JPS6320975B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a device for attaching a precast concrete beam to a precast concrete girder.

Conventionally, in this type of mounting device, as shown in FIGS. 1 and 2, a notch a with a rectangular cross section is cut out on the side surface of the precast concrete girder A.
Precast concrete beam B in the same notch a
The joint ends of the two are fitted together.

Therefore, the shearing force Q of the small beam B will be transmitted through the remaining cross-sectional portion b of the girder A, which is cut out from the notch a, which is structurally disadvantageous, requires reinforcement, and makes it necessary to increase the size of the girder. Furthermore, since the recessed portion a has a rectangular cross section, there is a drawback that machining of the recessed portion a is difficult.

The present invention was proposed in order to eliminate such drawbacks, and the present invention is a trapezoidal notch in the side of a precast concrete girder whose width gradually decreases toward the bottom. A trapezoidal joint end provided at the tip of a cast concrete beam that matches the shape of the notch is fitted, and the shear force of the beam is transmitted by the surface compression force of the inclined side surface of the notch. The present invention relates to a mounting structure for a precast concrete beam, which is characterized in that it is configured as follows.

In the present invention, as described above, the recess provided in the side surface of the precast concrete girder and the joint end of the precast concrete small beam are each formed into a trapezoid whose width gradually decreases as it reaches the lower part. Since the trapezoidal joint ends of the small beams are fitted into the trapezoidal notches of the large beam, the shearing force of the small beams is applied to the trapezoidal notches of the large beams that are in contact with the slopes on both sides of the trapezoidal joint ends of the small beams. Since the stress is transmitted by the surface compressive force of the inclined surfaces on both sides of the girder, excessive stress concentration on the recessed portion of the girder is avoided, eliminating the need for conventional reinforcing devices and eliminating the need to increase the girder size. do not have.

Further, according to the present invention, the recessed portion of the girder is formed into a trapezoid whose width gradually decreases as it reaches the bottom,
Since both sides are formed into tapered surfaces, there is an advantage that the formwork can be easily demolded and processed when manufacturing a precast concrete girder.

The present invention will be described below with reference to the illustrated embodiments.

A is a precast concrete girder, and a trapezoidal recess 1 whose upper end surface is open and whose width gradually decreases as it goes downward is cut out at the attachment part of the precast concrete beam on its side surface.

In the figure, 2 and 3 are the upper main reinforcement and the lower end main reinforcement, respectively.

Reference numeral B designates a precast concrete beam, the tip of which is formed into a trapezoidal joint end 4 having the same shape as the recess 1.

In the figure, 5 and 6 are the upper end main reinforcement and the lower end main reinforcement, respectively.

Therefore, when attaching the small beam B to the large beam A,
The trapezoidal joint end 4 of the small beam B is fitted into the notch 1 of the large beam A, and grout 7 is filled into the gap between both 1 and 4.

C in the figure indicates the concrete floor slab.

Therefore, the shearing force of the small beam B is transmitted by the compression stress between both sides of the trapezoidal joint end 4 and both sides of the trapezoidal notch 1 of the large beam A.

Figure 9 shows this stress transmission function. The shearing force τ of the small beam B is transmitted by the surface compressive force στ of the side surface of the notch 1 of the girder A, and the If the angle of inclination with respect to the vertical line is θ, then σ=τ・1/sinθ≦σ _a (allowable bearing stress), and the stress transmitted to the notch in the girder A is reduced compared to the conventional case. , reinforcement of girder A,
This eliminates the need for increasing beam size.

Although the present invention has been described above with reference to embodiments, the present invention is, of course, not limited to such embodiments, and can be modified in various ways without departing from the spirit of the present invention. .

[Brief explanation of the drawing]

Figures 1 and 2 are a vertical cross-sectional view and a vertical side view showing the precast concrete beam attachment part of a conventional precast concrete girder, respectively, and Figures 3 and 4 are explanatory diagrams showing its stress transmission function. , 5th
The figure is a longitudinal cross-sectional view showing an example of the mounting structure for precast concrete beams according to the present invention, FIG. 6 is a plan view thereof, and FIGS. FIG. 9, which is a sectional view taken along a line, is an explanatory diagram showing the stress transmission function. A... Precast concrete main beam, B... Precast concrete small beam, 1... Notch, 4...
Joint ends of beams.

Claims (1)

[Claims] 1 A trapezoidal notch in the side of the precast concrete girder whose width gradually decreases as it reaches the bottom corresponds to the shape of the notch provided at the tip of the precast concrete beam. installation of a precast concrete beam, characterized in that the trapezoidal joint ends of the beam are fitted, and the shearing force of the beam is transmitted by the surface compression force of the inclined side surface of the notch. structure.