JPH0786260B2 - PC floor board - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention uses a precast concrete floorboard (referred to as a PC floorboard in this specification) as a casting form, and casts cast-in-place concrete on the upper surface thereof. PC floorboards used to construct synthetic floorboards.

[Prior Art] The PC floorboard needs a joint structure that integrates the two in order to transmit the horizontal shearing force generated on the composite joint surface with the post-cast concrete. As a means for this, a method of enhancing the joining effect by using shear reinforcing bars (truss reinforcement, giveber reinforcement, spiral reinforcement) prepared for the joint, or for shear cotter or rough surface finishing on the joint surface of post-cast concrete A method of performing a splicing surface treatment is known.

A commonly practiced method is to provide a concave sheacotter on the entire upper surface of the PC floorboard to achieve integration with post-cast concrete.

However, if the sheacotter is provided on the entire upper surface,
In addition to increasing the amount of post-cast concrete, it may cause a practical cross-section loss near the central part where the bending moment increases, which may cause bending cracks during lifting or after erection.

Therefore, a method of providing a square-shaped sheer cotter only around the PC floor plate is proposed in Japanese Patent Publication No. 62-6061.

[Problems to be Solved by the Invention] With the PC floorboards described in the above-mentioned patent publications, the effect of joining with post-cast concrete cannot be expected in the central area. The PC floor is mainly intended to transmit the shear force in the direction perpendicular to the surrounding beams, and the shear force transmission in the diagonal direction is not considered so much.

Further, the conventional PC floorboard is thin, and tends to be cracked in the peripheral portion due to drying shrinkage after molding, but since a shear cotter is arranged in the peripheral portion, when a crack occurs, the shear cotter Not only is there a possibility of loss, but there is a problem in ensuring quality during the period up to construction.

Furthermore, conventional PC floorboards often depend on their size, but in many cases they are simply placed on the surrounding beam ends or supporting works with a margin of several cm, which may cause safety concerns. is there.

Therefore, the present invention, in view of the above, has a high joining effect with the post-cast concrete in the joining portion, and also ensures quality in the period from the molding to the erection, and the safety after erection is considered, and an improved PC Its main purpose is to provide a floorboard.

[Means for Solving the Problems] The PC floorboard according to the present invention has a sheer cotter provided in a central area surrounded by the strip-shaped areas rather than a sheer cotter provided in the strip-shaped areas parallel to the beams of the four-sided edge portions. The arrangement is rough, the mesh reinforcements are embedded in a grid pattern so as to surround at least the shear cotter arranged in the strip area, and the welding inserts for welding to the beam reinforcements or steel frames are embedded in the side surfaces. It is characterized by each.

[Operation] In the present invention, the shearing cotter is arranged roughly in the central area of the PC floorboard, so that the mechanical strength of the central area is not lowered and the effect of joining with the post-cast concrete is also achieved in the central area. It is possible to exert the effect, and is particularly effective in transmitting diagonal shearing force as a whole, and by embedding mesh streaks around the shear cotter, it is possible to prevent damage to the shear cotter due to drying shrinkage of concrete after molding, Further, the welding after installation is ensured by welding the beam reinforcement or the steel frame using the welding insert provided on the side surface.

[Examples] Next, a PC floorboard according to the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIGS. 1 and 2, the PC floorboard 10 according to the present invention.
Unlike conventional flooring, which is unidirectional,
It is a bi-directional floor covering received at 20, 21, 22, and 23. Therefore, the section surrounded by the columns (spans) in the beam-to-beam direction and girder direction is composed of a single rectangular PC floorboard.

As is clear from FIG. 1, a strip-shaped area on the periphery of the upper surface of the PC floor board 10 which becomes the joint surface with the post-cast concrete.
A sheer cotter 15 is placed in 11 to 14, and a band-shaped area
A sheer cotter 17 is arranged in a central area 16 surrounded by 11 to 14.

In the illustrated embodiment, the sheer cotters 15 arranged in the strip-shaped areas 11 to 14 are, for example, three rows parallel to the beams 20 to 23, and the shape of each sheer cotter 15 is a concave shape as shown in FIG. It is a hexagon. The length of one side of the hexagon is about 5 cm, the depth of the recess is about 1 cm, and each row has a staggered arrangement in which each row is alternately arranged.

A mode in which the arrangement of the sheacotter 15 is configured in two or more rows, or the cross-sectional shape of each sheacotter 15 is circular, elliptical,
The present invention also includes an aspect of forming a concave shape such as a triangle, a quadrangle, or a polygon, and the size and the depth thereof are not limited.

Further, the sheacotter 15, the number of arrays or the number theoretically required according to the size of the span and the construction load, for example,
At least outside the center of the span in the cross direction for 1/4 span, the peripheral portions are counted from the starting point and arranged.

Shear cotter 17 placed in the central area 16 of the PC floorboard 10
Makes the arrangement coarser than the arrangement of sheer cotters 15 arranged in the strips 11-14.

Coarse arrangement means to increase the arrangement interval, in other words, to reduce the number of arrangements.

Cross-sectional shape of the shear cotter 17 provided in the central area 16,
The size, depth, etc. may be the same as or different from the sheer cotters 15 provided in the strip-shaped areas 11 to 14.

The present invention also includes forming the sheer cotter 15 in a concave shape and the sheer cotter 17 in a convex shape, or vice versa. Furthermore, by the convex part (concave part) arranged on the lower formwork for PC floor board production, on the concrete surface after molding,
Not only the aspect in which the sheacotter is formed in a concave shape (convex shape), but the present invention also includes a configuration in which a stud or a reinforcing bar is arranged in the formwork so that the sheacotter is projected to the concrete surface after molding.

As described above, not only in the peripheral portion of the PC floor board, in the central area, without reducing the mechanical strength in the central area, enhance the dowel effect between the PC floor board 10 and the post-cast concrete, and further The horizontal shearing force generated on the joint surface
It is possible to transmit in either horizontal or diagonal directions.

As a hoisting jig used during erection work, for example, steel inserts 30 each having a female screw in the hollow portion are prepared at even positions. This insert 30
Is buried when the PC floorboard 10 is manufactured, and the upper end of the PC floorboard 10 is
It is configured so that the position is approximately equal to the top of.

Further, the lower end of the insert 30 is tightly connected to the slab lower end reinforcing bar embedded in the PC floor board 10.

The number of inserts 30 to be arranged varies depending on the supporting force of the lifting hook, the weight and size of the PC floor board 10, and the like.

Further, the insert 30 can be used not only as a hoisting jig during the above-mentioned erection work, but also for further enhancing the dowel effect (coupling effect) with post-cast concrete.

More specifically, as shown in FIG. 4, a shear reinforcing bar having a male screw is attached to the insert 30 from which the lifting work has been removed after the work of erection of the PC floor board 10 is completed, and this is attached to the upper end of the slab. Work so that it is tightly connected to the muscle.

As shown in FIG. 3 and FIG. 5, at least the strip area
Lattice-shaped mesh muscles 32 are embedded around the shear cotter 15 arranged in 11 to 14. When the sheacotter 15 is arranged in a zigzag pattern, the mesh lines 32 are arranged in an oblique lattice pattern.

The depth at which the mesh muscle 32 is embedded corresponds to the depth of the sheer cotter 15. Shea cotter 15 near the top of the PC floor
It is preferable that the position is shallower than the depth of.

With the above structure, even after drying and shrinking after molding, cracks can be prevented, and therefore, it is possible to prevent the shear cotter from being damaged due to cracks between the time of molding and the time of erection, unlike conventional PC floor boards. It is effective in ensuring quality.

As shown in FIG. 6, a steel welding insert 31 for welding the PC floor plate 10 and the beam or steel frame is embedded in the side surface of the PC floor plate 10.

This welding insert 31 is a lifting insert 30.
Like the above, a female screw may be prepared, or a simple iron piece without a female screw may be used.

The PC floorboard according to the present invention is parallel to the erection work, and its side end can be welded to the beam reinforcement or the steel frame by using the welding insert 31.
It is possible to prevent accidents such as displacement of the mounting position or dropping from the beam, which is an advantage in terms of safety measures.

[Effects of the Invention] According to the PC floorboard of the present invention, the sheer cotter in the central area is arranged to be rougher than the sheer cotter in the strip-shaped area of the four-sided edge portion. Even in the partial area, the shearing force generated on the composite joint surface with the post-cast concrete can be transmitted in both the cross direction and the diagonal direction, and unlike the conventional product in which the shear cotter is evenly present in the central area, near the central area. It is possible to effectively prevent cross-section loss and cracking in the case of the post-concrete concrete without lowering the mechanical strength of the central area as compared with the conventional product in which there is no sheer cotter near the central area. It is expected that the joining effect of the PC floorboard can be expected, and by embedding mesh lines around the shear cotter in the peripheral part which is particularly important for in-plane shear force transmission, it causes dry shrinkage after molding the PC floorboard. Since it can prevent cracks, it protects and reinforces the sheer cotter portion, and can be welded to beam reinforcement or steel frame using the welding inserts provided on the side surface, so it can be vibrated after installation. In addition, it is possible to prevent an accident such as a displacement of the mounting position or a fall from the beam, so that the above-mentioned problems can be solved.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a PC floor board according to the present invention, FIG. 2 is a cut end view, FIG. 3 is a partially enlarged plan view, and FIGS. 4 to 6 are partially enlarged sectional views. . In the figure, each code indicates the following. 10 …… PC floorboard 11〜14 …… Strip area 15 …… Shear cotter 16 …… Center area 17 …… Shear cotter 20〜23 …… Beam 30 …… Lifting insert 31 …… Welding insert 32 …… Mesh bar

Claims (3)

[Claims] 1. A PC floorboard characterized in that the arrangement of sheer cotters provided in a central area surrounded by the belt-shaped areas is rougher than the arrangement of sheer cotters provided in the belt-shaped areas parallel to the beams of the four-sided edge portions. . 2. The PC floorboard according to claim 1, wherein mesh streaks are embedded in a lattice shape so as to surround at least the periphery of the sheacotter arranged in the strip-shaped area. 3. The PC floorboard according to claim 1, wherein a welding insert for welding to the beam reinforcement or the steel frame is embedded in the side surface portion.