JPS62156454A - Prestressed concrete structure - 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 Field of Industrial Application This invention relates to a rigid frame prestressed concrete structure used for box-type culverts, underground garages, underground or above-ground WU-shaped ditches, swimming pools, and the like.

2. Description of the Related Art Conventional prestressed concrete structures with rigid frame structures include, for example, four hollow box-shaped culverts with a rectangular cross section.
It is restricted. When buried underground, external forces act on each of the box-shaped tanks from the outside, so the bending and tensile stress is greatest in the areas where they are given extraordinary strength.

Problems to be Solved by the Invention In such prior art, increasing the eccentricity of the PC steel bar increases the bending strength, reduces the wall thickness, and reduces the diameter of the reinforcing bar. It is also desirable to reduce the size and reduce the S=quantification and cost of the structure. However, if the eccentricity of the PC steel bar is set to 7 degrees or more in a prestressed concrete structure with a rigid frame structure, the introduced prestress will cause warping on each wall, and the inside of each steel tangent will be warped. There is a problem if structural cracks occur due to the application of pulling force.

In order to prevent this structure from cracking, the current commercially available prestressed concrete structures limit the eccentricity of the PC steel bars to less than 6.9 coefficients, so the radius of the reinforcing bars is large and the thickness of the concrete is reduced. The problem is that the required bending strength cannot be obtained unless the thickness is increased.

Means for Solving the Problems In order to solve these conventional problems, the present invention has developed a rigid frame structure prestressed concrete PC steel bar, etc.
A steel material is placed at each wall of the one-piece structure, and both ends of the prestressed steel material are located near the portion where the maximum negative bending moment acts within each wall, and the top of the prestressed steel material is placed at the The structure is such that it is placed near the portion of the wall where the maximum positive bending moment acts.

Effect With this configuration, even if prestress is introduced, only a very small tensile force will act on the steel tangents of each wall, thereby preventing the occurrence of structural cracks in the steel tangents. do.

At the point where the positive bending tensile force generated on the wall is greatest, that is, at the center of the wall, the PC square material is placed closer to the hollow part than the neutral axis with a large eccentricity, so that the negative bending moment is the greatest. Since the large points, that is, both terminals of the wall body and the outer side of the neutral axis, are arranged with a large eccentricity, sufficient bending strength can be obtained even if the diameter of the PC steel material is made small and the wall thickness of the wall body is made thin.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a partial sectional view showing an embodiment of the present invention, FIG. 2 is a plan view, and FIG. 3 is a side view.

In the figure, 1 is a prestressed concrete structure for a box-shaped underdrain, and four walls 2 of rigid frame structure...
・It has a rectangular cross-sectional shape.

This wall body 2 is provided with a PC steel rod 3 as a PO steel material, which has been formed into a parabolic shape in advance. This PCg14
Both ends of the PO steel bar 3 are located above the neutral axis The concrete 5 is placed in a formwork (not shown) by placing the concrete 5 with a large eccentricity of 7 to 35 widths near the center.

This PC steel rod 3 is unboarded, that is, a single layer of asphalt-based polymer is formed on the surface, and a film layer of polypropylene or the like is formed on the surface of this polymer j-.

One end of this PC-steel rod is set as a fixed end 3a, and concrete is buried in the wall 5 with the fixed end 3a inserted through the receiving hole 4a of the anchor plate 4 and fixed with a nut 6. It protrudes laterally through a small hole 5a formed on the side of the body 2.

In addition, the other end 1IllI3b of the @ki PC steel rod is inserted into the through hole 4a of the anchor plate 4 buried in the concrete 5 with one side facing the large hole 5b formed in the side of the wall 2. It protrudes into the hole 5b. Before, tr+
After the concrete 5 has hardened, tension is applied to the tensile end 3 of the PC steel bar 3. A prestress is introduced from this and the end of the PC steel bar 3 is fixed with a nut 6, and the end of the PC steel bar 3 protrudes outward from the large hole 5. Cut the part short. after that@
The small holes 5a and large holes 5bG formed in the F wall 2 are filled with resin mortar 7.

Effects of the invention According to this configuration, even if prestress is introduced,
Since only a small tensile force acts on the steel tangent portion of each wall body, this has the effect of preventing the occurrence of structural cracks in the steel tangent portion.

In addition, the PC steel material is placed in the center of the wall where the positive bending tensile force generated on the wall is greatest, with the hollow side facing away from the neutral axis with a large eccentricity, so that the negative bending moment is the greatest. It is possible to obtain the necessary bending strength by placing it in large places, that is, at both ends of the wall, with a large eccentricity of 74 to 35 points outside the neutral axis.
Since the diameter of the material can be as small as about 10 mm, and the wall thickness can be made thinner, it is possible to reduce the weight and cost of the structure, and to increase the cracking load sufficiently. There is an effect that it can be done.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing an embodiment of the present invention, FIG. 2 is a plan view, and FIG. 3 is a side view. 1. Prestressed concrete structure, 2... Wall, 3... PC steel, X... Neutral axis.

Claims (1)

[Claims] In a prestressed concrete structure having a rigid frame structure, a PC rigid member is arranged in a parabolic shape within each wall of the structure, and both ends of the PC rigid member are located near a portion of each wall where the maximum negative bending moment acts. A prestressed concrete structure characterized in that the top of the prestressed steel material is placed near a portion of the wall where the maximum positive bending moment acts.