JP2005336743A - Steel pipe damper and locking foundation - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize the whole; to reduce labor required for installation; and to shorten time, in a steel pipe damper and a locking foundation effective in enhancing aseismatic performance of a structure such as a bridge. <P>SOLUTION: This steel pipe damper 25 is interposed between a structure 3 and respective pile heads 24 of a plurality of piles 23 for supporting the structure 3; to damp or dissipate vibration generated in the structure 3 when an earthquake occurs. The steel pipe damper has a steel pipe 27 inserted into the pile heads 24 of the respective piles 23 so as to be relatively movable and swellingly/contractively deformable, a pressing bar 31 having one end part fixed to one end part of the steel pipe 27 and having the other end part fixed to the structure 3 by penetrating through the steel pipe 27, and a friction band 28 installed around the steel pipe 27 and restricting swelling deformation of the steel pipe 27. Since earthquake energy is dispersed by frictional force between the steel pipe 27 and a friction hole 34 of the piles 23 and frictional force between the steel pipe 27 and the friction band 28, the whole can be largely miniaturized more than the steel pipe damper composed of only the steel pipe 27. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a steel pipe damper and a rocking foundation, and more particularly to a steel pipe damper and a rocking foundation effective for enhancing the earthquake resistance of a structure such as a bridge.

  There are various types of rocking foundations used to enhance the seismic performance of structures such as bridges. For example, between the pier base of the bridge and the pile heads of the piles that support the pier base. A steel pipe damper is proposed.

When the rocking foundation with such a configuration is displaced in the direction in which the pier base rises (the direction away from the pile) due to the occurrence of an earthquake, the pulling force acts on the steel pipe damper, and the steel pipe is compressed to bulge and deform. The frictional force between is increased. Also, if the pier base is displaced in the direction in which it sinks (the direction approaching the pile), the pushing force acts on the steel pipe damper, the compressed state of the steel pipe is released and shrinkage deformation occurs, and the friction force between the steel pipe and the pile decreases. To do. By repeating such increase and decrease of the frictional force, the seismic energy is dissipated (for example, see Patent Document 1).
JP 2003-232046 A

  By the way, in the rocking foundation having the above configuration, the magnitude of the friction force generated between the steel pipe and the pile of the steel pipe damper is proportional to the surface area of the steel pipe. The surface area of the steel tube must be large, that is, the steel pipe must be thick and long. If the steel pipe damper is thick and long, the damper itself becomes expensive, and in order to install the steel pipe damper on the pile, it is necessary to open the box beforehand, but if the steel pipe damper becomes large, the void for box opening Since the equipment for temporarily fixing the material (for example, the winding pipe) becomes heavy, there is a problem in terms of cost.

  Further, in the case of place-to-place, there is a problem that the void material becomes an obstacle to placing concrete, and if the diameter of the void is reduced in order to avoid this, the grout material is difficult to fill.

  The present invention has been made in view of the above-described conventional problems, and can improve seismic performance without increasing the size of the steel pipe damper, reduce labor due to construction, and shorten time. It aims at providing the steel pipe damper and rocking foundation which can be performed.

  The steel pipe damper of the present invention that solves the above problems is interposed between a structure and each pile head of a plurality of piles that support the structure, and increases the function and attenuation of extending the natural period of the structure when an earthquake occurs. A steel pipe damper having a function, wherein the steel pipe is inserted into the pile head of each pile so as to be relatively movable and swellable / shrinkable, and at least one protrusion provided on the outer periphery of the steel pipe. (1st invention).

  The steel pipe damper according to the second invention is interposed between a structure and each pile head of a plurality of piles supporting the structure, and has a function of increasing the natural period of the structure and a function of increasing attenuation when an earthquake occurs. A steel pipe damper having a steel pipe that is relatively movable to a pile head of each of the piles and that is inserted so as to be able to bulge / shrink, and a plate-like body that is fixed to the outer periphery of the steel pipe and provided at least one circumference. It is characterized by comprising.

  A steel pipe damper according to a third invention is interposed between a structure and each pile head of a plurality of piles supporting the structure, and has a function of increasing the natural period of the structure and a function of increasing attenuation when an earthquake occurs. A steel pipe damper having a steel pipe that can be moved relative to a pile head of each pile and that can be swelled and contracted; a projection provided at least around the steel pipe; and an outer periphery of the steel pipe And at least one plate-like body that is provided around the plate.

  A steel pipe damper according to a fourth invention is characterized in that, in the second or third invention, a plurality of the plate-like bodies are provided at predetermined intervals in the longitudinal direction of the steel pipe.

  According to a fifth aspect of the present invention, there is provided the steel pipe damper according to any one of the first to fourth aspects, wherein the plate-like body or the protrusion is provided so as to be 10 to 15% of a surface area of the steel pipe. Features.

  A steel pipe damper according to a sixth invention is characterized in that, in any one of the first to fifth inventions, the surface of the steel pipe is subjected to water repellent treatment.

A rocking foundation according to a seventh invention is characterized in that the steel pipe damper according to any one of the first to sixth inventions is interposed between a structure and each pile head of a plurality of piles supporting the structure. The structure according to the invention of 8 is characterized in that the steel pipe damper according to any one of the first to sixth inventions is interposed between the structure and each pile head of a plurality of piles supporting the structure.

  According to the steel pipe damper with a friction band according to the present invention, the frictional force between the steel pipe and the pile is conventionally increased by the cooperation of the steel pipe and the friction band by setting the contact area between the steel band and the steel pipe to about 10 to 15%. The increase is about 1.5 times. Therefore, the diameter of the steel pipe damper can be reduced by about 20% (1 / √1.5 = 0.8). Reducing the diameter of the steel pipe damper makes it lighter, simplifies the installation of void materials, and secures a clearance (clearance) for placing concrete and grout, increasing the reliability of concrete or grout hardening and improving workability Can be reduced and the labor required for the construction can be reduced and the time can be shortened.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

  By attaching a friction band to a steel pipe damper, the present invention adds not only a contact surface between steel and concrete but also a contact surface between steel and steel, so that the steel tube is strong against repetition and has a high pulling load and is downsized. It is a damper. The result of confirming the effect of the friction band is shown below, and the result of further examination of the effective friction band shape is shown.

First, as shown in FIG. 1 (a), a trial design was performed for a bridge pier having a height of about 12 m, and the performance required for the steel pipe damper was confirmed. For example, assuming that the diameter of the steel pipe damper is 400 mm, as shown in FIG. 1 (b), the floating amount of the steel pipe damper is 12 cm, the acting horizontal shear stress level at the time of drawing is 5.0 N / mm ² , It was found that the acting horizontal shear stress was ^2.5 N / mm ² and the embedding length of the steel pipe damper was 7.1 m or less.

  FIG. 2 (a) is an explanatory view showing the entire locking foundation in the first embodiment of the present invention. As shown in FIG. 2A, the rocking foundation 20 includes a footing 22 provided on a pier base 21 of a bridge that is a structure, a plurality of piles 23 that support the footing 22, a pile head 24 portion of each pile 23, and a footing. The steel pipe damper 25 according to the present invention is interposed between the steel pipe damper 22 and the steel pipe damper 25.

  At the upper end of the pile head 24 of each pile 23, an annular cushioning material 26 made of an elastic body such as rubber is integrally provided, and when the footing 22 comes into contact with the upper end of the pile head 24 of each pile 23, The shock between the two is buffered.

  FIG. 2B is a partially enlarged cross-sectional view of the connecting portion of the locking foundation in the first embodiment of the present invention. As shown in FIG. 2 (b), the steel pipe damper 25 is filled in a cylindrical steel pipe 27 whose lower end is closed, a friction band 28 mounted around the steel pipe 27, and the inside of the upper half of the steel pipe 27. A filler 29 made of concrete, a sheath tube 30 penetrating through the center of the filler 29, a pressing rod 31 made of PC steel penetrating the steel tube 27 in a vertical direction with the sheath tube 30 inserted, and a pressing rod 31 The lower fixing material 32 for fixing the lower end portion of the steel tube 27 to the bottom portion of the steel pipe 27 and the upper fixing material 33 for fixing the upper end portion of the pressing rod 31 to the footing 22.

  The surface of the steel pipe 27 is subjected to water repellent treatment, and almost the entire portion excluding the upper end portion is inserted into the friction hole 34 provided in the pile head 24 of each pile 23. In this case, predetermined gaps are provided between the outer peripheral surface of the steel pipe 27 and the inner peripheral surface of the friction hole 34, and between the lower end of the steel pipe 27 and the bottom of the friction hole 34, respectively. The non-shrinkable grout material G is filled, and the steel pipe 27 is configured to be relatively movable in the friction hole 34 and capable of bulging and contracting in the radial direction.

  The upper end portion of the steel pipe 27 is inserted into a support hole 35 provided in a portion of the footing 22 corresponding to the friction hole 34 of the pile head 24 of each pile 23. In this case, a cylindrical steel pipe 36 is integrally fixed to the inner surface of the support hole 35, and the upper end portion of the steel pipe 27 is inserted inside the steel pipe 36. Predetermined gaps are provided between the outer peripheral surface of the steel pipe 27 and the inner peripheral surface of the steel pipe 36, and between the upper end portion of the steel pipe 27 and the ceiling portion of the support hole 35. The upper end portion is configured to be relatively movable in the support hole 35 and to be able to bulge and contract in the radial direction.

  In the steel pipe 27, the lower end portion of the pressing rod 31 penetrating the center portion is fixed to the lower end portion of the steel pipe 27 by the lower fixing material 32, and the upper end portion of the pressing rod 31 and the upper fixing material 33 are connected to the ceiling of the support hole 35 of the footing 22. By being buried in the part, it is arranged in a suspended state in the friction hole 34.

  FIG. 2 (c) is a view showing the entire steel pipe damper in the first embodiment of the present invention, and FIG. 2 (d) is a view showing a friction band of the steel pipe damper in the first embodiment of the present invention. As shown in FIGS. 2 (c) and 2 (d), the friction band 28 has an annular shape formed by combining, for example, two steel semi-annular band halves 28a, 28a. In the state in which the periphery of 27 is surrounded by both band halves 28a, 28a, the end portions of both band halves 28a, 28a are tightened with screw fastening bodies 37 (bolts, nuts) to be integrally attached around the steel pipe 27. It is done.

  The fastening force of the band halves 28a, 28a of the friction band 28 by the screw fastening body 37 is predetermined between the inner surface of the friction band 28 and the outer surface of the steel tube 27 when the steel tube 27 bulges and deforms due to the occurrence of an earthquake. The frictional force is set to be generated.

  A plurality of protrusions 38 are integrally provided on each band half 28a of the friction band 28 so as to protrude outward. Each protrusion 38 may be integrally connected to the band half portion 28a by welding, for example, with a bolt, a round bar, or the like. At least one protrusion 38 may be provided in each band half 28a.

  A plurality of friction bands 28 are provided on the outer periphery of the steel pipe 27 at predetermined intervals along the longitudinal direction. The friction band 28 is preferably provided so as to occupy about 10 to 15% (13% in this embodiment) of the surface area of the steel pipe 27. However, the present invention is not limited to this, and can be appropriately changed depending on the material of the steel pipe 27 and the friction band 28.

  In order to confirm the effect of this friction band, a repeated force test of pushing and pulling between a steel pipe damper with the friction band attached and a conventional steel pipe damper without the friction band was conducted.

FIG. 3A is a view showing a frictional force evaluation test apparatus for a steel pipe damper. As shown in FIG. 3 (a), in the applying method, first, a horizontal force (50 kN) corresponding to the acting shear stress (5.0 N / mm ² ) at the time of pier bending yielding is applied to perform drawing. After unloading the pull-out load when the predetermined displacement is reached, the horizontal force is pushed in half (25 kN). This was repeated. The predetermined displacement is when the slip amount δ is 1, 2, 4, 8, 16, 32, 64 mm. The number of repetitions is 2 cycles up to 32 mm corresponding to 30% of the outer diameter of the steel pipe, and 1 when δ is 64 mm. Cycle. The surface of the steel pipe was all water-repellent and the adhesion between the steel pipe and concrete was removed. A summary of the above test conditions is shown in FIG.

  FIG. 4 (a) is a diagram showing the result of friction stress between a steel pipe damper with a friction band attached thereto and a conventional steel pipe damper without a friction band in the first embodiment of the present invention, and FIG. It is a figure which shows each maximum frictional stress at the time of extraction of the steel pipe damper which attached the friction band in one Example, and pushing.

  In FIG. 4A, the solid line shows the conventional steel pipe damper without the friction band 28, and the broken line shows the friction force of the steel pipe damper 25 of the present invention with the friction band 28 attached thereto.

  The frictional stress is a value obtained by dividing the drawing (indentation) load by the surface area of the steel pipe in the concrete. In addition, the steel pipe length at the time of calculating a surface area has reduced the extracted length.

  As shown in FIG. 4A, the friction stress is greater in the steel pipe damper 25 to which the friction band 28 is attached than in the conventional steel pipe damper without the friction band 28. Further, the friction stress and the maximum friction stress are larger at the time of pulling out due to expansion and contraction of the steel pipe 27 than at the time of pushing in, and regardless of the presence or absence of the friction band 28, as shown in FIG. There is.

  Next, in order to elucidate the mechanism of the increase in the friction stress due to the attachment of the friction band, the relationship between the friction stress and the contact stress with and without the friction band is shown.

  FIG. 5 (a) is a diagram showing the relationship between the friction stress and contact stress of a conventional steel pipe damper without a friction band in the first embodiment of the present invention, and FIG. 5 (b) shows the friction band in the first embodiment of the present invention. It is a related figure of the frictional stress and contact stress of the attached steel pipe damper.

FIG. 5 (c) is a diagram comparing the values of the friction stress with and without the use of a friction band when the contact stress σ is 1.0 N / mm ² in the first embodiment of the present invention, and FIG. It is a comparison figure of the maximum value of contact stress by the presence or absence of the friction band use in the 1st example of the present invention.

As shown in FIGS. 5A to 5C, when the contact stress σ is 1.0 N / mm ² , the friction stress is the conventional steel pipe damper in which the steel pipe damper 25 to which the friction band 28 is attached does not have the friction band 28. Further, it has increased 1.3 times when pulled out and 1.8 times when pressed.

  However, as shown in FIGS. 5 (a), 5 (b), and 5 (d), the contact stress is greater when the steel pipe damper 25 with the friction band 28 attached is pulled than the conventional steel pipe damper without the friction band 28. Although it increases 1.1 times, it decreases to 0.85 times when pushed.

  FIG. 5 (e) is a diagram showing an increase rate of the friction force of the entire steel pipe damper to which the friction band is attached in consideration of both the friction stress and the contact stress in the first embodiment of the present invention.

  As shown in FIG. 5 (e), the overall friction force of the steel pipe damper 25 to which the friction band 28 is attached is 1.43 times when pulled out and 1 at the time of pushing in from a conventional steel pipe damper without the friction band 28. The frictional force increases by about 1.5 times.

  Therefore, even if the diameter of the steel pipe damper 25 with the friction band 28 is reduced by about 20% (1 / √1.5 = 0.8) compared to the conventional steel pipe damper without the friction band 28, the same as the conventional one. It is possible to ensure a frictional force.

  FIG. 6 is a view showing the entire steel pipe damper to which a friction band is attached in the second embodiment of the present invention. Hereinafter, in the case of using the same member as that of the first embodiment, the same reference numeral is given, and the description is omitted.

  As shown in FIG. 6, the friction band 61 has an annular shape like the friction band 28, and is tightened around the steel pipe 27 with a screw fastening body 37 (bolts, nuts) or the like. Can be attached to one piece.

  Since the friction band 61 is not provided with a beard stripe like the protrusion 38, the friction band 61 is made thicker than the friction band 28 to prevent displacement. In this embodiment, the friction band 61 is made of steel. However, by making the friction band 61 thicker than in this embodiment, a material such as plastic, high-strength mortar, and high-strength fiber mortar should be used. Is possible.

  Fig.7 (a) is a figure which shows the whole steel pipe damper which attached the friction band and pad in the 3rd Example of this invention. As shown in FIG. 7 (a), a plurality of pads 71 having the same curvature as the steel pipe are integrally provided on the outer peripheral surface of the steel pipe 27, and an annular friction is formed on the outer periphery of the pad 71 so as to hold down the plurality of pads 71. By fastening the band 72 with a screw fastening body 37 (bolts, nuts) or the like, the band 72 is integrally attached around the steel pipe 27. Furthermore, it tightens with the screw fastening body 37 so that each pad 71 may not slip | deviate at the time of grout material placement.

  Each pad 71 can be made of a material such as steel, high-strength mortar, high-strength fiber mortar, plastic, rubber, inorganic material, etc. by making it thick to prevent displacement. However, the friction band 72 is made thin to constrain each pad 71, steel having a tensile rigidity and a large elastic coefficient is used. Therefore, the friction band may be wound with a string steel plate.

  FIG.7 (b) is a figure which shows the whole steel pipe damper which attached the friction band and pad in the 3rd Example of this invention. As shown in FIG. 7 (b), a plurality of flat pads 73 are linearly in contact with the outer peripheral surface of the steel pipe 27, and friction is formed in an annular shape on the outer periphery of the pads 73 so as to hold down the plurality of pads 73. By fastening the band 72 with a screw fastening body 37 (bolts, nuts) or the like, the band 72 is integrally attached around the steel pipe 27. Furthermore, it tightens with the screw fastening body 37 so that each pad 73 may not slip | deviate at the time of grout material placement.

  Each pad 73 can be made of a material such as steel, high-strength mortar, high-strength fiber mortar, plastic, rubber, inorganic material, etc. by making it thick to prevent displacement. The pad 73 has a flat shape, and has an advantage that the cost is lower than that of the pad 71 because, for example, it does not take time and effort just by cutting the steel plate into a predetermined size.

  FIG. 8A is a view showing the entire steel pipe damper to which a friction band is attached in the fourth embodiment of the present invention. As shown in FIG. 8A, the friction band 81 is a rod-like plate that winds the outer peripheral surface of the steel pipe 27 in a coil shape, and both ends of the friction band 81 prevent the friction band from shifting in the outer peripheral direction. By fixing to the steel pipe 27 with the fixing projections 82, the steel pipe 27 is integrally attached around the steel pipe 27.

  FIG. 8 (b) is a view showing the entire steel pipe damper to which a friction band is attached in the fourth embodiment of the present invention. As shown in FIG. 8 (b), the friction band 83 winds the outer peripheral surface of the steel pipe 27 in a coil shape after the start end portion of the friction band 83 is circularly wound to provide an overlapped portion of the friction band 83. In the same manner as the starting end portion, the end portion is provided with a superposed portion of the friction band 83 and is fixed to the steel pipe 27 with a fixing protrusion 82 that prevents the friction band from being displaced in the outer circumferential direction. It is attached to the periphery of the unit.

  In the first to fourth embodiments of the present invention, the frictional stress and the restraining force of the steel pipe damper can be increased. A method for increasing only the frictional stress of the steel pipe damper is shown in the fifth embodiment of the present invention.

  FIG. 9 is a view showing the entire steel pipe damper to which the pad according to the fifth embodiment of the present invention is attached. As shown in FIG. 9, a plurality of pads 71 having the same curvature as the steel pipe are integrally provided on the outer peripheral surface of the steel pipe 27, and the pads 71 are fixed until the grout material is filled and cured. It is attached to the periphery of the steel pipe 27 by attaching it with an adhesive or the like.

  In the steel pipe damper 25 shown in the first to fifth embodiments of the present invention, the steel pipe 27 is provided by providing friction bands 28, 61, 72, 81, 83 or pads 71, 73 on the outer peripheral surface of the steel pipe 27 of the steel pipe damper 25. The steel pipe damper 25 can be reduced in size compared to the conventional one in which the seismic energy is attenuated only by the bulging deformation. Therefore, the installation of the steel pipe damper 25 is facilitated, the time can be greatly shortened, the construction cost can be kept low, and the construction period can be shortened.

It is a figure which shows the object bridge foundation of the steel pipe damper by this invention. It is a figure which shows the performance requested | required of the object bridge of Fig.1 (a). It is explanatory drawing which shows the whole locking foundation in 1st Example of this invention. It is a partial expanded sectional view of the connection part of the rocking foundation in the 1st example of the present invention. It is a figure which shows the whole steel pipe damper in the 1st Example of this invention. It is a figure which shows the friction band of the steel pipe damper in the 1st Example of this invention. It is a figure which shows the frictional force evaluation test apparatus of a steel pipe damper. It is a figure which shows the test conditions of the frictional force evaluation test of the steel pipe damper in the 1st Example of this invention. It is a figure which shows the result of the friction stress of the steel pipe damper which attached the friction band in the 1st Example of this invention, and the conventional steel pipe damper without a friction band. It is a figure which shows each maximum frictional stress at the time of extraction of the steel pipe damper which attached the friction band in 1st Example of this invention, and pushing. It is a related figure of the friction stress and the contact stress of the conventional steel pipe damper without a friction band in the 1st example of the present invention. It is a related figure of the frictional stress and contact stress of the steel pipe damper which attached the friction band in the 1st Example of this invention. It is the figure which compared the value of the friction stress by the presence or absence of a friction band when the contact stress (sigma) in the 1st Example of this invention is 1.0 N / mm < ² >. It is a comparison figure of the maximum value of contact stress by the presence or absence of the friction band use in the 1st example of the present invention. It is a figure which shows the increase rate of the frictional force of the whole steel pipe damper which attached the friction band at the time of considering both the frictional stress and contact stress in the 1st Example of this invention. It is a figure which shows the whole steel pipe damper which attached the friction band in the 2nd Example of this invention. It is a figure which shows the whole steel pipe damper which attached the friction band and pad in the 3rd Example of this invention. It is a figure which shows the whole steel pipe damper which attached the friction band and pad in the 3rd Example of this invention. It is a figure which shows the whole steel pipe damper which attached the friction band in 4th Example of this invention. It is a figure which shows the whole steel pipe damper which attached the friction band in 4th Example of this invention. It is a figure which shows the whole steel pipe damper which attached the pad in 5th Example of this invention.

Explanation of symbols

20 Rocking foundation 21 Pier base 22 Footing 23 Pile 24 Pile head 25 Steel pipe dampers 26, 72, 81, 83 Buffer material 27, 36 Steel pipes 28, 61, 72, 81, 83 Friction band 29 Filler 30 Sheath pipe 31 Press rod 33 Upper fixing material 34 Friction hole 35 Support hole 37 Screw fastening body 38 Protrusion 71, 73 Pad 82 Fixing protrusion

Claims (8)

A steel pipe damper interposed between a pile head of each of a plurality of piles that support the structure and the structure, and having a function of extending the natural period of the structure and a function of increasing damping when an earthquake occurs,
A steel pipe that can be moved relative to the pile head of each of the piles, and can be swelled and contracted;
A steel pipe damper comprising: one or more protrusions provided on an outer periphery of the steel pipe. A steel pipe damper interposed between a pile head of each of a plurality of piles that support the structure and the structure, and having a function of extending the natural period of the structure and a function of increasing damping when an earthquake occurs,
A steel pipe that can be moved relative to the pile head of each of the piles, and can be swelled and contracted;
A steel pipe damper comprising: a plate-like body that is fixed to the outer periphery of the steel pipe and is provided at least once. A steel pipe damper interposed between a pile head of each of a plurality of piles that support the structure and the structure, and having a function of extending the natural period of the structure and a function of increasing damping when an earthquake occurs,
A steel pipe that can be moved relative to the pile head of each of the piles, and can be swelled and contracted;
One or more protrusions provided around the steel pipe;
A steel pipe damper comprising: a plate-like body that is fixed to the outer periphery of the steel pipe and is provided at least once.   The steel pipe damper according to claim 2 or 3, wherein a plurality of the plate-like bodies are provided at predetermined intervals in the longitudinal direction of the steel pipe.   The steel pipe damper according to any one of claims 1 to 4, wherein the plate-like body or the protruding portion is provided so as to be 10 to 15% of a surface area of the steel pipe.   The steel pipe damper according to any one of claims 1 to 5, wherein a water repellent treatment is applied to a surface of the steel pipe.   A rocking foundation comprising the steel pipe damper according to any one of claims 1 to 6 interposed between a structure and each pile head of a plurality of piles supporting the structure. A construction comprising the steel pipe damper according to any one of claims 1 to 6 interposed between the construction and each pile head of a plurality of piles supporting the construction.

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