JP6660651B2 - Bridge substructure - Google Patents

Description

  The present invention relates to a lower structure of a bridge used for roads, railways, and the like.

  As bridges on which transportation vehicles such as railroads and automobiles travel, there are so-called viaducts that are continuously constructed in urban areas, in addition to narrow bridges that cross rivers and straits. From the viewpoint of efficient land use, such viaducts are continuously constructed in the space on roads, railways, or rivers. It also contributes to eliminating traffic jams.

  When constructing the viaducts described above, the lower structure is often constructed with a reinforced concrete rigid frame. At this time, it must be designed and constructed so as to ensure sufficient earthquake resistance.

JP 2004-270816 A JP 2005-188240 A JP-A-11-323826

  Under such circumstances, as shown in Patent Literatures 1 and 2, the present applicant has disclosed a viaduct lower structure 12 in which a damper mechanism 13 and a brace mechanism 14 are disposed in a reinforced concrete frame 3 composed of columns 1, 1 and beams 2. According to such a configuration, it is possible to greatly improve the earthquake resistance.

  However, in the above-described viaduct lower structure 12, the damper mechanism 13 and the brace mechanism 14 occupy the inner space of the ramen frame 3, so that the inner space cannot be effectively used as a road or a railway. .

  Incidentally, in Patent Document 3, a ramen structure 13 is constituted by a pair of columnar piers 11 and 11 facing each other and a beam 12 bridged on the top of the columnar pier, and a top is provided inside the ramen structure. There is disclosed a configuration in which a brace member 14 having an inverted V shape is arranged so as to be joined near the center of the beam 12 and both ends are respectively joined to the intermediate height positions of the pair of columnar piers 11, 11. In the configuration, since only the upper part of the inner space of the ramen structure 13 is occupied by the brace material 14, the inner space can be used to some extent effectively, but there is a case where earthquake resistance cannot be secured with a margin. .

  The present invention has been made in consideration of the above-described circumstances, and has an object to provide a bridge lower structure that can effectively utilize the internal space of a column-beam frame as much as possible while securing sufficient earthquake resistance. .

In order to achieve the above object, a lower structure of a bridge according to the present invention is, as described in claim 1, a column composed of a pair of columns erected so as to face each other and a beam bridged over their tops. In the substructure of a bridge with a beam frame,
A damper mounting portion is arranged in a form protruding from a material end of the beam or as a projecting portion of the beam so as to extend substantially parallel to the structure surface of the beam-and-column frame and outside the beam-and-column frame, and a damper is provided. One end thereof is disposed obliquely between the damper mounting portion and the column with the other end bonded to the side surface of the column located below the damper mounting portion, respectively , The damper is configured so that a damping force is exerted between the damper mounting portion and the column by expansion and contraction of a distance between both ends of the damper due to deformation of the column-beam frame .

  Further, in the lower structure of the bridge according to the present invention, the damper is a friction damper.

  Further, in the lower structure of the bridge according to the present invention, the damper mounting portion is made of a steel material.

  Further, in the lower structure of the bridge according to the present invention, the damper mounting portion is a projecting portion of the beam, and the beam is made of prestressed concrete.

  In the lower structure of a bridge according to the present invention, the present invention is applied to a lower structure of a bridge provided with a pair of pillars erected so as to face each other and a beam-and-column structure spanning the tops thereof. However, at this time, the damper attachment portion is arranged to protrude from the material end of the beam or as a projecting portion of the beam so as to extend substantially parallel to the structure surface of the beam-and-column frame and to the outside of the beam-and-column frame, The damper is disposed obliquely between the damper mounting portion and the column, with one end of the damper bonded to the damper mounting portion and the other end bonded to the side surface of the column located below the damper mounting portion.

  With this configuration, in the event of an earthquake, the distance between both ends of the damper expands and contracts due to the deformation of the beam-column structure, and the damper exerts a damping force. It becomes possible to control the beam frame.

  The beam-column structure is that if the damper obliquely arranged in the shape of a cane between the damper mounting part and the column expands and contracts along the axis from one end to the other end (hereinafter simply referred to as the material axis) during an earthquake The connection state between the column and the beam is arbitrary, and the above-mentioned expansion and contraction due to the bending deformation or the shear deformation of the column can be considered as a rigid connection or a rigid connection as well as a pin connection or a pin connection. The case where the operation is realized is also included. That is, in the column-beam frame of the present invention, a frame structure is not excluded, and a structural type such as reinforced concrete (RC), SRC, or S is arbitrary.

  Here, the bridge to which the present invention is applied, when viewed from the bridge axis direction, in other words, it is sufficient that the beam-column frame in the cross section is the above-described beam-column frame, and from the direction orthogonal to the bridge axis. When viewed, in other words, how the frame type in the vertical section is configured is arbitrary.

  In other words, the bridge according to the present invention includes a case in which the frame type when viewed from the bridge axis direction and the frame type when viewed from the bridge axis orthogonal direction are both rigid frame structures (called a viaduct in the field of railway civil engineering). When the frame type when viewed from the bridge axis direction is a ramen frame, and when the frame type when viewed from the bridge axis orthogonal direction is a girder system, that is, when the bridge girder is mounted on a ramen frame that is spaced apart along the bridge axis direction. The case of passing (called a bridge in the field of railway civil engineering) is included.

  The damper may be of any type as long as the damping force is exerted by the relative speed generated along the material axis, and may be constituted by a friction damper, a viscoelastic damper, a viscous damper, or the like.

  The damper mounting portion is disposed substantially parallel to the beam-to-column structure so that the component that vibrates in parallel with the structure of the beam-to-column structure is efficiently suppressed, and the internal space of the beam-to-column frame can be effectively used, What is necessary is just to arrange | position so that it may extend outside a column-beam frame, but the structure arrange | positioned horizontally is a typical example.

  What kind of material the damper mounting portion is made of is optional, but if it is made of steel or prestressed concrete, when a tensile load acts on the damper mounting portion as a reaction force when the damper contracts, the tensile load Can be reliably supported.

FIG. 2 is a front view of a lower structure 1 of the bridge according to the embodiment. FIG. 4 is a longitudinal sectional view of the friction damper 7. Explanatory drawing which showed the effect | action of the lower structure 1 of the bridge which concerns on this embodiment. The figure which showed the modification of the lower structure 1 of the bridge which concerns on this embodiment. The figure which showed another modification of the lower structure 1 of the bridge which concerns on this embodiment.

  Hereinafter, an embodiment of a bridge substructure according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a front view of a lower structure of a bridge according to the present embodiment as viewed from a bridge axis direction. As shown in the figure, the lower structure 1 of the bridge according to the present embodiment has pillars 3 erected so as to face the footings 2, 2, respectively, and a beam 4 is provided on top of the pair of pillars 3, 3. And the pillars 3 and 3 and the beam 4 constitute a ramen frame 5 as a column-beam frame. The ramen frame 5 can be made of reinforced concrete (RC).

  The beam 4 is provided with overhang portions 6 and 6 as damper attachment portions so as to extend in parallel with the plane of the ramen frame 5 and outside the ramen frame, respectively, and between the overhang portion 6 and the column 3. In the figure, the friction dampers 7 are arranged obliquely in a cheek stick shape. The overhang 6 may be configured as a part of the beam 4 so as to project from the outer side surface of the column 3.

  The friction damper 7 has one end joined to the lower surface of the overhang portion 6 and the other end joined to the outer side surface of the pillar 3 located below the overhang portion by pin joining, respectively, and is connected via the overhang portion 6 and the pillar 3. Damping force due to friction is exerted in response to the input relative speed in the axial direction of the material.

  As shown in FIG. 2, the friction damper 7 forms a slot 23 along a material axis in a web 22a of an H-section steel 21a connected to the column 3 by pin bonding, and forms the slot 22 along the material axis. While a long sliding member 24 is fixed to both surfaces, brackets 25 are attached to both surfaces of a web 22b of an H-shaped steel 21b which is connected to the overhang portion 6 by pin bonding, and slide on opposing inner surfaces of the bracket. A friction material 26 to be in contact with the material 24 is attached, and the web 22a to which the sliding material 24 is fixed on both surfaces is sandwiched by brackets 25, 25 to which the friction material 26 in contact with the sliding material is attached. The two H-shaped steels 21a and 21b are arranged relative to each other so that the shafts are shared, and the brackets 25 and the one of the friction members 26 are inserted into the slots 23 so as to pass through to the other friction member 26 and the bracket 25. The head 27 through disposed to the disc spring 28 attached to each end of the rod, there it as a tightening nut 29.

  In the bridge lower structure 1 according to the present embodiment, the beams 4 are provided with the overhang portions 6 and 6 so as to extend substantially parallel to the construction surface of the ramen frame 5 and to the outside of the ramen frame. However, the friction dampers 7 are obliquely arranged in a cheek stick shape such that the other ends are respectively joined to the side surfaces of the pillar 3 located below the overhanging portion.

  In this way, in the event of an earthquake, as shown in FIG. 3, as the rigid frame 5 is deformed, the distance between the two ends of the friction damper 7 alternately expands and contracts in such a manner that the right side in FIG. As a result, the friction damper exerts a damping force.

  As described above, according to the bridge lower structure 1 according to the present embodiment, the ramen frame can be damped without disposing dampers and braces in the internal space 31 of the ramen frame 5.

  Therefore, it is possible to maximize the effective use of the internal space, such as laying a railroad or a road in the internal space 31 of the ramen frame 5.

  In the present embodiment, the friction damper 7 is adopted as the damper. However, the damper of the present invention is not limited to the friction damper 7, and a viscoelastic damper or a viscous damper can be used instead of the friction damper. is there.

  Further, in this embodiment, the frame frame 5 is adopted as the column-beam frame, but a frame in which the top of the column 3 and the beam 4 are pin-joined as shown in FIG.

  Further, in the present embodiment, the vibration damping mechanism such as the damper or the brace is not arranged at all in the internal space 31 of the ramen frame 5. However, if the friction damper 7 alone is insufficient in the earthquake resistance of the entire frame, it may be used. In order to compensate for this, for example, a damper brace mechanism 41 may be arranged in the internal space 31 as shown in FIG.

  The damper brace mechanism 41 includes a hysteresis damper 42 vertically provided on the lower surface of the beam 4 and two brace members 43, 43 whose upper ends are connected to the hysteresis damper by pin bonding. The lower end of the brace material 43 is connected to the pillar 3 near the middle height of the pillar 3 by pin bonding.

  In such a modified example, it is difficult to make maximum use of the internal space 31 surrounded by the columns 3 and 3 and the beams 4, but the vibration to be installed in the internal space 31 by the vibration damping action of the friction damper 7. The degree of occupancy of the vibration mechanism can be kept to a minimum, and there is no difference from the above-described embodiment in that the effective use inside the frame is improved.

  Further, in the present embodiment, the damper attachment portion is constituted by the overhang portion 6 which is a part of the beam 4, but instead of this, the external dimension of the columns 3 and 3 is set as the member length as shown in FIG. Damper attachment members 51, 51 may be provided so as to protrude from the material end of the beam 4b, and may be used as the damper attachment portion of the present invention.

  Although not particularly mentioned in the present embodiment, in the event of an earthquake, when the friction damper 7 contracts, a tensile load acts on the left overhang portion 6 in FIG. 3 as a reaction force when the friction damper 7 contracts.

  In such a case, it is possible to cope with the problem by increasing the rebar amount of the overhang portion 6 or increasing the cross section, but this impairs the economy of the overhang portion 6 and further imposes a burden on the column 3 and the footing 2. If there is a concern that the overhang will occur, the overhang 6 may be made of steel instead of reinforced concrete. It is optional whether the entire beam 4 is made of steel or only the damper mounting member 51 is made of steel as shown in FIG.

  Further, when a similar situation is concerned, the beam 4 may be made of prestressed concrete.

  According to each of the above-described modified examples, it is possible to reliably support the tensile load without impairing economic efficiency.

  Although not particularly mentioned in the present embodiment, a configuration in which a coating by application, adhesion, or the like is formed on the sliding surface of the sliding member 24 may be adopted.

  The coating is formed so as not to hinder the sliding operation of the friction material 26, and it is desirable that the coating be as excellent as possible in weather resistance.

  According to this modification, when the friction damper 7 operates during an earthquake, the coating of the sliding material 24 peels over the sliding range of the friction material 26. By observing the state of the peeling, the maximum of the friction damper 7 can be obtained. The displacement can be easily grasped, and thus the above-described configuration can function as a peak sensor.

  Also, unlike the conventional peak sensor, no maintenance is required, so that the configuration is optimal as a peak sensor applied to a bridge or the like.

  It should be noted that it is sufficient to observe only one of the friction dampers 7, 7 arranged on the left and right, which is easy to observe, but it is sufficient to observe both according to the situation. It doesn't matter.

1 bridge lower structure 3 pillar 4 beam 5 ramen frame (column beam structure)
6 Overhanging part (damper mounting part)
7 Friction damper (damper)

Claims (4)

In a lower structure of a bridge provided with a pair of columns erected to face each other and a beam-to-column frame composed of beams spanned on the tops thereof,
A damper mounting portion is arranged in a form protruding from a material end of the beam or as a projecting portion of the beam so as to extend substantially parallel to the structure surface of the beam-and-column frame and outside the beam-and-column frame, and a damper is provided. One end thereof is disposed obliquely between the damper mounting portion and the column with the other end bonded to the side surface of the column located below the damper mounting portion, respectively , A lower portion of the bridge , wherein the damper exerts a damping force between the damper mounting portion and the column by expansion and contraction of a distance between both ends of the damper accompanying deformation of the column-beam frame. Construction. The bridge substructure according to claim 1, wherein the damper is a friction damper. The bridge substructure according to claim 1 or 2, wherein the damper attachment portion is made of a steel material. The bridge substructure according to claim 1 or 2, wherein the damper attachment portion is a projecting portion of the beam, and the beam is made of prestressed concrete.

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