JP4663563B2 - Saddle structure for bridge - Google Patents

Description

  The present invention relates to a saddle structure in a main tower structure such as a cable-stayed bridge or an extradosed bridge. In particular, the present invention relates to a saddle structure in which a saddle structure in a main tower structure of a bridge has a single pipe structure.

  Extradosed bridges, which are a type of cable-stayed bridge and cable-stayed bridge, are known as bridges provided on arterial roads and railway tracks. These cable-stayed bridges and extradosed bridges are configured to support the bridge girder by a plurality of diagonal cable (tension materials) extending diagonally from the main tower arranged perpendicular to the bridge girder.

  A saddle structure has been proposed for the main tower structure of the cable stayed bridge and the extradosed bridge as described above. Specifically, this saddle structure is constructed by holding the central part of the diagonal cable (tension material) with both ends fixed to the bridge girder in the main tower arranged perpendicular to the bridge girder, so that the main tower is connected to the diagonal cable. The bridge girder is hung through the bridge. A plurality of saddle structures are juxtaposed in the height direction of the main tower, and the bridge girder is supported by the main tower using a plurality of tendons. Usually, such a saddle structure has a double tube structure in which the outer periphery of the diagonal cable is covered with a double curved tube (for example, Patent Document 1).

  16A is a schematic configuration diagram of a saddle structure having a double-pipe structure, FIG. 16B is a cross-sectional view taken along line AA ′ in FIG. 16A, and FIG. 16C is a saddle structure. It is an enlarged view of an exit part. The saddle structure 100 having a double pipe structure is configured such that an outer pipe 120 is embedded in a main tower 200 made of concrete, and the inner pipe 110 is inserted into the outer pipe 120. Further, a tendon 130 is inserted into the inner pipe 110, and both ends of the tendon 130 are fixed to a main girder (bridge girder) (not shown). At this time, a spacer 150 is disposed between the outer tube 120 and the inner tube 110 to maintain the position of the inner tube 110 in the outer tube 120 and to grout the hose between the outer tube 120 and the inner tube 110. 160 can be inserted. Furthermore, an inner pipe straight pipe portion 115 having a thread groove formed on the outer peripheral surface is connected to both ends of the inner pipe 110, and a ring nut 180 is screwed to the outer circumference of the straight pipe portion 115. Can do. Then, as shown in FIG. 16 (C), a bearing plate 181 is fixed to the concrete side wall constituting the main tower 200, and the ring nut 180 is screwed into the inner pipe straight pipe portion 115 so as to face the main tower 200. The inner tube 110 is fixed to the main tower 200 by tightening the main tower 200 from the side wall (see FIG. 16A). In addition, reinforcing bars 170 are often arranged on the outer periphery of the outer pipe 120 in order to prevent cracking of the concrete that constitutes the main tower.

  In order to form the saddle structure 100 as described above, first, the outer tube 120 is embedded in the main tower 200, the inner tube 110 is disposed inside the outer tube 120, and the inner tube 110 and the outer tube are arranged. An exit part is formed so that both ends of 120 open to the opposite side wall of the main tower 200 (see FIG. 16C). Next, the tension member 130 is disposed in the inner pipe 110, the inner pipe straight pipe portion 115 is connected to both ends of the inner pipe 110, and the water stop structure 190 is formed at the end of the straight pipe portion 115 to form the inner pipe 110. Tube 110 is sealed. Subsequently, after tensioning the tendon 130, the grout 140 is injected from the grout hose 160 disposed between the outer tube 120 and the inner tube 110 so that the tendon 130 and the inner tube 110 are integrated. . At this time, since the inner peripheral surface of the inner pipe straight pipe portion 115 is formed in a taper shape tapered toward the end portion, the grout 140 filled in the inner tube 110 is also tapered at both end portions. Cured into a shape. Then, after the grout 140 has hardened, the ring nut 180 is screwed from the outer periphery of both ends of the inner pipe straight pipe portion 115, and the ring nut 180 is held against the main tower 200 via the bearing plate 181. By doing so, the tension of the tensioned tension member 130 is transmitted from the grout 140 to the main tower 200 via the inner pipe straight pipe portion 115, the ring nut 180, and the bearing plate 181. Therefore, the main tower 200 can hold the bridge girder via the cable (tension material 130). Furthermore, in addition to the tension force introduced to the tendon during the formation of the saddle structure, the main tower 200 can also receive the tension acting on the tendon due to vibration such as an earthquake.

  By the way, the saddle structure 100 having a double-pipe structure may cause a difference in tension between the left and right of the saddle structure 100 due to the passage of a train or an automobile, the occurrence of an earthquake, or the like. FIG. 17 is a schematic diagram showing a state of action of tension on the main tower 200 when a difference in tension between the left and right sides occurs in the saddle structure 100. The state shown in FIG. 17 is a state in which tension is acting so that the tendon 130 is pulled relatively to the right side, and this tension acts almost concentrated mainly on the left side wall of the main tower 200. Specifically, the tension that acted to pull the tendon 130 to the right in the figure is transmitted from the inner pipe 110 integrated with the tendon 130 by the grout 140 via the ring nut 180 and the bearing plate 181. Is transmitted to the left side wall.

JP 2002-88715 A

  However, since this saddle structure has a double-pipe structure, the outer diameter of the entire saddle structure is large, which means that the saddle structures in the main tower are arranged close to each other while downsizing the main tower. It was a hindrance.

  Moreover, since it has a double-pipe structure, the number of parts is large, and assembly work is complicated and uneconomical.

  Therefore, a main object of the present invention is to provide a saddle structure in which a plurality of saddle structures can be arranged close to one main tower and the height of the main tower can be reduced.

  Furthermore, another object of the present invention is to provide a saddle structure that can be easily constructed with a small number of members constituting the saddle structure.

  The present invention applies the above-mentioned object by applying a single pipe structure to the saddle structure, and further burdening the intermediate part of the single pipe with the transmission of the tension force from the tension material to the main tower through the single pipe. To achieve.

  The present invention is a saddle structure for a bridge in which a tension material is disposed inside a bending tube that is disposed so as to penetrate the main tower of the bridge, and a grout is filled between the bending tube and the tension material. The curved tube is formed of a single tube fixed in the main tower, and an outer peripheral protrusion is provided on the outer periphery of at least an intermediate portion of the curved tube so as to extend radially outward of the curved tube. It is comprised so that the adhesive force may be improved.

  According to the saddle structure of the present invention, the tension acting on the tendon can be transmitted to the main tower via the outer peripheral protrusion formed at the intermediate portion of the single pipe (curved tube) integral with the tendon. Therefore, it is possible to avoid the tension of the tension material from acting on the side wall of the main tower intensively, and even if the interval between the saddle structures provided in the main tower is reduced, the main tower can be prevented from being damaged.

  Further, since the saddle structure is a single pipe structure, an outer pipe is not required unlike the conventional double pipe structure, and the number of parts constituting the saddle structure can be reduced. Accordingly, the construction workability of the saddle structure can be improved.

  In the saddle structure of the present invention, the number of the outer peripheral projections may be one for one bending tube, or a plurality may be provided. The number of outer peripheral projections may be appropriately selected in consideration of the length of the bending tube and the adhesion between the bending tube and the main tower. Since an effect proportional to the number cannot be obtained even if a large number of outer peripheral protrusions are provided, it is sufficient that the number of outer peripheral protrusions provided in one bending tube is 1 to 5. When a plurality of outer peripheral protrusions are provided, it is preferable because the stress acting on one outer peripheral protrusion (due to the tension force or tension of the tension material) can be reduced.

  Further, the position where the outer peripheral projection is provided is at least an intermediate portion of the bending tube. The intermediate portion does not indicate only a position at an equal distance from both ends of the bending tube, but indicates all portions other than both ends of the bending tube. With this configuration, when the curved tube is embedded in the main tower, the outer peripheral projection can transmit the tension of the tendon to a place other than the side wall of the main tower, and the concentration of the load on the side wall can be avoided. . Of course, an outer peripheral projection may be provided at the end portion in addition to the intermediate portion of the bending tube. In the case where one outer peripheral projection is provided on the bending tube, it is preferably provided on the outer periphery of the central portion of the bending tube, and in the case where a plurality of outer peripheral projections are provided, it is preferably distributed and arranged at predetermined intervals in the longitudinal direction of the bending tube. With this arrangement, the tension force from the tension material can be transmitted to the main tower almost evenly over the longitudinal direction of the bending tube.

  The shape of the outer peripheral protrusion may be a shape that protrudes outward in the radial direction of the bending tube and improves the adhesion between the bending tube and the main tower. For example, a shape in which the outer diameter of the curved tube continuously varies or a shape in which the outer diameter varies discontinuously may be used.

  The former includes a spindle shape that bulges so that a balloon bulges in the middle of the curved tube. According to this shape, the corners that are recessed around the outer peripheral projection are not formed, and when the concrete constituting the main tower is placed around the curved pipe, the concrete is sufficiently spread around the curved pipe. Cheap. Therefore, it can prevent that a space | gap is made in concrete.

  On the other hand, the latter includes forming a flange-shaped outer peripheral protrusion on the outer periphery of the bending tube having a uniform diameter in the longitudinal direction. More specifically, an annular outer protrusion may be formed on the outer periphery of the bending tube having a uniform diameter in the longitudinal direction. According to this configuration, since the flange-shaped outer peripheral projection can sufficiently transmit the tension force from the tension material to the concrete constituting the main tower, more efficient transmission of the tension force can be realized.

  Whichever shape of the outer peripheral projection is selected, various factors (for example, the outer diameter and transmission length of the bending tube, the degree of adhesion between the bending tube and the concrete of the main tower, etc.) are taken into consideration. What is necessary is just to select protrusion length and the thickness of an outer periphery protrusion.

  Such an outer peripheral projection may be formed integrally with the bending tube, or may be formed by joining a member prepared separately from the bending tube.

  When the outer peripheral protrusion is formed integrally with the bending tube, for example, a portion having a larger diameter than other portions may be formed in a part of the bending tube, and this may be used as the outer peripheral protrusion. That is, the peripheral wall itself of the bending tube constitutes an outer peripheral projection.

  On the other hand, when the outer peripheral projection is a separate member from the bending tube, for example, an annular member is welded and fixed to the outer periphery of the bending tube to form an outer peripheral projection. In addition, the annular member may be screwed to the bending tube. In the case of screwing, the cross-sectional shape of the annular member is preferably an inverted T-shaped cross section in which a disc-shaped protrusion is orthogonal to the outer periphery of the cylindrical mounting portion. A screw hole is provided in the attachment portion, and a screw hole is also provided in the bending tube. And an annular member can be fixed to a bending pipe by screwing a volt | bolt into a bending pipe with an attaching part.

  Such an outer peripheral projection may be formed in an annular integrated configuration, or may be configured by combining a plurality of arc-shaped divided pieces. The integrally formed outer peripheral protrusion is fitted from the end of the bending tube and moved in the longitudinal direction, and then attached to the bending tube. The split outer peripheral projection can be directly attached to the outer peripheral surface from the outside of the bending tube. In addition, the outer peripheral protrusion may be formed on the entire outer periphery of the bending tube, or may be partially formed on the outer periphery.

  Furthermore, it is preferable that a reinforcing member for supporting the outer peripheral protrusion in the longitudinal direction of the bending tube is provided on the outer peripheral protrusion described above. The outer peripheral protrusion is a main part that transmits this tension to the main tower when tension is applied to the tendon material, and an excessive stress (tension) may act to damage the outer peripheral protrusion. In particular, when the outer peripheral protrusion is flange-shaped, stress concentrates on the root portion of the flange-shaped outer peripheral protrusion and the flange-shaped outer peripheral protrusion may be deformed. Therefore, by providing a reinforcing member that supports the outer peripheral protrusion in the longitudinal direction of the curved tube, even when stronger tension acts on the tension material, the outer protrusion is not deformed or damaged, and this tension is efficiently applied to the main tower. Can communicate. For example, when the outer peripheral projection is a flange shape in which an annular member is fixed to the outer periphery of the bending tube, the reinforcing member is a right triangle plate, and one side sandwiching the right angle of the triangle is on the outer peripheral surface of the bending tube, For example, the side is arranged on one surface of the annular member. With such a configuration, the outer peripheral protrusion can be supported in a direction orthogonal to the annular member, and therefore the outer peripheral protrusion is difficult to be damaged. A plurality of such reinforcing members may be arranged in the circumferential direction of the outer circumferential protrusion, or the outer circumferential protrusion may be supported from both sides.

  The reinforcing member is preferably provided with a through-hole penetrating in a direction shifted from the longitudinal direction of the bending tube. When constructing the main tower, concrete is placed around the curved pipe. At that time, there are cases where the fluid concrete is difficult to go around around the outer peripheral projections and the reinforcing member, and if the concrete does not sufficiently go around this portion, a gap is generated. Here, if a through-hole is formed in the reinforcing member, this through-hole can be used as a passage for concrete, and a void can be hardly formed in the concrete around the curved pipe. In particular, when the concrete is placed, the flow surface of the concrete moves from the bottom to the top. Therefore, when the surface of the reinforcing member is arranged in a substantially horizontal direction, a void is easily generated on the upper surface side of the reinforcing member. Therefore, when it is set as a plate-shaped reinforcement member, it is suitable for this through-hole to be a hole penetrated in the thickness direction of the reinforcement member.

  In addition, the saddle structure of the present invention may have a configuration for more efficiently transmitting the tension acting on the tendon to the main tower. More specifically, it is preferable to provide a supporting member for receiving the tension of the tendon on the side wall of the main tower as in the conventional saddle structure described above. For example, a straight pipe having a relatively short length is connected to both ends of the curved pipe in the present invention, a male screw is formed on the outer peripheral surface of the straight pipe, and a ring nut that is screwed into the male screw is provided. To do. With this configuration, the tension acting on the tendon is applied to the main tower by pressure welding of the side wall of the main tower via the straight pipe and ring nut from the curved pipe in addition to the adhesion between the curved pipe and the main tower due to the outer peripheral projection. Can be made. Along with this, it is possible to disperse and transmit tension transmission points throughout the longitudinal direction of the bending tube by the outer peripheral projection and the ring nut. In addition to the above configuration, a bearing plate may be arranged between the ring nut and the main tower so that the tension of the tendon is transmitted to the side wall of the main tower. At this time, since the force per unit area acting on the side wall of the main tower can be reduced by making the area of the bearing plate larger than the area of the end face of the ring nut, the side wall of the main tower is damaged. hard.

  Further, reinforcing bars for preventing damage to the main tower may be arranged on the outer periphery of the bending tube. As the reinforcing bar, for example, a helical line is used, and the helical line is disposed on the outer periphery of the curved tube to prevent the main tower from being damaged.

  By the way, if the bending tube is directly buried in the main tower, it is difficult to replace the tendon when the tendon is damaged for some reason. Therefore, in the saddle structure having the single-pipe structure of the present invention, it is preferable to provide a spare hole in the main tower so that a new tendon can be placed in addition to the curved pipe through which the tense tendon is inserted. . The preliminary hole is a curved pipe embedded in advance when concrete is cast to form the main tower, and may be in the vicinity of the curved pipe through which the tension material is inserted. By providing a spare hole, it becomes possible to maintain the number of tendons necessary to hold the bridge even if the tendons are damaged and the tendons have to be replaced. .

  In addition, the tension material used for the saddle structure of the present invention is not particularly limited. The tendon may be a single wire or a stranded wire. For example, an epoxy-coated steel strand can be suitably used. A plurality of tendons may be arranged inside one bending tube.

  The grout used in the present invention is not particularly limited. The grout only needs to be strong enough to transmit the tension acting on the tendon when it is cured to the bending tube. Of course, it may be a commercial product. A grout hose for filling the inside of the bent tube with the grout is preferably embedded in the main tower along the bent tube.

  Moreover, if the bending pipe used for the saddle structure of the present invention has a bending portion in which a tensioning material can be arranged so that the tensioning material extends in an oblique direction from the main tower toward the bridge girder in a part thereof. good. For example, the curved tube used in the present invention may be one having a gentle radius of curvature as a whole, or a straight tube bent at the center to form a curved portion. In particular, when a curved tube having a short straight tubular portion formed at the end of the curved portion having a gentle radius of curvature is used, the tension material is prevented from being bent and disposed at the end of the curved portion or the tube. This is preferable. In addition, it is easy to form a configuration that transmits the tension acting on the tendon to the side wall of the main tower via the end of the bending tube. Whichever shape is selected, it is preferable to select the curvature of the curved portion so that the bridge girder can be efficiently supported without excessive tension acting locally on the tendon.

  As a material of the bending tube, a material capable of maintaining the strength at the time of design may be appropriately selected. Examples thereof include carbon steel and polyethylene. In addition, it is preferable to form a water stop structure at the end of the bending tube so that the grout filled in the bending tube does not leak.

  According to the saddle structure of the present invention, the tension of the tension material does not concentrate on the exit portion of the saddle structure, that is, the side wall of the main tower, and the interval between the saddle structures can be reduced. Therefore, the saddle structure can be densely arranged, and the size of the main tower can be reduced.

  Furthermore, according to the saddle structure of the present invention, since the saddle structure is a single pipe structure, the number of parts of the saddle structure can be reduced. Thereby, the construction workability of the saddle portion is improved and the cost can be greatly reduced.

<Embodiment>
Here, the case where the saddle structure of the present invention is applied to a main tower of a bridge such as a cable-stayed bridge or an extradosed bridge will be described as an example. These bridges are composed of a bridge girder extending substantially parallel to the ground, a main tower extending substantially perpendicular to the bridge girder, and a diagonal cable (tensile material) extending from the main tower to the bridge girder. In this example, 11 saddle structures of the present invention were provided in parallel in the height direction of the main tower in this main tower. Each saddle structure is arranged in parallel at a predetermined interval.

  Of each saddle structure, the saddle structure (S-11) located at the uppermost position of the main tower will be described with reference to FIG. First, the overall configuration of the saddle structure will be described, and then each component will be described.

(Overview of overall configuration)
1A is a schematic configuration diagram of a saddle structure having a single-pipe structure, and FIG. 1B is a partially enlarged view of FIG. The saddle structure 1 having a single-pipe structure is composed of a saddle steel pipe 10 (curved pipe) embedded in the concrete constituting the main tower 2 and a saddle steel pipe for improving the adhesion between the main tower 2 and the saddle steel pipe 10. The anchor flange 40 (outer peripheral projection) provided on the outer periphery of the cable 10 and the cable 20 (tension material) inserted through the inside of the saddle steel pipe 10 are the main components.

  In order to form the saddle structure 1 as described above, first, when placing concrete, a saddle steel pipe 10 is embedded in the main tower 2, and both ends thereof are opened in opposite side walls of the main tower 2. The outlet portion is formed as follows. Here, a high frictional force acts between the main tower 2 and the saddle steel pipe 10 by the anchor flange 40 provided on the outer periphery of the saddle steel pipe 10. That is, since the main tower 2 and the saddle steel pipe 10 are firmly attached, the tension acting on the cable 20 is transmitted to the saddle steel pipe 10 and is transmitted to the main tower 2 via the saddle steel pipe 10.

  Next, the cable 20 is disposed on the saddle steel pipe 10, and the water stop structure 35 is formed at the end of the saddle steel pipe 10 to seal the saddle steel pipe 10. Subsequently, after tensioning the cable 20, the grout 30 is injected into the saddle steel pipe 10 using the grout injection hose 31 and the grout discharge hose 32 communicated with the saddle steel pipe 10, and the cable 20 and the saddle steel pipe 10 are integrated. To be. At this time, since the inner peripheral surfaces of both end portions (straight tubular steel tube 12) of the saddle steel tube 10 are tapered toward the end portion, the grout 30 filled in the saddle steel tube 10 is also the same. Both ends are cured in a tapered shape. After the grout 30 has hardened, a protective tube 38 that has been fitted in the cable 20 in advance is arranged so as to cover both ends of the saddle steel tube 10, and the end of this protective tube 38 is partially attached to the side wall of the main tower. It is fixed to a support plate (supporting plate) 60 that is embedded and fixed in On the other hand, both ends of the cable 20 are fixed to a main girder (bridge girder) (not shown) so that the main tower supports the girder via the cable.

  In the saddle structure according to the present embodiment, even when a design tension difference (272.0 kN), which is the maximum tension difference that may be applied during the construction or operation of the bridge, is applied, no problem occurs. In recent years, the lessons learned from the Great Hanshin-Awaji Earthquake have demanded bridges that can withstand level 2 ground motion. The saddle structure of this embodiment has a tension difference (3094.0 kN) assuming this level 2 ground motion. Even if it works, the possibility of damage is very low. Here, the level 2 ground motion is the input ground motion used for seismic design of structures and is the ground motion with the maximum strength that can be considered at this point from the present to the future. Activity report of the Earthquake Motion Research Subcommittee: March 2000).

  Hereinafter, each component will be described.

(cable)
As the cable 20, a cable in which seven steel wires were combined and the outer periphery thereof was coated with epoxy was used. In the present embodiment, 27 cables 20 are arranged inside the saddle steel pipe 10 as a unit. Here, the outer diameter of each stranded wire is 15.2 mm, and the tensile load (JIS standard) that is the maximum load that can be introduced into the cable 20 is 261 kN. Therefore, the saddle structure 1 of the present embodiment with 27 stranded wires as a unit can be tensioned by applying a load of 7047 kN (hereinafter referred to as Pu).

(Saddle steel pipe)
The saddle steel pipe 10 is formed by a curved steel pipe 11 having a gentle radius of curvature and a straight tubular steel pipe 12 connected to both ends of the curved steel pipe 11. In addition, two anchor flanges 40 (outer protrusions) were formed on the outer periphery of the curved steel pipe 11 at a predetermined interval. The curved steel pipe 11 is formed so as to have a gentle curvature, and the cable 20 disposed inside the bent steel pipe 11 is bent so that excessive lateral pressure does not act on the cable 20 locally.

(Anchor flange)
The anchor flange 40 is a member for enhancing the adhesion between the main tower 2 and the saddle steel pipe 10. FIG. 2 shows an enlarged view of the anchor flange 40 provided in the saddle steel pipe 10. In the present embodiment, the anchor flange 40 is formed by fitting a steel ring to the outer periphery of the saddle steel pipe 10 and welding it. That is, the anchor flange 40 is projected in a direction orthogonal to the axial direction of the saddle steel pipe 10. As described above, since the cable 20 is integrated with the saddle steel pipe 10 via the grout 30, the tension acting on the cable 20 is transmitted to the saddle steel pipe 10 and only transmitted to the main tower via the saddle steel pipe 10. Instead, it is also transmitted to the main tower via the anchor flange 40 fixed to the saddle steel pipe 10. That is, the saddle steel pipe 10 provided with the anchor flange 40 exhibits a large resistance to the pulling force in the longitudinal direction of the saddle steel pipe 10. The diameter (D1) and thickness (t) of the anchor flange 40 were determined based on a calculation example described later.

(Stiffener)
The anchor flange 40 is provided with a stiffener 50 (reinforcing member). The stiffener 50 is a member that reinforces the anchor flange 40 in order to prevent the anchor flange 40 from being damaged by the load when the tension of the cable 20 is transmitted to the main tower. Since the anchor flange 40 is easily bent in the longitudinal direction of the saddle steel pipe 10, in the present embodiment, the stiffener 50 is provided so as to support the anchor flange 40 in the longitudinal direction of the saddle steel pipe 10. As shown in FIG. 2, the stiffener 50 is a triangular steel plate disposed perpendicular to the anchor flange 40. In this stiffener 50, one side sandwiching the right angle of the triangle was fixed to the outer peripheral surface of the saddle steel pipe 10 and the other side was fixed to one surface of the anchor flange 40 by welding. Four stiffeners 50 are provided on both surfaces of the anchor flange 40 so as to be even in the circumferential direction. By doing in this way, it can prevent that the anchor flange 40 bends in the longitudinal direction of the saddle steel pipe 10, and the adhesive force of the saddle steel pipe 10 and the main tower falls.

(Grout and grout injection hose, grout discharge hose)
The grout 30 is for integrating the saddle steel pipe 10 and the cable 20 by filling the saddle steel pipe 10 and hardening it (see FIG. 1). The grout 30 may be a commercially available one. In this embodiment, the compressive strength of the grout 30 after curing is about 600 kgf / cm ² (about 58.8 N / mm ² ). The grout injection hose 31 and the discharge hose 32 for filling the grout 30 inside the saddle steel pipe 10 are connected to and communicated with the straight tubular steel pipe 12 and the curved steel pipe 11 of the saddle steel pipe 10, respectively. The filling of the grout 30 into the saddle steel pipe 10 is finished when the grout is injected from the injection hose 31 and discharged from the discharge hose 32.

(Water stop structure)
The water stop structures 35 provided at both ends of the saddle steel pipe 10 hold the grout 30 in the saddle steel pipe 10 until the grout 30 is hardened and prevent leakage to the outside of the saddle steel pipe 10. A known structure may be used as the water stop structure 35, and the water stop structure described in Patent Document 1 is used in the present embodiment. The water stop structure 35 can prevent the grout 30 from leaking from both ends of the saddle steel pipe 10. The straight tubular steel pipe 12 protruding from the water stop structure 35 and the outlet is covered with a protective pipe 38, and the outside of the water stop structure 35 is also protected.

(Support plate)
The support plate 60 is a steel rectangular plate that is embedded in the side wall of the main tower with its surface exposed. In the present embodiment, it is used to fix the end of the protective tube 38. However, it may be used to transmit the tension acting on the cable 20 to the main tower 2 more efficiently. Specifically, it is used for receiving the tension of the cable 20 on the side wall of the main tower 2 as in the conventional saddle structure as described above.

(Spiral muscle)
The spiral bars 71 and 72 are members that increase the strength of the main tower 2 and prevent the splitting of concrete in the outer peripheral diameter direction of the saddle steel pipe 10. As the spiral muscles 71 and 72, commercially available ones were used. In the saddle structure 1 of the present example, since stress acts on the entire outer periphery of the saddle steel pipe 10, the first spiral muscle 71 is disposed so as to surround the entire length of the saddle steel pipe 10. Furthermore, since the vicinity of the exit portion of the saddle structure is a place where a stronger stress is applied than in the central portion, the second spiral muscle 72 is disposed so as to surround the outer periphery of the first spiral muscle 71.

The main dimensions of the saddle structure described above are shown below.
Of the saddle steel pipe, the upper length of the curved steel pipe is 3426.0mm
Of saddle steel pipe, the length of the lower part of the curved steel pipe is 3340.0mm
Of saddle steel pipes, the length of straight tubular steel pipes is 540.0mm
Transmission length (length between support plates of the upper part of saddle steel pipe) 3472.0mm
Outside diameter of curved steel pipe and straight pipe steel pipe 165.2mm
Anchor flange width (refer to D2 in Fig. 2 (B)) 35.0mm
Anchor flange thickness (see t in Fig. 2 (A)) 16.0mm
Distance between two anchor flanges (top of saddle steel pipe) 2000.0mm

<Calculation example>
In designing the anchor flange 40, the following calculations were performed to determine the dimensions. In designing the anchor flange 40, the saddle structure of the uppermost stage where the difference in tension acts is modeled out of the saddle structures provided in the main tower. Refer to FIG. 2 for the dimensions of each part of the anchor flange 40.

  First, the adhesion resistance force P of the saddle steel pipe 10 in a state where the anchor flange is not provided on the outer peripheral surface of the saddle steel pipe 10 was calculated. The adhesion resistance P is an index for evaluating the adhesion performance between the saddle steel pipe 10 and the main tower concrete, and when tension exceeding the adhesion resistance P acts on the cable, the saddle steel pipe 10 is pulled from the main tower. You can think that it will come off. The adhesion resistance P indicates the degree of adhesion between the concrete and the saddle steel pipe 10, and was estimated by multiplying the surface area of the saddle steel pipe 10 embedded in the main tower by a predetermined coefficient. Table 1 shows the items used for calculating the adhesion resistance P and the calculation results of the adhesion resistance P. As shown in Table 1, when calculating the adhesion resistance P, the curved portion of the saddle steel pipe 10 (curved steel pipe portion) was assumed to be a straight steel pipe (normal round steel) having a circular cross section.

  From the results in Table 1, the adhesion resistance P when the anchor flange is not provided on the outer peripheral surface of the saddle steel pipe is 1514.0 kN. This is higher than the design tension difference of 272.0kN, which is the maximum tension difference that may be applied during the construction and operation of the bridge, but is lower than the tension difference of 3094.0kN assuming Level 2 earthquake motion. Therefore, when an earthquake corresponding to Level 2 ground motion occurs, in a saddle structure without an anchor flange, the saddle steel pipe is pulled out from the main tower and the bridge is expected to collapse.

  Next, the adhesion resistance force P of the saddle steel pipe when the anchor flange is provided on the outer peripheral surface of the saddle steel pipe is calculated, and the tension difference (anchor flange design force T) to be received by the anchor flange is calculated based on the result. The tension difference to be received by the anchor flange is examined using a value obtained by subtracting the adhesion resistance P between the saddle steel pipe and concrete from the tension difference when level 2 earthquake motion is assumed. That is, the tension flange design force T is a tension difference that cannot be absorbed by the adhesion resistance between the saddle steel pipe and the main tower.

  In the following, consider the case where the difference in tension acting on the cable is received by two anchor flanges (Case 1) and the case where the tension difference is received by one anchor flange (Case 2). However, even when pressure is received by one anchor flange, in reality, two anchor flanges are provided on the outer periphery of the saddle steel pipe, and one of the two anchor flanges is used as a fail safe. First, the adhesion resistance P was calculated, and the results are shown in Table 2. Here, when designing the anchor flange, there is no need to consider the adhesion resistance between the saddle steel pipe and the concrete from the anchor flange to the end of the saddle steel pipe, so the transmission length can be calculated as the distance between the anchor flanges. good. Of the words and symbols in Table 2, the same definitions and calculation methods as those in Table 1 are the same as those in Table 1.

  Based on the adhesion resistance P obtained as described above, the anchor flange is designed to withstand a tension difference of 3094.0 kN assuming a level 2 earthquake motion. In designing, since the adhesion resistance P reduces the tension difference acting on the left and right cables, the outer diameter D1 of the anchor flange is based on the value obtained by subtracting the adhesion resistance P from 3094.0kN (anchor flange design force T). The thickness t is obtained. Here, when the tension is received by the two anchor flanges, it is assumed that the two anchor flanges share the anchor flange design force T equally.

The diameter D1 of the anchor flange is calculated from the bearing area where the characteristic value of the bearing strength of the concrete is 60.0 N / mm ² (main tower design standard strength is 30.0 N / mm ² ) by the following formula. Characteristic values of the bearing capacity is likely to arise damage to the concrete exceeds 60.0 N / mm ^2.
T / A1 = 60
Here, A1 is the area of the end face of the anchor flange protruding from the saddle steel pipe, and is calculated by the following formula.
A1 = (D1 ² −D ² ) × (π / 4)

The thickness t of the anchor flange is calculated from the area where the shear stress degree of the anchor flange is the designed shear yield strength 135.0 N / mm ² by the following formula. The design shear yield strength 135.0 N / mm ² is a value derived from the material of the anchor flange being SS400. If this value is exceeded, the anchor flange may be damaged.
T / A2 = 135
Here, A2 = 519.0 × t. 519.0 (mm) is the circumference of a saddle steel pipe having a diameter of 165.2 mm. Table 3 shows the related items and the dimensions of the anchor flange obtained by calculation.

  Based on the results in Table 3, in the saddle structure of the embodiment, the outer diameter D1 of the anchor flange is 235.2 mm with a margin, and the protrusion amount (anchor flange width) D2 of the anchor flange from the saddle steel pipe is 35.0. mm. Further, the thickness t of the anchor flange was kept at 16.0 mm in consideration of providing a stiffener.

  In designing the anchor flange, when the adhesion resistance force P is not considered, the anchor flange design force T may be calculated as 3094.0 kN. The outer diameter D1 and the thickness t of the anchor flange at that time are 305.0 mm and 44.0 mm if there is one anchor flange, and 245.0 mm and 22.0 mm if there are two anchor flanges.

  In order to evaluate whether the saddle structure of the present invention described above can be applied to an actual bridge, the following test was performed.

<Test Example 1>
First, measure how much the maximum load that can actually be introduced into the cable differs depending on whether or not an anchor flange with the dimensions obtained from the calculation example is provided on the saddle steel pipe. did. The tension (load) that acted on the cable when some damage occurred in the saddle structure was taken as the maximum load.

  In this test, for the sake of simplicity, a specimen model was assumed in which a curved steel pipe with a saddle structure was assumed to be a straight pipe (see FIG. 3). The test body model is composed of a saddle steel pipe 17 composed of a curved pipe portion 17A (straight tube steel pipe) and a straight pipe portion 17B (straight tubular steel pipe), and a cable (not shown) inserted into the saddle steel pipe 17. And a grout (not shown) filled between the saddle steel pipe 17 and the cable. And model A-model C which reproduced a part of test body model were embedded in concrete, a test structure was produced, and the maximum load in each test structure was measured. Similar to the saddle structure of the embodiment, spiral bars (not shown) are arranged on the outer periphery of the saddle steel pipe 17 in the concrete. Here, the model A is a reproduction of a part of the curved pipe portion 17A, and the model B is a reproduction of a part of the curved pipe portion 17A including a portion where the anchor flange 40 is provided. Model C is a reproduction of a part of the curved pipe portion 17A including the anchor flange 40 and the straight pipe portion 17B. A tapered surface is provided on the inner periphery of the straight pipe portion 17B.

  The maximum load was measured for samples 1 to 6 in which the length of each model (saddle steel pipe length) was changed as shown in FIG. Model A saddle steel pipe length is 500mm (sample 1), 1000mm (sample 2), 1500mm (sample 3), model B saddle steel pipe length is 1000mm (sample 4), 1500mm (sample 5), model C saddle steel pipe length Was 2040 mm (sample 6). Samples 5 and 6 were tested twice.

In order to measure the maximum loads of the models A and B, an apparatus as shown in FIG. 5 was produced. FIG. 5 shows a case where a model B test structure 22 is used. In this apparatus, the test structure 22 is fixed on one side of the opposing surface of the concrete block 21, and the cable 20 extending from the test structure 22 is tensioned on the other side. Specifically, the test structure 22 is abutted against the one surface where the steel pipe 15 embedded in the concrete block 21 is opened via the support plate 62, and the jack 80 is interposed via the support plate 63 on the other surface. I stopped it. The jack 80 can grip and tension the cable 20 extending from the test structure 22 and inserted through the steel pipe 15. At this time, since the steel pipe 15 is not filled with grout, no adhesive force acts between the steel pipe 15 and the cable 20. In the models A and B, the compressive strength of the concrete was 30.8 N / mm ² and the compressive strength of the grout was 59.3 N / mm ² .

  When the tension introduced into the cable 20 of the model A test structure 22 is increased with the apparatus shown in FIG. 5, the saddle steel pipe 17 is pulled out from the concrete 21A, and the unitary cable 20 and grout 30A is pulled from the saddle steel pipe 17. I missed it. On the other hand, when the tension introduced into the cable 20 of the test structure 22 of the model B was increased, the saddle steel pipe 17 did not pull out from the concrete 21A, but the integrated body of the cable 20 and the grout 30A was removed from the saddle steel pipe 17. Pulled out. The output of the jack 80 at this time is shown in FIG. 7 as the maximum load.

In order to measure the maximum load of model C, an apparatus as shown in FIG. 6 was produced. In this apparatus, in addition to the apparatus shown in FIG. 5, a ram chair 85 is arranged between the concrete block 21 and the test structure 23 (model C) so that the end of the test structure 23 can be observed. did. In Model C, the compressive strength of concrete was 30.5 N / mm ² and the compressive strength of grout was 64.1 N / mm ² .

  When the tension introduced into the cable 20 of the test structure 23 of the model C is increased with the apparatus of FIG. 6, the saddle steel pipe 17 is pulled out from the concrete 21A, or the integrated body of the cable 20 and the grout 30A is removed from the saddle steel pipe 17. Although it was not pulled out, cracks occurred in the concrete 21A. The output of the jack 80 at this time is shown in FIG. 7 as the maximum load.

  8 is a graph showing the relationship between the total length of the saddle steel pipe and the maximum load based on the result of the maximum load shown in FIG. As shown in the graph of FIG. 8, the maximum load increased in proportion to the total length of the steel pipe.

  From the results of Test Example 1 (see FIG. 8), the maximum load increased as the length of the saddle steel pipe increased. Further, as is clear from the comparison of the square mark (model A) and the triangle mark (model B) in the graph of FIG. 8, even if the length of the saddle steel pipe is the same, the anchor flange is attached to the outer peripheral surface of the saddle steel pipe curved pipe. By providing the maximum load increased. Further, when the straight pipe portion was provided at the end of the curved pipe portion (model C), the maximum load was further increased by fitting the tapered surface provided on the inner peripheral surface of the straight pipe portion with the tapered portion of the grout. The increase in maximum load means that the saddle structure can withstand larger tension differences.

  Here, since the length of the saddle steel pipe of the test structure used in Test Example 1 is shorter than the saddle steel pipe of the embodiment, the maximum load is further increased in the actual saddle structure. For example, when the maximum load when the length of the saddle steel pipe of the embodiment (3426 mm) is extended by extending the straight line connecting the plots of model A (obtained by the least square method), it corresponds to level 2 earthquake motion It was almost the same as the tension difference (3094kN) at the time of the earthquake. Similarly to model A, when the maximum load when the steel pipe length was 3426 mm was examined from the broken line connecting the plots of model B (calculated by the least squares method), the tension difference at the time of the earthquake was greatly exceeded. From these facts, when there is no anchor flange on the outer peripheral surface of the steel pipe as in the model A, there is almost no margin from the tension difference at the time of the earthquake, so the saddle structure may be damaged. On the other hand, since Model B has a high tolerance, there is little possibility of damage to the saddle structure during an earthquake. Furthermore, in model C, the saddle steel pipe length greatly exceeded the earthquake tension difference at 2040 mm.

<Test Example 2>
In Test Example 2, a simulated structure having a full-size saddle structure was produced, and strain at each part of the saddle structure was measured. By this test, the soundness of the bridge having the saddle structure of the present invention is evaluated.

  A simulated structure of Test Example 2 is shown in FIG. The simulated structure 3 has a structure in which the saddle structure 1 is embedded in an ark type concrete casing 4 and the cables 20 extending from both ends of the saddle structure 1 can be tensioned by jacks 88 and 89. Here, the left side in FIG. 9 is the north, the right side is the south, the east toward the back of the drawing, and the west toward the front.

  The concrete casing 4 is composed of a casing upper part 4A and a casing lower part 4B, and the saddle structure 1 is embedded in the casing upper part 4A. On the other hand, the housing lower part 4B is provided with conduits 18 and 19 from the upper surface to the side surface of the housing lower part 4B, and the north cable 28 and the south cable extending from both ends of the saddle structure 1 (saddle steel pipe) to the north and south are extended. Each 29 can be inserted. When configuring the simulated structure, the cables 28 and 29 extending from both ends of the saddle steel pipe were inserted from the upper surface of the housing lower part 4B toward the side surfaces and held by the jacks 88 and 89. The jacks 88 and 89 are fixed to the side surface of the lower part 4B of the housing via the support plates 68 and 69 so that the cables 28 and 29 can be tensioned separately. Here, a spiral streak 73 is disposed in the vicinity of the side wall of the housing lower part 4B so that the housing lower part 4B is not damaged.

  Since the saddle structure 1 used in this test is the same as that described in the embodiment except that a plurality of strain gauges are attached along the longitudinal direction of the saddle steel pipe, only the arrangement of the strain gauges is described here. To do.

  FIG. 10 is an explanatory view showing the arrangement of strain gauges. Thirty-one strain gauges 90 are arranged in the longitudinal direction along the upper side in the downward triangular position in the figure, that is, in the saddle steel pipe 10 of the saddle structure 1. In addition, 31 strain gauges 90 were installed under the saddle steel pipe 10 of the saddle structure 1 (upward triangle in the figure). The strain gauges 90 are arranged at approximately equal intervals, but in particular, the strain gauges 90 positioned on the left and right of the support plate 60 and the anchor flange 40 are arranged so as to be close to both (40, 60). Further, although not shown in FIG. 10, strain gauges 90 are arranged in the longitudinal direction of the saddle steel pipe 10 on the west side and the east side of the saddle steel pipe 10.

  In this test example, the north jack 88 and the south jack 89 were operated in accordance with the load step shown in FIG. 11 (see FIG. 9), so that a tension difference was generated between the north and south (left and right) cables 28 and 29. The load step was performed in the order of step 1 to step 4, and the strain at each step was measured. The horizontal axis in FIG. 11 represents the elapsed time from the start of the test, and the vertical axis represents the load of the jacks 88 and 89 (tensile force introduced into the cable by the jack). In starting the test, a predetermined tension (0.334 Pu = about 2350 kN) was applied in advance to the cable 20 of the simulated structure 3. At this time, the tension force introduced into the cable 20 by the north jack 88 and the south jack 89 is the same, and there is no tension difference between the left and right (north-south) cables 28 and 29.

(Step 1)
In step 1, the load on the left jack (north jack 88) in FIG. 9 is loosened to create a tension difference between the left and right cables 28, 29, that is, the cable 20 is pulled to the right (south side). The tension difference generated at this time was set to 272.0 kN which is the design tension difference in the saddle structure 1 of the embodiment. After a certain period of time, the load on the north jack 88 was returned to 0.334 Pu so that there was no tension difference between the left and right cables 28 and 29. This operation was repeated 10 times.

(Step 2)
In Step 2 following Step 1, the load on the north jack 88 is gradually reduced to create a tension difference between the left and right cables 28 and 29. The tension difference generated at this time was 816.0 kN obtained by multiplying the design force difference by the safety factor 3. After a certain period of time, the load on the north jack 88 was returned to 0.334 Pu so that there was no tension difference between the left and right cables 28 and 29. This operation was repeated three times.

(Step 3)
In step 3, first, the load on the north jack 88 is loosened to a predetermined load of 500 kN or less, and then the load on the south jack 89 is increased stepwise to create a tension difference between the left and right cables 28 and 29. It was. The tension difference generated at this time was 3094.0 kN assuming level 2 earthquake motion. After a certain period of time, the load on the south jack 89 was returned to 0.334 Pu while the load on the north jack 88 remained unchanged. This operation was repeated three times.

(Step 4)
In step 4, the load on the north jack 88 remains at the end of step 3, and the load on the south jack 89 is increased stepwise to create a tension difference between the left and right cables 28 and 29. The tension difference generated at this time is 0.9 times (4819 kN) of fpy (load with respect to 0.2% permanent elongation) of the cable 20 and corresponds to the allowable tension load of the cable. After a certain period of time, the load on the south jack 89 was loosened until it became the same as the load on the north jack 88, and the test was terminated. Note that it is unlikely that the tension difference corresponding to Step 4 will act on the cable due to the earthquake.

  The results of strain of the saddle steel pipe measured at each step are shown in FIGS. 12 to 15, the horizontal axis indicates the position in the longitudinal direction of the saddle steel pipe, that is, the installation position of the saddle structure strain gauge, and the vertical axis indicates the strain value of the steel pipe measured by the strain gauge. That is, these figures show the strain distribution in the saddle steel pipe. The solid line on the left side parallel to the vertical axis in the figure indicates the exit position of the north side steel pipe, and the broken line indicates the position of the north side flange. Moreover, the solid line on the right side parallel to the vertical axis in the figure indicates the exit position of the south side steel pipe, and the broken line indicates the position of the south side flange. 12 shows the strain distribution on the upper side of the steel pipe, FIG. 13 shows the strain distribution on the lower side of the steel pipe, FIG. 14 shows the strain distribution on the east side of the steel pipe, and FIG. 15 shows the strain distribution on the west side of the steel pipe.

  When the cable is tensioned to the south side as shown in FIGS. 12 to 15, the strain is positive on the south side of the steel pipe and negative on the north side of the steel pipe. On the other hand, if the cable is tensioned to the north side, it will have a positive strain on the north side of the steel pipe and a negative strain on the south side of the steel pipe. According to the saddle structure of the present embodiment, the strain is distributed in the longitudinal direction of the steel pipe, and even if a tension difference (step 3) corresponding to level 2 seismic motion is applied to the cable, the strain value is The yield strain of the steel pipe (broken line parallel to the horizontal axis in the figure) was not exceeded over the entire length. Further, when a tension difference of 0.9 fpy was applied to the cable, the yield strain of the steel pipe was not exceeded over the entire length of the steel pipe except for the lower side of the steel pipe (see FIG. 13). From these facts, it was found that the soundness of the bridge using the saddle structure of the present invention is maintained not only within the range of the design tension difference but also when an earthquake corresponding to level 2 earthquake motion occurs.

  Furthermore, it became clear from the results of FIGS. 12 to 15 that the strain acting on the steel pipe with the anchor flange as a boundary is greatly relieved. That is, it has been clarified that the anchor flange greatly reduces the stress acting on the saddle steel pipe due to the difference in tension acting on the left and right cables. In particular, when two anchor flanges are provided on the outer peripheral surface of the saddle steel pipe as in the saddle structure of this test, the stress acting on the saddle steel pipe located between the two anchor flanges may be very small. all right. That is, even when a difference in tension occurs between the left and right cables, stress is unlikely to act on the center of the main tower, so the possibility that the main tower center that substantially supports the main tower will be damaged is very low. It is expected that. Therefore, the soundness of the bridge using the saddle structure of the present invention was proved.

  The present invention can be suitably used for a bridge provided on a main road or a railway track. In particular, it can be suitably used for a Shinkansen bridge.

It is a figure which shows embodiment of the saddle structure of this invention, (A) is a schematic block diagram of the whole saddle structure, (B) is a partial schematic diagram of a saddle structure. It is the elements on larger scale of embodiment, (A) is a front view, (B) is sectional drawing. 2 is a schematic explanatory diagram of a test specimen model used in Test Example 1. FIG. It is a detailed explanatory view of a specimen model. It is a figure which shows the test structure of model A and model B. FIG. 3 is a diagram showing a model C test structure. It is a figure which shows the result of Test Example 1. 6 is a graph showing the results of Test Example 1. 6 is a schematic view of a simulated structure used in Test Example 2. FIG. 6 is a diagram illustrating an arrangement of strain gauges provided in the simulated structure of Test Example 2. FIG. It is a figure which shows the load step of Test Example 2. It is a figure which shows the strain distribution in the upper part of a steel pipe. It is a figure which shows the strain distribution in the lower part of a steel pipe. It is a figure which shows the strain distribution in the east side of a steel pipe. It is a figure which shows the strain distribution in the west side of a steel pipe. It is a figure which shows the conventional saddle structure which has a double pipe structure, (A) is a schematic block diagram of the whole saddle structure, (B) is AA 'sectional drawing of (A), (C) is a saddle. It is an enlarged view of the exit part of a structure. It is explanatory drawing which shows the action state of the tension | tensile_strength in the conventional saddle structure which has a double pipe structure.

Explanation of symbols

1 Saddle structure 2 Main tower 21 Concrete block
22,23 Test structure 21A Concrete
3 Simulated structure
4 Concrete housing 4A Upper housing 4B Lower housing
10 Saddle steel pipe 11 Curved steel pipe 12 Straight tubular steel pipe 15 Steel pipe 18,19 Conduit
17 Saddle steel pipe 17A Curved pipe part 17B Straight pipe part
20 Cable 28 North cable 29 South cable
30,30A Grout 31 Grout injection hose 32 Grout discharge hose
35 Water stop structure 38 Protective pipe
40 Anchor flange 50 Stiffener
60,62,63,68,69 Support plate 71,72,73 Spiral muscle
80 Jack 85 Ram chair 88 North jack 89 South jack
90 Strain gauge
100 saddle structure 200 main tower
110 Inner pipe 115 Inner pipe straight pipe section 120 Outer pipe 130 Tensile material 140 Grout
150 Spacer 160 Grout hose 170 Spiral muscle
180 Ring nut 181 Bearing plate 190 Water stop structure

Claims (9)

A saddle structure for a bridge in which a tension material is disposed through a curved pipe arranged to penetrate the main tower of the bridge, and grout is filled between the curved pipe and the tension material.
The curved tube is a single tube fixed in the main tower,
The least the outer periphery of the middle The inter also of the bending tube, provided so as to extend radially outward of the bending tube, and an outer peripheral projection of improving the adhesion between the bending tube and the main column,
A reinforcing member that supports the outer peripheral protrusion in the longitudinal direction of the bending tube,
The bridge saddle structure , wherein the reinforcing member has a through-hole penetrating in a direction shifted from a longitudinal direction of the bending tube .   The bridge saddle structure according to claim 1, wherein 1 to 5 of the outer peripheral projections are provided on the curved pipe at a predetermined interval.   The saddle structure for a bridge according to claim 1 or 2, wherein the outer peripheral protrusion has a flange shape. The bridge saddle structure according to any one of claims 1 to 3 , wherein the outer peripheral protrusion is an annular member, and the annular member is fixed to the outer periphery of the bending tube by welding or screwing. The reinforcing member is a plate material having a substantially right triangle shape, and one side sandwiching the right angle is fixed to the outer peripheral surface of the bending tube, and the other side is fixed to the outer peripheral projection. Or the saddle structure for bridges of 4. The bridge saddle structure according to claim 5, wherein a plurality of the reinforcing members are provided at equal intervals in the circumferential direction of the bending tube.   The saddle structure for a bridge according to any one of claims 1 to 6, further comprising a supporting member that is disposed at both ends of the bending tube and transmits a tension force of the tension material to the main tower.   The saddle structure for a bridge according to any one of claims 1 to 7, wherein reinforcing bars are arranged on an outer periphery of the bending pipe.   The saddle structure for a bridge according to any one of claims 1 to 8, wherein a preliminary hole is provided so that a new tendon can be arranged in the main tower.

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