JPS6138307B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an assembly truss reinforcement used for reinforcing thin precast concrete plates (hereinafter referred to as PCa).

When thin-walled PCa boards are used as concrete molds for the floors or walls of buildings, there is a risk of excessive cracking or deformation due to lateral pressure during manufacturing, transportation, erection, and concrete pouring. be.

In order to prevent this, the assembled truss bars were installed in advance.
The PCa board is reinforced by driving it into the board.

Conventional assembled truss bars for reinforcing thin-walled PCa boards are shown in Figures 1a and b, in which reinforcing bars are bent into lattice bars between continuous reinforcing bars 1 of the upper chord and reinforcing bars 2 and 2' of the lower chord. 3 or 4 are assembled symmetrically on both left and right sides and in a continuous triangular shape.
By driving into the PCa board 5, it is used as a reinforcing material for the board 5 itself.

However, in the case of such assembled truss bars, since the lattice bars are arranged in a double symmetrical manner, the amount of reinforcing bars inevitably increases, and when assembling the truss bars, the amount of reinforcing bars must be increased, especially at the welded part to the upper chord. There are many duplications, making it difficult to manufacture, and furthermore, the reinforcing effect is not very high compared to the above.

In view of the above-mentioned circumstances, the present invention has been made to provide a reinforcing truss bar that has a better reinforcing effect than conventional assembly truss bars and is easier to manufacture. The gist of this is that one reinforcing bar diagonally crosses one continuous upper chord member and two consecutive lower chord members to the opposite side, and for the lower chord member, the reflection The point is that the unreasonableness of the above-mentioned bilaterally symmetrical double arrangement has been solved by making it follow the pattern of folding back at an angle.

Hereinafter, the present invention will be explained in detail based on the drawings.

As a result of the assembled truss bar of the present invention being constructed in the manner described above, the reinforcing bar as a lattice bar is attached to one side of the continuous reinforcing bars 1, 2, and 2', which are the upper and lower chord members, as shown in Fig. 2a. 6 and 7 are assembled with 8 and 9 on the other side, and as is clear from the figure, when viewed from the side, triangles and trapezoids are alternately continuous due to the lattice muscle, and the left and right sides are asymmetrical.

A longitudinal sectional front view of this product is shown in figure b.

With this assembled truss bar, as shown in figure c, the thin wall
It is used as a reinforcing material that is driven into the PCa board 5.

The assembled truss bar having the shape of the present invention can be constructed in the following manner.

That is, as shown in FIG. 3, the reinforcing bars 10 that are bent into a lightning bolt shape and will become the lattice bars 6, 7, 8, and 9 have the reinforcing bars that will become the upper chord members 1 in the center, and the lower chord members 2 at both ends. , 2' are placed, and their intersection points are welded (Fig. a). Then, this is bent at the position of the upper chord (Fig. B) to form a triangular assembly truss (Fig. C).

Alternatively, as shown in Fig. 4, the reinforcing bars 11, which will become the lattice bars bent at the center, can be arranged in a triangular arrangement such that the upper and lower chord members 1, 2, and 2' have the lattice shape shown in Figs. 2 and 3. Weld.

There are three possible ways to do this: a, b, and c shown in the figure.

Note that c and b are almost the same, but the surface where the lattice is attached to the upper chord member 1 is attached to the upper chord member 1 as shown in A and B in the figure.
are welded so as to sandwich them from the left and right sides, and the lower chord member 2 or 2' is bound or spot welded to prevent the lattice strip from falling off as shown in C.

Or, as shown in Figure 5a, the deformed spiral reinforcing bars 12, which will become lattice reinforcements, are arranged and welded so as to wrap around the upper and lower chord members 1, 2, and 2' to form the truss shown in Figures 2, 3, and 4. Configure into shapes.

At this time, as a variation of a, the lattice strip may not be wrapped around the upper chord material 1, but may be welded to the side surface thereof, as shown in FIG. b.

The truss of the present invention having the above-described structure is an unstable truss and does not have the performance as a reinforcing material unless the intersection of the upper chord and the lattice is a pin and the upper chord is not a continuous member.

However, like a conventional truss, the upper chord member is a single continuous member, and the truss is formed by welding the lattice bar to this member.

In addition, the truss shape formed by the lattice strips is a series of triangles and trapezoids, and the lateral displacement of the contact point between the top chord and the lattice due to the asymmetrical arrangement of the lattice with respect to the top chord can be avoided by driving into the thin PCa board. The rigidity of the lattice and the upper chord restrain the structure, making it a stable truss.

Figure 6 shows the load-displacement curve of the results of a bending failure experiment conducted to compare the bending performance of the truss of the present invention and a conventional truss when the same truss is the same size as the top chord. It is.

When the lattice spacing is the same, the truss of the present invention exhibits somewhat smaller initial cracking and ultimate yield strength than the conventional truss, but the truss of the present invention exhibits greater deflection at maximum yield strength.

When using the same amount of lattice muscle as a conventional truss (buckling strength is half), the initial crack and subsequent member stiffness are slightly smaller, but the maximum yield strength and deflection at that time are larger than that of a conventional truss. It is judged that the assembled truss has sufficient performance as a reinforcing material for thin-walled PCa plates.

If the lattice spacing is the same, the lattice muscle mass of the truss of the present invention will be half, and the truss will be manufactured using the third method.
Both the method of bending the lightning bars shown in the figure and the assembly method using the lattice strips bent at the center as shown in Fig. 4 result in an economical assembly truss with less overlap in welding points compared to conventional trusses. is obtained.

[Brief explanation of the drawing]

Figures 1a and 1b are overhead views of conventional assembled truss bars for reinforcing thin-walled PCa boards, Figure 1c is a vertical cross-sectional view of a thin-walled PCa board reinforced by driving these truss bars, and Figure 2a is a perspective view of a conventional assembled truss bar for reinforcing thin-walled PCa boards. An overhead view of the assembled truss bar of the example, Figure b is its longitudinal cross-sectional view, and Figure c is the thin wall reinforced by driving it.
A partially cutaway overhead view of a PCa plate, FIGS. 3 and 4 are process steps of the assembled truss bar of the present invention, and FIG. 5 is an overhead view of the assembled truss bar of the present invention assembled in another manner, FIG. 6 is a graph showing a load-displacement curve. 1...Top chord material, 2, 2'...Lower chord material, 3, 4...Reinforcement bar, 5...Thin PCa plate, 6, 7, 8, 9...Reinforcement bar, 1
0...Reinforcing bar, 11...Reinforcing bar, 12...Reinforcing bar.

Claims (1)

[Claims] 1 One continuous upper chord member and two continuous lower chord members, one reinforcing bar crosses over the upper chord member diagonally to the opposite side, and the lower chord member is folded back at a reflection angle. An assembly truss bar for reinforcing thin-walled precast concrete plates, characterized in that it is made to continuously follow the pattern of truss reinforcement.