JPH0726431B2 - Joint structure of half precast concrete beam and cast-in-place concrete beam. - Google Patents

Description

The present invention relates to a joint structure of a half precast concrete beam and a cast-in-place concrete beam for joining a half precast concrete beam to a cast-in-place concrete beam.

[Conventional technology]

In recent years, in the construction of buildings, as a means to save labor and improve the workability, a method has been widely adopted in which the beam is made into half-precast concrete (hereinafter referred to as half-PC) and a half-concrete slab is combined with it. It started to come.

Here, the connection between the half PC small beam and the concrete large beam supporting it is the same as half PC in the conventional reinforced concrete construction.
The bottom beam of the beam is fixed in the concrete beam 25 to 35 times the diameter of the reinforcing bar, as required by the structural regulation by law.

[Problems to be Solved by the Invention]

In the above-mentioned conventional half-PC beam, the protruding length of the down-beam is remarkable because it is necessary to secure a sufficient fixed length of the down-beam, which makes the assembling work of the half-PC beam difficult.

For steel-framed reinforced concrete structures, there are also those that bend the end of the bottom rib to a U shape at the beam end to secure the anchoring length and shorten the protruding length, but this is very much from the beam end surface. The difficulty of joining work due to the protruding reinforcing bars of No. 1 could not be solved, and improvement was desired.

The present invention has been made in view of the above circumstances, and its purpose is to solve the inconvenience in construction due to the end of the projecting lower bar, and the girder is either a reinforced concrete structure or a steel reinforced concrete structure. Is to provide a joint structure of a new half-PC beam and cast-in-place concrete girder that can be joined with a sufficient joining force by incorporating a half-PC beam.

[Means for Solving the Problems]

In order to solve the above problems, the present invention does not project the anchoring streaks on the forehead surface, and allows the forefront of the half-precast concrete beam to form a taper surface that spreads upward into the side surface joint portion of the concrete girder cast in place. , It is characterized by the joint structure of half precast concrete beam and cast-in-place concrete beam.

[Action]

Since half-PC beam has no anchoring streak protruding on the fore edge surface, when installing the half-PC beam to the girder before concrete placement, the half-PC beam is extremely easy to cast in place without any hindrance. Since it can be incorporated into the side joint of the girder, the workability is significantly improved, and after placing the girder concrete, the component component of the vertical shearing force applied to the half-PC girder is through the taper surface of the upper edge of the small mouth. Acts on the joint surface of the girder, and sufficient joint strength can be obtained without fixing the stirrups under the girder to the girder.

〔Example〕

 Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

1 is a vertical cross-sectional view of the structure of the present invention in the direction of a half-PC beam, FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 3 is a cross-sectional view taken along the line BB of FIG. It is a figure.

In the figure, 1 is a cast-in-place concrete girder, 2
Is a top beam of the girder 1, 3 is a bottom line of the girder 4, 4 is a stirrup of the girder, 5 is a half-PC beam that has been pre-manufactured and assembled in the side joint of the girder 1 on site, 6 is the same half PC
The bottom beam of the beam 5 is a stirrup of the half PC beam 5, the reference numeral 8 is a half concrete slab cast at the same time as the concrete beam 1, and the line 9 is an upper beam of the half PC beam 5.

Half PC beam 5 joined to the side of concrete beam 1
In the small edge of, the lower streak for fixing to the large beam like the conventional small beam does not protrude, and the small edge surface is formed by two surfaces of the lower taper surface 5a and the upper vertical surface 5b which spread upward, After placing the large beam concrete, the component force of the vertical load applied to the half PC small beam 5 exerts a wedge action on the joint surface of the large beam 1 via the tapered surface 5a, so that the small beam 5 is joined to the large beam with sufficient joint strength. It is supposed to be done.

Incidentally, as shown in FIG. 4, the small PC beam 5 may have only a taper surface 5a 'which is widened upward without a vertical surface as shown in FIG.

The stirrup 7 of the half PC beam 5 is projected from the upper surface of the beam and fixed to the half concrete slab 8.

Next, the construction method of the structure of the present invention will be described.

On the site, the concrete girder 1 is arranged with an upper bar 2, a lower bar 3, and a stirrup 4, and a formwork 10 for assembling concrete is assembled. The half-PC small beam 5 produced in the factory is carried into the site, and the tapered surface 5a of the small opening is appropriately inserted into the predetermined joint portion on the side surface of the large beam 1 and supported by the hanging support. Then, the upper stirrup 9 of the beam 5 that was put in the factory inside the star wrap 7 protruding from the upper surface of the half-PC beam 5 is pulled out, and the star of the beam 5 that opposes so as to cross the beam 1. When the girders are laid through the wrap 7 and then the girder concrete is placed, the joining of the girder 1 and the half PC girder 5 is completed.

According to the structure of the present invention, the small tapered surface 5a of the half PC beam 5 is made as smooth as possible, and grease is applied to the tapered surface 5a. The yield strength was obtained.

〔The invention's effect〕

As described above, the present invention does not project the anchoring streak on the fore edge surface, and the fore edge of the half precast concrete girder formed with the taper surface of the upward spread is appropriately inserted into the side surface joint portion of the cast concrete girder, A large beam concrete is cast to join a half precast concrete beam and a cast-in-place concrete beam,
Since there is no protrusion of anchoring streaks on the front surface of the half precast concrete beam, the half precast concrete beam is cast in place without any hindrance when it is assembled into the beam before placing concrete. Since it can be incorporated into the joint part of the girder, the workability is significantly improved, and after placing the girder concrete, the component force of the vertical load applied to the half-precast concrete girder is applied to the girder through the tapered surface that spreads upwards of the small mouth By exerting a wedge action on the joint surface of the beam, the small face of the beam is pressure-bonded to the beam, and even if the beam under the beam is not fixed to the beam, the bonding strength equal to or higher than that of the beam with fixing is obtained.

[Brief description of drawings]

The drawings show the embodiments of the present invention. Fig. 1 is a longitudinal sectional view of the structure of the present invention in the direction of a half-precast concrete beam, Fig. 2 is a sectional view taken along the line AA of Fig. 1, and Fig. 3 is FIG. 1 is a cross-sectional view taken along the line BB of FIG. 1, and FIG. 4 is a view showing another embodiment of the small face of the half precast concrete beam. 1 …… cast-in-place concrete beam, 5 …… half-precast concrete beam, 5a …… tapered surface, 8 …… cast-in-place half concrete slab.

Claims (1)

[Claims] 1. A small beam of half-precast concrete beam having a tapered surface that does not protrude from the edge of the frame and has a taper surface that widens upward is appropriately inserted into the side joint of the concrete beam to be cast in place, and the beam concrete is poured. A joint structure between a half precast concrete beam and a cast-in-place concrete beam characterized by being installed and joined.