JPH073100B2 - How to build precast PC beams - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention mainly relates to a precast PC beam in which a precast beam made of prestressed concrete (hereinafter referred to as PC) is erected while being supported by a precast concrete column when constructing a synthetic slab. Regarding the erection method.

(Prior Art) Conventionally, many constructions of multi-story buildings using precast beams have been proposed. When constructing the precast beams, a steel frame for connection is projected at the tip of the PC beam and the connection is performed. The steel frame was bolted to the steel frame for beam connection that horizontally protruded from the steel concrete column, and the periphery of the steel frame part was filled with cast-in-place concrete, or the reinforcing bar was projected at the tip of the precast beam. It was common that the steel rod was fixed to the rebar protruding from the precast column by welding or a coupler joint, and the rebar was embedded and cast-in-place concrete at the connecting portion was placed.

(Problems to be Solved by the Invention) In the conventional method as described above, a supporting work is required at the time of erection of the beam, and a formwork must be assembled to cast the cast-in-place concrete around the connecting portion. Moreover, since the precast concrete and the cast-in-place concrete at the connecting portion cannot be integrated, there is a problem that the stress distribution cannot be made uniform.

For this reason, there is a method of inserting an unbonded cable into a plurality of beams that are connected by sandwiching a column, and applying prestress to the plurality of beams after erection of the beam, but with this type of conventional method. Since the PC steel wire is inserted into the beams on both sides of the column by penetrating the column, it is necessary to open through holes in the column in advance, which requires time and labor for the manufacturing, and erection work is also difficult. It was a thing.

In view of such a conventional problem, the present invention makes the stress distribution of the beam uniform in the column portion, makes it possible to easily manufacture the erected end portion of the precast beam and the precast column, and efficiently perform the erection work. The purpose of the present invention is to provide a method for constructing a precast PC beam, which enables the connection between the PC beams to be strong.

(Means for Achieving the Problem) The object of the present invention to solve the above-mentioned conventional problems and achieve the intended purpose is to provide a flange-shaped beam erection portion for surrounding the beam. A precast concrete column having an integral structure is erected, and the ends of the precast PC beam are supported from above in four directions on the overhanging part.The PC beam has at least its tip portion formed wider than the precast concrete column. , The tip side of the PC beam is provided with a taper surface, the tip surfaces of the PC beams and the tip surfaces of the PC beams and the precast concrete columns are opposed to each other, and the tip ends of the PC beams are opposed to each other in the extension direction side. Next to each other
Precast PC characterized by tensioning with an end tension cable that penetrates the tip of the PC beam in the width direction
It depends on how to construct the beam.

(Operation) In this precast PC beam erection method, the PC beam is bridged between the overhanging portions of the precast concrete column for erection of the beam, and the end tension is provided between the PC beam tips in the mutually extending directions.
Prestressing is also applied between the PC beams that sandwich the column by tensioning with the PC cable, which results in continuous prestressing in the longitudinal direction across multiple beams. The tension PC cable is inserted into the outside of the side surface of the precast column without penetrating it, which improves workability.

Further, since the end portion tension PC cable is penetrated in the width direction of the tips of the adjacent PC beams in the orthogonal arrangement, all the PC beams are firmly coupled at the outer peripheral portion of the column.

(Example) Next, the Example of this invention is described about drawing.

In the figure, 1 is a precast concrete column and 2,2
…… is a precast PC beam. The precast concrete pillar 1 is integrally formed with an overhang 3 for beam erection at a beam erection height position.

The precast PC beam 2 is formed into a flat shape having a width wider than that of the column 1, and a step portion 4 for erection is formed on the lower surface of the tip. Both sides of the end portion of the PC beam 2 are tapered surfaces 2a, 2a having an angle slightly larger than 45 °, and the widthwise end tension cable insertion holes which are opened to communicate with the both tapered surfaces 2a, 2a. The central portion of the precast PC beam 2 excluding the end portion is provided with a concave portion 5 on the side surface in the longitudinal direction, and a PC is formed on the end plate portion 6 integrally formed so as to close the end portion of the concave portion.
The cable insertion hole 7 (shown in FIG. 5) is opened.
In addition to ordinary reinforcing bars, a bond-type PC steel wire 8 (shown in Fig. 3) attached to concrete over the entire length is embedded in this precast PC beam 2, and cast-in-place concrete is placed on the upper surface. A hoop-shaped connecting reinforcing bar 9 for projecting integrally with is projected.

The precast PC beam 2 configured as described above is erected while being supported by the overhanging portion 3 of the pillar 1. First, the pillar 1 is erected and the end portion is erected on the edge of the overhanging portion 3. The stepped portion 4 for use is fitted and is laterally bridged. At this time, PCs that are orthogonal to each other
The beams 2 and 2 have taper surfaces 2a and 2a on the projecting portion 3 and are arranged to face each other. In this way, the tips of the precast PC beams are supported on the four peripheral edges of the pillar 1, and the PC cable insertion holes 7 and 7 formed in the facing surfaces of the precast PC beams 2 and 2 in the mutually extending directions. The end tension PC cable 11 is inserted through the cable insertion holes 10 in the width direction of the PC beams 2 which are adjacent to each other in an orthogonal arrangement, and the PC is provided on the rear surface of each end plate portion 6.
The cable 11 is supposedly attached by the fixing metal fitting 12.

In this state, the joint concrete is filled in the gaps between the tapered surfaces 2a, 2a and between the column 1 and the PC beam end surface, and waits for the concrete to harden before PC.
Tension the cable 11 from one end, and both precast PC beams 2,2
Tension in the direction of pulling each other and apply prestress.

After erection of the precast PC beams 2, 2 in this way, the precast concrete slabs 14, 14 are placed between the precast beams 2, 2 which are adjacent to each other in parallel directions as shown in FIGS. 3 and 4. Hand over ... and each precast PC on it
A composite slab in which the cast-in-place concrete layer 15 and the cast-in-place concrete layer 15 and the precast concrete slab and the precast PC beam 2 are integrated by placing the cast-in-place concrete layer 15 by connecting and arranging to the connecting reinforcing bars 9 on the upper surface of the beam 2. Eggplant

(Effect of the invention) As described above, in the method for constructing the precast PC beam of the present invention, by tensioning the end portions of the precast PC beams in the extension direction to each other with the end tension PC cable, Since continuous prestress is applied between the beams that sandwich the pillar, and since the prestress is also applied to the entire length of the beam itself, continuous prestress will be applied to multiple beams in the extension direction, It is possible to form a structure in which stress is not concentrated on the connecting portion of the beam.

In addition, since the end portion tension PC cable is arranged outside the side surface of the column through the gap formed between the end surface of the precast PC beam and the side surface of the column, the column has a through hole for the end tension PC cable. It becomes unnecessary, and its manufacturing is easy, and also the work of arranging the PC cable at the end portion is easy, and it is possible to construct it with good workability.

Furthermore, the PC beams after being erected will be connected to each other at a position orthogonal to each other by the shearing force of the end-tensioned PC cable, and a strong connection will be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a beam installation state, FIG. 2 is a side view of the same, and FIG.
Figure is a cross-sectional view of the completed composite slab, and Figure 4 is AA in Figure 3.
FIG. 5 is a perspective view of the end portion of the precast PC beam, taken along the line. 1 …… Precast concrete pillar, 2 …… Precast PC beam, 2a …… Tapered surface, 3 …… Overhanging part, 4 …… Step part, 5 …… Concave part, 6 …… End plate part, 8 …… PC Steel wire, 9 ...
… Connecting rebar, 10 …… Cable insertion hole, 11 …… PC cable, 14 …… Concrete plate, 15 …… Spot concrete layer.

Claims (1)

[Claims] Claims: 1. A precast concrete column having a flange-like beam overhanging portion integrally provided around the periphery of the precast concrete column, and the ends of the precast PC beam are supported on the overhanging portion from four directions, and the PC The beam has at least its tip portion formed to be wider than the precast concrete column, and the tip side surface of the PC beam is provided with a tapered surface, and between the taper surfaces of the PC beams and the tip surface of each PC beam and the precast concrete column. Between each other, and opposite each other in the extension direction
A method of constructing a pre-catenated PC beam, characterized in that the ends of the PC beams are tensioned by an end tension cable that penetrates the ends of adjacent PC beams in the width direction.