JPH0455544A - Half PC board and its manufacturing method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides a half PC constructed of a concrete plate and a reinforcing bar assembly provided semi-buried in the concrete plate.
The present invention relates to a plate and a method for manufacturing the same.

[Conventional technology]

BACKGROUND ART Conventionally, among PC boards (precast concrete boards), there has been provided what is called a half PC board, in which a reinforcing member protrudes half from the concrete board. Fig. 7 shows an example of the configuration of a half PC board, with reference numeral 2.
3 is a concrete plate, and 3 is a reinforcing bar assembly semi-buried in the concrete plate 2. In the illustrated example, the reinforcing bar assembly 3 is a truss bar 4 in which reinforcing bars are assembled in a parallel chord or polygonal cross section. In order to create the half PC4i (1) as described above, the truss bar 4 (reinforcing bar assembly 3) is separately created in advance, and the truss bar 4 is used in the formwork (in which the concrete plate 2 is to be formed) (
(not shown), then concrete C is cast in the formwork so that the truss reinforcements 4 are partially buried, and the cast concrete C is allowed to harden. Half PCit as described above can be constructed into a general RC construction (reinforced concrete structure) by pouring concrete onto the concrete plate 2, that is, the reinforcing bar assembly 3 side at the site, and in that case, the concrete plate 2
It has the advantage that it acts as a formwork.

[Problem to be solved by the invention]

By the way, the conventional half PC board 1 as described above has the following disadvantages. That is, as shown in FIG. 8, on the concrete plate 2,
This means that the outer part of the concrete plate 2 often undergoes a deformation phenomenon in which it warps toward the reinforcing bar assembly 3. Recently, the above-mentioned half PC [1
However, when the half PC board 1 is used for the outer wall of a building in this way, there is a problem that the outer surface of the building is not flat and the appearance is impaired. In addition,
In FIG. 8, reference numeral 5.5. . . . indicates tiles attached to the outer surface of the concrete plate 2 to form the outer surface of the building. The warping deformation of the half PC board 1 as described above is caused by the warpage of the half PC board 1.
It is thought that the cause may be the shrinkage of the concrete during the production of ifi,t. In other words, Shipki Half PC
This seems to be because the upper surface of the poured concrete C rapidly shrinks during drying when the concrete C constituting the concrete plate 2 is steam-cured during manufacture of the plate 1 in a factory. Further, the warping deformation of the half PC board 1 is also caused by the pressure of concrete added at the site. The present invention has been made in view of the above circumstances, and aims to provide a half PC board that effectively prevents warpage of the concrete board during production and produces a flat product, and a method for manufacturing the same. .

[Means for Solving the Problems] The invention according to claim 1 of the present invention provides a half PC board composed of a concrete plate and a reinforcing bar assembly provided in a semi-buried state in the concrete plate. The solid is
The concrete plate is provided with a bulge in advance before being buried in concrete forming the concrete plate, and is loaded and deformed so that the bulge is eliminated, and the concrete plate has the bulge of the reinforcing bar assembly. The present invention is characterized in that a prestress is introduced that pulls the central portion of the concrete plate toward the reinforcing bar assembly by a return force in the direction. Further, the invention according to claim 2 of the present invention is a method for manufacturing the half PC board according to claim 1, wherein the reinforcing bar assembly is preliminarily curved along the longitudinal direction of the reinforcing bar assembly. and a step of deforming and constraining the reinforcing bar assembly so that it becomes a substantially straight line by opening the reinforcing bar assembly in the direction in which the bulging is eliminated;
installing the constrained reinforcing bar assembly in a formwork for forming the concrete plate;
By placing concrete so that the constrained reinforcing bar assembly is in a semi-buried state, and by releasing the restraining force on the reinforcing bar assembly after the concrete hardens,
This method is characterized by the step of introducing prestress into the formed concrete plate to pull the central portion of the concrete plate toward the reinforcing bar assembly. [Operation] Assemble the reinforcing bar assembly in a state where it has been exposed in advance,
By applying a force to this reinforcing bar assembly in a direction that eliminates the swelling and restraining it, a force is generated in this reinforcing bar assembly in a direction that causes it to return to its original state. Therefore, when manufacturing a half PC board, concrete is poured after applying the above deformation restraint to the reinforcing bar assembly, and after the concrete hardens, the deformation restraining force of the reinforcing bar assembly is released, so that the reinforcing bar assembly is not placed in the concrete. A prestress in the direction of solid return is introduced. This prevents the concrete plate from warping.

【Example】

Embodiments of the present invention will be described below with reference to the drawings. For convenience of explanation, in this example, the method for manufacturing a half PC board according to claim 2 of the present invention will be explained. 1 to 6 each show an embodiment of the method for manufacturing a half PC board according to claim 2 of the present invention. FIG. 1 shows a reinforcing bar assembly 3 constituting a half PC board according to the present invention. In this case, the reinforcing bar assembly 3 includes main bars 6
The truss muscle 6 is composed of the muscle a and the lattice muscle 6b. This truss bar 6 may be a parallel chord truss 6A as shown in FIG. 6(a), a triangular solid truss 6B as shown in FIG. 6(b), or a c.
) may be a square solid truss 6C as shown in FIG. This truss reinforcement 6 is assembled by welding the main reinforcement 6a and the lattice reinforcement 6b. However, as shown in FIG. 1, the truss bar 6 is assembled in advance by giving a bulge H that curves along the longitudinal direction of the truss bar 6. After forming the truss bars 6 (reinforcing bar assembly 3) as described above in advance, as shown in FIG.
Installed inside. At this time, the truss bar 6 is installed so as to curve upward with respect to the formwork 7. Once the truss bar 6 with the bulge H as described above is installed in the formwork 7, the bulge H is removed by applying a downward force to the longitudinal center of the truss bar 6. make it disappear. In other words, the truss muscle 6 that was curved upward
is deformed into a substantially straight line as shown in FIG. The above operation can be carried out by supporting both ends of the truss bar 6 and pressing the highest central part downward with a jack, or
Alternatively, this may be carried out by attaching an unbonded tension material such as a wire to the highest central portion and pulling the tension material downward. After the truss bar 6 is deformed into a substantially straight state by the above operation, the formwork 7 is held in that state, that is, with the deformation force restrained, as shown in FIG.
Concrete C is poured inside. Since the intended product is a half PC board, the thickness of the concrete C is such that the truss reinforcements 6 are buried approximately half way therein. Once the concrete C has been placed as described above, the concrete C is cured by steam curing as in the conventional method.During this curing period, the above-mentioned restraining force is applied to the truss bars 6.The above-mentioned curing When the concrete C has developed the required strength, the formwork 7 is removed and the restraining force is also released as shown in FIG. 5. As the concrete C hardens, the concrete plate 2 is formed. As a result, a half PCIilO consisting of the truss reinforcement 6 and the concrete 2 is completed. In the half PC board 10, a force acts on the concrete 2 to pull the center part of the concrete plate 2 toward the truss reinforcement 6. In other words, since the truss bar 6 has been given a bulge H in advance and has been loaded and deformed and restrained so that the bulge H is eliminated, the truss bar after the restraint is released. A force that tries to return to the original shape, that is, a peeling force acts on the reinforcement 6. As a result, a prestress is introduced into the concrete 2 in the direction of peeling of the truss reinforcement 6. Therefore, the above half P
With the C board IO, the concrete board 2 does not warp unlike the conventional half PC board 1 (FIG. 8). Therefore, even when the half PC board 10 is used for the outer wall of a building, a flat outer wall surface without warping can be formed, and the quality of the appearance can be improved. In the above, the amount of the peeling H provided in advance when forming the truss muscle 6 is the length of the half PC board l to be formed,
It is appropriately set in consideration of the thickness of the concrete plate 2, the bending rigidity of the truss bars 6, the number of truss bars 6 to be installed, etc. In addition, in the embodiment, the reinforcing bar assembly 3 provided semi-buried in the concrete 2 has been described as the truss bar 6, but the reinforcing bar assembly 3 in the half PC board according to the present invention is not limited to the truss bar. In addition, in the embodiment, the half PC board according to the present invention was explained as one for configuring the outer wall of a building, but the half PC board 1
0 can be used in the same way where half PC boards have been conventionally applied, and the same effects as above can be obtained. For example, if the half PC board 10 is applied to a small beam or slab, the upward prestress generated by the truss bars 6 can improve their bending strength and prevent deflection.

【Effect of the invention】

As explained above, according to the present invention, it is possible to prevent warping caused by shrinkage of concrete as much as possible during the production of half PC boards, and thereby to provide half PC boards with less warpage and deflection. Yes, half P
It is possible to improve the appearance quality of a structure constructed using C plates. Furthermore, since the bending strength of the half PC board itself can be improved, excellent effects can be achieved, such as a half PC board that is less likely to warp or bend due to the pressure of concrete poured on site.

[Brief explanation of drawings]

Figures 1 to 5 are a side view and Figure 6 (a
) to 6(c) are sectional views of the reinforcing bar assembly according to this embodiment taken in a cross section perpendicular to the axis, FIG. 7 is a side sectional view showing an example of a conventional half PC board, and FIG. 8 1 is a side cross-sectional view showing a half PC board applied to construct an outer wall of a building. 2...Concrete plate, 3...Reinforcement assembly, 7...Formwork, IQ...Half PC board, C...Concrete 、H・・・・・・Mukuri. Figure 1

Claims (2)

[Claims] (1) In a half PC board composed of a concrete plate and a reinforcing bar assembly provided semi-buried in the concrete plate, the reinforcing bar assembly is pre-buried before being buried in the concrete forming the concrete plate. The concrete plate has been given a bulge and has been deformed under load so that the bulge is eliminated, and the returning force of the reinforcing bar assembly in the direction of the bulge causes the concrete plate to have a center portion of the concrete plate as described above. A half PC board characterized by introducing prestress that pulls toward the reinforcing bar assembly. (2) A method for manufacturing a half PC board consisting of a concrete plate and a reinforcing bar assembly provided in a semi-buried state in the concrete plate, the method comprising: a step of forming a curved bulge by applying a load in a direction to eliminate the bulge to the reinforcing bar assembly on which the bulge has been formed, and deforming and restraining the reinforcing bar assembly so that it becomes substantially straight; a step of installing the constrained reinforcing bar assembly in a formwork for forming the concrete plate;
A step of pouring concrete so that the restrained reinforcing bar assembly is in a semi-buried state, and releasing the binding force to the reinforcing bar assembly after the concrete hardens, so that the concrete is placed in the formed concrete plate. A method for manufacturing a half PC board, comprising the step of introducing prestress to pull the central part of the board toward a reinforcing bar assembly.