JP3549183B2 - Underpass structure of viaduct - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a viaduct, and more particularly to a substructure of a railway RC viaduct.
[0002]
[Prior art]
Bridges such as roads and railways include so-called viaducts that are continuously constructed in urban areas, in addition to narrow bridges that cross rivers and straits. Such viaducts are often constructed continuously in a space on roads, railroads or rivers from the viewpoint of efficient land use. However, due to costs and the like, the conventional substructure of the viaduct is RC In most cases, a ramen structure was adopted.
[0003]
However, especially in railway viaducts, the weight of the superstructure tends to be large in general. Therefore, in the event of a large earthquake, the horizontal force acting from the superstructure must be supported only by the columnar piers of the RC rigid frame structure. There were many constraints on earthquake resistance, such as the need for foundation beams connecting the bases of piers.
[0004]
[Problems to be solved by the invention]
In view of this, the present applicant disposes an inverted V-shaped brace material in the plane of the RC frame structure, and provides an energy absorbing damper between the vicinity of the top of the brace material and the beam of the RC frame structure. A substructure was developed. And it turned out that according to such a structure, the improvement of seismic resistance significantly more than before can be realized.
[0005]
However, under the repeated horizontal load, plastic elongation remains only on the columnar pier of the RC frame due to the difference in the deformation performance between the brace material formed of steel and the RC frame, and as a result, The tensile force acts on the columnar pier as an axial force, causing a new problem that the toughness of the columnar pier decreases.
[0006]
The present invention has been made in view of the above circumstances, and has as its object to provide a viaduct lower structure capable of suppressing an increase in axial force acting on a columnar pier under repeated horizontal loads.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the underpass structure of the viaduct according to the present invention includes a pair of pillar piers erected at predetermined intervals and a beam bridged on the top of the pillar piers as described in claim 1. And forming an inverted V-shaped brace material in an in-plane space including the pair of columnar piers and the beam, and forming a RC frame structure between the vicinity of the top of the brace material and the vicinity of the center of the beam. An energy absorbing damper for absorbing energy with respect to the horizontal relative displacement is interposed between the beam and the brace material such that a vertical relative displacement between the beam and the brace material is allowed. It is a concatenation.
[0008]
Further, the lower structure of the viaduct according to the present invention, as described in claim 2, has an RC frame structure composed of a pair of columnar piers erected at a predetermined interval and a beam spanned over the top of the columnar pier. An inverted V-shaped brace material is disposed in an in-plane space including the pair of columnar piers and the beam, and a horizontal relative displacement is generated between the vicinity of the top of the brace material and the vicinity of the center of the beam. The energy absorption damper that absorbs energy is interposed therebetween, and is connected by a predetermined connection member, and at least one of the connection member, the beam, and the brace material is not restrained from plastic elongation deformation of the columnar pier. Is to surrender.
The underpass structure of the viaduct according to the present invention is configured such that the brace material is configured such that the lines of axial force of two brace bodies constituting the inverted brace material intersect at the beam. is there.
[0009]
In the lower structure of the viaduct according to the present invention, the horizontal force at the time of the earthquake transmitted from the upper structure to the beam of the RC frame structure is transmitted to a pair of columnar piers also constituting the RC frame structure, and the vicinity of the center of the beam. Are transmitted to the brace members via energy absorbing dampers connected to the brace members. When the seismic energy is small, the amplitude of the upper structure is suppressed by the high rigidity of the RC frame structure and the brace material, and when the seismic energy is large, the structure is interposed between the beam and the vicinity of the top of the brace material. The energy absorbing dampers undergo forced deformation in accordance with their horizontal relative displacement to absorb energy by hysteresis, and quickly converge the shaking of the lower structure and thus the entire viaduct.
[0010]
On the other hand, if the horizontal force at the time of the earthquake acts on the substructure of the viaduct, the bracing material would restrict the plastic elongation deformation of the columnar pier of RC frame structure, so the axial force corresponding to the restraint would be applied to the columnar pier. Although there was a problem that the toughness of the columnar pier was lowered by newly acting, in the present invention, the energy absorbing damper was added to the beam or the brace material so that vertical relative displacement was allowed between the beam and the brace material. Because of the connection, the tensile force of the brace material is not transmitted to the RC frame beam, and thus to the pillar pier, so that the axial force of the pillar pier does not increase.
[0011]
Further, in the present invention, since the connecting member connecting the energy absorbing damper to the beam or the brace material, at least one of the beam and the brace material is yielded so that the plastic elongation deformation of the columnar pier is not restricted, Again, the tensile force of the brace material is not transmitted to the RC frame beam and thus to the column pier, so that the axial force of the column pier does not increase.
[0012]
The pair of columnar piers includes not only a direction orthogonal to the bridge axis direction, for example, a direction laid on a track or a road laid on the ground, but also a direction parallel to the bridge axis direction. In the case of the former, a so-called portal-type ramen is often used, whereas in the case of the latter, a so-called continuous ramen.
[0013]
Regarding the upper structure of the viaduct, it does not matter whether it is a road bridge or a railway bridge.
[0014]
Any energy absorbing damper may be used as long as the energy absorbing damper is subjected to forced deformation according to the relative horizontal displacement between the beam having the rigid frame structure and the vicinity of the top of the brace material and energy absorption is performed by hysteresis damping. . For example, shear-type dampers that use hysteretic damping due to the shear deformation of ribbed steel plates, steel-rod bending dampers that use hysteretic damping due to bending deformation of steel rods, particularly steel-bar bending dampers that incorporate spherical bearings, etc. Conceivable.
[0015]
There are various possible configurations for connecting the energy absorbing damper to the beam or the brace material so that vertical relative displacement is allowed between the beam and the brace material.For example, while the energy absorbing damper is fixed near the top of the brace material, It is conceivable that an anchor bolt is fixed to the lower surface of the beam of the RC frame and the tip of the anchor bolt penetrates through the insertion hole provided in the energy absorbing damper. It is conceivable that an anchor bolt is fixed to the top of the brace material while the damper is fixed, and the tip of the anchor bolt penetrates through an insertion hole provided in the energy absorbing damper. When using a steel bar bending type damper incorporating a spherical bearing, the escape of the steel bar is originally considered, and the escape corresponds to the allowable vertical relative displacement according to the present invention. There is no need to devise anything.
[0016]
In addition, in order to yield at least one of the connecting member for connecting the energy absorbing damper to the beam or the brace material so that the plastic elongation deformation of the columnar pier is not restricted, for example, the connecting member In the case of (1), the anchor bolts and the like are yielded, in the case of a beam, the main reinforcement of the beam is reduced, and in the case of a bracing material, a low yield point steel material is used.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a viaduct lower structure according to the present invention will be described with reference to the accompanying drawings. In addition, the same reference numerals are given to components and the like that are substantially the same as those in the related art, and description thereof is omitted.
[0018]
FIG. 1 is a front view of a lower structure of a viaduct according to the present embodiment as viewed from a bridge axis direction. As can be seen from the figure, the lower structure of the viaduct according to the present embodiment is formed by a pair of columnar piers 1, 1 erected at predetermined intervals and a beam 2 bridged over the top of the columnar pier. RC frame structure 3, an inverted V-shaped brace member 4 arranged in an in-plane space including the pair of columnar piers 1, 1, and a beam 2, between the top of the brace member and the beam 2 And a shear type damper 5 as an interposed energy absorbing damper. Here, the columnar pier 1 may be configured such that, for example, a pile 6 is driven into the ground 8, a base 7 is provided at the pile head, and the pillar 6 is erected on the base. Further, the brace material 4 can be formed of, for example, a steel material.
[0019]
As shown in FIG. 2, the shear type damper 5 is fixed to the top of the brace material 4 below, and an insertion hole 12 is formed above the substrate 13 fixed in a T-shaped cross section. The shear-type damper 5 is allowed to move vertically with respect to the beam 2 by allowing the distal end of the anchor bolt 11 fixed to the lower surface of the beam 2 of the RC frame structure 3 to pass through the insertion hole. Connected. The shear-type damper 5 is made of, for example, a steel material that yields and yields on a web, and has, for example, a grid-like reinforcing rib protruding in an out-of-plane direction so as not to buckle locally on the web. Is good.
[0020]
The anchor bolt 11 smoothly transmits from the insertion hole 12 while repeatedly transmitting the horizontal force to the shearing damper 5 via the substrate 13 when the columnar pier 1 of the RC frame structure 3 gradually expands under the repeated horizontal load. The outer diameter is set to be slightly smaller than the inner diameter of the insertion hole 12 so as to prevent the tensile force in the vertical direction from being transmitted upward to the shear damper 5 and the brace material 4 so as not to be transmitted.
[0021]
Although a gap is provided between the substrate 13 of the shear damper 5 and the lower surface of the beam 2 in FIG. 2, when the RC frame structure 3 is compared with the brace material 4 formed of steel, a general In this case, the brace material 4 has better deformation capability, in other words, the brace material 4 is less likely to undergo plastic elongation deformation when repeatedly subjected to a horizontal load. It is not necessary to provide such a gap.
[0022]
The length of the anchor bolt 11 projecting downward from the substrate 13 is set to be larger than the maximum gap assumed to be generated between the substrate 13 and the lower surface of the beam 2 when repeatedly receiving a horizontal load. Just fine. Further, as long as this is satisfied, an anchor bolt with a head may be used instead of the anchor bolt 11 as shown in FIG.
[0023]
In the lower structure of the viaduct according to the present embodiment, the horizontal force at the time of the earthquake transmitted from the upper structure 9 (FIG. 1) to the beam 2 of the RC frame structure 3 at the time of the earthquake is a pair of the same RC frame structure. The power is transmitted to the columnar piers 1, 1, and also transmitted to the brace members 4 via the shear dampers 5 connected near the center of the beam 2. When the seismic energy is small, the amplitude of the upper structure 9 is suppressed by the high rigidity of the RC frame structure 3 and the brace member 4, and when the seismic energy is large, the beam 2 and the vicinity of the top of the brace member 4 are removed. The energy absorbing dampers 5 interposed therebetween are forcedly deformed in accordance with their horizontal relative displacement to perform energy absorption by hysteresis damping, thereby promptly converging the shaking of the lower structure and thus the entire viaduct.
[0024]
On the other hand, if the horizontal force at the time of the earthquake acts on the substructure of the viaduct, the bracing material would restrict the plastic elongation deformation of the columnar pier of RC frame structure, so the axial force corresponding to the restraint would be applied to the columnar pier. Although there was a problem that the toughness of the columnar pier was lowered due to a new action, in this embodiment, as shown in FIG. 3, the columnar piers 1, 1 of the RC frame structure 3 undergo plastic elongation deformation. Even if it occurs, the anchor bolt 11 fixed to the beam 2 escapes from the substrate 13 fixed to the upper end of the shear damper 5, so that no tensile force is transmitted, and thus the vertical between the beam 2 and the brace material 4 Relative displacement will be allowed. On the other hand, the horizontal force is transmitted from the beam 2 to the shear-type damper 5 via the anchor bolt 11 and the substrate 13, so that the shear-type damper absorbs the horizontal force during an earthquake.
[0025]
As described above, according to the viaduct lower structure according to the present embodiment, when the seismic energy is small, the amplitude of the upper structure 9 can be suppressed by the high rigidity of the RC frame structure 3 and the brace material 4. At the same time, when the seismic energy is large, the shear damper 5 interposed between the beam 2 and the vicinity of the top of the brace material 4 absorbs energy by hysteresis damping, and quickly converges the sway of the lower structure and the entire viaduct. It becomes possible.
[0026]
On the other hand, since the shear-type damper 5 is connected to the beam 2 so as to allow vertical relative displacement between the beam 2 and the beam 2, the tensile force of the brace member 4 causes the beam 2 of the RC rigid frame structure 3 and thus the columnar pier 1 to move. 1 is prevented, and the axial force of the pillar pier does not increase. It is also conceivable that plastic deformation of the shear damper 5 itself may cause a contraction in the vertical direction. However, such a vertical displacement is also absorbed by the escape of the anchor bolt 11, so that the axial force of the columnar pier is increased. It is not.
[0027]
Therefore, it is possible to secure the high seismic resistance by absorbing the energy of the horizontal force at the time of the earthquake by the shear type damper 5 while preventing the toughness ratio of the columnar piers 1 and 1 due to the increase of the axial force beforehand. . For earthquakes of a certain size or less, the deformation of the RC frame structure 3 and the brace members 4 can be kept in the elastic region and the seismic energy can be concentrated only on the shear damper 5, so that the energy is absorbed by plastic deformation. It is needless to say that the lower structure can be restored to the original lower structure by replacing the lowered shear damper 5.
[0028]
In this embodiment, the anchor bolt 11 is simply fixed to the beam 2. However, if the anchor bolt 11 is screwed into a female screw member embedded in the beam 2 in advance, the anchor bolt 11 can be removed from the beam 2. The replacement of the shear damper 5 can be easily performed.
[0029]
In this embodiment, the shear damper 5 is connected to the beam 2 such that vertical relative displacement is allowed between the beam 2 and the beam 2. Needless to say, the side may absorb the vertical relative displacement.
[0030]
Further, in the present embodiment, the lower end of the brace member 4 is fixed to the base of the columnar piers 1, 1, but it is needless to say that the lower end may be fixed to the intermediate portion of the columnar piers 1, 1. No.
[0031]
Further, in this embodiment, the vertical relative displacement between the shear damper 5 and the beam 2 is configured, but instead, as shown in FIG. 4, the upper end of the shear damper 5 is connected. The lower end is connected to the brace member 22 while at least one of the anchor bolt 21, the beam 2 and the brace member 22 is restrained by the plastic elongation deformation of the columnar piers 1, 1. It may be configured to yield at a predetermined yield strength so as not to be performed. Here, when the anchor bolts 21 yield, the number, diameter or material strength of the anchor bolts 21 may be adjusted. When yielding the beams 2, the main reinforcement may be reduced in the vicinity of the center, as shown in FIG. As shown in (1), the cross section may be reduced so that a plastic hinge may be formed at the location. When the brace material 22 is yielded, for example, a low yield point steel material may be used.
[0032]
With such a configuration, substantially the same operation and effect as those of the above-described embodiment can be obtained, but the description thereof is omitted here.
[0033]
In the present embodiment, the pair of columnar piers 1 and 1 are arranged in a direction orthogonal to the bridge axis direction, for example, so as to straddle a track or a road laid on the ground, but instead of this, as shown in FIG. It may be applied in a direction parallel to the bridge axis direction. In this case, a so-called continuous ramen is obtained. The details are the same as those in FIG. 2, and the description thereof is omitted here.
[0034]
Further, in the present embodiment, the shear type damper 5 is adopted as the energy absorbing damper. However, instead of this, a steel bar bending type damper 32 may be used as shown in FIG. The steel rod bending type damper 32 inserts the steel rod 33 fixed to the beam 2 into insertion holes formed in the two substrates 34, 34 fixed to the top of the brace material 4 by welding or the like. The hole is provided with a spherical bearing 31.
[0035]
In such a configuration, when a horizontal force at the time of an earthquake acts on the substrates 34 and 34 from the beam 2 via the steel rods 33 as shown in FIG. Energy absorption is performed by hysteresis damping due to bending of the steel bar 33 under a horizontal load. Further, when the steel rod 33 escapes upward from the substrates 34, 34 as shown by arrows in the figure, vertical relative displacement between the beam 2 and the brace material 4 is allowed. Although a gap is provided between the substrate 34 and the lower surface of the beam 2 also in FIG. 6, such a gap is not necessarily required as in the above-described embodiment.
[0036]
Although not particularly mentioned in the present embodiment, as shown in FIG. 7, the axial force action lines of the brace bodies 41, 41 constituting the brace material 4 having an inverted V shape intersect with the beam 2. The brace material may be configured as described above.
[0037]
In this configuration, as shown in FIG. 3B, the height position of the horizontal force H acting on the brace material 4 from the beam 2 substantially coincides with the intersection R of the axial force action lines of the brace bodies 41, 41. . That is, the beam 2 receives the horizontal force H ′ in the opposite direction as a reaction force from the brace material 4, but the height of the horizontal force H is set at the intersection R of the axial force action lines of the brace bodies 41, 41. Since they match, there is no concern that the bending moment acts on the beam 2 as a reaction force. Therefore, it is also possible to suppress an increase in the axial force of the columnar piers 1, 1 caused by the bending moment. Incidentally, when the lines of action of the axial forces of the brace bodies 41, 41 constituting the brace material 4 do not intersect at the beam 2, but intersect at a point Q as shown in FIG. The bending moment M '= dH' (d is the eccentric distance of the point Q from the beam 2) caused by the force H 'acts on the beam 2 as a reaction force, which causes an increase in the axial force of the columnar piers 1,1. .
[0038]
【The invention's effect】
As described above, according to the underpass structure of the present invention according to claims 1 and 2, the toughness of the columnar pier due to the increase in the axial force is prevented, and the earthquake caused by the energy absorbing damper is prevented. It becomes possible to secure high earthquake resistance by absorbing the energy of horizontal force.
[0039]
[Brief description of the drawings]
FIG. 1 is a front view of a viaduct lower structure according to an embodiment.
FIG. 2 is a detailed view of a lower structure of a viaduct according to the embodiment, (a) is a front view, and (b) is a horizontal cross-sectional view along the line AA of (a).
FIG. 3 is a front view showing the operation of the viaduct lower structure according to the embodiment.
FIG. 4 is a detailed view showing a lower structure of a viaduct according to a modification.
FIG. 5 is an overall view showing a lower structure of a viaduct according to another modification.
FIG. 6 is a detailed view showing a lower structure of a viaduct according to another modification and its operation.
FIG. 7 is a detailed view showing a lower structure of a viaduct according to another modification and its operation.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Column pier 2 Beam 3 RC frame structure 4, 22 Brace material 5 Shear type damper (energy absorption damper)
21 Anchor bolt (connecting member)
32 Steel rod bending type damper (energy absorbing damper)
41 Brace body

Claims (3)

An RC frame structure is formed by a pair of pillar piers erected at predetermined intervals and a beam bridged on the top of the pillar pier, and an inverted V-shape is formed in an in-plane space including the pair of pillar piers and the beam. While disposing a brace material having a shape, an energy absorption damper for absorbing energy with respect to horizontal relative displacement is interposed between the vicinity of the top of the brace material and the vicinity of the center of the beam, and the energy absorption damper is A viaduct lower structure, which is connected to the beam or the brace material such that vertical relative displacement between the beam and the brace material is allowed. An RC frame structure is formed by a pair of pillar piers erected at predetermined intervals and a beam bridged on the top of the pillar pier, and an inverted V-shape is formed in an in-plane space including the pair of pillar piers and the beam. A brace material having a shape is arranged, and an energy absorption damper for absorbing energy with respect to horizontal relative displacement is interposed between the vicinity of the top of the brace material and the vicinity of the center of the beam, and connected by a predetermined connection member. A lower structure of a viaduct, wherein at least one of the connecting member, the beam and the brace material is yielded so that plastic extension deformation of the columnar pier is not restricted. The lower structure of a viaduct according to claim 2, wherein the brace member is configured such that axial action lines of two brace bodies that form the brace member in an inverted V shape intersect at the beam.

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