installed with their end faces butted together, without being connected to each other. At this time, the conduits 24 of adjacent precast wall parapets 2 are made continuous. Also, the area around the boundary between the conduits 24 is sealed with a waterproof packing (not shown).

[0020] According to the joint structure 1 of this embodiment, since formwork is not required at the joint, the labor involved in construction can be reduced. Additionally, a fixing body is attached to the tip of the reinforcing bar 4 for the connecting floor slab. 6 Because this is formed, the anchoring length can be shortened, and as a result, the height of the recess 5 can be minimized, allowing for more piping space to be secured. Also, fixing body 6 Because the connecting floor slab reinforcement 4 is provided, the necessary load-bearing capacity can be secured. Therefore, the jigs for joining the precast wall parapets 2 together can be omitted, and a continuous conduit can be formed across multiple precast wall parapets 2. Furthermore, since the recess 5 (box cutout) is not exposed on the outer surface, the recess 5 does not become a weak point. Furthermore, since the front side of the recess 5 is reinforced with diagonal bars, the necessary resistance to bending stress is ensured.

[0021] By making the amount of reinforcing steel corresponding to recess 5 greater than the amount of reinforcing steel distributed in other general areas, the reduction in load-bearing capacity in recess 5 is suppressed. By extending the horizontal reinforcement bars 32 of the precast floor slab 3 to form the connecting floor slab reinforcement bars 4, the effort required to arrange the connecting floor slab reinforcement bars 4 can be reduced. Since the conduit 24 is formed of pipe material that provides sufficient slack for the wiring, even if there is some misalignment in the precast wall parapet 2, the wiring will not be cut at the joints between the precast wall parapets 2.

[0022] By interposing a filler material 61 between the precast wall parapet 2 and the precast floor slab 3, the precast floor slab 3 can be joined together even if its upper surface is uneven. 7 This can also prevent data leaks. Filler material 7 has a load of 70 N / mm 2 Because the above high-strength mortar is used, filler 7 It exhibits high tensile resistance.

[0023] The upper surface of the recess 5 has a slope that takes into account the road's transverse gradient, with the highest point being either on the road side or the opposite side. Specifically, with the precast wall parapet 2 installed on a horizontal plane, the slope of the upper surface of the recess 5 is greater than the transverse gradient (for example, 8%), so even if the upper surface of the precast floor slab 3 is sloped according to the road's transverse gradient, the slope of the upper surface of the recess 5 does not become a reverse slope, and exhaust from the air vents is possible. Because reinforcing bars 25 for preventing widening are placed horizontally within the recess 5 from the front to the back, the recess 5 at the base of the precast wall parapet 2 is prevented from widening. Therefore, even if a force is applied that would cause the recess 5 to open, the adhesion between the concrete of the precast wall parapet 2 and the filler material 7 will not decrease.

[0024] Here, the reinforcing bars for the connecting floor slab of this embodiment. 4 and filler 7 The results of confirming adhesion with the material are shown. In this experiment, the reinforcing bars on which the anchoring body was formed had a design strength of 70 N / mm². 2 The amount of reinforcing steel extracted from the high-strength mortar described above was confirmed by pull-out experiments. In this experiment, a D22 reinforcing bar with a φ50 plate (anchoring body) fixed to it was inserted into an 89 mm diameter insertion hole, and high-strength mortar was filled in. The inner surface of the insertion hole was roughened. Experiments were conducted for reinforcing bar embedding depths of 2.5D, 5.0D, 7.5D, and 12.5D. The experimental results are shown in Figure 4.

[0025] As shown in Figure 4, it was confirmed that by embedding the reinforcing bars to a length of 5.0D or more, the reinforcing bar stress is transmitted up to the yield point of the reinforcing bars, and the load-bearing capacity of the joint can be ensured. The force transmitted from the reinforcing steel to the filler material is transmitted through the adhesion between the filler material and the concrete of the precast wall parapet 2.

[0026] Although embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and each component can be modified as appropriate without departing from the spirit of the present invention. For example, in the above embodiment, the portion of the transverse reinforcement 32 of the precast floor slab 3 was extended and used as the connecting floor slab reinforcement 4, but the connecting floor slab reinforcement 4 may be arranged separately from the reinforcing bars of the precast floor slab 3.

[0027] Fixing body 6 The shape is not limited to that shown in the above embodiment, and may be, for example, a circular or rectangular steel plate having a width and length of at least twice the diameter of the reinforcing bar and a thickness of 12 mm or more. The reinforcing bars 4 used for joining the floor slab may be coated with a synthetic resin such as epoxy resin if necessary. Resin coating provides the same effect as not applying a resin coating, while also preventing corrosion.

[0028] The filler material 7 may be manufactured on-site or transported from an off-site plant. Furthermore, fiber-reinforced mortar or fiber-reinforced concrete may be used for the filler material 7. The shape, arrangement, and number of irregularities formed in the recess 5 to improve adhesion with the filler 7 are not limited, and may include, for example, shear key protrusions or depressions, or a large number of protrusions or depressions may be formed on the inner surface. Reinforcement bars to prevent widening can be added as needed, or they may be omitted altogether. [Explanation of Symbols]

[0029] 1. Joining structure (Joining structure for precast wall parapets) 2 Precast wall parapet 21 Oblique muscles 22 Main reinforcement 23. Muscles that distribute force 24 Conduit 25 Reinforcement bars to prevent widening 3. Precast floor slab 31 Vertical reinforcement of the floor slab 32. Horizontal reinforcement of floor slab 4. Reinforcement bars for connecting floor slabs 5 recesses 51 Air vent holes 6 Fixing body 7 Filling material

Claims

1. A precast wall parapet that is attached to the top of a precast floor slab, The lower surface is open and has a recess formed into which the connecting floor slab reinforcement erected on the upper surface of the precast floor slab can be inserted. Diagonal reinforcement bars are arranged from the front upwards in the aforementioned recess. A precast wall parapet characterized in that reinforcing bars for preventing widening are arranged horizontally from the front to the back inside the recess.

2. A precast wall parapet that is attached to the top of a precast floor slab, The lower surface is open and has a recess formed into which the connecting floor slab reinforcement erected on the upper surface of the precast floor slab can be inserted. Diagonal reinforcement bars are arranged from the front upwards in the aforementioned recess. A precast wall parapet characterized in that the upper end of the recess is inclined with a gradient greater than or equal to the transverse slope of the road.

3. The precast wall parapet according to claim 1 or claim 2, characterized in that the cross-sectional shape of the recess is an inverted trapezoid shape in which the width of the upper end is greater than the width of the lower end.

4. A joining structure for a precast wall parapet that connects a precast floor slab to a precast wall parapet placed on the upper surface of the precast floor slab, A recess formed to open into the lower surface of the precast wall parapet, A reinforcing bar for joining the floor slab, which is provided protruding from the upper surface of the precast floor slab and inserted into the recess, The filling material is filled into the recess, The aforementioned precast wall parapet is reinforced with diagonal bars extending upward from the front of the recess, and horizontal reinforcing bars for preventing widening that are installed inside the recess from the front to the back. A joint structure for a precast wall parapet, characterized in that the reinforcing bars for the jointing floor slab have a larger diameter than the main reinforcing bars of the precast wall parapet, and an anchoring body is formed at the tip.

5. A joining structure for a precast wall parapet that connects a precast floor slab to a precast wall parapet placed on the upper surface of the precast floor slab, A recess formed to open into the lower surface of the precast wall parapet, A reinforcing bar for joining the floor slab, which is provided protruding from the upper surface of the precast floor slab and inserted into the recess, The filling material is filled into the recess, The aforementioned precast wall parapet has diagonal reinforcement bars arranged from the front of the recess upwards. The upper end of the recess is inclined with a gradient greater than the transverse gradient of the road. A joint structure for a precast wall parapet, characterized in that the reinforcing bars for the jointing floor slab have a larger diameter than the main reinforcing bars of the precast wall parapet, and an anchoring body is formed at the tip.

6. The joint structure for a precast wall parapet according to claim 4 or claim 5, characterized in that the embedding length of the reinforcing steel for the jointing floor slab into the recess is 5.0 times or more the diameter of the reinforcing steel.

7. The aforementioned filler material is 70 N / mm ２ A joint structure for a precast wall parapet according to claim 4 or claim 5, characterized by being a high-strength mortar.

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