JP2016023443A - Vibration control structure for bridge, and setting method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration control structure for a bridge, which can reliably and effectively improve earthquake performance of the bridge by vibration control, and a setting method for the same.SOLUTION: A vibration control mechanism B, in which an inertia mass damper 4 and a spring member 5 are connected together in series, is installed in the state of being connected to upper and lower structures 2 and 3 in parallel with a bearing 6. The upper and lower structures 2 and 3 are relatively displaced, and a weight of the inertia mass damper 4 is rotated to exert an inertia mass effect. A frequency of the vibration control mechanism B, which is determined by the inertia mass damper 4 and the spring member 5, is synchronized with a predominant frequency of a bridge 1 by the spring member 5.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a bridge damping structure and a bridge damping structure setting method.

  In recent years, with the advancement of bridge technology, many multi-span continuous girder bridges that are effective in reducing vibration and noise and improving running performance have been designed and constructed. In addition, with the increase in the scale of the bridge, many structures that distribute the inertial force of the superstructure (superstructure such as girders and floor slabs) to the substructure (understructure such as piers and abutments) are often used. . For example, by using a rubber bearing for the bearing between the lower structure and the upper structure, and adjusting the horizontal rigidity (shear rigidity) of this rubber bearing, the inertial force acting on the lower structure can be adjusted and distributed arbitrarily. Many such structures are adopted.

  On the other hand, rubber bearings have much lower horizontal rigidity and larger deformation capacity than conventional pin bearings, but the damping is a few minutes compared to seismic isolation devices such as LRB (lead plug laminated rubber) and high damping rubber bearings. There is only about 1 and the deformation capability is small. For this reason, if an excessive seismic force exceeding the inertial force at the time of earthquake assumed at the time of design acts, there is a possibility that a bearing part and a substructure will be damaged. In particular, due to the Great Hanshin Earthquake and the Great East Japan Earthquake, design seismic ground motion has been reviewed and the input seismic force has increased, and as a result, there is an urgent need to develop technology for improving the earthquake resistance of existing infrastructure such as long-period ground motion. ing.

  Then, it has been proposed and studied to adopt seismic isolation technology and vibration control technology that have been applied to buildings and the like as a technical method for improving the seismic performance of bridges (for example, Patent Document 1, Patent Document 2, Patent) (Refer to Literature 3, Patent Literature 4, and Patent Literature 5).

JP 2009-228296 A JP 2006-9503 A JP-A-7-317822 Japanese Patent No. 3046192 JP 2004-332478 A

  First, the seismic isolation structure is effective when the response of the structure to be isolated is reduced by increasing the natural period. On the other hand, in the isolation of a bridge, it is necessary to suppress the deformation of the bridge, and a large laminated rubber bearing having a shear rigidity G of about 3 to 4 times that for construction is used. For this reason, the natural period is about 2 seconds, and it is not possible to effectively lengthen the period. Especially when the ground conditions are poor or long-period ground motion is required, a sufficient seismic isolation effect is exhibited. It is hard to be applied and its application becomes difficult. Furthermore, when existing bridges are to be seismically isolated, there are problems such as high costs and the inability to use the bridges during construction.

On the other hand, the damping structure can reduce the response relatively easily and at low cost by additionally installing a damping damper between the lower structure and the upper structure of the bridge to provide damping performance. The seismic performance of the bridge can be improved.
However, there is a problem that the effect of the damping damper becomes worse due to the deformation of the lower structure during an earthquake. Conversely, if the damper performance is increased to suppress the deformation of the bearing part, the shearing force of the lower structure and the acceleration of the upper structure are reduced. There is a disadvantage that it increases significantly.

  In view of the above circumstances, the present invention has an object to provide a bridge damping structure and a method for setting the bridge damping structure that can reliably and effectively improve the earthquake resistance performance of the bridge by damping. To do.

  In order to achieve the above object, the present invention provides the following means.

  The bridge damping structure according to the present invention includes a damping mechanism formed by connecting an inertial mass damper and a spring member in series, and connected to the upper structure and the lower structure in parallel with the support. As the structure is relatively displaced, the weight of the inertial mass damper rotates to exert an inertial mass effect, and the spring member reduces the vibration frequency of the damping mechanism determined by the inertial mass damper and the spring member. It is configured to be tuned to a superior frequency.

  In the bridge damping structure of the present invention, another damping damper is installed in parallel with the support in the upper structure and the lower structure, and the damping coefficient c ′ of the damping damper is expressed by the following formula (1) ) May be satisfied.

ここで、ｍ_２は橋桁質量（多径間の場合は一体化された橋桁の総重量）、ｋ_１は橋脚部の総水平剛性、ｋ_２は支承の総水平剛性である。

Here, m ₂ is the mass of the bridge girder (in the case of multiple spans, the total weight of the integrated bridge girder), k ₁ is the total horizontal rigidity of the bridge pier, and k ₂ is the total horizontal rigidity of the bearing.

Setting of the damping of the bridge of the present invention is a method for setting an optimum specifications of the damping of the bridge, the inertial mass of the inertial mass damper [psi _d and the damping coefficient c _d, the spring The stiffness k _d of the member is set by the following formulas (2) and (3), and k _d / k ₂ and Ψ are set using the total horizontal stiffness k ₁ of the bridge pier / the total horizontal stiffness k ₂ of the bearing as parameters in advance. The relationship between _d / m ₂ , h _d (= c _d / 2√Ψ _d k _d ) and Ψ _d / m ₂ is determined, and Ψ _d / m ₂ is set and k _d / k ₂ and Ψ relationship _d / _{m 2, h} seek optimal _{k d} and _{h d} from the relationship between _d and [psi _d / _{m 2,} the optimum [psi the optimal _{k d} and _{h d} and equation (2) from equation (3) and obtains the _d and _{c d.}

  In the bridge vibration control structure of the present invention, the upper structure and the lower structure are relatively moved by an earthquake or the like by installing a vibration control mechanism formed by connecting an inertial mass damper and a spring member in series to the support portion in parallel. While displacing, the inertial mass effect by the inertial mass damper can be exhibited. In addition, by adjusting the vibration frequency of the damping mechanism to the dominant frequency of the bridge (for example, the primary natural frequency of the bridge) by the spring member, it is possible to effectively inertia the vibration near the dominant frequency of the bridge. A mass effect can be exhibited.

 And since the damping mechanism is tuned and the inertial mass effect is exhibited only near the resonance frequency near the dominant frequency of the bridge, the displacement of the bearing and the acceleration of the superstructure (girder) are simultaneously reduced. it can. Moreover, the horizontal displacement of a support part can be suppressed effectively.

 Furthermore, since the shearing force acting on the substructure in the event of an earthquake is generally multiplied by the mass and acceleration of the superstructure, the bending moment of the pier and the force acting on the foundation, that is, the force acting on the substructure are also reduced. It becomes possible.

  Further, since it works only in the vicinity of the resonance frequency, there is no possibility that the burden force increases in a high frequency range unlike a conventional vibration damping device such as an oil damper. In addition, since the effectiveness of the damping mechanism can be adjusted by the spring member, it is possible to prevent the casing (upper structure, lower structure) from being damaged by the damper reaction force.

  As a result, by providing the bridge damping structure of the present invention, the strength of the bridge piers and piles of the existing bridge is small, and the response of the part that has caused great damage when not damped can be greatly reduced. It is possible to prevent (reduce) damage caused by earthquakes. In particular, the seismic performance can be improved without increasing the proof stress of a member such as a pile that is difficult to reinforce even by repair work such as a pile, and the seismic margin can be improved.

In addition, in the method for setting a vibration damping structure of a bridge according to the present invention, in addition to the effects of the above-described bridge vibration damping structure, “range of Ψ _d / m ₂ ”, “k _d / k ₂ and Ψ _d / m”. ₂ relationship "," h from _d relationship between [psi _{d /} m ₂ ", it is possible to obtain the other optimal specifications conveniently by setting the [psi _{d /} m _2, to achieve a tunable damping mechanism Can provide a practical method for. Further, if Ψ _d / m ₂ is increased, the response reduction effect is increased, but the reaction force of the vibration control mechanism is also increased, so that it can be set to an appropriate value in consideration of the strength of the beam and the pier.

It is a figure which shows the vibration damping structure (a) of a bridge and this vibration analysis model (b) concerning one embodiment of the present invention. It is sectional drawing which shows an example of the inertia mass damper of the vibration suppression structure of the bridge concerning one Embodiment of this invention. Side view of bridge (a), floor plan (b) showing a vibration analysis model used when performing a simulation to confirm the seismic performance of the bridge provided with the bridge damping structure according to one embodiment of the present invention, It is a X1-X1 arrow directional view (c) of (b). It is a diagram illustrating an example of a relationship of k _{d /} k ₂ and Ψ _{d /} m ₂ for use in a method of setting the bridge damping structure according to an embodiment of the present invention. Is a diagram illustrating an example of a relationship of h _d and Ψ _{d /} m ₂ for use in a method of setting the bridge damping structure according to an embodiment of the present invention. It is the result of the simulation performed in order to confirm the seismic performance of the bridge provided with the vibration damping structure of the bridge concerning one embodiment of the present invention, and is a figure showing the relation between the vibration frequency ratio and the acceleration response magnification. It is the result of the simulation performed in order to confirm the seismic performance of the bridge provided with the bridge damping structure according to one embodiment of the present invention, and is a diagram showing the relationship between the excitation frequency ratio and the reaction force response magnification. . It is the result of the simulation performed in order to confirm the seismic performance of the bridge provided with the vibration damping structure of the bridge concerning one embodiment of the present invention, and is a figure showing the relation between the vibration frequency ratio and the displacement response magnification. It is the result of the simulation performed in order to confirm the seismic performance of the bridge provided with the bridge damping structure according to one embodiment of the present invention, the vibration frequency ratio and the displacement response magnification (case with the damping structure) Only). It is a figure which shows the waveform of the input ground motion used in the simulation which confirms the seismic performance of the bridge provided with the damping structure of the bridge concerning one Embodiment of this invention. It is a result of the simulation performed in order to confirm the seismic performance of the bridge provided with the vibration damping structure of the bridge concerning one embodiment of the present invention, and is a figure showing the time history acceleration response waveform of the bridge girder part. It is a result of the simulation performed in order to confirm the seismic performance of the bridge provided with the vibration damping structure of the bridge concerning one embodiment of the present invention, and is a figure showing a time history displacement response waveform of a support part. It is a result of the simulation performed in order to confirm the earthquake resistance performance of the bridge provided with the vibration damping structure of the bridge concerning one embodiment of the present invention, and is a figure showing the time history shear force response waveform of a bridge pier. It is a result of the simulation performed in order to confirm the seismic performance of the bridge provided with the vibration damping structure of the bridge concerning one embodiment of the present invention, and is a figure showing the time history acceleration response waveform of the bridge pier top part.

  A bridge damping structure and a bridge damping structure setting method according to an embodiment of the present invention will be described below with reference to FIGS.

  As shown in FIG. 1, the bridge damping structure A of the present embodiment is a bridge damping structure such as a multi-girder continuous girder type viaduct, between the lower structure 3 and the upper structure 2 of the bridge 1. The vibration damping mechanism B is installed in the main body.

  Further, the vibration damping mechanism B of the present embodiment is configured by connecting the inertial mass damper 4 and the spring member 5 in series. For example, one end of the vibration damping mechanism B is superstructured so as to be arranged in parallel with the support portion (support 6). The other end of the bridge girder is connected to the bridge pier top (or the abutment top) of the lower structure 3.

  Further, the upper structure 2 and the lower structure 3 are relatively displaced and the weight of the inertial mass damper 4 is rotated to exert an inertial mass effect, and the vibration determined by the inertial mass damper 4 and the spring member 5 by the spring member 5. The number is tuned to the dominant frequency (for example, the primary natural frequency) of the bridge 1.

  That is, in the bridge damping structure A of the present embodiment, the inertial mass damper (inertial mass mechanism) 4 and the additional vibration system spring member (series spring) 5 are provided as the damping mechanism B, and the inertial mass damper is provided. The spring value (the inertia mass and the value of the spring member) is set so as to synchronize with the natural frequency determined from 4 and the spring member 5.

Here, an example of the vibration damping mechanism B of the present embodiment is shown in FIG.
The vibration damping mechanism B includes a rotary inertia mass mechanism (inertial mass damper 4) B1 and an additional spring mechanism (spring member 5) B2, and is configured by connecting the rotary inertia mass mechanism B1 and the additional spring mechanism B2 in series. Has been.

  The rotary inertia mass mechanism B1 includes a ball screw 10 provided with a central axis O1 coaxially arranged with the axis O1 of the vibration damping mechanism B, a ball nut 11 screwed to the ball screw 10, and The rotary nut 12 is attached to the ball nut 11 and rotates in accordance with the rotation of the ball nut 11.

  A connection member 13 such as a ball joint or a clevis for connecting to the upper structure 2 or the lower structure 3 of the bridge 1 is attached to one end 10 a of the ball screw 10.

  A ball nut 11 screwed to the ball screw 10 is supported by a bearing 14. The bearing 14 is disposed in an inner hole of the outer ring 14a and is rotatably supported around the axis O1. The annular outer ring 14a is fixed so as not to rotate around the axis O1 and cannot move in the direction of the axis O1. And an annular inner ring 14b. The ball screw 10 is disposed through the center hole of the inner ring 14 b of the bearing 14, and the ball nut 11 is fixed to the inner ring 14 b of the bearing 14. Thereby, the ball nut 11 is disposed so as to be rotatable around the axis O1 and immovable in the direction of the axis O1.

  Further, a rotating weight 12 is integrally fixed to the ball nut 11. The rotary weight 12 is formed, for example, in a substantially cylindrical shape, and is fixedly attached to the ball nut 11 with the ball screw 10 inserted therein and the ball screw 10 and the axis O1 of each other being coaxially arranged.

  On the other hand, the additional spring mechanism B <b> 2 is formed in a cylindrical shape with an outer cylinder 15 having a smaller outer diameter than the outer cylinder 15, and the axis O <b> 1 is coaxially arranged inside the outer cylinder 15. And an additional spring (spring member) 5 disposed between the outer cylinder 15 and the inner cylinder 16.

  The outer cylinder 15 is a hollow cylindrical body having a predetermined length of high-axis rigidity and high bending rigidity, and a disk-shaped connecting plate 17 is provided so that the other end (the left end in the figure) 15a is closed. A connecting member 18 such as a ball joint or a clevis for connecting the other end of the damping mechanism B to the lower structure 3 or the upper structure 2 of the bridge 1 is attached to the connection plate 17. Further, an annular support plate 19 penetratingly formed around an insertion hole through which the inner cylinder 16 is inserted is fixed to one end side (right end portion in the figure) 15b of the outer cylinder 15 so as to close the inside. Yes.

  Further, the outer cylinder 15 is provided on one end 15b side and fixed to the support plate 19, and guides the outer cylinder 15 in the direction of the axis O1 with respect to the inner cylinder 16 to relatively advance and retreat. Is provided. Further, the outer cylinder 15 is provided with a convex portion 21 protruding radially inward from the inner surface and extending from the other end 15a toward the one end 15b in the axis O1 direction on the other end 15a side. Further, the convex portion 21 is formed with a length dimension in the direction of the axis O1 according to the stroke amount of the vibration damping mechanism B.

  The inner cylinder 16 is a hollow cylinder having a predetermined length of high-axis rigidity and high bending rigidity, and is inserted into the insertion hole of the support plate 19 from the other end 16a side and disposed in the outer cylinder 15, and one end 16b. The side is provided outside the outer cylinder 15. At this time, one end 16b of the inner cylinder 16 is fixed to the outer ring 14a of the bearing 14 that rotatably supports the ball screw 10, and the inner hole of the inner ring 14b and the mutual axis O1 are coaxially arranged. It is provided as such. Further, the inner cylinder 16 has a predetermined interval (an interval defining the stroke amount of the vibration control mechanism) between the other end 16a and the connecting plate 17 fixed to the other end 15a of the outer cylinder 15 in the direction of the axis O1. Are disposed in the outer cylinder 15.

  In addition, the inner cylinder 16 protrudes radially outward on one end 16b extending outward from the support plate 19 of the outer cylinder 15 and extends in the direction of the axis O1, and the linear guide 20 engages with the outer cylinder 15 to engage with the outer cylinder 15. Is provided in the direction of the axis O1 with respect to the inner cylinder 16, and a linear guide rail 22 for advancing and retreating without relative rotation is provided. Further, a disc-shaped locking plate 23 having a diameter larger than the outer diameter of the inner cylinder 16 and smaller than the inner diameter of the outer cylinder 15 is fixed to the other end 16 a of the inner cylinder 16.

  On the other end 16 a side of the inner cylinder 16, a stroke defining plate 24 having an inner diameter substantially equal to the outer diameter of the inner cylinder 16 and an outer diameter slightly smaller than the inner diameter of the outer cylinder 15 is formed in a substantially annular shape. However, the other end 16a side of the inner cylinder 16 is inserted into the center hole and attached. The stroke defining plate 24 includes an outer peripheral roller 24 a that contacts the inner surface of the outer cylinder 15 and an inner peripheral roller 24 b that contacts the outer surface of the inner cylinder 16. The stroke defining plate 24 is provided so as to be movable back and forth in the direction of the axis O1 relative to the outer cylinder 15 and the inner cylinder 16 by the rollers 24a and 24b. At this time, the stroke defining plate 24 is brought into contact with one end in the axis O1 direction of the convex portion 21 of the outer cylinder 15, thereby restricting movement of the outer cylinder 15 toward the other end 15a in the axis O1 direction. By making contact with the locking plate 23 of the inner cylinder 16, the relative movement of the inner cylinder 16 toward the other end 16 a in the direction of the axis O <b> 1 is restricted.

  The spring member (addition spring) 5 of the additional spring mechanism B2 is provided between the outer surface of the inner cylinder 16 and the inner surface of the outer cylinder 15 and between the stroke defining plate 24 and the support plate 19 in the direction of the axis O1. In this embodiment, the spring member 5 is configured by arranging a set of disc spring groups in which a plurality of disc springs are stacked in series in the direction of the plurality of assembly axis O1. In FIG. 2, the spring member 5 at the intermediate portion in the axis O1 direction is omitted.

  As a result, a force that presses the stroke defining plate 24 toward the other end in the direction of the axis O1 is applied to the stroke defining plate 24 by the urging force of the spring member 5. It is provided so as not to move further to the other end side in the axis O1 direction. In this state, the locking plate 23 provided on the inner cylinder 16 contacts the stroke defining plate 24.

  When the outer cylinder 15 is relatively displaced toward the one end side in the axis O1 direction with respect to the inner cylinder 16, that is, when a compression-side force is applied to the vibration damping mechanism B, the stroke defining plate is applied to the convex portion 21. 24 is pressed, and at the same time, the stroke defining plate 24 is relatively displaced toward the one end side in the axis O1 direction with respect to the inner cylinder 16, and the spring member 5 is contracted. Further, when the outer cylinder 15 is displaced relative to the inner cylinder 16 relative to the other end in the axis O1 direction, that is, when a tensile force is applied to the vibration damping mechanism B, a stroke is applied to the locking plate 23. The regulating plate 24 is pressed, and at the same time, the stroke defining plate 24 is relatively displaced toward the one end side in the axis O1 direction with respect to the outer cylinder 15, and the spring member 5 is contracted.

  A cushioning material such as hard rubber is attached to the surface of the stroke defining plate 24 and the support plate 19 that contacts the spring member 5, the inner surface of the outer cylinder 15, and the outer surface of the inner cylinder 16, and noise ( It is preferable to prevent occurrence of mechanical noise) and wear.

  And when an earthquake etc. generate | occur | produces and vibration energy acts on the bridge 1 and relative displacement arises in the lower structure 3 and the upper structure 2 (when input), according to this displacement difference, a rotation inertia mass mechanism ( Inertial mass damper 4) The ball screw 10 of B1 advances and retreats in the direction of the axis O1, the ball nut 11 supported by the inner ring 14b of the bearing 14 rotates, and the rotating weight 12 rotates. As a result, an inertial mass effect several thousand times as large as the actual mass of the rotary weight 12 can be obtained, and the response displacement is greatly reduced as compared with the case where a conventional vibration damping device such as an oil damper is installed.

  Further, when a compression-side force acts on the vibration damping mechanism B and the outer cylinder 15 is displaced relative to the inner cylinder 16 of the additional spring mechanism B2 toward one end side in the axis O1 direction, a stroke defining plate is formed on the convex portion 21. 24 is pressed, and at the same time, the stroke defining plate 24 is relatively displaced toward the one end side in the axis O1 direction with respect to the inner cylinder 16, and the spring member 5 is contracted. Further, when a tension-side force acts on the vibration damping mechanism B and the outer cylinder 15 is displaced relative to the inner cylinder 16 toward the other end side in the axis O1 direction, the stroke defining plate 24 is pressed against the locking plate 23. At the same time, the stroke defining plate 24 is relatively displaced toward the one end side in the axis O1 direction with respect to the outer cylinder 15, and the spring member 5 is contracted.

  Then, due to the expansion and contraction of the spring member 5, the frequency determined by the rotary inertia mass mechanism (inertial mass damper 4) B1 and the additional spring mechanism (spring member 5) B2 is set to the frequency that is superior to the bridge 1 (for example, the primary natural vibration). Number).

  In addition, the rotary inertia mass mechanism B1 can obtain a large inertial mass effect several thousand times the mass of the weight by rotating the weight 12 with a relative displacement acting on both ends by a ball screw mechanism or the like, and is proportional to the acting relative acceleration. Reaction force. For this reason, the expansion and contraction (low speed) due to the temperature of the superstructure 2 of the bridge 1 follows with almost no reaction force.

  Next, as shown in FIG. 1 (a), FIG. 3 (a), FIG. 3 (b), and FIG. 3 (c), the vibration damping mechanism B of the present embodiment has a lower structure of the bridge 1 as described above. An inertia mass damper 4 and a spring member 5 are connected in series between a bridge pier top and the like 3 and an upper structure 2 such as a bridge girder.

The vibration model is as in FIG. 1 (b), the inertial mass [psi _d and the damping coefficient c _d in parallel, is modeled as a rigid k _d of the spring member 5 and the spring member 5 in series therewith. Then, the frequency determined by the inertial mass Ψ _d and the series spring k _d is set so as to be synchronized with the primary natural frequency of the bridge 1 to obtain a tuned vibration damping mechanism.

Here, in the setting method of the bridge damping structure A of the present embodiment, the bridge girder mass (total weight of the integrated bridge girder in the case of multiple spans) is m ₂ , and the mass of the bridge pier top portion (a plurality of piers are plural). In this case, the total sum) is m ₁ , the total horizontal stiffness of the bearing is k ₂ , the total horizontal stiffness of the pier is k ₁ , the inertia mass Ψ _d and the damping coefficient c _{d of} the inertia mass damper 4, and the stiffness of the spring member 5 k _{d is set} by the following equations (4) and (5).
Further, in _advance, the relationship of k d / _{k 2} and Ψ _d / _{m 2,} the relationship of _{h d} and Ψ _d / _{m 2} 4, previously obtained as shown in Figure 5.

ｋ_ｄ、ｈ_ｄについては図４、図５によって設定する。

k _d, the _{h d} is set by 4, 5.

  Here, the structural damping of the pier part which becomes the lower structure 3 is 5% with respect to the primary natural frequency, and the damping of the support part is ignored. Also, these values are the total values of the specifications for the integrated bridge girder. If the damper specifications are too small, there is no response reduction effect, and if they are too large, the bearing rigidity is increased (pin bearings are used). In the same manner as above, deformation can be suppressed, but the response reduction effect cannot be obtained. Considering this, the specifications are set as in the above range.

  Next, the result (trial design) of simulating the earthquake resistance performance of the bridge 1 when the bridge damping structure A of the present embodiment is provided using the above vibration model will be described.

  In this simulation, non-damping Case 1 without the vibration damping mechanism B and Case 2 with the vibration damping mechanism B formed by connecting the inertia mass damper 4 and the spring member 5 in series (the vibration damping of the bridge of the present embodiment). Two cases of structure A) were simulated and their simulation results were compared.

In addition, a bridge 1 with 3 spans was modeled as a vibration control target. The specifications of this bridge 1 are: bridge girder mass m ₂ = 1578 ton including road surface, pier mass m ₁ = 319 ton, bearing stiffness k ₂ = 73.5 kN / mm, substructure stiffness (understructure stiffness) k ₁ = 477 kN / mm. As a result, m ₁ / m ₂ = 0.2 and k ₁ / k ₂ = 6.5.
Further, the inertial mass of the vibration control mechanism B was set to ψ _d = 442 ton.

Then, as described above, by determining each item, and thus Ψ _d / m ₂ = 0.28 and k ₁ / k ₂ = 6.5, k _d / k ₂ = 0.45 from FIG. 4 and FIG. h _d = 0.29 can be obtained. As a result, k _d = 0.45 k ₂ = 33.1 kN / mm and c _d = 2.22 kN · sec / mm = 22.2 kN / kine.

  Next, the result of examining the difference in vibration characteristics in the frequency domain depending on the presence / absence of the vibration damping mechanism B of the present embodiment (Case 1 and Case 2) using a frequency transfer function will be described.

Here, the effective mass m _{1 of} the bridge pier, the mass m _{2 of the} bridge girder, the total displacement x _{i of} each mass point, the stiffness k _{i of} each layer, the inertia mass Ψ _d provided in the second layer, the additional damping c _d , the series spring ( Spring member) k _d , input acceleration (surface acceleration) x ₀ (above ・ ・), and setting as shown in the following formula (6), the acceleration response magnification can be obtained by the following formula (7) Can do. Note that i is an imaginary number (i = √ (−1)), ω is an excitation angular frequency (ω = 2πf (f is an excitation frequency)), and ω ₀₁ is the mass m ₁ of the first layer. An angular frequency determined by the stiffness k ₁ and ω ₀₂ is an angular frequency determined by the mass m ₂ of the second layer and the stiffness k ₂ .

Fig. 6 shows the response of the ratio of the excitation angular frequency (x ₂ (up to "..."), x ₁ (up to "...")) to the ground surface acceleration x ₀ (up to "...") It is the result shown by multiplying. The excitation frequency ratio ζ in FIG. 6 is a ratio of the excitation angular frequency ω = 2πf (f is the excitation frequency) with respect to ω ₀₂ = √ (k ₂ / m ₂ ).

From FIG. 6 and FIG. 7, it was confirmed that the response magnification at the time of resonance is significantly reduced by providing the tuning type vibration damping mechanism B (Case 2) of the present embodiment. In addition, since m ₂ >> m ₁ , it was confirmed that the reaction force of the lower structure 3 is approximately proportional to the acceleration of the bridge girder and that the reaction force of the lower structure 3 is similarly reduced.

In the case of the vibration damping structure A of the present embodiment (Case 2), the ratio of the reaction force of the part to the value obtained by multiplying the total mass above the part by acceleration is defined as the response magnification. The reaction force response magnification of the damping mechanism B is (reaction force of the damping mechanism) / m ₂ x ₀ (above “··”), and the reaction force response magnification of the lower structure 3 is (reaction force of the substructure) / ( m ₁ + m ₂ ) x ₀ (above “••”).

Then, as shown in FIG. 7, it was confirmed that the response magnifications of “support 6 + vibration control mechanism B” and lower structure 3 are substantially the same as the acceleration response magnification. Further, it was confirmed that the response magnification of the damping mechanism B increases only in the vicinity of the resonance frequency.
As a result, the vibration damping mechanism B of the present embodiment has a feature that works only in the resonance region and does not work in the high frequency region, and compared with the case where a vibration damping device such as a conventional oil damper is installed due to this feature, The power is reduced.

FIG. 8 shows the result of the ratio of each part displacement (relative displacement x ₂ −x ₁ , x ₁ −x ₀ ) to the ground surface displacement x ₀ as a response magnification. FIG. 9 shows the vertical axis in an enlarged manner only when the vibration damping structure A of the present embodiment is provided.

  From these FIG. 8 and FIG. 9, it was confirmed that the response magnification in the resonance region is significantly reduced by the vibration damping mechanism B of the present embodiment, and the displacement of the support portion is suppressed.

  Next, the result of examining the difference in response depending on the presence / absence of the vibration suppression mechanism B (Case 1 and Case 2) using time history analysis will be described.

Here, we input the II-II-3 seismic wave (maximum acceleration 736 gal) corresponding to the two types of ground in the level 2 earthquake motion shown in the Japan Road Association: Road Bridge Specification, and display the response result in the time history waveform Compared.
The waveform of this input ground motion is as shown in FIG.

  11 shows the acceleration of the bridge girder, FIG. 12 shows the displacement of the bearing, FIG. 13 shows the shearing force of the pier, and FIG. 14 shows the acceleration of the pier top.

  From FIG. 11, it was confirmed that the vibration damping mechanism B of the present embodiment halves the maximum response acceleration and greatly reduces the duration of shaking.

  From FIG. 12, it was confirmed that the displacement of the support portion was also halved by the vibration damping mechanism B, and was approximately within 200 mm. Furthermore, the number of times that the displacement exceeded 200 mm was also decreased from 7 to 1 each by the vibration damping mechanism B. In addition, the damper maximum reaction force during vibration suppression is 5690 kN (474 kN per vehicle), and since it is in series, the inertia mass damper 4 and the spring member 5 are the same. The maximum displacement (228 mm) was 210 mm for the inertia mass damper 4 and 141 mm for the spring member 5, and it was confirmed that the simple sum was larger than the bearing displacement. Since the damper maximum reaction force when the damping mechanism B is provided is in series, the inertia mass damper 4 and the spring member 5 are the same.

  From FIG. 13, it was confirmed that the shearing force acting on the substructure (pier pier) was also halved by the damping mechanism B, and the stress amplitude was also quickly attenuated. This proves that fatigue failure is less likely to occur because the number of occurrences of large stress is reduced.

  From FIG. 14, it was confirmed that although the acceleration at the pier top portion (lower support portion) is slightly reduced by the vibration control mechanism B, the reduction effect is not significant. Thereby, it was confirmed that the vibration control structure A of the bridge pier of this embodiment cannot aim at the response reduction of the acceleration of a bridge pier top part.

  Therefore, in the bridge damping structure A of the present embodiment, the horizontal displacement of the bearing 6 can be suppressed only by installing the rotary inertia mass damper 4 and the spring member 5 connected in series to the bearing 6 in parallel. The force (shearing force, moment) acting on the lower structure (pier pier) 3 can also be reduced, and the seismic force acting on the foundation can also be reduced.

  Thereby, the response in the site | part which had produced the big damage when the existing bridge pier part and the pile are low in proof and is not damped is greatly reduced by damping, and damage can be prevented or reduced. In particular, the seismic performance can be improved without increasing the proof stress of a member that is difficult to reinforce even during repair work such as a pile. That is, the seismic margin can be improved.

  In addition, since it is not necessary to replace the support 6 and the vibration control mechanism B is simply added, the bridge 1 can be used continuously during construction.

  Further, by using a tuned vibration damping mechanism including the inertial mass damper 4 and the series spring member 5, it is possible to effectively reduce the response only in the vicinity of the resonance frequency. ) Does not increase the acceleration response in the high frequency range.

  Further, since the high frequency component is not included, a large response reduction effect can be exhibited even though the reaction force (burden force) of the vibration damping mechanism B is smaller than that of the conventional vibration damping device. In particular, the cross-sectional performance of the girder beam is small in an old bridge, and the strength of the girder may be insufficient with respect to the reaction force of the vibration control device. Even if the reaction force is small, this embodiment has a high vibration damping effect. By adopting the bridge damping structure A, it is possible to suitably improve the seismic performance.

  Furthermore, since the vibration control mechanism B is a relatively simple operation that is simply arranged in parallel with the support portion 6, no special skills are required for the construction, and the vibration control mechanism B can be applied not only to a new construction but also to a vibration control repair of the existing bridge 1.

In addition, in the method for setting the bridge damping structure of the present embodiment, in addition to the above-described effects of the bridge damping structure A, “range of Ψ _d / m ₂ ”, “k _d / k ₂ and Ψ _d / M ₂ ”and“ relationship between h _d and Ψ _d / m ₂ ”, if Ψ _d / m ₂ is set, other optimum specifications can be easily obtained. A practical way to achieve this can be provided. Furthermore, if Ψ _d / m ₂ is increased, the response reduction effect is increased, but the reaction force of the vibration control mechanism B is also increased, so that it can be set to an appropriate value in consideration of the strength of the girders and piers.

  As mentioned above, although one embodiment of the bridge damping structure and the method for setting the bridge damping structure according to the present invention has been described, the present invention is not limited to the above embodiment and does not depart from the gist thereof. The range can be changed as appropriate.

  For example, in the present embodiment, the damping structure A is configured to include only the damping mechanism B formed by connecting the inertial mass damper 4 and the spring member 5 in series, but the inertial mass damper 4 and the spring are configured. In addition to the damping mechanism B formed by connecting the members 5 in series, another damping device (another damping damper) is added between the upper structure 2 and the lower structure 3 of the bridge 1 to suppress the vibration of the bridge. Structure A may be configured. Examples of other vibration damping devices include oil dampers, Bingham dampers, and other viscous dampers. By adding such vibration damping devices, the displacement of the support portion 6 is reduced, and the earthquake resistance is further improved. Can be made.

  However, if the added damping device (damping damper) is excessive, the displacement of the bearing portion can be reduced, but the response of the lower structure (bridge pier) increases, so the damping coefficient c ′ of the added damping device is It is desirable to attach a constraint condition represented by Expression (8).

  In addition, as a fail-safe mechanism against unexpected input ground motion, the inertial mass damper 4 is configured to include an overload prevention mechanism that stops the transmission torque, for example, by joining the rotary weight 12 and the ball screw mechanism via a friction material. It is preferable to do. Furthermore, it is preferable that the oil damper is provided with a relief valve on the piston, and an overload prevention mechanism that suppresses an excessive pressure increase in the cylinder.

DESCRIPTION OF SYMBOLS 1 Bridge 2 Superstructure 3 Substructure 4 Inertial mass damper 5 Spring member 6 Support (support part)
10 Ball screw 11 Ball nut 12 Rotating weight (weight)
13 connecting member 14 bearing 15 outer cylinder 16 inner cylinder 17 connecting plate 18 connecting member 19 support plate 20 linear guide 21 convex portion 22 linear guide rail 23 locking plate 24 stroke defining plate A bridge damping structure B damping mechanism B1 rotation Inertial mass mechanism B2 Additional spring mechanism O1 Damping mechanism axis

Claims (3)

A vibration damping mechanism consisting of an inertial mass damper and a spring member connected in series is connected to the upper structure and the lower structure in parallel with the bearing.
The upper structure and the lower structure are relatively displaced and the weight of the inertial mass damper is rotated to exert an inertial mass effect,
A bridge damping structure configured to synchronize a vibration frequency of the damping mechanism determined by the inertia mass damper and the spring member with an excellent vibration frequency of the bridge by the spring member. In the vibration damping structure of a bridge according to claim 1,
In parallel with the bearing, other damping dampers are installed connected to the upper and lower structures,
A damping structure for a bridge, wherein the damping coefficient c ′ of the damping damper satisfies the following expression (1).

Here, m ₂ is the mass of the bridge girder (in the case of multiple spans, the total weight of the integrated bridge girder), k ₁ is the total horizontal rigidity of the bridge pier, and k ₂ is the total horizontal rigidity of the bearing. A method for setting the optimum specifications of the bridge damping structure according to claim 1 or 2,
The inertia mass Ψ _d and the damping coefficient c _{d of} the inertia mass damper and the stiffness k _{d of the} spring member are set by the following equations (2) and (3),
In addition, the relationship between k _d / k ₂ and Ψ _d / m ₂ with the total horizontal rigidity k ₁ of the bridge pier / total horizontal rigidity k ₂ of the bearing as a parameter, h _d (= c _d / 2√Ψ _d k _d ) And the relationship between Ψ _d / m ₂ and
Relationship _k d / _{k 2} and Ψ _d / _{m 2} and sets the Ψ _d / _{m 2,} determined an optimal _{k d} and _{h d} from the relationship _{h d} and Ψ _d / _{m 2,} and the optimal _{k d} h _d and equation (2) and configure the damping structure of bridges and obtains the equation (3) from the optimum [psi _d and c _d.

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