JP2002173976A - Anchor age structure of unbonded prestressed concrete steel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide anchor age structure of unbonded prestressed concrete steel that can control the bending performance of a prestressed concrete member. SOLUTION: An elastic body with specified spring rigidity is installed between a plate of an anchor head for anchoring the unbonded prestressed concrete steel, and an anchor plate that transmits the load of the anchor head to a structure, and the degree of rigidity of the elastic body is set to such a degree that the prestressed concrete member exhibits specified bending performance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an unbonded PC.
It belongs to the technical field of a fixing part structure for transmitting a load (prestress or other load) of an anchor head for fixing a steel material to a structure via a fixing plate, and particularly, an elastic body is provided in a fixing part of the unbonded PC steel material, The present invention relates to an unbonded PC steel anchoring portion structure in which the bending performance of a prestressed concrete member constituting a structure can be controlled by setting the rigidity of the elastic body.

[0002]

2. Description of the Related Art Generally, a prestressed concrete member using an unbonded PC steel material (hereinafter, may be abbreviated as a PC member) is, for example, an unbonded PC steel material arranged inside a concrete member constituting a beam or the like of a structure. Then, the unbonded PC steel is tensioned to introduce a predetermined amount of prestress. In such a prestressed concrete member, various fixing unit structures for fixing the end of the unbonded PC steel have been proposed.

[0003] Fig. 8 shows details of the structure of a fixing part of unbonded PC steel which is generally used in the past, and Fig. 9 shows a beam-column joint having the structure of fixing part of unbonded PC steel as described above. FIG. 9A shows a state before deformation, and FIG.
(B) shows the state after the deformation.

[0004] In FIG. 8, a plurality of unbonded PC steels 106 are arranged in the longitudinal direction inside the frame of a beam 104 as a PC member, and the ends of the unbonded PC steels 106 penetrate through the pillar 102 and are on the opposite side surface 102 a. And is fixed by the fixing unit structure 108a.

Anchor structure 108a of unbonded PC steel
According to FIG. 8, the end 106a of the unbonded PC steel material 106 having the column 102 penetrated to the left is fixed with a wedge structure anchor head 110 after introducing a predetermined amount of prestress. Then, a reaction force is applied to the side surface 102a of the pillar 102 via the fixing plate 112.

Assuming that the magnitude of the prestress introduced into the unbonded PC steel 106 is Po, the prestress Po is shown in FIG. Right end face 104b of
Is shown as L. Since the PC member 104 using the unbonded PC steel 106 has no adhesive force between the unbonded PC steel 106 and the concrete skeleton,
The magnitude of the tensile force acting on the unbonded PC steel 106 depends on the magnitude of the elongation (ΔL) between the left and right fixing portions of the PC steel due to the deformation of the PC member 104, and the increase or decrease is determined. Further, the bending performance (rigidity, proof stress, and deformation performance) when the PC member 104 is deformed as shown in FIG. 9B due to a disturbance such as an earthquake is determined by the magnitude of the tensile stress of the PC steel material 106. .

[0007] In short, in the case of the conventional fixing portion structure 108a, the PC member 10 using the unbonded PC steel 106 is used.
The bending performance of No. 4 is determined by the amount of elongation (L + ΔL) of the PC steel material between the fixing portions at both ends.
Therefore, when the distance L between the fixing units at both ends is determined, the PC
The bending performance of the member 104 will be determined. Therefore, there is almost no design freedom for controlling the bending performance.

[0008] Such a performance is disclosed in Japanese Patent Publication No. Hei 4-20069.
The same applies to the fixing portion structure of the unbonded PC steel described in Japanese Patent Application Laid-Open Publication No. HEI 10-115,086. The reason is as follows. The fixing unit structure of the unbonded PC steel described in this publication is a structure in which a primary fixing unit and a secondary fixing unit are provided, and a compression coil spring is provided in the secondary fixing unit. Normally, the image is fixed at the primary fixing section, and the structure of the primary fixing section is not different from the prior art shown in FIG. In the case of fixing in the secondary fixing section, it is when the primary fixing section is damaged for some reason, and this secondary fixing section is also basically fixed by the same structure as the above-described prior art of FIG. Therefore, the above-described performance is exhibited.

[0009]

As described above, in the prior art, the bending performance of a prestressed concrete member using unbonded PC steel is determined by the fixing portions 10 at both ends.
Since it is uniquely determined according to the size of the interval L between 8a and 108b, there is the following disadvantage.

(1) When the unbonded PC steel elongates due to aging or the like, the bending performance of the prestressed concrete member decreases, and the seismic performance against disturbances such as earthquakes decreases.

(2) Even if designed under desired conditions, when disturbance such as an earthquake is applied, it is not possible to obtain a restoring force characteristic according to the design conditions.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an unbonded PC steel anchoring structure improved to a configuration having a degree of freedom for controlling seismic performance and restoring force characteristics to disturbances as desired.

[0013]

As a means for solving the above-mentioned problems, an unbonded PC steel anchoring structure according to the first aspect of the present invention comprises a prestressed concrete member using an unbonded PC steel. In the fixing part structure of the structure to be formed, an elastic body having a predetermined spring rigidity is installed between a plate of the anchor head for fixing the unbonded PC steel material and a fixing plate for transmitting the load of the anchor head to the structure. In addition, the rigidity of the elastic body is set to a size at which the prestressed concrete member exhibits a predetermined bending performance.

According to a second aspect of the present invention, in the fixing part structure of the unbonded PC steel material according to the first aspect, the elastic body is various springs such as a coil spring, a disc spring, a plate spring, or a rubber elastic body or plastic. It is characterized by being one of elastic bodies.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an exploded perspective view showing an embodiment of a structure for fixing an unbonded PC steel material according to the present invention.

FIGS. 1 and 2 show an unbond P according to the present invention.
Fig. 2 shows a beam-column joint to which a fixing part structure of C steel material is applied.

The unbonded PC steel material 6 arranged in the direction of the material axis inside the beam 4 holds the outer surface 2 of the column 2 by the anchoring portion structure 8a.
a.

As shown in FIG. 3, details of the fixing part structure 8a are as follows. After a pre-stress of a predetermined size is introduced into the unbonded PC steel material 6 penetrating the column 2 by a machine (not shown),
The end 6a is fixed by the anchor head 10.
A coil spring 16 is interposed between the plate 12 attached to the anchor head 10 and the fixing plate 14 applied to the outer surface 2a of the column 2 as an elastic body having a predetermined rigidity.
The pre-stress (and increasing / decreasing unbonded PC steel 6)
Is transmitted from the coil spring 16 to the column 2 via the fixing plate 14 to take a reaction force.

The opposite fixing unit structure 8b (see FIG. 4)
Naturally, the configuration is exactly the same as that of the fixing structure 8a.

The rigidity of the coil spring 16 is set to a value at which the bending performance of the prestressed concrete member (beam 4) exhibits a desired performance.

Therefore, when the magnitude of the static prestress force before deformation in the PC steel material 6 is Po, as shown in FIG. 4, the magnitude of the tensile stress acting on the PC steel material 6 when deformed is Po + ΔP. Become. The magnitude of the tensile stress during this deformation (Po + ΔP) is hereinafter referred to as “total prestress force P”. The total prestress force (Po + ΔP) is
As shown in FIG. 4, the deformation amount δ of the beam 4, which is a PC member,
The bending moment M acting on the beam 4 has a close relationship as described below.

First, FIG. 5 shows an unbonded PC according to the present invention.
FIG. 9 is a characteristic diagram showing a relationship between a deformation amount δ and a magnitude of a total prestress force in a fixing portion structure of a steel material. Deformation δ on the horizontal axis
And the vertical axis represents the magnitude P of the total prestressing force.

When the rigidity of the elastic body (coil spring 16) disposed between the head plate 12 and the fixing plate 14 is made rigid, after a predetermined amount of deformation δp has passed, as shown by a broken line i in FIG. Stiffness characteristics. That is, the progress of the deformation amount δ is relatively small, but the total prestress force P sharply increases and becomes considerably large.

Conversely, if the rigidity (elastic force) of the coil spring 16 is made soft, the rigidity characteristic shown by the solid line j in FIG. 5 is obtained. That is, the deformation amount δ increases, but the increase in the total prestress force P is gentle and does not change much. In other words, by changing the rigidity of the coil spring 16 to a large or small value,
It can be seen that the amount of increase in the total prestress force P can be controlled. By controlling the magnitude of the tensile stress of the PC steel material 6 in this way, it is possible to control the bending properties (rigidity, proof stress, deformation performance, restoring force characteristics) of the PC member.

In FIG. 5, the dashed line k shows the rigidity characteristics of the fixing structure of the conventional unbonded PC steel material without the coil spring 16 interposed therebetween. It clearly shows that the deformation amount δ is small and the total prestress force P tends to be very large.

Next, FIG. 6 shows an unbond P according to the present invention.
6 shows the relationship between the amount of deformation and the magnitude of the bending moment in the fixing portion structure of the C steel material. The horizontal axis represents the amount of deformation δ, and the vertical axis represents the bending moment M.

If the rigidity of the elastic body (coil spring 16) disposed between the plate 12 and the fixing plate 14 is made rigid, the characteristic shown by a broken line i is exhibited after a predetermined amount of deformation δp has elapsed. . That is, although the deformation amount δ advances considerably,
The magnitude of the bending moment M also increases accordingly.

Conversely, when the rigidity (elastic force) of the coil spring 16 is made soft, the characteristic becomes as shown by the solid line j in FIG. That is, although the deformation amount δ becomes very large, the magnitude of the bending moment M exhibits a characteristic that does not increase much. In other words, as a result of controlling the amount of increase in the total prestress force, it is possible to control the bending strength and the rigidity, delay the crushing of the concrete, and improve the deformability.

In the case of the conventional unbonded PC steel anchoring structure without the coil spring 16, the deformation amount δ is small and the bending moment M is very large, as indicated by the dotted line k in FIG. It can be seen that it exhibits characteristic properties.

FIG. 7 shows the restoring force characteristics. The horizontal axis represents the deformation amount δ, and the vertical axis represents the bending moment M.

The thin line k in FIG. 7 shows the restoring force characteristics of the conventional unbonded PC steel fixing portion structure without the coil spring 16 interposed therebetween. A broken line i indicates the restoring force characteristics of the fixing portion structure of the unbonded PC steel material having a high rigidity of the coil spring 16, and a thick line j indicates the restoring force characteristics of the fixing portion structure having a low rigidity of the coil spring 16. Each characteristic in FIG.
Are plotted with the predetermined deformation δr as a starting point, and indicate a state of restoration.

As can be seen from FIG. 7, in the case of the fixing portion structure in which the coil spring 16 having high rigidity is arranged, as shown by the broken line i, the restoring force due to the prestress is large, so that the present invention is applied from the outside. Energy absorption performance is low, but the residual deformation characteristic is small with little residual deformation.

Conversely, in the case of the fixing portion structure in which the coil spring 16 having low rigidity is arranged, the restoring force due to the prestress is small, as indicated by the thick line j, so that the residual deformation becomes large.
The ability to absorb externally applied energy has high restoring force characteristics.

As is clear from the above description, according to the fixing portion structure of the present invention, (1) whether to have a restoring force characteristic having a large residual deformation but a high energy absorption performance; (2) Whether the energy absorption performance is low but the residual deformation characteristics are small. (3) Is it between the former two? (4) Is it on the (1) side above the middle? (5) Is it on the side (2) above the middle? For example, there is a degree of freedom in arbitrarily selecting and designing at the stage of designing a structure.

Therefore, in contrast to the bending performance of the PC member which was conventionally limited by the distance L between the fixing portions of the unbonded PC steel material, the fixing portion structure according to the present invention can freely control the bending performance of the PC member. As a result, the degree of freedom in design is increased, and the sectional force (bending and shearing force) input to the prestressed concrete member and the stress concentration near the anchoring portion can be reduced.

In the above embodiment, the coil spring 16 is used as the elastic body. However, the present invention is not limited to this. Various metal springs such as a disc spring and a leaf spring having a predetermined rigidity, or a rubber elastic body or a plastic elastic body having a predetermined rigidity can be similarly used.

In the above embodiment, the PC member has been described as a prestressed concrete member, but is not limited to this. It may be a steel frame material.

[0038]

According to the fixing part structure of the unbonded PC steel according to the first and second aspects of the present invention, the bending performance of the PC member can be controlled without being restricted by the size of the interval between the fixing parts. In addition to increasing the degree of freedom in design, the sectional force input to the PC member and the stress concentration near the fixing portion can be reduced, and damage to the member and the frame can be prevented.

[Brief description of the drawings]

FIG. 1 is a front view showing a beam-column joint to which an anchor structure of unbonded PC steel according to the present invention is applied.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an enlarged view showing a fixing unit structure according to the present invention.

FIG. 4 is a diagram for explaining bending deformation of a beam to which an anchor structure of unbonded PC steel according to the present invention is applied.

FIG. 5 is a characteristic diagram showing a relationship between deformation and prestress in the fixing portion structure of the unbonded PC steel according to the present invention.

FIG. 6 is a characteristic diagram showing a relationship between deformation and bending moment in the fixing portion structure of the unbonded PC steel according to the present invention.

FIG. 7 is a view showing a restoring force characteristic of a fixing portion structure of an unbonded PC steel material according to the present invention.

FIG. 8 is a view showing an example of a fixing unit structure of a conventional unbonded PC steel material.

FIGS. 9A and 9B are views showing a column-to-beam joint before and after deformation using a conventional unbonded PC steel anchoring structure.

[Explanation of symbols]

 2 Column 2a Side surface of column 4 Beam 6 Unbonded PC steel material 6a End of unbonded PC steel material 8a, 8b Fixing part structure of unbonded PC steel material 10 Anchor head 12 Plate 14 Fixing plate 16 Coil spring (elastic body)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2E125 AA03 AA13 AB12 AC08 AG02 AG04 AG12 AG60 BD01 BE05 BE07 CA62 EA17 EB06 EB12 2E164 AA31 DA01 DA22

Claims (2)

[Claims] In an anchoring structure of a structure constituted by a prestressed concrete member using unbonded PC steel, a plate of an anchor head for anchoring unbonded PC steel and a load of the anchor head are transmitted to the structure. An elastic body having a predetermined spring rigidity is installed between the fixing plate and the fixing plate, and the rigidity of the elastic body is set to a size at which the prestressed concrete member exhibits a predetermined bending performance. An anchored structure of unbonded PC steel. 2. The elastic body according to claim 1, wherein the elastic body is one of various springs such as a coil spring, a disc spring, and a leaf spring, or a rubber elastic body or a plastic elastic body.
The fixing part structure of the unbonded PC steel material described in the above.