JPS60133146A - Construction of synthetic large beam using u-shaped precast beam material - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for constructing a precast beam having a U-shaped cross section, which incorporates lower end main reinforcements and unoccluded ribs on the upper end side, and then removes the upper end main reinforcements and the upper ends of the said ribs. The present invention relates to a method of constructing a composite girder in which the precast beam material and cast-in-place concrete are structurally integrated, by closing the sides and pouring concrete using the precast beam material as a pouring formwork.

The above composite girder construction method uses precast beam materials for girders, which tend to be larger and heavier than small beams, to have a U-shaped cross section. Reducing the award to the same level as pre-cast material for slabs,
This is a method that simplifies the delivery of materials to the site and construction.

Therefore, the upper end side of the reinforcing bars embedded in the U-shaped precast beam material makes it easy to remove the inner formwork when manufacturing the precast beam material and to easily arrange the upper main reinforcing bars after erection at the construction site. It is left open for the purpose of operation and then closed off for on-site operations.

By the way, in this type of conventional synthetic girder construction method, the upper end side of the ribs was closed by the following two methods, which had the disadvantage of being heavily constrained by the slab thickness and beam rlJ.

As shown in FIG. 1(A), the first method is to engage the upper main reinforcements 12' at the tips of the protruding parts of the reinforcing bars 7' that protrude from the upper surface of the precast beam 5' having a U-shaped cross section. In this method, a hook 13' is bent and formed, and a stop 15' having a hook 14' that engages with the upper main reinforcement 1z is separately provided to close the upper end side of the rib.

The second method is to bend the tips of the protruding parts of the ribs 7' on site, as shown in FIG.
b' and welding a linear stopper 15' between both horizontal portions a' and b' to close the upper end side.

In the former case, if the height h from the top surface of the precast beam 5' to the bending part of the reinforcing bar 7' is low, the required bending angle θ and the required length t of the hook 13' will be Therefore, depending on the thickness of the slab, the above method of constructing a composite girder cannot be applied.

In addition, in the case of the latter, two locations of welding are required for each reinforcing bar 7', which has poor workability, and if the beam width is narrow, it is not possible to secure the specified welding length, and depending on the beam width, Composite girder construction methods cannot be applied.

The present invention solves the above-mentioned conventional drawbacks, and even if the pitch of reinforcing bars is small, it is easy to join the reinforcing bars, the rolling of cast-in-place concrete is good, and the reinforcing bars can be strengthened by joining on-site. The purpose of this is to prevent any unbalance from occurring, and in the method of constructing composite girders mentioned at the beginning, the precast beams are made of a horizontal part that is clear in the beam width direction and a horizontal part that rises from both ends of the precast beam material. The ribs are made up of a pair of upright parts with different lengths, and the lengths of the parts protruding from the top surface of the precast beam in the beam [1] direction are different from each other, and the protruding parts are long in the longitudinal direction of the beam. The long and short protruding parts facing each other in the direction of the beam are bent inward at the same height from the top surface of the precast beam. It is characterized by bending to form a horizontal portion and joining both horizontal portions with a crimp joint.

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 2 and 3 show a method for constructing a reinforced concrete structure using the method for constructing a composite girder according to the present invention, and its outline is as follows.

I Suspension of column reinforcing bars For column reinforcing bars I, the main bars and tie bars are assembled into the ground prior to hanging. The main reinforcement joints will be crimp joints at the four corners, and lap joints at the others.

■ Erection of column formwork The column formwork 2 is made of steel panel formwork that has been pre-assembled and integrated into a rectangular tube shape, and is erected using a crane or the like.

■ Concrete pouring for columns Use hopper 3, etc. to pour concrete up to the top of the girder.

1%) [Erection of J-type precast beam material After demolding the column formwork 2, marking is done and the level of the top of the column 4 is adjusted, and the precast beam material 5 for the composite girder is erected. The precast beam 5 has a U-shaped cross section, and has built-in main reinforcing bars 6 at the lower end and ribs 7 that are not closed at the upper end, with pillars 4 at both ends and temporary supports at two points in the middle (not shown). figure)
The structure shall be supported and erected. In addition, at the joint portions of columns and thick beams, joint reinforcements 8 of the required length are arranged as shown in FIG.

(2) How to construct a precast beam 9 The precast beam 9 is erected by supporting the precast beam 5 at both ends and a temporary support (not shown) at one point in the center.

■ Laying Omnia boards for floor slabs In order to eliminate support for the floor slab formwork, Omnia boards (a pre-cast concrete board with three-dimensional truss-shaped reinforcing bars anchored on one side)10 were used, reducing the amount of temporary construction materials. We aim to save labor by

vIl Reinforcement for beam reinforcements and floor reinforcements The joints of the main reinforcements used for reinforcing the upper ends of large beams and small beams shall be pressure joints, and the floor reinforcements shall be pre-assembled in the form of a mesh.

Concrete 1 is placed on the head of the concrete column 4, the hollow part of the precast beam 5, the omnia plate 10, and the top of the precast small beam 9.
1.

In this example, the synthetic girder construction method of the present invention is applied to the above-mentioned construction method (particularly the steps from Vl to vlil).

That is, as shown in FIGS. 4 and 5, the precast beam material 5 having a U-shaped cross section as described above has a horizontal portion along the beam width direction and a pair of pairs having different lengths rising from both ends of the horizontal portion. The ribs 7 are made up of rising portions, and have different lengths of portions 7a and 7b that protrude from the top surface of the precast beam material 5 in the beam width direction, and a long protruding portion 7a and a short protruding portion in the longitudinal direction of the beam. The parts 7b are buried so that they are alternately located.

Then, in the step (■) above, as shown in Figure 6,
Insert the upper end main reinforcement 12 into the hollow part of the precast beam material 5,
Kanzashi hardware installed between the upper surfaces of the precast beams 5 (
(not shown), etc., with these upper end main reinforcements 12 temporarily supported, the long and short protruding portions 7a and 7b facing each other in the beam width direction are bent upwardly of the precast beam material 5, and the horizontal Parts a and b are formed, and both horizontal parts a and b are joined using a crimp joint. Incidentally, the steel sleeve C for crimping is fitted over one of the protruding portions μ, 7b after the bending operation.

Next, the position of the upper end main reinforcement 12 is corrected, and the upper end main reinforcement 12 and the cost reinforcement 7 are tied together.

After that, as shown in Fig. 7, concrete 11 is poured, and precast beams 5 and cast-in-place concrete are placed! J-
) 11 will be constructed into a composite girder that is structurally integrated.

A crimping joint requires a crimping tool and a working space, but as mentioned above, the long and short protruding parts 7a and 7b are
Since the crimping joints (sleeves C) are arranged alternately, the positions of the crimping joints (sleeves C) are staggered, and the gap on both sides of the sleeve C can be made large in relation to the pitch of the ribs 7, making it easier to insert the crimping tool. , easy to operate. Also, concrete)
11 has good rotation, and the position of the crimp joints is staggered, the strength is well balanced and a high quality composite girder can be obtained.

As described above, according to the present invention, the parts of the ribs protruding from the upper surface of the precast beam are folded inward and bent to form horizontal parts, and both horizontal parts are joined with a crimp joint, so that the thickness of the slab can be adjusted. There is less restriction due to width, and since the long and short protruding parts are arranged alternately in the direction of the beam, the crimp joints are placed in a staggered manner, and even if the pitch of the ribs is small, the crimp sleeve can be placed on both sides. A high-quality synthetic girder that can create a wide space, makes crimping work easy, and has good concrete rolling despite the presence of a crimping sleeve, and has a staggered joint position with a good balance of strength. This has the effect of providing.

[Brief explanation of the drawing]

FIG. 1 (0) and (b) are explanatory diagrams of a conventional example. Figure 2 and subsequent figures show examples of the present invention, Figure 2 is a perspective view showing the outline of the construction method of a reinforced concrete structure, Figure 3 is a schematic cross-sectional view of the joint between columns and thick beams, and Figure 4. 5 is a partially cutaway perspective view of a precast beam, FIGS. 5 to 7 are cross-sectional views illustrating the procedure for constructing a composite girder, and FIG. 8 is a plan view of the main part. 5... Precast beam material, 6... Bottom main reinforcement, 7...
・costal muscles, 7a, 7b...protruding parts. 1st (a) (b)

Claims (1)

[Claims] After completing the erection of a precast beam with a U-shaped cross section that incorporates the lower end main reinforcement and the cost reinforcement whose upper end is not closed, the upper end main reinforcement is arranged and the upper end of the cost reinforcement is closed.
In a method of constructing a composite girder in which the precast beam material and cast-in-place concrete are structurally integrated by pouring concrete using the precast beam material as a pouring formwork, the precast beam material may overflow in the beam width direction. A rib consisting of a horizontal portion and a pair of rising portions of different lengths rising from both ends thereof, the lengths of the portions protruding from the top surface of the precast beam material in the beam width direction are different from each other, and , the long protruding parts and short protruding parts are buried alternately in the longitudinal direction of the beam, and the long and short protruding parts facing each other in the beam width direction are placed at the same position from the top surface of the precast beam. A method for constructing a composite girder using U-shaped precast beams, characterized by bending them inward at a height to form a horizontal portion, and joining both horizontal portions with a crimp joint.