JP4338870B2 - Flexible structure by PSC method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flexible structure by a prestressed concrete (hereinafter referred to as “PSC”) construction method, and more particularly, a flexible structure type buried tunnel that can freely follow uneven subsidence of submarine ground and crustal deformation during a large earthquake, or It will be implemented in construction of large span bridges where considerable deflection is assumed.
[0002]
[Prior art]
The PSC construction method that builds an integrated structure by connecting multiple precast concrete (hereinafter referred to as “PC”) members with PC cables is very good in terms of shortening the construction period and reducing construction costs. Has a rich track record in the field.
[0003]
Moreover, by giving flexibility to the joint part between PC members, the integrated structure can be made flexible and the earthquake resistance can be remarkably enhanced.
[0004]
By the way, when a plurality of PC members are connected with a PC cable, there are a bond method in which cocrete and PC steel material are integrally attached and an unbond method in which the cocrete and the PC steel material are not attached. There is.
[0005]
That is, since the strain (Φ) generated when the bending M moment (M) is applied is held flat in the case of the bond type, the rigidity of the member does not decrease that much when the material is in the elastic region even if the tension is generated ( (See FIG. 8).
Whilst those unbonded manner, since the distortion of Kokurito and PC steel after tensile member section occurs is different, become softer as small tension spring Ambo down de lengths longer incremental strain, member stiffness reduction To do. (See Figure 8)
Therefore, in order to realize a flexible structure by the PSC method, it is advantageous to use an unbonded structure. By using the unbonded structure, a flexible structure similar to that joined by bolts can be obtained.
[0006]
By the way, in the conventional unbonded PSC method, in order to arbitrarily set the unbond free length between the PC members, it is necessary to arrange the PC steel material 21 for each PC member 20 as shown in FIG. For this reason, when the amount of use of the PC steel 21 is increased, there are problems such as the time and labor required for the placement and tensioning of the PC steel material 21.
[0007]
In addition, in order to make a flexible structure by this PSC method, it is necessary to allow the opening between the PC members to be pulled as shown in FIG. 9B, so PC steel is simply installed between the PC members. As a result, the PC steel material may corrode and break with the passage of time, and therefore it is necessary to take measures to prevent the corrosion of the PC steel material.
[0008]
This invention was made in order to solve the above subject, and makes it a subject to provide the flexible structure by the PSC method which made it possible to construct | assemble the flexible structure by the PSC method easily.
[0009]
[Means for Solving the Problems]
As means for solving the above problems, the flexible structure by the PSC method according to the present invention connects a plurality of PC members with a PC steel material that is continuously inserted in the axial direction, and both ends of each PC member. The part has an unbonded structure, and the inner part from both ends has a bonded structure.
[0010]
As a second aspect, in the flexible structure by the PSC method according to the first aspect, a PC steel material is continuously inserted into a sheath tube embedded in each PC member, and an expandable portion and an expandable portion are provided at both ends of each sheath tube. The cover part of each part is provided, and the expansion and contraction parts of the adjacent sheath tubes are connected to each other.
[0011]
As a third aspect, in the flexible structure according to the PSC method of the first aspect, a sheath tube is continuously embedded in a plurality of adjacent PC members, and a PC steel material is continuously inserted into the sheath tube, and the PC steel material and Edge cutting members for attaching the PC steel material and the sheath tube are attached to portions of the sheath tube that pass through both end portions of each PC member.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
1 to 3 show an example of the present invention. In the drawings, a plurality of PC members 1 are installed adjacent to each other, and a plurality of PC steel materials 2 are continuously connected to the adjacent PC members 1 in the adjacent direction. (Hereinafter referred to as “PC cable 2”) is inserted.
[0013]
The PC member 1 is used as a unit structural member such as a beam of a building structure, a bridge girder of a civil engineering structure, or a submerged box of a submarine structure. For example, an RC structure, a PC structure, an SRC structure, or a steel plate formwork It is constructed to a length of several meters to several tens of meters by a steel / concrete composite structure in which concrete is placed.
[0014]
The PC cable 2 is continuously inserted into the sheath tube 3 embedded in each PC member 1, and both ends 2a are tensioned at the end of the PC member 1 installed on the outermost side, and then the fixing nut. It is fixed by a fixing member 4 such as a wedge.
[0015]
Further, a grout material 5 such as cement mortar is filled around the PC cable 2 over its entire length.
[0016]
Further, the portion A of each PC member 1 of the PC cable 2 that penetrates both ends, that is, the joint portion A between the PC members 1, 1 is configured as an unbonded structure that is not attached to the PC member 1. A portion B that penetrates the inside from both ends is configured as a bond structure that is integrally attached to the PC member 1.
[0017]
In order to make the joint portion A between the PC members 1 and 1 have an unbonded structure, for example, as shown in FIG. 2B, the bellows are formed at both ends of the sheath tube 3 embedded in each PC member 1. A stretchable portion 6 that can be stretched and a cover portion 7 of the stretchable portion are formed outside the stretchable portion 6 so as to cover the stretchable portion 6. As a result, both end portions of each sheath tube 3 have a double structure including the stretchable portion 6 and the cover portion 7 of the stretchable portion.
[0018]
Also, a joint flange 6a protruding like a hook at the tip of the telescopic part 6 is formed continuously in the circumferential direction of the telescopic part 6, and the joint flanges 6a are a plurality of joint bolts 8 or a high-strength adhesive. As a result, the sheath tubes 3 are connected to each other.
[0019]
In such a configuration, when a tensile force is applied as an axial force by a bending external force to a plurality of PC members 1 coupled by a plurality of PC cables 2, the PC member 1 has a portion penetrating the inner side B from both ends. Since the cable 2 has a bond structure, strain generated in the cross section of the PC member 1 maintains a flat surface, so that the member rigidity does not decrease so much.
[0020]
On the other hand, since the PC cable 2 has an unbonded structure in the portion penetrating both end portions A of each PC member 1, the longer the unbond length, the smaller the strain increase and the softer the tension spring. Will decline.
[0021]
Further, since the PC cable 2 is completely covered with the extendable / contractible part 6 at both ends A of each PC member 1, that is, the joint part between the adjacent PC members 1 and 1, the joint part is shown in FIG. Even if an opening as shown in FIG. 5B occurs, there is no concern that the PC cable 2 is exposed and corroded.
[0022]
3A and 3B show another example in which the sheath tubes 3 of the PC members 1 are connected to each other. In FIG. 3A, the distal end portion of the expandable portion 6 is connected by a screw coupler 9. Has been. In this case, the screw coupler 9 is reversely threaded on both sides from the center, and can be connected while pulling the stretchable parts 6 on both sides when turned to one side.
[0023]
Further, in FIG. 3B, one end 6b of the telescopic part 6 connected to each other is formed to have a slightly larger diameter than the other end part 5c, and the one end part 6b of the telescopic part 6 is A stopper 10 that protrudes inwardly protrudes, and a stopper 11 that protrudes outwardly protrudes in a hook shape at the other end 6c.
[0024]
And the end part 6c of the other telescopic part 6 is inserted in the end part 6b of one telescopic part 6, and the stoppers 10 and 11 are engaged, so that the sheath tubes 3 of the PC members 1 are connected to each other. Are connected. In addition, between the stoppers 10 and 11, the water stop member 12 which consists of a gasket for the purpose of water stop or water-expandable rubber is filled.
[0025]
Next, a construction method in such a configuration will be described.
{Circle around (1)} First, the sheath tube 3 is set in a mold (not shown), concrete 13 is placed around it, and the PC member 1 in which the sheath tube 3 is embedded is molded. At that time, the extendable portions 6 projecting from the end portions of the sheath tubes 3 and the cover portions 7 of the extendable portions are actually connected so that the material axes of the sheath tubes 3 of the PC members 1 coincide with each other. The concrete 13 is placed while checking the position.
[0026]
(2) Next, a plurality of PC members 1 formed in this way are installed at predetermined intervals while ensuring a constant work space A between the adjacent PC members 1, 1.
[0027]
(3) Next, in each work space A between the adjacent PC members 1 and 1, the joint flanges 6a are connected to each other with joint bolts or an adhesive, and the sheath tube 3 of each PC member 1 is connected to one sheath tube. To be continuous.
In the case of an adhesive and coupler type connection, since the joint flange 6a protrudes from the end face, the joint flange 6a is automatically crimped when the PC members 1 are connected to each other, and the connecting operation of the sheath tube 3 is unnecessary. is there.
On the other hand, in the case of connection using a joint bolt or the like, when the height (working height) of the PC member 1 is very high, from several meters to several tens of meters, for example, shown in FIG. The aerial work vehicle 14 equipped with such a lift is used to improve work efficiency and safety.
[0028]
(4) Next, adjacent PC members 1 are brought into close contact with each other, and a plurality of PC members 1 are continued in the axial direction.
[0029]
(5) Next, the PC cable 2 is continuously inserted into the sheath tube 3 of the plurality of PC members 1, and both ends 2a thereof are fixed to the ends of the PC members 1 at the outermost ends by fixing nuts or wedges. The tension is fixed by the fixing member 4 such as. Finally, the sheath tube 3 is filled with a grout material 5 such as cement mortar.
[0030]
7 (a) and 7 (b) show another example for making the joint portion A between the PC members 1 and 1 have an unbonded structure. In FIG. 7 (a), a plurality of adjacent PC members 1 are shown. , 1, the sheath tube 3 is continuously embedded, the PC cable 2 is continuously inserted into the sheath tube 3, and the surroundings are filled with the grout material 5.
[0031]
Further, in the joint portion A between the PC members 1 and 1, an edge cutting member 15 is attached to the outer periphery of the sheath tube 3 for cutting off the adhesion between the sheath tube 3 and the concrete 14. In addition, an edge cutting member 16 for cutting off the adhesion between the PC cable 2 and the grout material 5 is attached to the outer periphery of the PC cable 2.
[0032]
As the edge cutting members 15 and 16, for example, urethane, asphalt, rubber, or silicon materials are used.
In FIG. 7B, the outer sheath tube is used as an edge cutting member for bordering the adhesion between the sheath tube 3 and the concrete 14 on the outer periphery of the sheath tube 3, particularly in the joint portion A between the PC members 1 and 1. 17 is attached, and grease or the like is filled between the sheath tube 3 and the outer sheath tube 17 as a friction reducing material 18.
[0033]
【The invention's effect】
The present invention is as described above, and in particular, a plurality of PC members are connected by a PC steel material inserted continuously in the axial direction, and both ends of each PC member are unbonded, and the inner side from both ends is bonded. Since it is configured by the structure, when a tensile force due to bending external force is applied, the PC steel material has a bond structure in the part penetrating the inside from both ends of each PC member. Since the generated strain maintains a flat surface, the member rigidity does not decrease so much.
[0034]
On the other hand, since the PC steel material has an unbonded structure in the part penetrating both ends of each PC member, the longer the unbond length, the smaller the strain increase and the softer the tension spring, the lower the member rigidity. .
[0035]
Therefore, a flexible structure having the necessary conditions can be easily constructed by appropriately increasing or decreasing the length of the unbonded structure.
[0036]
In addition, since the PC steel material is completely covered with the extendable / contractible part at both ends of each PC member, that is, the joint part between adjacent PC members, even if the joint part is opened, the PC steel material There is no worry of being exposed and corroding.
[Brief description of the drawings]
FIG. 1 shows an example of a flexible structure by a PC method, (a) is a sectional view showing the whole, and (b) is a sectional view showing a structure of a joint portion between PC members.
FIG. 2 shows an end of a sheath tube, (a) is a perspective view thereof, and (b) is a cross-sectional view.
FIGS. 3A and 3B are cross-sectional views showing the structure of a joint portion between PC members.
4A to 4D are cross-sectional views showing a construction process for joining PC members together.
FIGS. 5A to 5C are cross-sectional views showing a construction process for joining PC members together.
FIGS. 6A to 6D are cross-sectional views showing a construction process for joining PC members together, and FIG. 6E is a cross-sectional view showing a case of performing work at a high place.
7A and 7B are cross-sectional views showing the structure of a joint portion between PC members.
FIG. 8 is a graph showing the relationship between bending stress and strain.
9A is a cross-sectional view showing a conventional example of a flexible structure, and FIG. 9B is an enlarged view showing an open state between adjacent PC members.
[Explanation of symbols]
1 PC member 2 PC cable (PC steel)
DESCRIPTION OF SYMBOLS 3 Sheath pipe 4 Fixing member 5 Grout material 6 Telescopic part 6a Joint flange 7 Cover part of telescopic part 8 Joint bolt 9 Screw coupler 10 Stopper 11 Stopper 12 Water stop member 13 Concrete 14 Height work vehicle 15 Edge cutting member 16 Edge cutting member 16 17 Outer sheath tube 18 Friction reducing material

Claims (3)

  A PSC method characterized in that a plurality of PC members are connected by a PC steel material that is continuously inserted in the axial direction, and both end portions of each PC member have an unbonded structure and an inner side portion from both end portions has a bonded structure. Flexible structure by. PC steel material is continuously inserted into the sheath tube embedded in each PC member, and each sheath tube is provided with a stretchable portion and a cover portion of this stretchable portion, and each sheath tube adjacent to each other is stretchable. The flexible structure by the PSC method according to claim 1, wherein the parts are connected to each other.   A sheath tube is continuously embedded in a plurality of adjacent PC members, a PC steel material is continuously inserted into the sheath tube, and a PC steel material and a portion that penetrates both ends of each PC member of the PC steel material and the sheath tube The flexible structure by the PSC method according to claim 1, wherein an edge cutting member for attaching the sheath tube is attached.

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