JP3844861B2 - Cable reinforcement structure of structure - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lower structure such as a bridge pier and an upper structure such as a bridge girder that is installed on the lower structure, and a cable that is attached to the lower surface side of the upper structure so as to extend in the longitudinal direction and to which tension is introduced. In particular, a cable reinforcing structure that enhances load bearing performance for a structure including a tension member having a tension member, and more particularly, an internal compressive force that causes the upper structure to warp upward is generated, and a concentration that occurs in a fixing region based on the compressive force is generated. The present invention relates to a cable reinforcing structure for a structure capable of improving durability against a design load while smoothly distributing stress and reducing a reinforcing member in the fixing region.
[0002]
[Prior art]
A typical prior art of this type of conventional construction is illustrated in FIG. The structure 1 shown in this figure is an elevated road, and a plurality of lower structures 2 realized by bridge piers standing on the ground 18 at intervals, and simply on the lower structures 2. It is known that the upper structure 3 is composed of a plurality of upper structures 3 realized by bridge girders that are divided and supported horizontally. The upper structure 3 is known to be deflected and displaced by a horizontal / vertical external force that is a design load. As shown in FIG. 10, the design load may increase due to a change such as a range that is limited to a 25-ton vehicle, for example, when the 20-ton vehicle is the limit during the service period. The structure 3 may be deteriorated or damaged, and as a result, the design load may exceed the allowable yield strength of the upper structure 3.
[0003]
In this way, if it is attempted to actually cope with the increased design load, the superstructure 3 may be replaced with a new one corresponding to this increase. However, this increases the cost for improvement. Since there is a problem, as shown in the drawing on the left side in FIG. 11, in order to improve the durability of the current upper structure 3, the tensile material 4 is disposed on the damage reinforcing member of the upper structure 3. Thus, an improved construction method has been adopted in which an internal compressive force that causes the upper structure 3 to warp upward is generated to reduce the flexural displacement.
[0004]
[Problems to be solved by the invention]
However, when such a tension member 4 is disposed, referring to FIGS. 11 to 13, the fixing bracket region S (FIG. 11) which is an area adjacent to the front and rear of the fixing bracket 8 in the upper structure 3. (See FIG. 12), the stress flow A (see FIG. 12 (a)) caused by the introduction of the cable tension changes suddenly in the vertical direction between the girder member of the upper structure 3 and the fixing bracket 8. Since a high stress concentrates on the fixing portion of the girder member and the front and rear end portions of the fixing bracket 8, a new reinforcing structure is required. Conventionally, a plurality of bolts are welded and fixed as shown in FIG. Several reinforcing plates 20 are attached to the girder member. Therefore, there are problems of increasing time and man-hours for attaching the reinforcing plates 20 and increasing the weight of the upper structure 3.
[0005]
Further, as shown in FIG. 12 (b), the shaft plate shown with the oblique cross section of the fixing bracket 8 and the shaft plate shown with the oblique cross section of the girder member are misaligned due to the surface being shifted. Therefore, the stress flow B (see FIG. 12B) suddenly changes in the left-right width direction, and a reinforcing structure corresponding to this is required. As a result of the necessity for further increase, specifically, with reference to FIG. 13, in order to prevent distortion, buckling and the like from occurring, the reinforcing plate 20 is attached in a square shape, which reduces the reinforcing cost. The increase and the weight increase of the upper structure 3 were more problematic.
[0006]
On the other hand, referring to FIGS. 14 and 15, the tensile material 4 attached to the lower surface side of the upper structure 3 has a distance between the longitudinal line connecting the centers of gravity of the upper structure 3, that is, an eccentric distance, Although it was e ₀ before the bending deformation, when the design load W is applied, the eccentric distance becomes e ₁ (<e ₀ ) due to the bending deformation of the upper structure 3, and as a result, the upper structure 3 There was also a problem that the bending durability was reduced.
[0007]
The present invention has been made to solve such conventional problems, and therefore the object of the present invention is to reduce the weight of the fixing member including the omission of an additional reinforcing member, particularly in connection with a tension member. In addition, it is possible to establish a structure that can establish and improve the bending durability of the upper structure at a low cost by making the eccentric distance of the tensile material constant even when the upper structure is deformed. It is to provide a cable reinforcement structure.
[0008]
[Means for Solving the Problems]
The present invention has the following configuration in order to achieve the above object. That is, regarding the invention of claim 1 in the present invention, the lower structure that is erected, the upper structure that is laid horizontally on the lower structure, and the lower surface side of the upper structure in the longitudinal direction via the fixing bracket. In a structure including a tension member provided with a cable that is extended and provided with tension, the fixing bracket includes a steel plate mounting substrate, a steel pipe cylinder, and a steel plate shaft. Is attached to the lower surface of the upper structure in such a manner that the shaft plate is aligned with the vertical surface including the shaft plate of the girder member of the upper structure , and both front and rear ends of the fixing bracket that supports both ends of the cable. A buffer portion for integrally transferring stress generated by introducing tension to the cable between the girder member of the upper structure and the shaft plate of the fixing bracket is provided integrally with the cable portion. It is characterized by It is a cable reinforcing structure of Tsukibutsu.
[0010]
The invention according to claim 2 of the present invention relates to the metal according to claim 1 , wherein the buffer portion is provided integrally with the shaft plate so as to match a vertical surface including the shaft plate of the fixing bracket. It is formed of a plate, and is formed in an unequal side trapezoidal shape having a boundary portion with the shaft plate as a bottom side and a side edge portion to be brought into contact with the lower surface portion of the girder member of the upper structure as an orthogonal side. .
[0011]
According to a third aspect of the present invention, there is provided the invention according to the first or second aspect , wherein the tension member is provided for supporting the intermediate portion of the cable at an intermediate position between the fixing brackets. An intermediate support fitting attached to the lower surface is provided, and the cable supported by the intermediate support fitting is formed so as to be able to secure the eccentric distance in the vertical direction with respect to the center of gravity of the girder of the superstructure at a required value. .
[0012]
According to the present invention, the tension material is provided to generate the internal compressive force that warps the upper structure upward, so that the bending durability of the upper structure is improved and the damage reinforcement and displacement are improved. It works effectively for reduction.
[0013]
According to the first aspect of the present invention, the buffer member is provided in the fixing member of the tensile material, so that the concentrated external force in the fixing member region related to the tensile material is smoothly dispersed through the buffer member. Stress can be relaxed. In addition, by aligning the shaft plate of the fixing bracket and the shaft plate of the upper structure with a common vertical plane, the concentrated external force flows smoothly between the girder member of the upper structure and the shaft plate of the fixing bracket. Thus, the concentrated stress in the fixing bracket region is further relaxed.
[0015]
The invention according to claim 2 is effective by simple means of adding a buffer portion having a simple structure based on a fixing bracket having a simple structure, since the buffer portion is formed of a substantially uneven trapezoidal metal plate. Therefore, it is possible to perform improvement work quickly in a short period of time while maintaining the light weight of the superstructure.
[0016]
According to the third aspect of the present invention, even if the upper structure is bent and deformed by the load, the intermediate support metal keeps the eccentric distance constant, so that the bending durability is always ensured stably.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings. 1, 2, and 3 show a schematic structure of a fixing bracket mounting portion, a cable structure, and a fixing bracket structure in a structure according to an embodiment of the present invention.
[0018]
Referring to FIG. 1, a plurality of substructures 2 realized by respective piers provided upright on a ground (not shown) at appropriate intervals, and horizontally arranged on them in series In the elevated road 1 as a structure composed of a plurality of superstructures 3 realized by each bridge girder, a tension member 4 is attached to the bridge girder 3 as a damage reinforcing member for improving the durability performance. The tension member 4 includes a fixing bracket 8 fixed to the bottom surface of the bridge girder near the portion supported by the bridge pier 2 at both ends in the longitudinal direction of the bridge girder 3, and both ends supported by both fixing brackets 8 so that the bridge girder 3 is supported. The element member is provided with a cable 5 extending in the longitudinal direction on the lower surface side of the cable.
[0019]
The cable 5 has a structure in which caps 6 are fixed and integrated at both ends of a bundle of wires formed by converging a plurality of strands of PC steel, for example, and a cable having a large tensile load is formed. Usually, it has a structure similar to a cable used as a PC (Prestressed Concrete) tendon. The cap 6 is screwed on the outer periphery, and the anchor head 7 is screwed onto the screw.
[0020]
The fixing bracket 8 is integrally fixed by welding or the like in the direction perpendicular to the longitudinal center line of the steel plate, which is a rectangular steel plate as a mounting seat, and protrudes in a T shape. Also, a shaft plate 9 made of a steel plate, a tubular body 11 made of a steel pipe which is in contact with an end edge of the shaft plate 9 opposite to the mounting substrate 10 and fixed integrally by welding, the shaft plate 9 and the tube Formed by an end plate 12 fixed to one end portion on the same side of the body 11, and a buffer portion 13 made of a steel plate, which will be described in detail later, and is integrally extended to both end portions on the long side of the shaft plate 9 Is done.
[0021]
As described above, the fixing bracket 8 is fixed to the lower surface side of the bridge girder 3 at both ends in the longitudinal direction, but the caps 6 at both ends of the cable 5 are inserted into the cylindrical body 11 as shown in FIG. When the anchor head 7 is screwed into the cap 6 and tightened, the cable 5 extends in the longitudinal direction on the lower surface side of the bridge girder 3 and is tensioned by applying tension. In this case, it is possible to slightly warp the bridge girder 3 evenly over the entire width by arranging a plurality of cables 5 in parallel at appropriate intervals in the width direction of the bridge girder and stretching them under tension. Thus, by introducing tension into each cable 5 in this way, an internal compressive force is generated in the bridge girder 3, and a bridge girder can be configured to reduce the bending deformation of the own weight or live load with respect to the vertical external force.
[0022]
The buffer portion 13 provided integrally with the fixing bracket 8 is an element member that characterizes the present invention. As is apparent with reference to FIGS. 1 and 3, the shaft plate is disposed at both longitudinal ends of the fixing bracket 8. 9 is connected to 9 and extended to the front and rear. The buffer portion 13 is preferably formed integrally with the same steel plate when the shaft plate 9 is formed. That is, the buffer portion 13 conforms to a vertical surface including the shaft plate 9 and extends in an ear shape in the front-rear direction. In the state where the fixing bracket 8 is attached to the lower surface side of the bridge girder 3 by fixing means such as bolting, the buffer portion 13 is arranged to abut against the shaft plate 9 and the lower surface of the bridge girder 3 and hang down. It will be arranged in a form just like the brace brace. In addition, as a specific form of the buffer portion 13, a substantially unequal trapezoidal shape in which a boundary portion with the shaft plate 9 is a bottom side and an edge portion to be brought into contact with the lower surface of the bridge girder 3 is an orthogonal side to the bottom side. Is made.
[0023]
Next, the operation of the above embodiment according to the present invention will be described with reference to FIG. First, when the fixing bracket 8 is attached to the bridge girder 3, the shaft plate 9 is provided so as to be aligned with the vertical plane including the shaft plate 19 of the bridge girder 3 as shown in FIG. When the fixing bracket 8 is attached in this way and a predetermined tension is applied to the cable 5 supported by the fixing bracket 8, an internal compressive force that slightly warps the bridge girder 3 upwards acts on the bridge girder 3 in the vertical direction of its own weight and live load. A bridge girder is formed to reduce the bending deformation with respect to the external force. As described above, stress is generated in the fixing bracket region S of the bridge girder 3 as the tension is introduced. This stress flows in the shaft plate 19 in parallel with the tension direction of the cable 5, then turns and flows in the shaft plate 9 of the fixing bracket 8, and then in the shaft plate 9 in parallel with the tension direction of the cable 5. It flows and turns around again to flow into the shaft 19.
[0024]
In the embodiment of the present invention, the buffer portion 13 is disposed across the bridge girder 3 and the end portion of the fixing bracket 8 with respect to the dynamic state of the stress flow. The stress flowing parallel to the direction flows into the shaft plate 9 with a smooth vector change with a small change angle through the bracing buffer portion 13 without turning downward at a steep angle, and in the shaft plate 9 The stress flowing parallel to the tension direction of the cable 5 also flows through the bracing section 13 with a smooth vector change with a small change angle and turns into the shaft 19 (see C in FIG. 1). As a result, the stress concentration in the fixing bracket region S is buffered, so that local distortion and buckling can be prevented from occurring in the shaft plate 19, and an additional reinforcing member is unnecessary or minimal. . In addition, with reference to FIG. 1, it is preferable that the angle (theta) which the hypotenuse part and bridge girder 3 attachment surface in the said buffer part 13 which comprises a substantially unequal side trapezoid form is an acute angle of 45 degrees or less, and as optimal conditions It is around 30 °.
[0025]
Further, in this embodiment, since the shaft plate 19 of the bridge girder 3 and the shaft plate 9 of the fixing bracket 8 are arranged so as to coincide with the same vertical plane, the stress flow D (see FIG. 1 (B)) is one. A smooth vector change in a two-dimensional plane with a small change angle causes a transition from the shaft plate 19 to the shaft plate 9 and the shaft plate 9 to the shaft plate 19, and thus stress concentration in the fixing bracket region S. Is further buffered, and an additional reinforcing member is almost unnecessary.
[0026]
Next, another embodiment of the present invention will be described with reference to FIG. The tension member 4 according to this embodiment is provided with intermediate support fittings 14 in addition to the fixing fittings 8 attached to both ends of the bridge girder 3 in the longitudinal direction. The intermediate support metal fitting 14 is located in the middle between the fixing metal fittings 8, preferably at an equally divided center, and is attached to the lower surface of the bridge girder 3 so as to support the intermediate portion of the cable 5. The intermediate support bracket 14 is understood as described above with reference to FIG. 15, but when the bridge girder 3 is bent downward due to the design load W, the cable 5 and the bridge girder that are tensioned between the fixing brackets 8. 3 is provided to cope with the problem that the distance from the lower surface of 3 is significantly narrowed at the center portion of the bridge girder 3 and as a result, the action of the internal compressive force is reduced and the bending durability performance is lowered.
[0027]
7 and 8 show the structure of the intermediate support bracket 14 according to each embodiment of the present invention. The intermediate support bracket 14 is integrally formed with a thick steel plate 15 and a shaft 15 that is orthogonal to the shaft 15. Are formed by a thick steel plate rib plate 16 and a steel support portion 17 integrally provided in contact with the lower end edge of the shaft plate 15, and an intermediate portion of the cable 5 is supported by the support portion 17. It is supposed to be. In the example shown in FIG. 7, the support portion 17 is formed in a saddle shape having a cable receiving portion having a gently curved semicircular groove shape, and the bending angle with respect to the supporting cable 5 is about 10 °, for example. The effective height of the support bracket is set so that the support portion 17 is made of a steel pipe and the cable 5 is inserted into the pipe. The effective height of the support bracket is set so that the bending angle with respect to the angle is about 0.5 °.
[0028]
In the embodiment configured as described above, even if the design load W acts on the bridge girder 3 and bends downward as shown in FIG. 4, the intermediate support fitting 14 attached to the intermediate part of the bridge girder 3 It is possible to keep the eccentric distance e ₂ between the longitudinal center of gravity line L connecting the center of gravity of the bridge girder 3 and the cable 5 constant at a constant e ₂ = e ₀ . The bending durability performance can be stably maintained regardless of the bending.
[0029]
【Example】
Embodiments of the present invention will be described below with reference to the accompanying drawings. 5 and 6 show a construction of another embodiment according to the present invention in an elevation view and a sectional view. With reference to both figures, the bridge girder 3 as the superstructure has a bridge length of 35 m and a total width of 9 m. Based on the fact that the conventional design load of 20 ton vehicles was the limit, but it was newly increased to 25 ton vehicles, the bridge girder 3 has a tension member 4 introduced with a design tension of 100 ton below the girder in the width direction. It is stretched in a row. With the introduction of the tension member 4, the girder is pushed up from below to bend and reinforce in terms of durability. In this case, the effective height of the intermediate support bracket 14 is selected to an appropriate value, and the cable support angle in the fixing bracket 8 is appropriately set in accordance with this, thereby allowing the cable 5 to be at an arbitrary angle and direction with respect to the bridge girder 3. In addition, the cable 5 can be prevented from being excessively bent.
[0030]
The cable 5 has a safety factor ν = 3, a tensile load Pu = 322 tf, and a yield load 276 tf. The configuration of the cable 5 is seven bundles of 19.3 mm strands of PC steel. A cross-sectional area, in 1706Mm ^2, unit weight is at 15.8 kg / m, an elastic modulus is 19000kg / mm ^2. This cable 5 is covered with a polyethylene resin having a thickness of 5 mm, and a grease-based anticorrosive material is sealed inside. Further, as the caps 6 at both ends of the cable, crimp grips are attached.
[0031]
On the other hand, the fixing bracket 8 is formed of a general structural rolled steel plate having a thickness of 28 mm and a 190 mm steel pipe made of the material SS400, and a buffer portion 13 having a horizontal length of 190 mm is provided at an end thereof. Further, the shaft plate 9 of the fixing bracket 8 is attached to the central portion so as to coincide with the shaft plate of the bridge girder 3 on a common surface.
[0032]
By providing the reinforcing structure as described above, the weight of the reinforcing plate can be reduced with respect to an increase in the design load of 5 tons, and sufficient bending durability performance can be secured. That is, in the case of the present embodiment, it is only necessary to use four vertical reinforcing members having a mounting size of 1300 mm × 200 mm × 12 mm, and the weight increment is 100 kg, whereas in the conventional example shown in FIG. 6 and 10 reinforcements with a mounting size of 1300mm x 200mm x 12mm are required, as well as 4 reinforcements of 1200mm x 300mm x 12mm (weight increment 300kg). As is clear from the comparison between the two, this book In the embodiment, it is shown that there is an advantage that the reinforcing member is reduced to 0.5 in the mounting dimension and reduced in weight to 0.3.
[0033]
【The invention's effect】
The present invention is implemented in the form as described above, and has the following effects. That is, since the concentrated stress in the fixing bracket region of the tensile material is dispersed and relaxed by the buffer portion, there is an effect that the newly provided relief member for relaxation can be reduced. Furthermore, the concentrated stress of the fixing bracket is transmitted on the axis of the shaft plate by providing the shaft plate of the fixing bracket so as to coincide with the vertical plane in which the shaft plate of the girder member of the superstructure is included. Therefore, the reinforcing member for relaxation can be further reduced. In addition, by providing an intermediate support bracket, the eccentric distance from the center of gravity of the girder member can be kept constant at all times without being affected by the bending of the girder member due to the design load. Thus, the effect of stably securing the load resistance resistance of the upper structure can be obtained.
[Brief description of the drawings]
FIG. 1 shows a schematic structure of a fixing bracket mounting portion of a structure according to an embodiment of the present invention, where (A) is an elevation view and (B) is a side view.
FIG. 2 is a plan view of a cable used in the embodiment of the present invention.
3 is a structural diagram of the fixing bracket according to the embodiment shown in FIG. 1. FIG. 3A is a front view, FIG. 3B is a left side view, and FIG. 3C is a right side view.
FIG. 4 is an elevation view of a structure according to an embodiment of the present invention in a bent state.
FIG. 5 is an elevational view of a construct according to another embodiment of the present invention.
6 is a cross-sectional view of the structure shown in FIG. 5 along the line EE.
7 is a structural diagram of an intermediate support metal fitting according to the embodiment shown in FIG. 4, in which (a) is a front view and (b) is a right side view.
FIGS. 8A and 8B are structural views of an intermediate support metal fitting according to another embodiment of the present invention, where FIG. 8A is a front view and FIG. 8B is a right side view.
FIG. 9 is a schematic elevation view of an elevated road.
FIG. 10 is an explanatory diagram of a bending phenomenon of an elevated road.
FIG. 11 is an elevation view of a superstructure on a conventional elevated road.
FIGS. 12A and 12B show a schematic structure of a fixing bracket mounting portion in a conventional structure, where FIG. 12A is an elevation view and FIG. 12B is a side view.
13 is an elevational view showing a mounting mode of a reinforcing member used in the superstructure shown in FIG. 11. FIG.
FIG. 14 is an elevational view of the conventional superstructure on an elevated road when no load is applied.
FIG. 15 is an elevational view of a conventional elevated road when a superstructure is loaded.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Structure 2 ... Lower structure 3 ... Upper structure 4 ... Tensile material 5 ... Cable 6 ... Cap 7 ... Anchor head 8 ... Fixing bracket 9 ... Shaft plate 10 ... Mounting board 11 ... Cylindrical body 12 ... End plate 13 ... Buffer Part 14: Intermediate support bracket 15 ... Shaft plate 16 ... Rib plate 17 ... Support part 18 ... Ground 19 ... Shaft plate 20 ... Reinforcement plate

Claims (3)

A lower structure that is erected, an upper structure that is laid horizontally on the lower structure, and a cable that is attached to the lower surface side of the upper structure, extending in the longitudinal direction via a fixing bracket, and in which tension is introduced. The fixing bracket includes a steel plate mounting substrate, a steel pipe cylinder, and a steel plate shaft, and the fixing bracket is used as a girder member of the upper structure. Stress caused by introduction of tension to the cable at the front and rear ends of the fixing bracket attached to the lower surface of the upper structure in an arrangement matching the vertical plane including the shaft plate and supporting both ends of the cable A structure for reinforcing a cable of a structure, wherein a buffer portion is provided integrally so as to be able to be transferred with a smooth vector change between a girder member of an upper structure and a shaft plate of a fixing bracket. The buffer portion is made of a metal plate integrally provided on the shaft plate so as to match a vertical plane including the shaft plate of the fixing bracket, and a boundary portion with the shaft plate is a bottom, and the upper structure The cable reinforcement structure for a structure according to claim 1, wherein the structure is formed in an unequal side trapezoidal shape in which a side edge abutted on a lower surface of the girder member is an orthogonal side. The tension member includes an intermediate support bracket that is attached to the lower surface of the upper structure to support an intermediate portion of the cable at an intermediate position between the fixing brackets, and the cable supported by the intermediate support bracket has an upper structure. The cable reinforcement structure for a structure according to claim 1 or 2 , wherein the structure is formed so as to ensure an eccentric distance in a vertical direction with respect to a center of gravity of an object girder at a required value.

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