JP2000192661A - Prestress concrete structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To always hold constant tightening force by providing a nonlinear spring of small resilient force variation for the deflection deformation at the time set tightening force giving on a locking part of a concrete structure and a tightening material end. SOLUTION: A tightening material 5 is expanded to produce tightening force by tightening nuts 13a, 13b, an initially coned disc spring 7 is deformed until it is resilient force balanced with the tightening force, and the resilient force is transmitted to a concrete rectangular parallelepiped 3 via anchor plates 9a, 9b as compression force. Next, after prestress giving, an expansion and contraction difference is absorbed by the deflection deformation of the initially coned disc spring 7 when the expansion and contraction difference of the axial direction of the tightening material occurs on the tightening material 5 and the rectangular parallelepiped 3 by the relaxation of the tightening material 5, the creep of the rectangular parallelepiped 3 or the like. Next, because the initially coned disc spring 7 is set so that the set value of the tightening force and a resilient force variation insensitive band coincide with each other, change in the resilient force does not occur even when the deflection deformation occurs, and as the result, the set tightening force of the tightening material, namely, compression force transmitted to the rectangular parallelopiped 3 is maintained constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a prestressed
In a concrete structure (hereinafter abbreviated as a PC structure), when tension is applied to a tension member such as a PC steel material, there is a means for always maintaining a constant tension regardless of expansion and contraction of the tension member and concrete. PC structure.

[0002]

2. Description of the Related Art In a prestressing method, after placing and hardening concrete, a tension member is slidably inserted into the concrete, and tension is applied to the tension member. In this method, a prestress is applied to the concrete structure, and a compressive stress is applied to the concrete structure in advance to improve the tensile strength.

[0003] The tensile strength of the PC structure constructed by this method is ensured by the tension of the tendon, and if the tension falls below a predetermined value due to long-term use, sufficient strength cannot be obtained. This is due to relaxation of tendons, creep of concrete, and drying shrinkage. This is because, when the tension acting on the tendon and the compressive force acting on the concrete as this reaction force are maintained for a long time, the tensile strain for the tendon and the compressive strain for the concrete increase with time. As a result, the tension of the tendon and the compressive force of the concrete are reduced by the difference in expansion and contraction between the elongation deformation due to the tensile strain of the tendon and the shrinkage due to the compressive strain of the concrete. .

Here, as an example of a PC structure which has solved the above-mentioned problems, there is a prestressed concrete beam (hereinafter abbreviated as PC beam) as shown in FIG. As shown in the figure, this PC beam has a concrete rectangular parallelepiped 3 which is a beam body,
A pair of anchor plates 9a, 9b for prestressing the compressive force on the concrete rectangular parallelepiped 3 from both sides, a tension member 5 penetrating the anchor plates 9a, 9b and the concrete rectangular parallelepiped 3, and one end of the tension member 5 A nut 13b that is screwed and tightens the anchor plate 9b to the side of the concrete rectangular parallelepiped, a nut 13a that is screwed to the other end of the tendon member 5, and is interposed between the nut 13a and the anchor plate 9a. And a coil spring 8 for transmitting the tension of the tension member 5 generated by the tightening of the nut 13a to the anchor plate 9a. The spring constant of the coil spring 8 is extremely small as compared with the tension member or concrete. Has become.

Accordingly, in the PC beam, when a difference in expansion and contraction occurs in the concrete rectangular parallelepiped 3 and the tension member 5 in the axial direction of the tension member, the difference in expansion and contraction is absorbed by the bending deformation of the coil spring 8. In this case, since the spring constant of the coil spring 8 is extremely small as compared with that of the tendon or concrete, even if the difference in expansion and contraction is absorbed, the reduction of the resilience is small, and thus the tension of the tendon 5 and the concrete cuboid 3 are exerted. A decrease in compression force is suppressed.

In order to always maintain the tension constant, hydraulic jacks are provided at both ends of the tension member of the concrete structure, and the tension of the tension member is measured by a pressure detector of the hydraulic jack, and the measurement is performed. The value of P is controlled so as to control the operation of the hydraulic jack by keeping the value constant.
Automatic tension management system for C structures (Japanese Patent Laid-Open No. 9-21)
No. 7493) has also been proposed.

[0007]

However, in the prestressed concrete structure in which the coil spring is interposed, the elastic force of the coil spring 8 changes linearly with respect to bending deformation. Because of the linear spring, the prestress cannot be maintained at a constant level due to the fact that the tension changes in accordance with the amount of flexural deformation of the absorbed difference in expansion and contraction.

[0008] In addition, the automatic tension management system described above requires a huge amount of equipment cost to install, and thus has a major problem in terms of cost.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and when a tension is applied to a tendon such as a PC steel material in a PC structure, relaxation of the tendon, creep of concrete, and drying shrinkage. It is an object of the present invention to provide a PC structure which has means for always maintaining a constant tension and which can be easily manufactured and constructed at low cost.

[0010]

As a means for solving the above-mentioned problems, the invention according to claim 1 of the present invention is a means for applying a tension to a tension member of a PC structure. A non-linear spring having a small resilient force variation with respect to bending deformation at the time of applying a force is interposed in a locking portion between a concrete structure and a tendon member end.

According to the above construction, the difference in expansion and contraction between the tendon and the concrete caused by the relaxation of the tendon, the creep of the concrete structure, the drying shrinkage, etc., generated after the set tension is applied, It is absorbed by the bending deformation of the non-linear spring interposed in the locking portion between the concrete structure and the end portion of the tendon material, and the non-linear spring is set so that the elastic force fluctuation against the bending deformation at the set tension becomes small. Therefore, even if the bending deformation occurs, the elastic force does not fluctuate, and therefore, the set tension of the tendon does not change.
For this reason, the prestress after applying the set tension can be maintained at an expected value, and the safety of the PC structure is significantly improved.

According to a second aspect of the present invention, the non-linear spring according to the first aspect is a disc spring.

According to the above configuration, since a disc spring is used as the non-linear spring, the ratio of the plate thickness t of the disc spring to the height H, which is the maximum amount of deflection thereof, is H / t = 1.2 to 1. 6. Desirably, by setting H / t = 1.4, it is possible to easily set a characteristic having a region where the resilience fluctuation against bending deformation is small.

According to a third aspect of the present invention, the PC structure according to the first or second aspect is a beam member, a floor slab member, or a bridge member.

According to the above construction, the difference between the tension of the tendon and the concrete structure in the axial direction due to the relaxation of the tendon and the creep, drying and shrinkage of the concrete structure can be measured by using the concrete structure and the end of the tendon. The elastic deformation of the non-linear spring interposed in the locking part is absorbed by the flexural deformation in the small area, so that the pre-stress after applying the set tension can be maintained at the expected value, and the PC beam member and the PC floor slab can be maintained. Member, PC
The safety of bridge members is significantly improved.

According to a fourth aspect of the present invention, the PC structure according to the first or second aspect is a container structure such as a tank, a reactor pressure vessel, a reactor containment vessel, or an egg digester. Features.

According to the above construction, the difference between the tension member relaxation and the tension member axial direction expansion / contraction between the concrete member and the concrete structure due to creep, drying shrinkage, etc. of the concrete member is determined by comparing the concrete structure with the tension member end. Since the elastic deformation of the non-linear spring interposed in the locking part with the part is absorbed by bending deformation in the area where the fluctuation is small, the pre-stress after applying the set tension can be maintained at the expected value, and the tank and the reactor pressure vessel In addition, the safety of container structures such as a reactor containment vessel and an egg-shaped digestion tank is significantly improved. Particularly, the reactor pressure vessel is very useful because the prestress can be kept constant irrespective of neutron irradiation and relaxation of the tendon due to a very high temperature of 40 to 50 °.

[0018]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a beam showing a schematic configuration of a first embodiment in which the present invention is applied to a PC beam. As shown in the figure, the PC beam 1 has a concrete rectangular parallelepiped 3 as a beam main body, and a pair of anchor plates 9a, which prestresses the concrete rectangular parallelepiped 3 from both sides.
9b, and a plurality of tendons 5 inserted through the anchor plates 9a and 9b and the concrete rectangular parallelepiped 3.
And a nut 13b which is screwed to one end of the tendon member 5 to fasten the anchor plate 9b to the side surface of the concrete rectangular parallelepiped, and another stop screwed to the other end of the tendon member 5 A nut 13a, which is a non-linear spring, which is a non-linear spring interposed between the nut 13a and the anchor plate 9a and transmitting the tension of the tension member 5 by tightening the nut 13a to the anchor plate 9a. It is configured.

The tension member 5 is a PC steel material or a PC steel wire. Both ends of the tension member 5 are externally threaded so as to be screwed with the nuts 9a and 9b, and can be slid freely in the concrete rectangular parallelepiped 3. Grease or other lubricant on the surface,
Rust inhibitor is applied.

In this case, a tension member slidable in the concrete is directly disposed, but a tube is put on the tension member, and a sheath in which a rust inhibitor or a lubricant is filled in a gap between the tension member and the tube. Strands may be used.

The disc spring portion 7 is composed of a pair of disc springs laminated in parallel, in which a plurality of disc springs 7a of frustoconical spring steel having a hole at the center are stacked in the same direction. As shown in FIG. 2, the disc spring unit 7 a has a region where the resilient force variation with respect to the bending deformation of the disc spring is small (hereinafter, referred to as “elastic force variation dead zone”). The ratio of t to its maximum deflection H is preferably H / t = 1.2 to 1.6,
More preferably, H / t = 1.4.

When the elastic force of the disc spring portion 7 is set in the elastic force variation dead zone, the disc spring laminated body is set so as to match the tension set value of the tendon material at the time of applying prestress. It is adjusted by changing the number of disc springs per group. The elasticity fluctuation dead zone width shown in FIG. 2 is such that a plurality of sets of disc spring laminates are alternately attached to each other in opposite directions so as to absorb the maximum expansion difference between the tendon and the concrete rectangular parallelepiped. In this embodiment, the disc spring laminate is a set.

Although not shown here, the nut 1
A washer may be interposed between 3a and the disc spring portion 7.

Next, the operation of the first embodiment will be described.

The prestressing of the compressive load to the concrete rectangular parallelepiped 3 is performed by tightening the nuts 13a and 13b screwed to both ends of the tendon member 5. That is, when the tension member 5 is stretched by this tightening and a tension is generated, the disc spring 7 bends until the elastic force is balanced with the tension,
This elastic force is transmitted to the concrete rectangular parallelepiped 3 as a compressive force via the anchor plates 9a and 9b.

After the application of the prestress, if the tension member 5 and the concrete rectangular parallelepiped 3 generate a difference in expansion and contraction in the axial direction of the tension member 5 due to relaxation of the tension member 5, creep, drying shrinkage, etc. The difference is absorbed by the bending deformation of the disc spring. At this time, since the disc spring 7 is set so that the set value of the tension and the resilient force fluctuation dead zone coincide with each other, the resilient force does not fluctuate even if the bending deformation occurs. The set tension of the material 5, that is, the compressive force transmitted to the concrete rectangular parallelepiped 3 is kept constant. Further, even if a temperature contraction difference occurs due to a temperature change due to a difference in linear expansion coefficient between the concrete rectangular parallelepiped 3 and the tension member 5, the set tension can be maintained constant in the same manner as described above.

Therefore, the pre-stress after applying the set tension can be maintained at the desired value for a long period of time, and the strength of the PC structure 1 represented by the PC beam can be remarkably and stably improved.

Further, since the structure is simple in that the non-linear spring 7 is interposed in the locking portion 13a between the concrete structure 1 and the end of the tendon member 5, the installation space is not large and the cost is easily reduced. Can be implemented.

With respect to the equipment diagnosis and equipment maintenance of the first embodiment, abnormality can be easily detected by recognizing the tension by measuring the amount of deflection of the disc spring, and the tension can be easily adjusted by adjusting the amount of deflection of the disc spring. Can be reset.

Further, if it is possible to predict the difference in the axial expansion and contraction of the tendon 5 and the tension of the concrete structure 3 due to the relaxation or the like after the application of the set tension based on laboratory experiment data, etc. By setting the force fluctuation dead zone width, subsequent adjustment is unnecessary, and maintenance-free operation can be achieved.

Although the first embodiment of the present invention has been described above, the present invention is not limited to the first embodiment, and various modifications can be made without departing from the gist thereof.

For example, in the first embodiment, a nut 13 is used as a locking structure between the concrete structure 3 and the end of the tendon 5.
Although a and 13b are used, the present invention is not limited to this, as long as a non-linear spring can be interposed between the tension member and the concrete rectangular parallelepiped and the end of the tension member can be locked to the side surface of the concrete rectangular parallelepiped. For example, in the case of a wedge type in which a male cone with fixed tendon ends is bitten and locked in a female cone fixed to a concrete structure, a disc spring is interposed between the male cone and female cone. Is applicable because it is possible.

Although the first embodiment discloses an example in which a disc spring is used as a non-linear spring, any spring having a resilient force fluctuation dead zone with a small resilient force fluctuation against bending deformation of the spring can be used. Yes, but not limited to this.

Further, the PC beam according to the first embodiment has been described with reference to the case where the cross-sectional shape is rectangular. However, the present invention is not limited to this. It may have an I-shaped cross section.

Although the first embodiment has been described with reference to PC beams, the present invention is also applicable to prestressed concrete slabs (hereinafter abbreviated as PC slabs) and prestressed concrete bridges (hereinafter abbreviated as PC bridges). The invention is applicable. Here, the PC floor slab and the PC bridge are different from the concrete rectangular parallelepiped 3 of the PC beam only in length and width, and the main structure is the same as that of the PC beam.

FIG. 3 shows a prestressed concrete tank (hereinafter referred to as PC) as a container structure according to the second embodiment.
FIG. 4 is a vertical cross-sectional view taken along the line IV-IV.

As shown in FIG. 3 and FIG.
Is a disk-shaped bottom plate 47 having an annular recess at the periphery of the upper surface fixed on the foundation 49, and a side wall 43 formed of a cylindrical shell that is erected and fitted into the recess at the periphery of the bottom plate 47.
And a spherical shell-shaped dome roof 45 mounted on a locking portion that protrudes inward in the radial direction along the upper inner peripheral surface of the side wall 43. When the liquid is stored in the PC tank, the liquid pressure acts on the side wall 43 in the radial direction outward, and a tensile force acts on the side wall 43 in the circumferential direction. For this reason, the bottom plate 47 and the dome roof 45 are made of reinforced concrete, while the side walls 43 are made of prestressed concrete.

As shown in FIG. 3, rectangular fixing columns 44a, 44b and 44c are provided on the outer peripheral surface of the side wall 43 at intervals of 120 ° in the circumferential direction. Circumferential tension member 5 slidably inserted in the circumferential direction
Are fixed by the fixing members 14a and 14b at the fixing columns 44a and 44b adjacent to each other. The fixing member 14b at one end of the circumferential tension member 5 includes a nut 13b serving as a locking portion and an anchor plate 9b, and the fixing member 14a at the other end includes a nut 13a serving as a locking portion, a disc spring portion 7, and an anchor. And a plate 9a. Here, since the configuration of the locking portion is the same as that of the first embodiment, the same members are denoted by the same reference numerals and detailed description thereof will be omitted.

The vertical tension member 105 slidably inserted in the vertical direction in the side wall 43 has one end passing through a connection 126 between the side wall 43 and the bottom plate 47.
7 and the fixing members 11 such as nuts in the bottom plate 47.
4b and fixed by being embedded in the bottom plate 47. Further, the other end of the tension member 105 protrudes upward from the upper end surface of the side wall 43, and the fixing member 14
a. The fixing member 14 a
An anchor plate 9a into which the nut 05 is inserted, a nut 13a serving as a locking portion screwed to the other end, and a disc spring portion 7 interposed between the nut 13a and the anchor plate 9a.

Next, the operation of the second embodiment will be described.

The circumferential prestressing of the side wall 43 is performed by tightening the nuts 13a and 13b of the fixing columns 44a and 44b. When the tension in the circumferential direction tension member 5 is stretched by this tightening and a tension is generated, the disc spring 7 is bent until the resilient force is balanced with the tension, and the resilient force is transmitted via the anchor plates 9a and 9b. Fixing columns 44a, 44
b is transmitted as a compressive force. The application of the vertical prestress is performed by tightening the nut 13 a on the upper end surface of the side wall 43. When the tension member 105 is stretched and tension is generated, the disc spring 7 bends until the elastic force balances with the tension, and the elastic force acts as a compressive force on the side wall 43 via the anchor plate 9a. Is transmitted.

After the application of the prestress, the circumferential expansion and contraction difference between the tendon 5 and the side wall 43 and the difference between the tendon 105 and the side wall 43 due to the relaxation of the tendon 5 and the creep and drying shrinkage of the side wall 43. Even if a difference in expansion and contraction in the vertical direction occurs, the difference in expansion and contraction is absorbed by the bending deformation of the disc spring 7. Since this deflection varies within the elastic force variation dead zone width, the elastic force does not decrease and is kept constant. As a result, the tension of the tension members 5, 105, that is, the circumferential direction of the side wall 43 and the vertical direction. The transmitted compressive force can be kept constant.

Therefore, the tension of the tendon after the prestress is applied can be maintained at a desired value, and the strength and proof stress of the PC tank 41 can be stably secured over a long period of time.

Here, as a container structure similar to the above-described PC tank, application to a reactor pressure vessel (hereinafter abbreviated as PCPV), a reactor containment vessel (hereinafter abbreviated as PCCV), and an egg type digester is also possible. However, since the operation and effect are the same, and the configuration according to the present invention is also generally the same, the same members are denoted by the same reference numerals and detailed description thereof will be omitted. Only the installation positions of the spring and the fixing member will be described. Also, the drawings for the following description are abbreviated as diagrams so that the arrangement route of the tendon and the installation positions of the non-linear spring and the fixing member can be understood.

FIG. 5 is a vertical sectional view of PCPV.

The PCPV 51 has an integral structure in which the upper and lower end openings of the cylindrical shell-shaped side wall 53 are sealed by a disk-shaped upper plate 55 as a roof and a disk-shaped bottom plate 57 fixed on a foundation 49. 53, the upper plate 55, and the bottom plate 57 are all made of prestressed concrete. The side wall 53 has the same configuration as that of the PC tank described above.
Are arranged in the circumferential direction and the vertical direction. The upper plate 55 and the bottom plate 57 have a plurality of tension members 20 slidably in the radial direction.
5 are inserted radially, and both ends of the tendon 205 are fixed on the outer circumferential surface of the PCPV by the fixing members 14a and 14b, and prestress is applied. One of the fixing members 14a and 14b is the same as in the first embodiment, and one is a nut 13b and an anchor plate 9b, and the other is a nut 13a.
And a disc spring portion 7 and an anchor plate 9a.

FIG. 6 is a vertical sectional view of the PCCV.

The PCCV 61 has an integral structure in which the upper and lower end openings of the cylindrical shell side wall 63 are sealed by a spherical shell dome roof 65 and a disc-shaped bottom plate 67 fixed on a foundation 49. , The dome roof 65 and the bottom slab 67 are both made of prestressed concrete. The arrangement of the tension members 5 in the circumferential direction of the side wall 67 and the tension members of the bottom plate 67 is the above P
It is the same as CPV.

However, with respect to the vertical tension member 305, the same tension member 305 prestresses the bottom plate 67, the side wall 63, and the dome roof 65. That is, the tension member 305 having one end fixed to the lower surface of the bottom plate 67 by the fixing member 14b is formed into an inverted U shape along a vertical section passing through the center line of the PCCV, and the bottom plate 67, the side wall 63, and the dome roof 65 And the other end is fixed by the fixing member 14 a on the lower surface of the bottom plate 67.

FIG. 7 is a side view of the egg type digester, and FIG.
It is sectional drawing of the II-VIII line. The egg-shaped digester 71 has a structure in which a digester main body 72 is supported on a base 49 via a ring-shaped base portion 79a. On the ring-shaped base portion 79a, a side wall 73 of an egg-shaped shell is supported,
An inverted conical bottom plate 7 is provided below the ring-shaped base portion 79a.
7 are formed, and these are integrated to form the digester tank main body 72. And the whole is made of prestressed concrete, and the tension member is also helically arranged on the bottom plate 77. However, since the present invention is not applied to the bottom plate 77, the description of the arrangement route is omitted and not shown.

On the outer peripheral surface of the side wall 73 of the egg-shaped shell located above the bottom plate 77, four rectangular fixing columns 74 are arranged at intervals of 90 ° in the circumferential direction as shown in FIG. . Then, both ends of the circumferential tension member 5 slidably inserted in the side wall 73 in the circumferential direction are fixed to the fixing pillar (for example, 74a) having a positional relationship of 180 ° in the circumferential direction. And 74b) are fixed via the fixing members 14a and 14b.

One end of a vertical tension member 405 inserted and slidably inserted in the side wall 73 in the vertical direction is connected to a bottom plate 77.
Is fixed by being screwed and embedded in a fixing member 114b such as a nut, and the other end is provided with an upper end surface 81 of the side wall and a ring-shaped overhang provided on the outer periphery of the side wall between the upper end surface and the ring-shaped base portion. On the upper surface 83, the image is fixed by the fixing member 14a.

[0054]

As described above, according to the first aspect of the present invention, in a PC structure, a non-linear spring having a small elastic force variation with respect to a bending deformation at the time of applying a set tension is provided by a concrete structure and a tendon. The expansion and contraction difference between the tendon and the concrete structure in the axial direction due to relaxation of the tendon, creep, drying shrinkage, etc. of the tendon, and tension with the concrete structure Since the difference in temperature shrinkage in the axial direction of the tendon material is absorbed from the material, the prestress can be maintained at an expected value, and the strength and proof stress of the PC structure can be significantly improved and stabilized.

Further, since the structure is simple in that the non-linear spring is interposed in the locking portion between the concrete structure and the end portion of the tendon member, the non-linear spring can be easily implemented at low cost. Since the tension can be recognized by measuring the amount of bending, abnormality can be easily detected, and the tension can be easily reset by adjusting the amount of bending of the nonlinear spring.

Furthermore, if the difference in the axial expansion and contraction between the tendon and the tendon of the concrete structure due to relaxation or the like after application of the set tension can be predicted from laboratory experiment data or the like,
By setting the amount of flexural deformation in a region where the resilience variation greater than the difference in expansion and contraction is small, subsequent adjustments are unnecessary and maintenance-free operation can be achieved.

According to the second aspect of the present invention, since a disc spring is used as the non-linear spring according to the first aspect of the present invention, the ratio of the plate thickness t of the disc spring to the height H, which is its maximum deflection, is H /. t
= 1.2 to 1.6, desirably H / t = 1.4, it is possible to easily set a characteristic having a region where a desired resilience variation is small.

According to the third aspect of the present invention, since the PC structure according to the first or second aspect is a beam member, a floor slab member, or a bridge member, the prestress can be maintained at an expected value, The strength and strength of the beam member, the PC slab member, and the PC bridge member are significantly improved and stabilized.

According to a fourth aspect of the present invention, the PC structure according to the first or second aspect is a PC tank, a PCPV.
Alternatively, since it is a container structure such as a PCCV or an egg-shaped digester, the prestress can be maintained at an expected value, and the strength and proof stress of these container structures are significantly improved and stabilized. Especially for reactor pressure vessels, neutron irradiation and 40-50
It is very useful because prestress can be maintained regardless of relaxation of tendon due to slight high temperature of ℃.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a PC beam, a PC slab, and a PC bridge showing a first embodiment of a PC structure according to the present invention.

FIG. 2 is a conceptual diagram showing spring characteristics of a disc spring used in the present invention.

FIG. 3 is a horizontal sectional view of a PC tank showing a second embodiment of the PC structure according to the present invention.

FIG. 4 is a sectional view of the PC tank taken along line IV-IV in FIG.

FIG. 5 is a vertical sectional view of a reactor pressure vessel showing a third embodiment according to the present invention.

FIG. 6 is a vertical sectional view of a containment vessel showing a fourth embodiment according to the present invention.

FIG. 7 is a side view of an egg-shaped digester showing a fifth embodiment according to the present invention.

8 is a cross-sectional view of the egg-shaped digester in FIG. 7 taken along line VIII-VIII.

FIG. 9 shows a PC in which conventional measures for reducing prestress have been implemented.
It is a longitudinal direction sectional view showing the schematic structure of a beam.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 PC beam (PC structure) 3 Concrete rectangular parallelepiped (concrete structure) 5,105,205,305,405 Tensile material 7 Belleville spring part (non-linear spring) 7a Belleville spring unit 9a, 9b Anchor plate 13a, 13b Nut ( Stop portion) 14a, 14b, 114b Fixing member 41 PC tank (PC structure) 43, 53, 63, 73 Side wall (concrete structure) 44a, 44b, 44c, 74, 74a, 74b, 74
c, 74d Anchoring column 49 Foundation 51 Reactor pressure vessel (PC structure) 55 Top plate (concrete structure) 47, 57, 67, 77 Bottom plate (concrete structure) 61 Primary reactor containment vessel (PC structure) 65 Dome Roof (concrete structure) 71 Egg-type digester (PC structure) 72 Digester tank body (concrete structure) 79a Ring-shaped base 81 Side wall upper surface 83 Ring-shaped overhanging upper surface 126 Connection part

Claims (4)

[Claims] As a means for applying a tension to a tendon of a prestressed concrete structure, a non-linear spring having a small elastic force variation with respect to a bending deformation at the time of applying a set tension is provided. A prestressed concrete structure characterized by being interposed in a locking portion of the concrete. 2. The prestressed concrete structure according to claim 1, wherein said non-linear spring is a disc spring. 3. The prestressed concrete structure according to claim 1, wherein the prestressed concrete structure is a beam member, a floor slab member, or a bridge member. 4. The prestressed concrete structure according to claim 1, wherein the prestressed concrete structure is a container structure such as a tank, a reactor pressure vessel, a reactor containment vessel, or an egg digester.・ Concrete structures.