JPH0913504A - Arrangement method for tendon of prestressed concrete arch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To offset positive and negative bending moment and to prevent the generation of tensile stress of concrete by passing a tendon through the neighborhood of the circumference of an arch in the top section, the neighborhood of the outer circumference in displacement parts inclined at specific angles and joint parts between the tendon and pins in leg sections. SOLUTION: Tendon 12 embedded in prestressed concrete 10 is smoothly bent through the neighborhood of the circumference of an arch in the arch top section (a), the neighborhood of the outer circumference in displacement parts (b) inclined at 45 degrees and joint parts between tendon and pins 16 in leg sections 10a to place. By the constitution, when tensile force is added to the tendon 12, positive bending moment of the tendon 12 generated with the top section (a) as the center is offset by negative bending moment caused by dead-weight of concrete 14. Negative bending moment of the tendon 12 and positive bending moment caused by dead-weight are offset by each other. As a result, the bending moment becomes 0 in the joint parts between tendon and pins 16, the generation of tensile stress of concrete is prevented, and safety and durability are promoted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for arranging tension members in a prestressed concrete arch constructed by applying tension to a tension member embedded in concrete.

[0002]

2. Description of the Related Art A large space facility such as an indoor stadium is often used as a circular dome because of its structure. As disclosed in Japanese Patent Publication No. 5-68582, such a circular dome is used.
An arch is used to form a large opening while suppressing a decrease in strength. In this case, the arch has a prestressed concrete structure with extremely high strength. The prestressed concrete is constructed by pouring concrete so as to bury a prestressed tension material, and a large internal stress is generated in a state where the concrete is hardened. By the way, the prestressed concrete is such that the tendons are usually substantially parallel to the surface of the concrete, that is, to be embedded along the outer shape of the concrete, if constructed as a prestressed concrete arch as described above, It will be embedded in a curved shape that follows the outer shape of the arch.

[0003]

However, in such a conventional prestressed concrete arch,
When the tension material is embedded in a curved shape that conforms to the outer shape of the arch, the bending moment is reduced by the vertical load of its own weight.
As shown in, the top a of the arch 1 and approximately 45 from the top a
A large reversal occurs with the displacement portion b inclined. That is, the bending moment becomes maximum on the negative side at the apex a, and is approximately 4
In the displacement part b of 5 degrees, it becomes the maximum on the positive side. For this reason, there is a possibility that tensile stress, which is a weak point of concrete, may act, particularly in a portion where a positive bending moment is generated.

In this way, when the bending moment acting on the arch differs depending on the part, it is necessary to design the cross section of the arch on the basis of the point of the maximum moment acting on the negative side. For this reason, the cross-sectional area of the arch is increased as a whole, the weight of the arch 1 is further increased, and the vertical load,
Furthermore, there is a problem that the bending moment is further increased.

The left half of FIG. 7 shows the case where the leg portion 1a is pin-connected, and the right half of the figure shows the case where the leg portion 1a has a fixed structure. 1
In the case of the fixed structure, the bending moment acts on the negative side.

In view of the conventional problems, the present invention adjusts the embedding position of the tension material that applies prestress to the concrete, thereby canceling the positive and negative bending moments acting on the arch, and It is an object of the present invention to provide a method for arranging tension members in a prestressed concrete arch that eliminates tensile stress, which is a weak point.

[0007]

In order to achieve the above object, the first method of the present invention is constructed by applying a tension force to a tension member embedded in concrete, and the legs have a pin structure. In the method for arranging the tension members of the prestressed concrete arch, the tension members pass through the vicinity of the inner circumference of the arch at the top of the arch, and the vicinity of the outer circumference of the arch at a displacement portion inclined by about 45 degrees from the top, In addition, the legs are smoothly curved and arranged so as to pass through the pin connecting portions.

A second method of the present invention is a method for arranging tension members in a prestressed concrete arch, in which a tension member is embedded in concrete to apply tension to the tension members, and the legs have a fixed structure. At the top of the arch, pass the tension material near the inner circumference of the arch, and approximately 4
The displacement part inclined by 5 degrees passes through the vicinity of the outer circumference of the arch, and the leg portion passes through the inner circumference, and is smoothly curved.

According to the first method for arranging the tension members of the prestressed concrete arch of the present invention having the above-mentioned structure, the tension members embedded in the prestressed concrete arch are applied when the leg members of the arch have a pin structure. ,
At the top of the arch, pass near the inner circumference of the arch, at the displacement part inclined by about 45 degrees from the top, pass near the outer circumference of the arch, and at the leg, pass through the pin connection part. Since it is smoothly curved, a positive bending moment is generated at the apex and a negative bending moment is generated at a displacement of about 45 degrees by applying tension to the tension member arranged in this manner. . Then, the moments generated at the apex and the displacement portion cancel each other out with the negative bending moment generated at the apex and the positive bending moment occurring at the displacement portion due to the even distribution load due to the self-weight acting after the completion of the arch. Further, in the leg portion of the arch having the pin structure, the bending moment due to the tension member and the bending moment due to its own weight become zero at the pin connecting portion.

The second prestressed concrete arch tension member arranging method according to the present invention is applied to a structure in which the leg portions have a fixed structure. The tension member is passed through the top of the arch near the inner circumference of the arch. Since the curved portion is smoothly curved so as to pass through the vicinity of the outer circumference of the arch at a displacement portion inclined by approximately 45 degrees from the top portion and also pass through the inner peripheral portion of the leg portion, tension is applied to the tension member, so that the top portion is A positive bending moment and a negative bending moment at a displacement of about 45 degrees, respectively, and these moments are distributed evenly due to its own weight after the completion of the arch, the negative bending moment generated at the top, and It cancels out with the positive bending moment generated in the displaced part. Further, in the leg portion of the arch having the fixed structure, the bending moment due to the tension member becomes positive, and it is possible to cancel out the negative bending moment due to its own weight.

[0011]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. 1 to 3 show an example of an embodiment of a tensioning material arranging method for a prestressed concrete arch according to the present invention, FIG. 1 is a schematic configuration diagram of the prestressed concrete arch, and FIG. 2 is a case where tensioning force is applied to the tensioning material. FIG. 3 is an explanatory view of a region of bending moment acting on the, and FIG. 3 is an explanatory view of a region of bending moment due to a uniformly distributed load.

That is, as shown in FIG. 1, the prestressed concrete arch 10 is formed in an arch shape having a prestressed concrete structure in which a tension material 12 is embedded inside and concrete 14 is cast. Both end legs 10a, 10a of the prestressed concrete arch 10
Has a pin structure that is coupled via a pin 16.

Here, as shown in FIG. 1, the tension member 12 passes near the inner circumference of the arch a at the apex a of the arch, and at the displacement portion b inclined approximately 45 degrees from the apex of the arch. The leg portion 10a is arranged so as to be smoothly curved so as to pass through the vicinity of the outer periphery of the leg portion 10a, and to pass through the joint portion with the pin 16 in the leg portion 10a.

In the above-mentioned method of arranging the tension members, the tension member 12 embedded in the prestressed concrete arch 10 passes through the vicinity of the inner circumference of the arch 10 at the apex a of the arch from the apex a. At the displacement portion b which is inclined by about 45 degrees, it is smoothly curved so as to pass through the vicinity of the outer circumference of the arch 10. Therefore, by applying tension to the tension member 12 arranged in this manner, the top portion a is centered. As a result, a region T1 having a positive bending moment (+ X) is generated, and a region T2 having a negative bending moment (-Y) is generated around the displacement portion b of about 45 degrees.

On the other hand, an evenly distributed load due to its own weight is constantly acting on the prestressed concrete arch 10. Due to this evenly distributed load, the prestressed concrete arch 10 has a negative load centered on the top portion a as shown in FIG. A bending moment (-X) region T3 is generated, and a positive bending moment (+ Y) region T4 is generated around the displacement portion b of about 45 degrees.

Therefore, in the state where the prestressed concrete arch 10 is completed, the bending moment regions T1 and T2 due to the tension of the tension member 12 shown in FIG.
Bending moment area T3, T due to its own weight shown in FIG.
4 and will act at the same time. Therefore, the bending moment (+ X) on the positive side and the bending moment (−X) on the negative side cancel each other at the top portion a, and the bending moment (−Y) on the negative side and the bending moment on the positive side at the displacement portion b cancel each other. The bending moment (+ Y) of will cancel each other out. Therefore, the prestressed concrete arch 10 can prevent the bending moment from acting in the region centered on the apex a and the region centered on the displacement part b, and, in extension, the tension which is a weak point of concrete. Prevents stress from occurring, improving safety and durability,
And an economical structure can be obtained.

Further, in the leg portion 10a of the prestressed concrete arch 10, since the tension member 12 is smoothly curved so as to pass from the displacement portion b to the joint portion of the pin 16, the displacement portion b is The bending moment region T2 due to the tension of the tension member 12 as the center and the bending moment region T4 due to its own weight are terminated at the pin connection portion and become zero.

4 to 6 show another embodiment, in which the same components as those in the above embodiment are designated by the same reference numerals and a duplicate description will be omitted. FIG. 4 is a schematic configuration diagram of the prestressed concrete arch corresponding to FIG. 1, FIG. 5 is a region explanatory view of a bending moment that acts when a tension force is applied to the tension member corresponding to FIG. 2, and FIG. It is the area | region explanatory drawing of the bending moment by the corresponding uniformly distributed load.

That is, in this embodiment, the present invention is applied to the prestressed concrete arch 10 in which the legs 10a have a fixed structure.
The displacement portion b is smoothly arranged so as to pass through the inner peripheral portion of a. It should be noted that at the top part a of the arch, the tension member 12 passes smoothly in the vicinity of the inner circumference of the arch 10 and at the displacement part b inclined by about 45 degrees from the top part a, passes smoothly around the outer circumference of the arch 10. I am allowed.

Therefore, even in this embodiment, the tension member 1 is used.
When a tension force is applied to No. 2, as shown in FIG. 5, a region T of a positive bending moment (+ X) centering on the apex a
1 is generated, and a region T2 of negative bending moment (-Y) is generated around the displacement portion b of about 45 degrees.
Further, as shown in FIG. 6, a negative bending moment (-X) region T3 is generated about the apex a and the displacement part b of about 45 degrees is also centered by the action of the evenly distributed load due to its own weight. As a result, a positive bending moment (+ Y) region T4 is generated.

Therefore, in the state where the prestressed concrete arch 10 is completed, the bending moment regions T1 and T2 due to the tension of the tension member 12 and the bending moment regions T3 and T4 due to its own weight cancel each other out. Generation of tensile stress can be prevented.

Further, in the leg portion 10a of the prestressed concrete arch 10, the tendons 12 are arranged smoothly from the displacement portion b so as to pass through the inner peripheral portion of the leg portion 10a, and therefore, as shown in FIG. By applying a tension force to the tension member 12 in this manner, a positive bending moment (+ Z) region T5 is generated in the leg portion 10a, while a negative bending is applied to the leg portion 10a due to an evenly distributed load due to its own weight. A moment (-Z) region T6 is generated. Therefore, the leg 10
In the portion a, in the completed state of the prestressed concrete arch 10, the positive bending moment (+ Z) of the region T5 and the negative bending moment (-Z) of the region T6 can be canceled out.

[0023]

As described above, according to the first aspect of the present invention,
In the prestressing and tension material placement method for concrete arches shown in Figure 5, when the arch leg has a pin structure, the tension material embedded in the prestressed concrete arch is placed at the top of the arch. Smoothly through the inner circumference of the arch, near the outer circumference of the arch at the displacement part inclined by about 45 degrees from the top, and at the leg part through the pin connecting part. Therefore, the positive bending moment generated at the apex and the negative bending moment generated at the displacement of about 45 degrees when tension is applied to the tension member are generated at the apex by the even distribution load due to the weight of the arch. The negative bending moment and the positive bending moment generated in the displacement part cancel each other out, and at the leg part of the arch, due to the bending moment due to the tension member and the self-weight. Bending moment is terminated at the pin connection part to zero, preventing bending moment from acting on the entire arch, which in turn prevents the occurrence of tensile stress, which is a weak point of concrete, for safety and durability. Improve
And an economical structure can be obtained.

Further, in the method for arranging the tension members of the prestressed concrete arch according to claim 2 of the present invention,
It is applied to the one in which the legs have a fixed structure, and passes through the vicinity of the inner circumference at the top of the arch, passes through the vicinity of the outer circumference of the arch at a displacement portion inclined by approximately 45 degrees, and at the inside of the legs. Since the tendon was smoothly curved so that it would pass through,
Even in this case, the positive bending moment generated at the apex by applying tension to the tension member, and about 45
The negative bending moment generated in the displacement portion of the degree cancels out the negative bending moment generated in the apex due to the even distribution load of its own weight acting on the arch and the positive bending moment generated in the displacement portion, and In the leg part of the arch that has a fixed structure, the positive bending moment due to the tension material and the negative bending moment due to its own weight cancel each other out,
This has an excellent effect that a bending moment is prevented from acting on the arch and a tensile stress can be prevented from being generated.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a prestressed concrete arch showing an example of an embodiment according to the present invention.

FIG. 2 is a region explanatory view of a bending moment that acts when a tension force is applied to a tension member showing an example of the embodiment according to the present invention.

FIG. 3 is a region explanatory view of a bending moment due to a uniformly distributed load showing an example of an embodiment according to the present invention.

FIG. 4 is a schematic configuration diagram of a prestressed concrete arch corresponding to FIG. 1 showing another embodiment of the present invention.

FIG. 5 is a region explanatory view of a bending moment that acts when a tension force is applied to the tension member corresponding to FIG. 2 showing another embodiment of the present invention.

FIG. 6 is a region explanatory view of a bending moment due to a uniformly distributed load corresponding to FIG. 3 showing another embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing a conventional prestressed concrete arch.

[Explanation of symbols]

 10 Prestressed concrete arch 10a Leg part 12 Tension material 14 Concrete 16 pin a Top part b Displaced part

Claims (2)

[Claims] 1. A method for arranging a tension member in a prestressed concrete arch in which a tension member is embedded in concrete to apply tension to the tension member, and the legs have a pin structure. Smoothly around the inner circumference of the arch, near the outer circumference of the arch at the displacement part inclined about 45 degrees from the top, and at the leg part through the pin connection part. A method for arranging tension members in a prestressed concrete arch characterized by being arranged. 2. A method for arranging a tension material in a prestressed concrete arch, wherein tension material is applied to a tension material embedded in concrete, and the legs have a fixed structure, wherein the tension material is at the top of the arch. The curved part so that it passes through the inner circumference of the arch, passes through the outer circumference of the arch at the displacement part inclined approximately 45 degrees from the top, and passes through the inner circumference of the leg. A method for arranging tension members in a prestressed concrete arch characterized by being arranged.