JPS6347861B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a floor construction method using a precast board that integrates a precast board spanning between beams and cast-in-place concrete poured on the top surface to form a composite floor. Conventionally, in the floor construction method using precast boards made of PC concrete, cast-in-place concrete is placed on the top surface of the precast boards that span between the beams. By the way, it is known that the stress level of concrete structures is generally proportional to the square of the thickness. Therefore, when cast-in-place concrete is placed on the top of a precast board, if the two are completely integrated, the thickness of the two overlapping can be regarded as the thickness of the structure for calculating the stress level. If the bond between the two is insufficient, the overall stress must be calculated based only on the stress of the precast plate. Therefore, if cast-in-place concrete is simply placed on the top surface of a smooth precast board, the bond between the two will not be sufficient, and as a result, in order to obtain the necessary stress level, the thickness of the precast board will have to be increased. I don't get it. Focusing on these points, a method that allows the precast board and cast-in-place concrete to be integrated and the overall thickness of the structure to be taken into account when calculating the stress level is to A synthetic floor construction method has been developed that involves embedding it within a precast board, leaving the remaining two sides exposed on the surface of the precast board, and embedding it in cast-in-place concrete to integrate the two. However, in this conventional method, a part of the gauntlet ribs protrudes from the surface of the precast board, so the precast board cannot be continuously formed, the manufacturing cost is high, and the gravure bars protrude during storage, transportation, and installation. Because the gauntlet ribs are easily deformed, they had to be handled carefully, which caused problems in workability. In view of the above-mentioned conventional problems, the present invention uses a precast board that is easy to form and is inexpensive, and can be easily implemented without adding any special members or processes when constructing a floor. The purpose is to provide a floor construction method that reliably integrates cast-in-place concrete and provides the necessary stress level with the same thickness as a floor that is entirely formed in one piece. In the floor construction method, a concrete precast board is stretched between the beams of the concrete, and cast-in-place concrete is poured on the top surface of the precast board. After installing this pre-cast board so that the recesses are arranged obliquely at least with respect to the direction of hanging, the cast-in-place concrete is poured into the surface of the pre-cast board and into the recesses, and the concrete in the recesses is poured into the recesses. By integrating the precast board and the cast-in-place concrete by causing the poured concrete to act as a shackle starter, the shear stress distribution in the direction along the length of the beam in the precast board is averaged. There is a floor construction method. Note that the above-mentioned staggered distributed arrangement in which the recesses are placed close to each other means that each recess is arranged in a line in the direction in which the precast board is stretched and the recesses are adjacent to each other, as shown in the examples described later. The recesses in the rows lined up are different from each other and have a partially intricate positional relationship when viewed from the spanning direction, so that the rows of recesses are oblique to the spanning direction. It shows the relationship. Next, one embodiment of the present invention will be described with reference to the drawings. First, the concrete precast board used in the present invention will be explained with reference to FIGS. 1 to 4. FIG. 1 is a partial perspective view of an example of a precast board used in the present invention, and this precast board A has a plurality of hollow holes 1 in its thickness in the longitudinal direction.
1... is opened through the hollow hole, and a large number of PC steel wires 2, 2... are buried under tension in the lower part of the hollow hole, and if necessary in the upper and lower positions. On the other hand, a large number of shallow recesses 3, 3, . . . are formed on the upper surface. As shown in FIG. 2, the recesses 3, 3 are formed in a tapered shape with a diameter reduced from the top of the vertical inner wall to the bottom, with an opening diameter a of 25 mm and a bottom diameter b of 17 mm. , the depth h is 5 mm, the angle α of the tapered surface is 45 degrees, and the beams are arranged in a staggered manner obliquely with respect to the spanning direction perpendicular to the beam. The planar shape of the concave portion 3 may be not only the circular shape described above but also any other suitable shape such as triangular, square, or other polygonal shape, and its size may also be changed as appropriate. Furthermore, the precast plate used in the present invention has a solid shape without hollow holes, as shown in the precast plate A' shown in FIG.
A large number of recesses 3 may be formed on the surface by embedding under tension. To give an example of the manufacturing method for each of these precast plates A and A', the PC steel wire 2 is placed under tension on a flat mold such as a floor surface, and the formwork is moved while pouring concrete to embed it. After molding using the immediate demolding method and finishing the surface flat, a concave mold with a large number of protrusions 5, 5, etc. protruding from the outer periphery of a circular drum 4 as shown in FIG. The molding of the concave portion 3 is sequentially performed by rolling contact. After the surface is molded in this manner, it is allowed to stand and harden, and after reaching a certain level of strength, it is cut into required lengths to obtain precast plates of unit length. Next, the process of constructing a synthetic floor using the precast board A will be described. First, the precast board A is stretched between horizontal beams at regular intervals. If the beam is a concrete beam, as shown in Figure 5, the anchor reinforcing bars 11 are protruded from the upper surface of the beam 10, and the ends of the precast plates A and A are placed on both sides of the anchor reinforcement bars 11, as shown in Figure 5. It spans in the span direction that extends to . If the beam is a steel frame, a stud 13 is provided protruding from the center of the beam 12 as shown in FIG. 6, and the ends of the precast plates A, A are placed on both sides of the stud 13. After a large number of precast plates A, A, etc. are spanned in this way, reinforcing bars 15 for cast-in-place concrete are installed on the top surface, and cast-in-place concrete B is poured between the precast plates A and A and over the entire upper surface thereof. , an integrated composite floor. In the composite floor constructed in this way, the cast-in-place concrete B is placed in the concave portion 3 on the surface of the precast board A,
3... By entering and hardening, the concrete inside the recesses 3, 3... becomes a stagnation, and the precast board A and cast-in-place concrete B
Since the concave portion of the precast plate is oriented obliquely in the direction of passing, the shear stress distribution is averaged in the direction of passing and in the direction perpendicular to this, and bending due to vertical loads is achieved. They will act as one. Further, the precast plates A are integrated with each other via cast-in-place concrete by the action of the above-mentioned concrete starter. Test example The thickness _h1 shown in Fig. 7 is 100 mm and the width X is 500 mm.
On the surface of the PC precast board A, recesses 3 having the size and shape shown in FIG. Pour cast-in-place concrete B with h ₂ of 80 mm to make the overall thickness h 180 mm.
A composite floor test piece with a diameter of mm was manufactured, and this and the PC
A short-term loading experiment was conducted on precast plate A alone, and the results were as shown in Table 1.

[Table] In addition, when a deflection test was conducted on synthetic floor test piece No. 1 in Table 1, the results were as shown in the graph in Figure 8. The flatness was maintained as shown in the graph of FIG. Discussion (1) Regarding strength and fracture properties Both the cracking load and maximum yield strength of the experimental setup exceeded the calculated setup as a single piece, confirming the integrity of the floorboard from the standpoint of strength. Furthermore, the fracture behavior was normal bending or shear fracture, and the fracture phenomenon of the joint surface was not observed until the end, and integrity was confirmed from the fracture behavior. (2) Regarding the load deformation curve The elastic stiffness of all experimental values exceeds the calculated values. Furthermore, when looking at the history characteristics of the curve, no phenomenon in which the integrity of the joining surface was lost was observed. These confirmed the integrity of the floorboards. (3) About crack properties The crack passes through the splicing surface almost in a straight line, and no progress is observed along the splicing surface. Therefore, the integrity of the floorboards was confirmed from the viewpoint of crack properties. (4) Regarding slippage on the joint surface The slippage on the joint surface was 0 to 0.01 mm or less, confirming that integrity was maintained. (5) Regarding flatness retention Looking at the results of plotting the skewness in the thickness direction, we find that
It is observed that the cross section maintains a substantially flat surface. Therefore, the integrity of the composite floor board, which was formed by integrally casting cast-in-place concrete on the top surface of a precast concrete board, was confirmed. Conclusion As described above, the structural integrity of the composite floorboard was confirmed in terms of strength, rigidity, fracture property, cracking property, slippage on the joint surface, and ability to maintain the plane of the cross section. The present invention is constructed as described above, and a large number of recesses are provided in a staggered manner on the surface of a precast board, and cast-in-place concrete is poured on the upper surface of the recesses, so that the cast-in-place concrete that fits into the recesses serves as a caster. As a result, it is expected that the shear stress distribution will be averaged, and as shown in the experimental example, a strong integration will be achieved. It is clear that the strength can be calculated using the thickness of the integrated structure, and as a result, it is extremely advantageous compared to conventional construction methods in terms of cost and workability.

[Brief explanation of drawings]

Figure 1 is a partial perspective view of an example of a precast board;
Figure 2 is an enlarged sectional view of the recessed part, Figure 3 is a partial perspective view of another example of the precast board, Figure 4 is a sectional view of the mold for the recessed part, and Figure 5 is the installed state of the end of the precast board. A partial sectional view of one example, FIG. 6 is a sectional view of another example, and FIG. 7 is a sectional view of a synthetic floor test piece.
FIG. 8 is a graph showing the results of the deflection test, FIG. 9 is a graph showing the amount of slippage of the joint surface, and FIG. 10 is a graph showing the maintenance of the flatness of the cross section. A... Precast board, B... Place concrete, 1... Hollow hole, 2... PC steel wire, 3... Concave part, 10, 12... Beam.

Claims (1)

[Claims] 1. In a floor construction method in which concrete precast boards are stretched between steel frames or concrete beams, and cast-in-place concrete is poured on the top surface, the precast boards have a number of recesses on the surface that are close to each other and distributed in a staggered manner. After installing this precast board so that the recessed portions are arranged obliquely at least with respect to the spanning direction, pour the cast-in-place concrete into the surface of the precast board and into the recessed portion. By integrating the precast board and the cast-in-place concrete by making the poured concrete in the recess act as a shackle, the distribution of shear stress in the direction along the length of the beam in the precast board can be averaged. A floor construction method that is characterized by its unique design.