JP3287820B2 - Partial unbonding method for PC member and PC member by partial unbonding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prestressed concrete member (PC member) capable of improving deformation performance by a partial unbonding method and a personal unbonded PC member.

[0002]

2. Description of the Related Art In general, as a method of improving the defect of a concrete member, which is weak against tensile stress, a method of introducing a prestress into a concrete member by a pretensioning method or a post-tensioning method using a PC steel is known. I have. PC with post tension system
The members are classified into a bond system in which the PC steel material and the concrete are integrated by adhesion and an unbond system without adhesion.

[0003] In the bonding method, a sheath is placed in advance between fixing devices provided at both ends of a PC member, and after concrete is cast, a PC steel material provided in the sheath is tensioned, and then grout mortar is put into the sheath. It is a system in which the PC steel material and concrete are integrated by injecting and hardening the grout mortar. In the unbond method, P
Apply rust-prevention treatment to C-steel material and add grout to the part near the end in the sheath to attach the end of PC steel to prevent the PC steel from jumping out when the PC steel breaks This is a method in which grout is filled to such an extent that it can be adjusted.

In recent years, the trend of seismic design of PC members is toughness-dependent design based on the intended collapse type.
In such a seismic design method relying on toughness, securing the required plastic deformation capacity (toughness) together with the strength at the site where the hinge is expected to be generated is a key point of the member design.

However, in the bonding method, the PC steel material and the concrete are bonded and integrated by the adhesion over their entire length.
Deformation is constrained by concrete and grout mortar, so despite the inherent plastic deformation performance of PC steel alone, the plastic deformation capacity of PC steel is not fully utilized, and PC steel breaks and loses prestress P
The C member is destroyed. In the unbond method,
Since the PC steel and concrete do not adhere to each other over almost the entire length, the deformation of the PC steel is not restrained by the adhesion to the concrete at the time of ultimate load application, but the concrete is not Compression failure occurs, and the PC member is destroyed. As described above, the bonding method and the unbonding method each have advantages and disadvantages.

[0006]

SUMMARY OF THE INVENTION The present invention is based on the conventional grouting method and improves the sheath of a section to be grouted so that any one of a plurality of PC steels in a plurality of PC steels is arranged. The section is in an unbonded state with no adhesion to the concrete base member, that is, the disadvantages of the bonding method and the unbonding method can be skillfully combined to eliminate the disadvantages of each method and improve the deformation performance of the PC member. The present invention has been accomplished based on the knowledge that can be improved, to provide a prestressed concrete member (PC member) with improved deformation performance, and to further improve the plastic deformation ability of the PC steel at the time of ultimate load loading on the PC steel. The purpose is to provide a PC member by the partial unbonding method that fully demonstrates and improves the deformation performance. That.

[0007]

In order to advantageously solve the above problem, according to the first aspect of the present invention, when a sheath is previously arranged in a PC steel material arrangement portion of a predetermined section of a member such as a beam or a column. , the part of a larger portion of the sheath of strain of the cross-section force is relatively large cross-section of an earthquake load acts, together with arranging the unbonded sheath over a predetermined length, the a
The bond sheath is placed outside the bond sheath of the specified length.
To prevent adhesion between concrete and bond sheath.
The adhesive insulation layer over the entire circumference of the predetermined section of the bond sheath
Are formed is coated Te, after placing the Bondoshisu the including portion arranged partial or said unbonded sheath not place Unbonded sheath portion was Da設concrete to fill each of said sheath, said concrete Develops a predetermined strength, tensions and fixes the PC steel material inserted between the bond sheath or the bond sheath and the unbond sheath, and subsequently fills the inside of the bond sheath or the bond sheath and the unbond sheath with grout mortar. And

[0008] In the case of the second aspect of the present invention, in the first aspect of the present invention, the unbonded sheath is formed by filling the gap between the bond sheath and the outer sheath disposed outside thereof with a stress insulating filler. It is characterized by having.

Further, in the case of the invention of claim 3, in the invention of claim 1, the unbonded sheath is characterized in that the outer surface thereof is a flexible soft material such as rubber or plastic.

[0010]

[0011]

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an example in which a PC steel material 9, a bond sheath 5 and an unbond sheath 4 are arranged on a beam member 2 of a concrete building 1. A section of the bond sheath 5 is shown as A, and a section of the unbond sheath 4 is shown as B. An unbonded sheath 4 is provided in the vicinity of the joint between the beam member 2 and the column member 6. The portion B (near the joint) of the unbonded sheath 4 is a portion where a large sectional force is applied when an earthquake load such as a horizontal force or a vertical force is applied, a hinge is expected to be generated, and a plastic deformation occurs. In the same cross section (II) shown in FIG. 2A, the portion relatively close to the cross-sectional center (PC steel material arranged near the neutral axis) has a small strain, so the bond sheath 5 is used over the entire length in the longitudinal direction. are doing.

In the section (II-II) shown in FIG. 2 (b), a large sectional force is not applied when an earthquake load is applied, so that the bond sheath 5 is used for all the sheaths. As described above, the used portion of the unbonded sheath 4 is as follows.
In the same cross section, a portion having a large strain apart from the center of the cross section is used, and in the longitudinal direction of the member, a portion where a large cross section force is applied when an earthquake load is applied is used.

Next, the form of forming the used portion of the unbonded sheath 4 shown in FIG. 1 will be described in order with reference to FIGS.

FIGS. 3A and 3B show a first embodiment of an unbonded sheath 4 used in the present invention. The unbonded sheath 4 is mounted on an outer peripheral surface of a bonded sheath 5 such as a conventional steel sheath. The sheath 5 and the base material concrete 7
A sheath-shaped (tubular) adhered insulating layer 11 for preventing (insulating) adhesion between the substrate and the non-attached state (separated state) with almost no force transmission action, and performing an adhesion insulation process. It is a thing. As a material of the adhesion insulating layer 11 for the adhesion insulation treatment, a material having or without a single-sided adhesive or pressure-sensitive adhesive layer can be used. For example, a tape-like material such as an asphalt impregnated tape, a synthetic resin foam sheet, and a rubber sponge sheet can be used. Alternatively, a sheet-like soft material may be used, and these may be wound or pasted around the bond sheath 5 to form a sheath-like (tubular) adhesion insulating layer 11 and partially formed into the unbonded sheath 4, or asphalt or synthetic. There is a method in which a paste-like sealing material such as resin or synthetic rubber is directly applied on the outer peripheral surface of the bond sheath 5 to form the adhered insulating layer 11, and the unbonded sheath 4 is partially unbonded.

In the case where the insulating treatment is performed on the outer peripheral surface of the bond sheath 5 or the like using a tape-like or paste-like soft material, one or more layers may be superimposed on the outer peripheral surface of the bond sheath 5. It may be formed to be higher (thicker) and relatively uniform in height than the irregularities on the outer peripheral surface of the bond sheath 5. By thus forming the sheath-like (tubular) adhesion insulating layer 11 on the outer peripheral surface of the bond sheath 5 for separating the adhesion into a non-adhesion state in which there is almost no force transmission, partial unbonding is achieved. The sheath 4 can be configured. Concrete 7 is cast so as to embed the sheaths 4 and 5 configured as described above.

After the concrete 7 has developed a predetermined strength, the PC steel material 9 inserted into the bond sheath 5 such as the steel sheath as shown by a two-dot chain line is tensioned,
After the both ends are fixed by a screw type or wedge type fixing device 8, a grout mortar 10 is filled and hardened between the bond sheath 5 and the PC steel material 9, and the reinforced concrete 7 and the PC steel material 9 which are base materials are filled. Is unified with the grout mortar 10 via the bond sheath 5 and in the unbonded unbonded sheath 4, the reinforced concrete 7 and the bond sheath 5 are in a non-adhered state, and there is almost no force transmitting action. The PC member 3 in a partially non-adhered state can be formed. In the case of this embodiment, the sheath 5 inside the adhesion insulating layer 11, the grout mortar 10, and the PC steel material 9 are integrated, but the cross-sectional area of the portion of the grout mortar 10 in the unbonded sheath 4 is Since it is very small compared to the concrete cross-sectional area of the base material concrete 7, that is, the PC member 3 main body, at the time of a high load action such as an earthquake load action,
The PC steel 9 is not restrained. The bond sheath 5 inside the unbonded sheath 4 acts together with the PC steel 9 when a high load such as an earthquake load is applied. However, since the strength is smaller than that of the PC steel 9,
The PC steel 9 is not restrained.

FIGS. 4A, 4B, and 4C show a second embodiment of the unbonded sheath 4 used in the present invention, in which a steel sheath and a steel sheath are provided outside a bonded sheath 5 made of a conventional steel sheath. A tubular outer sleeve 11 such as a rubber pipe, a paper pipe, a vinyl pipe, or the like is fitted over the bond sheath 5 with a gap therebetween to form a layer, and the gap is made of a soft filler such as grease, eye gas, paraffin, or the like. The unbonded sheath 4 is formed by filling the adhesion preventing filler 12. Other configurations are the same as those of the above-described embodiment.
The same reference numerals are given and the description is omitted.

In this embodiment, after the soft filler is applied to the outside of the bond sheath 5, the outer sleeve 11 may be fitted.

FIGS. 5 to 7 show a third embodiment of the unbonded sheath 4 used in the present invention. FIGS. 5 and 6 correspond to FIGS. 1 and 2 in the above embodiment. Since the drawing is a diagram, to avoid repetition of the description, the same portions are denoted by the same reference numerals, and description thereof will be omitted. Only different portions will be described. This form is a form in which the flexible unbonded sheath 4 is arranged in series with the bond sheath 5. The means for forming the flexible unbonded sheath 4 will be described with reference to FIGS. 7A, 7B and 7C.

FIGS. 7a, 7b and 7c show that a conventional sheath is not used in order to form a duct in the unbonded section, but instead a soft rubber or plastic or the like coated with a release material on the outside is used. An unbonded sheath 4 made of a flexible tubular body is used, and its end is fitted on the outer peripheral surface of the end of the bond sheath 5 adjacent in series so as to be overlapped, and if necessary, the overlapped end is appropriately attached with a band or tape or the like. After tightening and sealing, concrete 7 is cast to embed them, and after the concrete 7 has developed a predetermined strength, the PC steel material inserted in advance in each of the sheaths 4 and 5 or at an appropriate time is arranged. After the tension is fixed at 9, each of the sheaths 4
The grout mortar 10 is filled in and hardened. In the case of this embodiment, the unbonded sheath 4 between the bond sheaths 5, 5 has a structure in which the concrete 7 as the PC member main body and the PC steel material 9 do not adhere.

The unbonded sheath 4 may be made of a material that is smooth without irregularities on the outer surface, or a material that is a low-strength material that has low adhesion to the concrete 7, for example, flexible rubber or plastic. A tubular body may be used.

Also in the above embodiment, the cross-sectional area of the grout mortar 10 in the unbonded section is much smaller than the concrete cross-sectional area.
Is not bound.

FIGS. 8 and 9 show a fourth embodiment in which the present invention is applied to a pillar. In this embodiment, a PC steel member 9 and a bond sheath are attached to a PC pillar member 14 of a concrete building 1. 5 shows an example in which an unbonded sheath 5 is arranged. A section of the bond sheath 5 is shown as A, and a section of the unbond sheath 4 is shown as B. The portion B (near the joint) of the unbonded sheath 4 is a portion where a large sectional force acts upon the application of an earthquake load such as a horizontal force or a vertical force, and is a portion where a hinge is expected to occur. In the case of this embodiment, the lower end of the PC steel material 9 arranged on the sheaths 4 and 5 in the column member 14 joined to the beam member 2 and the like is locked by the screw type or wedge type fixing device 8. . After the PC steel 9 is tensioned and fixed by the fixing tool 8 at the upper end, the grout mortar 10:00 is filled between the unbond sheath 4 and the bond sheath 5 and the PC steel 9.

An unbonded sheath which has been unbonded on the side of the column member 14 near the PC column base port 13 of the column member 14 in the same manner as in the first or second embodiment shown in FIGS. 1, 3 and 4. 4 are disposed vertically and embedded and fixed in concrete 7. An unbonded sheath 4 that has been unbonded in the same manner as the third embodiment shown in FIGS. 5 and 7 is vertically disposed on the column member 14 side of the PC steel material 9 in the vicinity of the PC column capital joint portion 15. It is embedded and fixed in concrete 7.

Regarding the embodiment of the unbonded sheath 4 and the bonded sheath 5, the arrangement in the horizontal state of the first to third embodiments shown in FIGS. 3, 4 and 7 may be changed to the vertical arrangement. , Illustration is omitted.

The unbonded sheath 4 at the lower end of the PC steel 9 may be the same as the unbonded sheath 4 at the upper end, or the unbonded sheath 4 at the upper end of the PC steel 9 may be replaced with the lower end. The same thing as the unbonded sheath 4 on the side may be adopted.

In practicing the present invention, a low-strength material, for example, a plastic material can be used as a material forming the unbond sheath 4 and the bond sheath 5.

In each of the above embodiments, the case where the present invention is applied to the joint (joint portion) of the beam member or the column member has been described. However, when the present invention is applied, a concrete floor slab or a concrete vertical slab is used. It may be applied to walls or concrete foundations. The PC steel material may be a PC cable such as a PC steel wire or a PC steel rod. Further, the present invention provides a PC
The present invention can be applied not only to the grout type in which the grout mortar is filled after the steel material is tensioned but also to the pre-grout type PC method in which a resin is injected into the sheath before the PC steel material is tensioned.

[0030]

The effects of the present invention are as follows. A: The deformation performance of the PC member is improved in the portion where the strain is large when the seismic load is applied, and a seismic design with high toughness can be easily performed. B Since the unbonded sheath section can be set freely and easily, the deformation performance of PC steel can be controlled freely.
Seismic design that eliminates the disadvantages of conventional bond and unbond systems is possible. Since the conventional sheath and the unbonded sheath are connected and used, grout can be continuously injected from one end as in the past, and complicated work occurs because only the unbonded part is not separately constructed. Absent. As in the conventional bonding method, the PC steel material can be protected from corrosion.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal side view showing a state in which a PC member having improved deformation performance by implementing a partial unbonding method according to an embodiment of the present invention is disposed.

FIG. 2A is a sectional view taken along the line II of FIG. 1, and FIG.
FIG. 2 is a sectional view taken along line II-II of FIG. 1.

FIG. 3A is a side view of an unbond sheath portion used in the partial unbond method according to the first embodiment of the present invention, and FIG. 3B is a cross-sectional view taken along line III-III of FIG.
(C) is a cross-section showing a state embedded and arranged in the concrete base material.

FIG. 4A is a side view of an unbonded sheath used in a partial unbonding method according to a second embodiment of the present invention, and FIG. 4B is a cross-sectional view taken along the line IV-IV of FIG.
(C) is sectional drawing which shows the state embedded and arranged in the concrete base material.

FIG. 5 is a partial longitudinal side view showing a state in which a PC member having improved deformation performance by implementing a partial unbonding method according to a third embodiment of the present invention is arranged.

6A is a sectional view taken along line VV of FIG. 5, and FIG.
FIG. 6 is a sectional view taken along line VI-VI of FIG. 5.

FIG. 7A is a side view of an unbonded sheath portion used in a partial unbonding method according to a third embodiment of the present invention, and FIG. 7B is an enlarged sectional view taken along line VII-VII of FIG. (c) is a cross-sectional view showing a state where the concrete base material is embedded and arranged.

FIG. 8 is a partially longitudinal side view showing a state in which a PC member having improved deformation performance by implementing a partial unbonding method according to a fourth embodiment of the present invention is arranged.

9A is a sectional view taken along line VIII-VIII of FIG.
(B) is a sectional view taken along line IX-IX of FIG. 8, and (c) is a sectional view of FIG.
FIG. 3 is a sectional view taken along line XX of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concrete building 2 Beam member 3 PC member 4 Unbonded sheath 5 Bonded sheath 6 Column member 7 Concrete 7 8 Fixing tool 9 PC steel material 10 Grout mortar 11 Outer sleeve 12 Adhesion preventing filler 13 PC pillar base joint 14 Column Member 15 PC capital connection part 16 recess

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) E04C 3/26 E04C 5/08-5/10

Claims (3)

(57) [Claims] When a sheath is preliminarily disposed on a PC steel material disposed portion of a predetermined section of a member such as a beam or a column, a part of the sheath at a portion where a cross-sectional force is relatively large when an earthquake load is applied and a cross section is large. An unbonded sheath is provided over a predetermined length, and the unbonded sheath has a predetermined length.
Concrete and bond sheath outside the bond sheath
Adhesive insulating layer is used to make bond
Is formed so as to cover the entire circumference of a predetermined section of the
Ri, wherein after placing the Bondoshisu to not place the unbonded sheath portion or portions, including the portion of arranging the Unbonded sheath, said to Da設concrete to fill each sheath, after the concrete is expressed predetermined strength Tensioning and fixing the PC steel material inserted between the bond sheath or the bond sheath and the unbond sheath, and subsequently filling grout mortar in the bond sheath or the bond sheath and the unbond sheath. Construction method. 2. The PC member according to claim 1, wherein an unbonded sheath is formed by filling a gap between the bond sheath and an outer sheath disposed outside the bond sheath with a stress insulating filler. Partial unbond method. 3. The partial unbonding method for a PC member according to claim 1, wherein the outer surface of the unbonded sheath is a flexible soft material such as rubber or plastic.