JPH08333723A - Manufacture of precast concrete floor slab and connecting method thereof - Google Patents

Abstract

PURPOSE: To make the positional adjustment of connecting part of a threaded main reinforcement embedded in a precast concrete floor slab so as to be correctly performable at all times, and to reduce the width of a connecting joint part as well as to make the connection by a screw thread achievable. CONSTITUTION: Those of threaded main reinforcements 15 of plural pieces of precast concrete floor slabs to be connected are set up as being pierced through three forms 11, 12 and 13 of respective floor slabs in a state of being continued. After concrete 16 is placed and cured in these forms 11, 12 and 13, the main reinforcement 15 to be situated in a void space among respective floor slabs is cut off and temporarily placed there.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a precast floor slab mainly used as a road surface for a bridge or a road, and a method for connecting main bars of the precast floor slab.

[0002]

2. Description of the Related Art When slab replacement work on a bridge or road is in use, the slabs will be replaced by divisional construction with lane restrictions. In this case, traffic is released in a reduced lane (reduced width). It is necessary to complete the construction early. Therefore, precast floor slabs are often used as new floor slabs in order to shorten the process.

1A, 1B, and 1C are process explanatory views showing an example of this floor slab replacement work, and are examples of floor slab replacement on a bridge having three lanes on each side. In the figure, 1 is a bridge girder of a bridge, 2 is a floor slab on the bridge girder, 3 is a block provided in a separation zone at the center of the road, 4 is a crane rail installed on the block 3, and 5 is a crane installed outside the road. Rail, 6
Is a crane spanning between rails 4 and 5, and 7 is a hook for suspending and carrying.

In order to replace the floor slab 2, as shown in FIG. 1 (a), first, one lane outside the three lanes is blocked, the old slab of that portion is removed, and the new slab 8 is removed. Lay. Next, as shown in FIG. 1 (b), the first lane in the center is blocked, the old slab of that part is removed, and a new slab 9 is laid, and finally, as shown in FIG. 1 (c). , The inner one lane is blocked, the old slab of that part is removed, and the new slab 10 is laid.

As described above, the new slabs 8, 9
It is necessary to connect 10 to be integrated as a floor slab. Conventionally, as this connection method, main bars are connected by lap joints, and distribution bars, etc. are arranged and integrated by cast-in-place concrete, or joints by reinforcing bars are not used and they are integrated only by prestressing force. The method etc. were used.

[0006]

However, the former of the above-mentioned conventional connecting methods has a large construction area for on-site reinforcement work and cast-in-place concrete, which is negative in terms of construction period, quality and construction. It is possible to form a screw on the main bar to eliminate the defect due to the lap joint of the main bar, and connect the opposing main bars by screwing with a coupler etc., but the position of the main bar of the conventional precast floor slab varies in construction. Therefore, there is a problem that it is difficult to screw and connect with a coupler or the like.

In the latter case, it is necessary to introduce full prestress to prevent the tensile force from being generated in the concrete against the bending moment generated in the joints.
Since the PC steel materials must be densely arranged in the direction of the main bars, there is a problem in that many man-hours are required.

[0008]

In order to solve the above-mentioned problems, in the present invention, when manufacturing a plurality of precast floor slabs to be connected, a threaded main bar is continuously penetrated through the form of each floor slab. After the concrete is placed and cured in each of the molds, the precast floor slab is manufactured by cutting and temporarily placing the main bar located in the space between the floor slabs.

When introducing prestress to the precast floor slab produced by the method of the first invention at the time of use, prestress slabs of the same group, which are temporarily placed, are prestressed in the same direction at substantially the same time. It is better to install it.

Further, the method of connecting the main bars of the precast floor slab of the present invention is such that the precast floor slabs manufactured by the above-mentioned first and second inventions are arranged at the relevant positions at the time of manufacturing, and the main bars with screws facing each other are arranged. The lock nut and coupler are screwed together on one side, and the lock nut is screwed on the other threaded main bar, and the coupler screwed onto one threaded main bar is screwed onto the other threaded main bar approximately half. Then, lock the lock nuts on both sides of this coupler by tightening them on the coupler.

[0011]

As described above, in the present invention, the threaded main bars of a plurality of precast floor slabs to be connected are continuously arranged so as to pass through the formwork of each slab, and then the concrete is placed in each formwork. After casting and curing, the precast floor slabs were laid at adjacent positions because the precast floor slabs were manufactured by cutting and temporarily placing the main bars located in the spaces between the floor slabs. Since the production times of the two are the same, the ages of the adjacent precast floor slabs are the same, and the drying shrinkage and creep phenomenon of the concrete are all the same.

Therefore, the adjacent precast floor slabs produced as described above are always placed in the same state. Moreover, the threaded main bar embedded in this precast floor slab is provided as a continuous main bar that penetrates the adjacent floor slabs, and after the concrete of the floor slabs hardens, cut the part located in the space between each floor slab. Therefore, when the precast floor slab is laid in place later, the adjacent threaded main bars do not always shift and are correctly aligned. Therefore, it is possible to easily connect the main bars with the screws described later.

When prestress is introduced into the precast floor slab manufactured by the above-mentioned method during use, the prestress is introduced into the precast floor slab temporarily placed at about the same time. The deformation of the precast floor slab due to stress is also the same between adjacent floor slabs.

Further, in the case of connecting the main bars of the precast floor slab manufactured by the above-mentioned method, in the present invention, each precast floor slab is arranged at a related position at the time of manufacturing and locked to one of the opposing threaded main bars. With the nut and coupler screwed together, the lock nut is screwed onto the other threaded main bar, and the coupler screwed onto the one threaded main bar is screwed onto the other threaded main bar almost half as well. Since the lock nuts on both sides of this coupler are tightened to the coupler, the width of the joint for connecting the floor slabs required for the connection can be significantly narrowed compared to the conventional connecting method using the lap joint of the main bar. . As an example, a conventional lap joint requires a joint width of 60 cm or more, but according to the present invention, a width of 21 cm is sufficient.

Therefore, according to the present invention, the amount of cast concrete at the joints for connection between floor slabs is significantly reduced, and
Since the welding work required when reducing the width of the lap joint is not necessary, the amount of work at the site is reduced, and the work types are also reduced, so that labor saving can be promoted.
In addition, anyone can perform connection work using screws without requiring skill, and it is easy to secure construction accuracy and quality control. Further, according to the present invention, the welding work becomes unnecessary and the area where the concrete is placed in the joint portion is reduced. Therefore, even in rainy weather, the work can be performed with a small amount of equipment and measures.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 2 and 3 show a method for manufacturing the precast floor slab of the present invention, in which 11 is the new floor slab 8 of FIG.
Formwork for a precast floor slab corresponding to No. 12, 12 is a formwork for a precast slab corresponding to the new slab 9 in FIG. 1, and 13 is a formwork for a precast slab corresponding to the new slab 10 in FIG. ,
Reference numeral 14 is a mount for moving the formwork.

In this embodiment, the molds 11, 12 and 13 are arranged on the pedestal 14 at predetermined positions, and a plurality of threaded main bars (screw bars) 15 of the precast floor slabs to be connected are arranged. As shown in FIG. 4 (a), the molds 11, 12 and 13 of the floor slabs are arranged so as to pass through the molds in a single state, and then each mold is placed as shown in FIG. 4 (b). Concrete 16 is placed in the frames 11, 12, and 13,
After curing the cast concrete 16 as shown in FIGS. 5 (a) and 5 (b), it is located in the space between the floor slabs 8, 9 and 10 as shown in FIG. 6 (b). The main bar 15 is cut at a predetermined position and temporarily placed.

2 (a) to 2 (f) show an example of the production cycle of the precast floor slab for the floor slab 8.
First, on the pedestal 14, the formwork 11 for the floor slab 8 is placed on the bottom formwork 11.
a, the side molds 11b, 11c, and the mold 1
1 and FIG. 3, the threaded main bars 15 are arranged at predetermined positions by penetrating the molds 12 and 13, and the main bars 15 are connected by the force distribution bars 17, and then concrete is poured to the predetermined shape. Be cured for a period of.

Next, as shown in FIG. 2B, the floor slab 8 is placed on the pedestal 14 together with the bottom mold 11a in a state where both side frames 11b and 11c are removed from the floor slab 8 which has been completely cured. It is moved as shown by arrow A in a) and set at the position of (b). Then, as shown in (c), the bottom formwork 11a and the side formwork 11c are set at positions adjacent to the floor slab 8 on the pedestal 14.

Next, as shown in FIG. 2D, the mold 1
After arranging the reinforcing bar consisting of the main bar 15 and the connecting bar 17 in 1 and applying the release agent to the side surface 8a of the floor slab 8,
As shown in (e), concrete 16 is placed in the mold 11. Then, as shown in (f), when the curing of the cast concrete is completed, the floor slab (two-dot chain line) 8 produced previously is removed from the pedestal 14 and temporarily placed, and at the same time, the floor slab 8 shown by the solid line is shown. Is set to the state shown in (b) as indicated by arrow B, and the above operation is repeated.

When prestress is introduced into the precast floor slabs 8, 9 and 10 produced by the above-described method during use, as shown in FIG. 7, the precast floor slabs 8, 9 and 10 are temporarily placed. At about the same time as in 10, the prestress is introduced by the tension cord 18.

Further, as a method of connecting the main bars 15 of the precast floor slabs 8, 9 and 10 produced by the above-mentioned method, the precast floor slabs 8, 9 and 10 are arranged at the relevant positions at the time of production and As shown in FIG. 8, the lock nut 19 and the coupler 20 are screwed into one of the opposing threaded main bars 15 (the right main bar 15 in FIG. 8) and the other threaded main bar 15 (the left main bar 15 in FIG. 8). ) To lock nut 1
9 is screwed together, and as shown in the lower part of FIG. 8, the coupler 20 screwed to one threaded main bar 15 is also screwed to the other threaded main bar 15 in a substantially half way. Tighten the lock nuts 19 on both sides of the connector to the coupler 20 to lock. After fastening with this screw, grout is injected through a hole 20a provided in the coupler 20.

FIGS. 9 (a) to 9 (e) show a method of replacing the precast floor slab according to the present invention described above, which is carried out by the procedure of FIGS. 1 (a) to 1 (c). That is, in (a), the old floor slab is removed, the new floor slab 8 is laid after that, and the widening floor slab portion 21a on the outer side of the old floor slab is poured with the filling concrete, as shown in (b). The widening floor slab 21 is formed.

Next, while removing the old floor slab 2 of (a), a new floor slab 9 is installed thereafter as shown in (b),
The opposing main bars 15 between the new slabs 8 and 9 are screwed and coupled by the coupler 20 shown in FIG. 8, and both sides of the coupler 20 are locked by the lock nuts 19. Also, like the main bar 15, a PC that penetrates the floor slabs 8 and 9
The steel rods 22 are also connected by screws. Then, expansive concrete is placed in the joint portion 23a between the floor slabs 8 and 9, and a primary prestress is introduced into the PC steel rod 22 as shown by an arrow C. Further, as shown in (c), after forming the joint floor slab 23, after removing the adjacent old floor slab to the PC steel rod 22 as shown by the arrow D, the secondary prestress is introduced. .

Next, as shown in (d), the new floor slab 10 is installed at a position where the old floor slab adjacent to the new floor slab 9 is removed, and the main bar 15 and the PC between the new floor slabs 9 and 10 are installed. The steel rods are connected by the coupler 20, and the joint floor slab 24 is formed between the floor slabs 9 and 10 as shown in (e) in the same manner as described above, and the PC steel rod 22 is prestressed as indicated by the arrow E. Introduce.

[0026]

As described above, according to the present invention, the formwork 1 of each floor slab 8, 9, 10 is continuously connected with the threaded main bar 15 of the plurality of precast floor slabs 8, 9, 10 to be connected.
After arranging through 1,12,13, each form 11,
After the concrete 16 is set and cured in the 12, 13, the precast floor slabs 8, 9 and 10 are manufactured by cutting and temporarily placing the main bar 15 located in the space between the floor slabs. Therefore, since the production times of the precast slabs laid adjacent to each other are the same, the ages of the adjacent precast slabs are the same, and the drying shrinkage and the creep phenomenon of the concrete are all the same.

Therefore, the adjacent precast floor slabs produced as described above are always placed in the same state. Moreover, the threaded main bar 15 embedded in this precast floor slab is provided as a continuous main bar that penetrates the adjacent floor slabs, and after the concrete of the floor slabs hardens, the portion located in the space between the floor slabs is Since it is cut, when the precast floor slab is laid in place later, the adjacent threaded main bars 15 are always aligned without misalignment. Therefore, it becomes possible to connect the main bar 15 with a screw described later without difficulty.

When prestress is introduced into the precast floor slab manufactured by the above-mentioned method during use, the prestress is introduced into the temporarily placed precast floor slab at substantially the same time. The deformation of the precast floor slab due to stress is also the same between adjacent floor slabs.

Further, in the case of connecting the main bars 15 of the precast floor slabs manufactured by the above-mentioned method, in the present invention, one of the facing main bars 15 with screws is arranged by arranging the respective precast floor slabs at the relevant positions at the time of manufacturing. The lock nut 19 and the coupler 20 are screwed together, the lock nut 19 is screwed on the other threaded main bar 15, and the coupler 20 screwed onto one threaded main bar 15 is attached to the other threaded main bar 15. This coupler 2 with almost half screwed
Since the lock nuts 19 on both sides of 0 are fastened to the coupler 20, it is possible to remarkably narrow the width of the joint for connecting the floor slabs required for the connection, as compared with the conventional connection method using the lap joint of the main bar. it can. By way of example, a conventional lap joint which requires a joint width of 60 cm or more, but a width of 21 cm is sufficient according to the present invention.

Therefore, according to the present invention, the amount of cast concrete at the joints for connection between floor slabs is significantly reduced, and
Since the welding work required when reducing the width of the lap joint is not necessary, the amount of work on site is reduced and
The number of work processes is reduced and labor saving can be promoted. In addition, the screw connection work can be done by anyone without requiring any skill, and the construction accuracy and quality control are facilitated. Further, according to the present invention, welding work becomes unnecessary, and since the area for placing concrete in the joints is reduced, it is possible to work even in rainy weather. can get.

[Brief description of drawings]

FIG. 1 (a) is an elevation view showing a first step of floor slab replacement work on a road surface, (b) is an elevation view showing a second step thereof, and (c) is an elevation view thereof. It is an elevation view showing a 3rd process.

2 (a) to (f) are explanatory side views showing an example of a production cycle of a precast floor slab.

FIG. 3 is a front view showing a manufacturing process of a precast floor slab.

4A and 4B are plan views showing a manufacturing process of a precast floor slab.

5A and 5B are plan views showing a manufacturing process of a precast floor slab.

6 (a) and 6 (b) are plan views showing a manufacturing process of a precast floor slab.

FIG. 7 (a) is a plan view showing a state in which prestress in the longitudinal direction of the road is introduced into the precast floor slab when temporarily placed, and FIG. 7 (b) is a side view thereof.

FIG. 8 is a cross-sectional view showing a method of connecting threaded main bars embedded in a precast floor slab.

9A to 9E are process explanatory views of a precast floor slab replacement construction method.

[Explanation of symbols]

 1 Bridge girder 2 Floor slab 3 Block 4,5 Crane rail 6 Crane 7 Hook 8, 9, 10 New floor slab (precast floor slab, floor slab) 11, 12, 13 Formwork 14 Frame 15 Threaded main bar (main bar) 16 Concrete 17 Distribution Muscle 18 Tension Rope 19 Lock Nut 20 Coupler 21 Widening Floor Slab 22 PC Steel Rod 23, 24 Joint Floor Slab

Claims (3)

[Claims] 1. When producing a plurality of precast floor slabs to be connected, concrete is placed and cured in each form while the threaded main bars are continuously arranged through the form of each slab. After that, the method for producing a precast floor slab is characterized in that the main bar located in the space between the floor slabs is cut and temporarily placed. 2. When introducing prestress to the precast floor slab produced by the method according to claim 1 during use, prestress slabs of the same group that are temporarily placed are also prestressed in the same direction at substantially the same time. A method of manufacturing a precast floor slab characterized by being introduced. 3. Pre-cast floor slabs produced by the method according to claim 1 or 2 are arranged at a relative position at the time of production,
The lock nut and coupler are screwed onto one of the opposite threaded main bars, and the lock nut is screwed onto the other threaded main bar, and the coupler screwed onto one threaded main bar is attached to the other threaded main bar. A method for connecting precast floor slabs, characterized in that the lock nuts on both sides of this coupler are tightened to the coupler while being screwed in approximately half.