JPH0469268B2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention relates to a method for constructing a prestressed concrete structure extending between already formed concrete structures when constructing a concrete structure. be.

"Prior Art" As is well known, pre-tensioning methods and post-tensioning methods have been conventionally used to introduce prestressing when manufacturing prestressed concrete structures. In the former case, the tensile force applied to the prestressing steel material is applied before concrete is poured, and after the concrete hardens, the tensile force applied to the prestressing steel material is applied.
This is a method of applying prestress to the concrete by adhesion of the prestressing steel and concrete.In the latter, when pouring concrete, a sheath is embedded in the position where the prestressing steel is passed through, and after the concrete has hardened, the prestressing steel is passed through the sheath and one end of the prestress is applied. The other end is tensioned by water pressure or hydraulic jacks, and the reaction force is used to compress the concrete before it is fixed using wedges, screws, etc. In this case, in order to protect the steel material and ensure the safety of the members, it is desirable to inject mortar into the lead-through hole to attach the steel material and sheath (bond method).

"Problems to be Solved by the Invention" However, each of the above two methods had the following problems.

In other words, in the pretension method, there is no cost for the anchoring part and no work such as grouting is required, but it requires a strong reaction force (abbutt) to pre-tension the prestressing steel material, and In the tension method, it is relatively easy to introduce prestressing on-site because it does not require very large tension equipment, but it takes time and effort to arrange the sheath and fill it with grout.

The present invention was made in view of the above circumstances, and
A method of introducing prestressing that does not require large reaction tables that require time and effort to transport and set up, and also eliminates work such as placing sheaths and filling grout.In other words, introducing prestressing that shortens construction time and reduces costs. Its purpose is to provide a method.

"Means for Solving the Problems" Therefore, in order to achieve the above object, in the present invention, when constructing a concrete structure having horizontal structural parts such as beams and floor slabs that connect multiple columns,
A method of constructing a prestressed concrete structure that becomes the horizontal groove structure extending between the columns on a plurality of columns that have already been erected, the method comprising providing a sheath at each end of the prestressed concrete structure to be constructed. a step of pouring concrete to form a reaction force support that is integrated with some of the plurality of columns; and a step of forming a reaction force support that is integrated with some of the plurality of columns;
The process of setting up a PC steel material and tensioning it, and this PC
After tensioning the steel, concrete is poured between the reaction supports, and after the concrete hardens, the PC
The process includes the step of introducing prestress by transmitting the tensile force applied to the steel material to the actual concrete through adhesion between the prestressing steel material and the concrete.

"Operation" Reaction force supports are formed at both ends of the prestressed concrete to be constructed, and this is used to tension the prestressed steel, so there is no need to use a large-scale reaction table, and the tension of the prestressed steel can be reduced on site. It becomes possible.
In addition, most of the prestressed concrete structures that are formed are prestressed using the so-called pretension method, so most of the work such as sheath placement and grout filling can be eliminated.

"Embodiments" Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 5. Figures 1 to 5 are
This figure shows the application of the present invention to a beam constituting a PC (reinforced concrete) structure.

The object indicated by the reference numeral 1 in FIG. 1 is the target prestressed concrete beam (hereinafter abbreviated as beam) 1. The beam 1 and the pillars 9 that support it form a concrete structure A, and the pillars 9 that should support the beam 1 have already been erected on the ground G. The beams 1 are formed on these columns 9 by the following method. In addition, all reinforcing bars are omitted in the figures, and one span at both ends is shown shortened in FIGS. 2 to 5, and the middle column 9 is omitted.

First, as shown in FIG.
A sheath 2 is installed on top of each of the sheaths 2, with the axes of these sheaths 2 aligned. This sheath 2
The length is assumed to be at least one span of the column 9.

Next, concrete 3 is cast in the upper part of the column 9 where the sheath 2 is installed, and is completely hardened to form a reaction force support 4 that is integrated with the column 9. The formed reaction force support body 4 corresponds to the sheath 2 and spans one span of both ends of the pillars 9 that stand side by side. The size of the reaction force support 4 is appropriately determined in accordance with the tension of the PC steel material, which will be described later. Further, during this work, the opposing open ends of the sheath 2 are not blocked for later work.

Once the reaction supports 4 are formed, a PC steel material 5 is inserted between these two reaction supports 4 as shown in FIG.
is embedded in the reaction force support 4 and inserted into the opposing sheath 2.

After the PC steel material 5 is installed, a fixing device 6 is attached to one end of the PC steel material 5 as shown in FIG. 4, and a tension jack 7 is set to the other end. get nervous. At this time, each of the reaction force supports 4 and the fixing device 6
It also acts as a reaction force stand for the tension jack 7. The tensioning jack 7 may be one that has been conventionally used in the field when introducing prestressing by the post-tensioning method.

Once the PC steel material 5 is tensioned, next, in the formwork,
The actual concrete 8 is placed in a portion located between the two reaction force supports 4. Since a prestressed steel material 5 has already been constructed under tension between the two reaction force supports 4, this prestressed steel material 5 is connected to the main concrete 8.
It will be buried in this by pouring.

Once the actual concrete 8 has hardened, the tension on the PC steel material 5 is released using the tension jack 7 or a wedge, screw, etc. temporarily attached to maintain the tension state instead of the tension jack 7, and the fixing device 6 is removed. . As a result, the actual concrete 8
Prestress is introduced into concrete using the same principle as the general pretension method. In other words, the PC steel material 5
tries to compress it by releasing its tension. At this time, since the actual concrete 8 is attached to the PC steel material 5, this compressive force is introduced into the actual concrete 8, that is, prestressing is introduced. Furthermore, if the sheath 2 is filled with grout after tensioning the PC steel material 5, the reaction force support 4 can also be provided with so-called post-tensioning.
Prestressing using the bond construction method can be introduced. Further, the cast concrete 8 hardens together with the concrete 3 forming the reaction force support 4, and the reaction force support 4, the actual concrete 8, and the PC steel material 5 are combined as shown in FIG. As shown, the desired prestressed concrete beam 1 is formed. In addition, although the example explained the beam of the PC structure, the present invention is not limited to this example.
Of course, SRC (steel reinforced concrete) structures are also suitable, and in addition to beams, it can also be used for slabs, external walls, earthquake-resistant walls, etc.

"Effects of the Invention" As explained above, the present invention provides a method for constructing concrete structures that have horizontal structural parts such as beams and floor slabs that connect multiple columns. A method for constructing a prestressed concrete structure that will become the horizontal structure extending over the entire length of the structure, wherein a sheath is provided at each end of the prestressed concrete structure to be constructed, concrete is poured therein, and one of the plurality of columns is constructed. A step of forming a reaction force support that is integrated with the column of the section, a step of providing a prestressing steel material between the reaction force supports and tensioning it, and a step of forming a main body between the reaction force supports after tensioning the prestressing steel material. The method includes the step of pouring concrete and, after the concrete has hardened, transmitting the tensile force applied to the prestressed steel material to the prestressed concrete through adhesion between the prestressed steel material and the concrete to introduce prestress. PC on site without using the large-scale reaction force table that was previously required.
It is possible to carry out tensioning of steel materials, and in that case, it is not necessary to separately install a reaction force table, which is generally heavy, so that the work of installing and removing the reaction force table itself is also unnecessary. Moreover, most of the structures are prestressed using the so-called pretension method, which eliminates most of the work such as sheath placement and grout filling, which shortens the construction period and It has excellent effects such as cost reduction.

[Brief explanation of drawings]

1 to 5 each illustrate an embodiment of the method for manufacturing a prestressed concrete structure of the present invention, and FIG. 1 is a front sectional view of a concrete structure A in which a prestressed concrete beam 1 is in the middle of construction; 2 to 5 are enlarged front sectional views showing the prestressed concrete beam 1, respectively. A... Concrete structure, 1... Prestressed concrete beam, 2... Sheath, 3... Concrete, 4... Reaction force support, 5... PC steel material,
7... Nervousness, 8... Real concrete, 9
...pillar.

Claims (1)

[Claims] 1. When constructing a concrete structure with horizontal structural parts such as beams and floor slabs that connect multiple columns,
A method of constructing a prestressed concrete structure that will serve as the horizontal structure extending between the columns on a plurality of columns that have already been erected, wherein a sheath is provided at both ends of the prestressed concrete structure to be constructed, and the concrete is placed therein. forming a reaction force support that is integrated with some of the plurality of columns, and placing a PC between the reaction force supports.
A step of providing a steel material and tensioning it, and after tensioning this prestressed steel material, concrete is poured between the reaction force supports, and after the concrete hardens, the tensile force applied to the prestressed steel material is applied to the prestressed steel material. A method for constructing a prestressed concrete structure, comprising the step of introducing prestress by transmitting it to the concrete by adhesion to the concrete.