JP3373426B2 - Saddle structure for cable stayed bridge cable - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a saddle structure for supporting a cable such as a prefabricated cable in a supporting column (hereinafter referred to as a main tower) of a cable-stayed bridge and an extradosed bridge similar thereto.

[0002]

2. Description of the Related Art Cables are supported by saddles that pass through and are fixed to the main tower of cable-stayed bridges, and stoppers provided at both ends of the inner pipe or saddle abut the main tower body, so that the cables are fixed by a so-called stopper method. In recent years, the structure has been widely used, but in the case of this stopper method, uneven tension that occurs during or after bridge construction (the tension applied to the cable stayed on both sides of the main tower is not equal) Due to this, the cable may slip at the location of the main tower, so various measures have been taken in the past to prevent this slip, and there are roughly the following four methods.

A method of providing a shear cotter for fixing a cable at the center of a saddle structure is disclosed in Japanese Patent Laid-Open No. 7-90813, "Prestressed Concrete Vol. 39, No. 1, Jan. 19".
97 [(Construction Report) Hokuriku Shinkansen Yashiro Bridge Design and Construction], "Prestressed Concrete Vol.36, No.5, Se
pt.1994 [(Research Report) Full-scale test of fixed structure (ordinary fixing method) of diagonal timber main tower of Hokuriku Shinkansen Yashiro Minami / Yashiro Kita Bridge]

There are prior arts such as a method of cutting a screw on a saddle inner pipe and fixing it with a nut, such as Japanese Patent Laid-Open No. 8-170306 and "1997.7 Bridge [Kanizawa Ohashi Bridge and Odate Noshiro Airport Access Road]". The method of attaching a projection to the inner pipe of the saddle and fixing it with shims and the method of grouting the inside of the socket by attaching sockets to both ends of the saddle
l.36, No.5, Sept. 1994 [(Paper) Study on saddle structure at Odawara Minato Bridge]. This is a method in which fixing tools are provided at both ends of the saddle and the cable is stopped with a "wedge."

[0005]

The method of the above-mentioned prior art has a problem in that the saddle structure is structurally complicated and the cost of the apparatus increases. ，
The method of (1) has a complicated structure because it is necessary to process the end portion of the inner pipe that has been bent, and when uneven tension is generated, the movement of the inner pipe is based on the direction in which the uneven tension acts. Since it is a stopper system that tries to hold down at the rear end side, there is a possibility that the cable may temporarily slip, though slightly. On the other hand, the method (1) cannot perform "wedge anchoring" when using prefabricated cables (cables that are processed and manufactured at the factory side, not at the site).
Even if it is possible, the fixing tool will have a complicated structure, and at the same time, indentation on the cable will inevitably occur,
Cable fatigue may be greatly affected.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a double structure consisting of an outer pipe and an inner pipe, which are important components of a saddle structure. (EN) Provided is a saddle structure for a cable-stayed bridge, which simplifies the structure of the pipe structure and can prevent the cable from slipping when uneven tension occurs.

[0007]

The present invention has the following constitution in order to achieve the above object. That is, the invention of claim 1 according to the present invention has a double pipe structure of an outer pipe penetrating and embedded in a supporting column of a cable-stayed bridge and an inner pipe loosely inserted into the outer pipe, A saddle structure in which a cable is inserted into the inner pipe and fixed with an injection filling material,
The inner surface of the body divided into at least two has a tapered shape,
Spacers that are inserted into both ends of the inner pipe to plug the pipe openings around the cable, anchor members that are embedded in the support columns outside both ends of the outer pipe, and are supported and fixed to the anchor members. And a pressing block that is pressed against the spacer from the outside, thereby forming a saddle structure for a cable-stayed bridge cable.

According to a second aspect of the present invention, in addition to the first aspect of the invention, the pressing block is supported and fixed to an anchor member to which prestress has been introduced in advance. It is characterized in that the uniform tension is absorbed by the anchor member.

The invention of claim 3 according to the present invention relates to the invention of claim 1 or 2, wherein the outer tube has flanges integrally on the outer peripheral surfaces of both end portions, and the pressing block has the flange. And being pressed against the spacer from the outside.

According to the present invention as described above, as for the inner pipe and the outer pipe which are bent, the inner pipe is holed for injecting the filler, and the outer pipe is necessary for positioning the inserted inner pipe. Since it is only necessary to process the screw holes for the bolts provided and the flange mounting process (welding), and the anchor member, the spacer, and the pressing block can be machined to complete the products on the factory side.
Processing on the local side is simplified.

Further, according to the present invention, as a means for transmitting uneven tension to the supporting columns of the cable-stayed bridge, a so-called anchor bolt method, in which a tension block is transmitted to the anchor member, is adopted, whereby a conventional stopper is used. The method of the present invention is such that the movement of the inner pipe is suppressed by the support column at the rear end side thereof, whereas the present invention is a structure in which the movement of the inner pipe can be suppressed by the support column at the front end side thereof. The body can be fixed in a tight state so that the cable does not slip due to uneven tension loads.

In particular, the present invention makes it possible to introduce a prestressing force in the anchor member which is equal to or slightly greater than the previously envisaged unequal tension, which results in It is possible to reliably prevent even a slight slip of the cable.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. Figure 10
The schematic structure of the cable-stayed bridge implemented as one embodiment of the present invention is shown in elevation. The cable-stayed bridge shown is a pier 25
And the main tower 26 and the piers 25 on both sides across the main tower 26.
It is composed of a main girder 27 that spans between
At the same time when the top portion of 6 is concrete-cast, the saddle structure 10 is formed, and the main girders 2 on both sides are concrete-cast.
A cable-stayed bridge is formed by supporting 7 at both ends of a cable 11 whose middle portion is supported by the saddle structure 10. In this case, as the cable 11, for example, a prefab cable is used.

The saddle structure 10 is composed of an outer pipe having an upwardly convex curved shape which is embedded in the main tower 26 and embedded therein, and an inner pipe which is loosely inserted into the outer pipe with a slight clearance. The cable 11 has a double tube structure, and the cable 11 is inserted into the inner tube and fixed by an injection filling material, whereby the middle portion of the cable 11 is fixed to the main tower 26 via the saddle structure 10.

An embodiment of the double pipe structure unit in the saddle structure 10 is shown in a sectional view and a left side view in FIGS. 1 and 2, and an assembly drawing of the saddle structure 10 is shown in FIGS. 3 and 4. . Further, the structures of the outer tube 1, the inner tube 2, the pressing block 3, the spacer 4 and the pressing plate 9 which are the element members constituting the saddle structure 10 are illustrated in FIGS. 5 to 9, respectively.

With reference to FIGS. 1 to 9, a saddle structure 10
Is an outer tube 1, an inner tube 2, a holding block 3, a spacer 4, a flange 5, an anchor member 6, and a holding plate 9.
It is configured to include and. The outer pipe 1 is made of a steel pipe having a predetermined length that is bent in a curved shape that is convex upward, and flanges 5 are integrally fixed to the outer peripheral surfaces of both ends by welding. In the outer tube 1, a plurality of screw holes 12 for bolts are screwed at an upper portion of which the outside is convex and are dispersed at appropriate intervals in the longitudinal direction. The spiral streak 13 is wound around the wire. The spiral streak 13 is a member for strengthening the degree of adhesion between the outer pipe 1 and the concrete cast on the outer periphery thereof, and is provided as necessary. On the other hand, the flange 5 is made of, for example, a thick steel plate formed in a square shape, and holes 14 for inserting anchor bolts 7 to be described later are formed at four corners thereof.

The inner pipe 2 is made of a steel pipe bent in an upward convex curve corresponding to the outer pipe 1 which can be inserted into the outer pipe 1 with a slight gap, The chord length at the center of the tube is slightly shorter than that of the outer tube 1 by about several mm. A hose nipple 15 is attached to the inner pipe 2 by means of screwing in a central curved pipe portion of an upper portion whose outside is convex and a straight pipe portion near both ends, and the hose nipples 15 at both ends are provided with a grout. An injection hose 21 is connected, and a grout exhaust hose 24 is connected to the hose nipple 15 at the center.

Referring to FIG. 7, the pressing block 3 is made of a thick steel plate formed in a square shape that is substantially the same as the shape of the flange 5. The stepped round hole 16 is formed in the center of the pressing block 3 and the four corners are formed. A hole 17 for inserting an anchor bolt 7 described later is formed in each of these. The stepped round hole 16 has a small diameter side round hole having a diameter slightly smaller than that of the inner pipe 2 through which the cable 11 can be loosely inserted, and a large diameter side round hole through which a circular collar portion of a spacer 4 described later can be inserted. It has a round hole. The holding block 3 shown in the figure is attached to the grout injection side of the double pipe structure unit and has two hose insertion holes 18 formed therein, but the holding block 3 is attached to the opposite side. In the block 3, the hose insertion hole 18 is omitted.

As shown in FIG. 8, the spacer 4 has a main body which is in the form of a flanged bush as a whole and is axially divided into two or more parts (the illustrated embodiment is divided into two). Both ends of the inner surface are tapered so that the inner diameter gradually increases toward the outside. The spacer 4 is a member that is inserted into both ends of the inner pipe 2 to serve as spacers and that seals the pipe opening around the cable 11 that is inserted into the inner pipe 2. The small-diameter portion is brought into close contact with the jacket of the cable 11, and the flange portion is brought into contact with the end edge portion of the inner pipe 2 and the flange 5 of the outer pipe 1 to close both ends of the double pipe structure unit. It is provided. The spacer 4 shown in the figure is attached to the grout injection side of the double-tube structure unit and has two hose insertion holes 19, but the spacer 4 attached to the opposite side to this. The hose insertion hole 19 is omitted.

Referring to FIG. 1, the anchor member 6 is formed by an anchor bolt 7 made of, for example, a full-threaded PC steel rod and a nut 8 screwed to the bolt 7, and both ends of the double pipe structure unit body. On each side, four anchor bolts 7 are embedded outside the outer pipe 1 in the concrete layer of the main tower 26. Although not shown, it is a preferable means to attach a nut and a pressure plate to the tip of the anchor bolt 7 embedded in the concrete in order to ensure the fixation to the concrete layer. When prestressing the anchor bolt 7, a sheath tube (not shown) is attached up to about 50 cm from the concrete surface to cut the edge from the concrete, and after prestressing the grout between the sheath tube and the PC steel rod. Injecting is also an effective means for ensuring the prestressing effect.

The holding plate 9 is made of a thin steel plate formed as a donut plate as shown in FIG. 9, is divided into two in the radial direction, and the inner diameter is made substantially equal to the outer diameter of the cable 11, Is formed to have a diameter slightly larger than the small diameter side round hole of the pressing block 3. The pressing plate 9 is a member used to close the gap between the cable 11 and the small-diameter round hole of the pressing block 3.

To support the cable 11 by the saddle structure composed of the above-mentioned constituent members, the following procedure is carried out. First, the saddle structure 10 is mostly assembled on the factory side in order to simplify local work as much as possible. Referring to FIGS. 3 and 4A to 4D, the outer tube 1 is adjusted and fixed to the fixed frame 20 whose arrangement position is determined in accordance with the local aspect. The inner pipe 2 to which the grout injection hose 21 and the grout exhaust hose 24 are attached is inserted into the outer pipe 1, and the bolt is screwed into the bolt hole 12 provided in the outer pipe 1 so that the lower surface of the inner pipe 2 is the outer pipe 1. The inner pipe 2 is fixed so that the inner pipe 2 is perfectly aligned with the inner bottom surface.

Then, the urethane foam 22 is injected into the gap between the outer tube 1 and the inner tube 2, and after the urethane foam 22 is cured, the bolts that have been fixed are removed. Next, the anchor block 7 is temporarily attached by fitting the anchor bolt 7 to the hole 14 provided in the flange 5 of the outer tube 1 and the flange 5.
It is passed through the hole 17 and is fixed at a predetermined position using a nut or the like attached to the fixed frame 20. In this way, the assembly of the saddle structure 10 on the factory side is completed. The saddle structure 10 is carried into the field by a truck or the like.

At the site, the saddle structure 10 assembled in the factory is installed in the main tower 26 while adjusting its height while being fixed to the fixed frame 20. After mounting the formwork, concrete is poured by the usual means. After the demolding, the prefabricated cable 11 brought in from the factory is inserted into the stepped round hole 16 and the inner tube 2 of the holding block 3 temporarily placed at both ends of the saddle, the outer cover is removed, and the filling material (grout) is removed. ) 23 is firmly attached to the inner tube 2 in a bare portion, and both ends of the prefabricated cable 11 are fixed to the tension end fixing tool provided on the main girder 27 (FIGS. 3 and 4 (A)). reference).

Then, the spacer 4 is divided into two parts inside both ends of the inner tube 2 (see FIG. 4B), and the pressing block 3 is temporarily fixed to the outside thereof (see FIG. 4C). After tensioning the prefabricated cable 11 which has been stretched, the anchor bolts 7 projecting from the pressing block 3 are tightened with nuts, whereby the attachment of the saddle structure 10 to a predetermined position is completed.

At this time, when prestressing is introduced, a force corresponding to the number of anchor bolts per cable is used for each anchor bolt 7 by using a hydraulic jack or the like (not shown). The tension is fixed with a force equal to or slightly higher than the uneven tension of. Then
Putty material made of resin or the like was filled in a gap formed between the spacer 2 and the pressing block 3 to stop water, and the pressing plate 9 was attached to the pressing block 3 (see FIG. 4D).
Then, the inside of the inner tube 2 is grouting by using both the hoses 21 and 24. The attachment of the saddle structure 10 is completed as described above.

After the filling material 23 is hardened and adhered and the prefabricated cable 11 and the inner pipe 2 are integrated, the main tower 2
If uneven tension is generated in the left and right pre-fab cables 11 of 6, when the uneven tension is weak, the adhesive force of the filling material 23 in the saddle structure 10 is sufficient. When the unequal tension is strong, the frictional force between the inner pipe 2 and the outer pipe 1 is added to deal with this, but it is still not possible and if the inner pipe 2 tries to cause a slip in the outer pipe 1, The tension corresponding to the slip is transmitted from the pressing block 3 to the anchor bolt 7 via the spacer 4 inserted in the pipe 2. However, since the anchor bolt 7 is prestressed corresponding to the presumed uneven tension, the prefabricated cable 11 does not slip at all, thus achieving the intended purpose.

[0028]

The present invention is carried out in the form as described above, and has the following effects.

According to the present invention, since the anchor member acts on the front end side with respect to the tension direction by receiving the uneven tension, the movement of the inner tube is restrained on the rear end side. Compared to the stopper method, the saddle structure can be attached while keeping the inner tube in a tighter state, and the cable can be prevented from slipping due to uneven tension.

In particular, the present invention introduces a tension corresponding to the uneven tension preliminarily assumed at the time of attaching the saddle structure into the anchor member as prestress, so that a slight and temporary occurrence of the uneven tension occurs. The slip of the cable can be surely suppressed.

Further, in the double pipe structure consisting of the outer pipe and the inner pipe, the most difficult processing of the steel pipe can be carried out on the factory side by bending the inner pipe, bending the outer pipe and mounting the flange. Therefore, the processing cost can be further reduced. Furthermore, regarding cables, in the case of prefabricated cables that have been widely used recently, the only part of the inner tube that contacts the saddle structure other than the grout part is the inner surface of the spacer, and this part is protected by the jacket. Therefore, the deterioration of fatigue performance due to frictional corrosion can be reduced and the service life of the cable can be extended.

[Brief description of drawings]

FIG. 1 is a sectional view of a saddle structure according to an embodiment of the present invention.

FIG. 2 is a left side view corresponding to FIG.

FIG. 3 is an assembly diagram of a saddle structure according to an embodiment of the present invention.

FIG. 4 is an assembly sequence of a saddle structure according to an embodiment of the present invention, which is sequentially shown in (A) to (D).

5A is a plan view of an outer pipe in the saddle structure shown in FIG. 1, FIG. 5B is a front view showing a cross section, and FIG. 5C is a left side view.

6 (a) is a plan view of an inner tube in the saddle structure shown in FIG. 1, and FIG. 6 (b) is a sectional front view of the same.

7A is a front view of a holding block in the saddle structure shown in FIG. 1, and FIG. 7B is a right side view of the same.

8A is a front view of a spacer in the saddle structure shown in FIG. 1, and FIG. 8B is a right side view of the same.

9 is a front view of a pressing plate in the saddle structure shown in FIG.

FIG. 10 is an elevational view showing a schematic structure of a cable-stayed bridge in which an embodiment of the present invention is implemented.

[Explanation of symbols]

1 ... Outer pipe 2 ... Inner pipe 3 ... Pressing block 4 ... Spacer 5 ... Flange 6 ... Anchor member 7 ... Anchor bolt 8 ... Nut 9 ... Pressing plate 10 ... Saddle structure 11 ... Cable 12 ...
Screw hole for bolt 13 ... Spiral muscle 14 ... Hole 15 ...
Hose nipple 16 ... Stepped round hole 17 ... Hole 18 ...
Hose insertion hole 19 ... Hose insertion hole 20 ... Fixed frame 21 ...
Grout injection hose 22 ... Urethane foam 23 ... Filler 24 ...
Grout exhaust hose 25 ... Bridge pier 26 ... Support pillar (main tower) 27 ...
Main girder

Claims (3)

(57) [Claims] 1. A double pipe structure having an outer pipe penetrating and embedded in a supporting column of a cable-stayed bridge and an inner pipe loosely inserted into the outer pipe, and a cable is inserted into the inner pipe. And a spacer which is fixed by an injection filling material, wherein the inner surface of the main body divided into at least two parts has a taper shape, and is inserted into both ends of the inner pipe to seal a pipe opening around the cable. ,
An anchor member embedded in the support column outside both ends of the outer pipe, and a pressing block that is supported and fixed to the anchor member and is pressed against the end of the outer pipe and the spacer from the outside. Characteristic saddle structure for cable-stayed bridge cables. 2. The cable-stayed bridge according to claim 1, wherein the pressing block is supported and fixed to an anchor member to which prestress has been introduced in advance, and the uneven tension generated in the cable is absorbed by the anchor member. Saddle structure for cable. 3. The outer tube has flanges integrally formed on the outer peripheral surfaces of both ends, and the pressing block is pressed against the flange and the spacer from the outside.
Saddle structure for cable-stayed bridge cable described.