JPH0441733B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a post-tensioned PC beam structure fixed to a steel pipe concrete column.

[Conventional technology]

In so-called prestressed concrete (hereinafter abbreviated as PC), which is a method of applying prestress to concrete, there are two methods for introducing prestress into concrete: pretension method and posttension method. In the former case, the prestressing steel material is kept under tension with a predetermined tensile force, concrete is poured around it, and after the concrete hardens,
The tensile force of the prestressing steel is relaxed, and the adhesion between the prestressing steel and the concrete prevents the shrinkage of the prestressing steel within the concrete, giving prestress to the concrete. In the latter case, the prestressed steel material covered with a sheath is usually placed in the formwork, and after the poured concrete has hardened, it is removed from the mold, and the prestressed steel material is tensed with jacks using the concrete as a pedestal, and then pre-cast into the concrete. By applying stress, the prestressing steel is fixed and finished so that it does not elongate. After the prestressing steel is tensioned and fixed, it is common to grout the inside of the sheath to create adhesion between the prestressing steel and concrete and to prevent corrosion of the prestressing steel. There is also a method (unbond method) that breaks the adhesion between the prestressing steel and concrete.

Figure 2 is a front view showing the method for manufacturing PC beams using the post-tension method, where 1 is the beam, 2 is the sheath,
3 is a PC steel material, 4 is a jack, 5 is a jack holder,
6 is a fixing end.

Figure 3 is a plane cross-sectional view and b side cross-sectional view showing the joint structure when post-tensioned PC beams are attached to the pillars of the structure. In the figure, 10 is the pillar, 11
is a PC beam, 12 is a sheath, 13 is a PC steel material, 14 is a fixing device, 15 is a grid reinforcement, 16 is a bracket,
17 is a pad, 18 is joint mortar, 19 is a jack support, and 20 is a jack.

In the figure, a PC beam 11 holding a PC steel material 13 in a sheath 12 is placed on a bracket 16 of a column 10 via a pad 17, and the PC beam is placed inside a sheath 12 held in advance in the concrete of the column. No. 11 PC steel material 13 is inserted, and one end thereof is fixed to the pillar 10 with a fixing device 14. Next, PC beam 11 and column 1
After curing the joint mortar 18 at the joint with 0, actuate the jack 20 to pull the end of the PC steel material 13 on the opposite side fixed by the fixing tool 14,
After tensioning the PC steel material 13, the PC steel material 13 is fixed on the jack support stand 19. Then sheath 1
Grouting is carried out within 2 and the PC steel material 13 is attached to the concrete, completing the fixing of the PC beam 11 to the column.

[Problem that the invention seeks to solve]

By the way, the PC using the post tension method mentioned above
For beam structures, it is important to maintain constant tension in the prestressing steel even during long-term use. For this purpose, the anchoring end of the prestressing steel must be strong, and as shown in Figure 3, if the column is of reinforced concrete structure, grid bars are placed to reinforce the anchoring end. However, it takes time and effort to arrange grid reinforcement, and since the fixed ends are made of concrete, reliability in maintaining tension is low.
Particularly in the case of the unbonded method, when subjected to repeated loads such as seismic force, a large load is applied to the anchoring end, and fatigue strength at the anchoring end becomes a problem. If it is too severe, there is a risk of fatigue failure at the fixing end.

The present invention provides a PC using the above-mentioned post-tension method.
This was done to solve problems with the parts.
The purpose is to provide a PC structure using a post-tension method that has high reliability in terms of strength at the fixing end.

[Means for solving problems]

In order to achieve the above purpose, steel pipe concrete columns are used for the columns, and at the joint between the two steel pipe concrete columns and the beam that connects the columns, the beam
The PC steel material is passed through the steel pipe concrete column, and its both ends are fixed to the outer surface of the steel pipe on the opposite side of the joint with the beam of each column via fixing devices.

[Effect]

When joining a PC beam to a conventional reinforced concrete column, the anchoring end of the PC steel material of the PC beam becomes the outer surface of the reinforced concrete column as described above. Therefore, when repeated loads are applied to the beam, tensile force is repeatedly applied to the anchored ends, and there is a risk that the anchored ends of the concrete will suffer fatigue failure. However, in the case of the steel pipe concrete column, since the outer surface of the steel pipe serves as the anchoring end, the fatigue strength of the beam due to repeated loads is large and there is no fear of fatigue failure. Also, there is no need for special reinforcement such as grid muscles.

[Embodiments of the invention]

FIG. 1 shows a post-tensioned PC beam structure according to an embodiment of the present invention, in which a is a plan sectional view and b is a side sectional view. In the figure, 30a and 30b are steel pipe concrete columns, 31 is a PC beam, and 32 is a side sectional view. is sheath, 33 is PC
The steel material, 34 and 35 are fixing devices, and 36 is the tension direction of the PC steel material.

As shown in the figure, when steel pipe concrete columns 30a and 30b are used as pillars of a structure, etc., and when these two columns 30a and 30b are joined to a post-tension type PC beam 31, the PC beam 31 A sheath 32 of the prestressed steel material 33 is connected to two columns 30a, b and a beam.
The PC steel material 33 is inserted through the inside, and its one end is fixed on the outer surface of the steel pipe on the opposite side from the joint with the beam 31 of the column 30a via the fixing device 34. Then, the prestressing steel material 33 is tensed by being pulled in the direction of the arrow. The other end of 33 is fixed onto the outer surface of the steel pipe on the opposite side to the joint of the pillar 30b via a fixing device 34. Thereafter, grouting is performed inside the sheath as necessary.

〔Effect of the invention〕

In the present invention, when joining a post-tensioned PC beam to a column of a structure, etc., the PC steel material of the PC beam is passed through the column and fixed on the outer surface of the steel pipe of the column. Fatigue fracture at the anchored end of the steel material was prevented, and it became possible to construct a prestressed beam using the post-tension method, which is highly reliable in maintaining tension in the prestressed steel material.

[Brief explanation of the drawing]

Figure 1 shows an embodiment of the present invention, in which a is a plan sectional view of a post-tensioned PC beam structure, b is a side sectional view, and Figure 2 is a post-tensioned PC beam structure.
FIG. 3 is an explanatory diagram of PC beam manufacturing, in which a is a plan sectional view and b is a side sectional view of a conventional post-tensioned PC beam structure. In the figure, 30a and 30b are steel pipe concrete columns, 3
1 is a PC beam, 32 is a sheath, 33 is a PC steel material, 3
4 and 35 are fixing tools, and 36 is an arrow indicating the tension method.

Claims (1)

[Claims] 1. Based on pillars of structures etc. and post tension system
In connection with the PC beam, a steel pipe concrete column is used as the column, and the PC steel material of the above-mentioned PC beam is passed through the beam and the two columns that sandwich the beam, and one end of the PC steel material is connected to one of the columns. Fix it on the outer surface of the steel pipe on the opposite side of the joint with the beam via an anchor, and fix the other end of the above PC steel material on the outer surface of the steel pipe on the opposite side of the joint with the beam of the other column. By the post-tension method, which is characterized by fixation through a tool.
PC beam structure.