JPH09158126A - Cutting method of existing pc structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cut and remove an unnecessary part in the state a tension is effectively and continuously applied on a tendon in a PC structure. SOLUTION: An existing PC structure 1 in which a compressive force is applied through tendons 5 is cut off at a specified cutting position C together with the tendons 5. The rest structure 1A to be used thereafter is separated from the unnecessary cut-off structure 1B. In this time, the tendons to be cut off, it exposed by chipping the part adjacent to the cut-off position of the rest structure and intermediate anchors are fixed to the exposed tendons. The tendons on which the intermediate anchors are fixed are partly filled back together with the intermediate anchors to construct an anchorage foundation 9a. In this state, the tendons in the exposed condition are cut off and the end of the rest structure side of the cut-off tendons is anchored by regular setting tools 13. Thereafter, the existing PC structure is cut off at a cutting position.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is suitable for application to existing PC structures such as PC bridges, where unnecessary parts are cut while effectively leaving a part of the existing PC structure. The present invention relates to a cutting method for existing PC structures.

[0002]

2. Description of the Related Art In a so-called post-tension type PC structure in which prestress is introduced after the construction of a concrete skeleton, a part of the PC structure is cut and removed,
Even when trying to effectively utilize the remaining part as a structure, when the tension material is cut, the prestress introduced by the tension material is dissipated, and reuse as a structure is impossible. there were.

[0003]

However, this causes a disadvantage that the post-tension type PC structure cannot be repaired or modified.

In view of the above circumstances, the present invention is capable of cutting and removing the remaining portion of a post-tension type PC structure while the tension material in the remaining structure is being effectively tensioned. It is intended to provide a possible cutting method for an existing PC structure.

[0005]

That is, the first aspect of the present invention is as follows.
In the invention, the existing PC structure (1) in which a compressive force is applied to the skeletons (2, 3) by the tension member (5) to which tension is applied is set at the predetermined cutting position (C) at the tension member (5). ), And when separating and cutting into the residual structure (1A) to be used thereafter and the unnecessary structure (1B) to be cut,
By exposing a portion of the residual structure adjacent to the cutting position, the tension member to be cut is exposed, and the intermediate fixing member (6) is fixed to the exposed tension member,
A fixing foundation (9) in which the tension member to which the intermediate fixing device is fixed is partially backfilled together with the intermediate fixing device and connected to the residual structure side.
a) is constructed, and in that state, the exposed tension material is cut between the fixing foundation and the cutting position, and the end portion of the cut tension material on the residual structure side is set by the setting device. (13)
After that, the existing PC structure is cut at the cutting position.

A second aspect of the present invention is configured such that the final setting attachment is attached to the fixing base. Further, in the third aspect of the present invention, the existing PC structure is a PC bridge, and the anchoring foundation is constructed of quick-hardening concrete. Note that the numbers and the like in parentheses are for convenience showing the corresponding elements in the drawings, and therefore, this description is not limited to the description on the drawings. The same applies to the following “action” column.

[0007]

According to the first aspect of the present invention having the above-mentioned structure, the residual structure (1A) is provided from the time when the intermediate fixing device (6) cuts the tension member (5) to the fixing of the setting device. It acts so as to temporarily hold the tension of the side tension member (5). A second aspect of the present invention operates so that the setting device (13) is mounted in a form that utilizes a fixing base (9a) in which an intermediate fixing device is embedded. The third aspect of the present invention acts so that the fixing foundation can be constructed in a short time with the quick-hardening concrete.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a diagram showing an example of a PC structure to which the present invention is applied, FIG. 2 is a sectional view taken along the line Z2-Z2 of FIG. 1, FIG. 3 is a front view showing an example of an intermediate fixing device, and FIG. FIG.

As shown in FIGS. 1 and 2, an existing PC structure 1 such as a post tension type PC bridge to which the present invention is applied has a slab 2 which constitutes a concrete skeleton portion.
And a beam 3 for supporting the slab 2, and at the intersection of the slab 2 and the beam 3 (hence, the upper part of the beam 3), as shown in FIG.
As shown in FIG. 2, a plurality of tension members 5 made of PC steel stranded wire or the like whose outside is covered with a sheath are provided, and the existing PC structure 1 is used.
In the figure, a known fixing device (not shown) provided at the left and right ends is used to apply a predetermined tension (therefore, a compressive force acts on the concrete skeleton portion), and arrows A and B
Direction. The existing PC structure needs to be cut at the cut surface C of the PC structure 1 because the left part of the drawing is damaged by an earthquake or the like, or the left part of the drawing is reconstructed. On the other hand, the intermediate fixing tool 6 used for cutting the existing PC structure has a quadrangular prism-shaped main body 7 as shown in FIG. 3 and FIG. The material fixing hole 7a is formed by penetrating in the directions of arrows D and E, that is, the axial direction of the main body 7. As shown in FIG. 4, the main body 7 has two main body pieces 7c and 7d, and each of the main body pieces 7c and 7d has a respective main body piece 7c and 7d.
Form tensioning member fixing holes 7a when they are assembled so as to face each other through their joint surfaces 7i, 7i. Grooves 7e, 7e having a semicircular cross section are formed in the directions of arrows D, E. There is. Further, the main body 7 has a plurality of bolt mounting holes 7f.
However, as shown in FIG. 4, the main body pieces 7c and 7d are
7e is provided with a tension material fixing hole 7a so that the tension material fixing hole 7a can be fastened and fixed by a bolt nut (not shown), and the main body piece 7c is further injected with a fixing material for fixing a tension material such as an expansion material. The hole 7g and the air vent hole 7h are provided so as to communicate the tension member fixing hole 7a with the outside.

Since the existing PC structure 1 and the like have the above-described structure, the left part of the existing PC structure in FIG. 1 is damaged by an earthquake or the left part of the drawing is reconstructed. In the case where the PC structure 1 is cut along the cut surface C and separated into the residual structure 1A to be reused as a structure and the to-be-cut structure 1B to be removed, the following is performed. That is, first, as shown in FIG. 1, concrete at the position on the residual structure side adjacent to the cutting plane C, which is the planned cutting position of the existing PC structure 1, is mounted to form a fixing hole 9 and embedded inside. The tensioning material 5 being exposed is exposed. A scale provided with a fixing hole 9 is shown in FIGS. 3 and 4.
In a state where the intermediate fixing tool 6 is divided into two, the main body pieces 7c, 7
d with the grooves 7e, 7e facing each other,
Are inserted into the tension member fixing hole 7a formed by the groove portions 7e, 7e. Then, in that state, FIG.
As shown in FIG. 7, the joint surfaces 7i, 7i of the main body pieces 7c, 7d
The main body pieces 7c and 7d are integrated with each other by a bolt nut (not shown) through the bolt mounting hole 7f.

Next, as shown in FIG. 3, a fixing material 10 such as an expansive material is injected into the tension material fixing hole 7a from a fixing material injection hole 7g formed in the main body piece 7c of the intermediate fixing tool 6. The tension member 5 is fixed and fixed to the intermediate fixing tool 6, and a washer 11 is attached to the position of each intermediate fixing tool 6 on the right side in FIG. 1, and the intermediate fixing tool 6 is temporarily placed in the fixing hole 9 by an appropriate means. Stop. In this state, tension is still introduced into the tension member 5, and the compressing force on the concrete forming the slab 2 and the beam 3 of the PC structure 1 around the fixing hole 9 is locally caused by the fixing hole 9. Although it is open, when viewed as the entire structure, due to the tension introduced into the tension member 5 by the known fixing tool provided at the left and right ends of the existing PC structure 1 shown in FIG. The compressive force is effectively applied to the PC structure 1 as prestress.

Next, as shown in FIG. 1, the tension member 5 is fixed in the fixing hole 9 on the right side in the drawing, that is, the residual structure 1A on the right side of the cut surface C, which remains as a structure after cutting. Concrete 12 such as ultra-rapid hardened concrete is partially backfilled on the side of the fixing end to be formed, and the fixing foundation 9a is connected to the residual structure 1A at the right side portion of the fixing hole 9 in FIG.
The intermediate fixing portion 6 is constructed so as to be embedded therein together with the washer 11 and the like. The surface of the fixing base 9a on the left side in the drawing is formed as a permanent fixing surface 9b in the fixing hole 9 so as to be substantially perpendicular to the directions of arrows F and G, which are the laying directions of the tension members 5. In addition, when super-rapid hardening concrete whose design strength is developed in a shorter time than that of normal concrete is used as the concrete 12, the curing time of the concrete is short, so that the subsequent work can be started quickly. Therefore, the existing P
This is effective when the C structure needs to be put into general use as soon as possible by shortening the construction period as much as possible, such as a PC bridge.

Thus, when the fixing base 9a is formed in the fixing hole 9, between the permanent fixing surface 9b of the fixing base 9a and the left side surface of the fixing hole 9 in the drawing, that is, the residual structure 1A and the cut surface C. In the space between the structures to be cut 1B on the left side in FIG. 1, the tension member 5 still exposed is cut at a position K apart from the permanent fixing surface 9b by a predetermined fixing distance LX. Then, the cut tension member 5 releases the tension acting on the tension member 5 up to the left of the position K from the position K, but the reused residual structure 1A side Even if the tension material 5 is cut, the intermediate fixing tool 6 embedded and fixed in the fixing base 9a and the tension material 5 are fixed and fixed, so that the intermediate fixing tool 6 and the existing PC structure 1 are not shown. Due to the existing fixing device provided at the middle right end, the tension state of the tension member 5 on the right side of FIG. 1 is maintained without change, and the remaining structure 1A portion is the same as before the tension member 5 was cut. A predetermined compressive force acts, and the residual structure 1A is maintained in a good stress state that is the same as before.

Next, the ends of the respective tension members 5 which are cut off and remain on the residual structure 1A side in a state of protruding from the permanent fixing surface 9b of the fixing base 9a are fixed to the fixing base 13a known to the fixing base 9a. To fix and fix.

In this way, when fixing is performed on the residual structure 1A side by the permanent fixing tool 13, the existing PC structure 1 is cut from the cut surface C shown in FIG. 1 and the cut structure 1B side is removed. Build new structures. Residual structure 1
In A, the prestress is introduced by the existing fixing device provided at the right end portion (not shown) of the fixing device 13, the intermediate fixing device 6, and the existing PC structure 1 in spite of the cutting of the tension member 5. The structure to be cut 1B
It can survive in a good condition even after the removal of.

[0016]

As described above, the first aspect of the present invention is as follows.
According to the invention, the existing P in which the compressive force is applied to the skeleton portion such as the slab 2 and the beam 3 by the tension member 5 to which the tension is applied.
When the C structure 1 is cut together with the tendon 5 at a predetermined cutting position such as the cut surface C, and when the residual structure 1A to be used thereafter and the unnecessary cut structure 1B are separated and cut,
The tension member to be cut is exposed by hanging a portion of the residual structure adjacent to the cutting position, the intermediate fixing tool 6 is fixed to the exposed tension material, and the intermediate fixing tool is fixed. The tension member is partially backfilled together with the intermediate fixing tool to construct the fixing base 9a connected to the residual structure side, and in that state, the exposed tension member is cut between the fixing base and the cutting position. Then, the end of the cut tension member on the side of the residual structure is fixed by the main setting fixture 13, and then the existing PC structure is cut at the cutting position. The tension of the tension material on the residual structure side can be temporarily held from the time of cutting the tension material to the fixing of this setting garment, and in the post-tension type PC structure, Continue to apply tension to the tension material effectively In state, it is possible to cut off the remaining portion.

According to a second aspect of the present invention, the main setting device is configured to be attached to the fixing base,
This setting device has the advantage that it does not require a special fixing base because it is attached using a fixing base with an intermediate jig embedded therein.

The third invention of the present invention is the existing P
The C structure is a PC bridge, and since the anchoring foundation is constructed by constructing a quick-hardening concrete such as super-hardening concrete, the anchoring foundation can be constructed in a short time by using a quick-hardening concrete. It is possible to use it immediately.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a PC structure to which the present invention is applied.

2 is a cross-sectional view taken along the line Z2-Z2 in FIG.

FIG. 3 is a front view showing an example of an intermediate fixing device.

FIG. 4 is a side view of FIG. 3;

[Explanation of symbols]

 1 ... Existing PC structure 1A ... Residual structure 1B ... Structure to be cut 2 ... Skeletal part (slab) 3 ... Skeleton part (beam) 5 ... Tension material 6 ... Intermediate fixing device 9a .... Fixing basics 13 …… This setting Kimono (fixing equipment) C …… Cutting position (cutting surface)

Claims (3)

[Claims] 1. An existing PC structure whose compressive force is applied to a skeleton portion by a tensioning material to which tension is applied is cut together with the tensioning material at a predetermined cutting position, and a residual structure to be used thereafter and an unnecessary cover When separating and cutting into a cutting structure, the tension member to be cut is exposed by hanging a portion of the residual structure adjacent to the cutting position, and the intermediate fixing tool is fixed to the exposed tension member. In addition, the tension member to which the intermediate fixing device is fixed is partially backfilled together with the intermediate fixing device to build a fixing base connected to the residual structure side, and in that state, the exposed tension member is fixed to the fixing base. And the cutting position, the end of the cut tension member on the residual structure side is fixed with the setting fixture, and then the existing PC structure is cut at the cutting position. Existing PC structure constructed Cutting method. 2. The method for cutting an existing PC structure according to claim 1, wherein the final setting device is configured to be attached to the fixing foundation. 3. The method for cutting an existing PC structure according to claim 1, wherein the existing PC structure is a PC bridge, and the anchoring foundation is constructed of quick-hardening concrete.