JPH11222820A - Construction and vibration-control of bridge pier - Google Patents

Abstract

PROBLEM TO BE SOLVED: To construct a bridge pier in one stage while sufficiently securing safety of the work, in a steel pipe-concrete composite structure. SOLUTION: In the construction method of a bridge pier, a plurality of hollow steel pipes 2 erected on a foundation 1 and arranged in accordance with the sectional shape of the bridge pier, are erected up to a specified height at every steel pipe and integrally welded together. And concrete is placed from the ground side to the uppermost side in order in the slip form method, at the outer periphery of the erected group of steel pipes 2, to form the pier frame body. After the group of steel pipes 2 nave been erected up to a designed height or the bridge pier, a TLD 5 is put on the uppermost scaffold arranged by connecting the steel pipes and then, the slip form method is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pier construction method and a vibration control method.

[0002]

2. Description of the Related Art The present applicant has previously developed a steel pipe / concrete composite pier. This pier is erected on the foundation,
A plurality of hollow steel pipes arranged in accordance with the cross-sectional shape of the legs are built up to the required height for each steel tube and integrated by welding, and a steel tube group integrated by welding, and concrete integrated on the outer periphery of the steel tube group, It constitutes the skeleton.

In this method of constructing a composite bridge pier, a group of steel pipes is erected in advance, and in the subsequent work of placing concrete, a number of longitudinal bars arranged around the group of steel pipes are joined as a preceding work. And, work to sequentially wind the PC strand around the outer periphery of the vertical streak,
In conjunction with this, by continuously casting concrete while gradually raising the formwork by the slip form method, it is possible to perform consistent construction from the ground to the top, rapid construction, automation, labor saving It is suitable for.

[0004]

In a pier having the above structure, when a tall pier having a height from the above-ground portion exceeding, for example, more than 60 m is to be constructed, when a group of steel pipes is built up to 60 m at a time. When a strong wind or an unsteady external force due to a small or medium-sized earthquake is applied, the rocking may continue, and in some cases, resonate, so that the stop portion of the steel pipe or the reinforcing bar may be broken.

[0005] Therefore, in the past, of course, while avoiding the time when strong winds are expected, it is obvious that the work is performed in two steps, such as the installation work of the steel pipe group and the joining work by welding and the like, and the slip forming method, to a certain height. (For example, 30m),
After the primary installation of the steel pipe group, the primary slip-form method was performed, and then the secondary installation and welding work of the steel pipe group was performed to the top, and then the secondary slip-form method was performed.

[0006] However, this two-stage construction method involves the removal of equipment to carry out the slip-form method after the completion of the primary work, the re-assembly work, and other setup changes, as well as the construction of work scaffolds and elevators. The work must be performed in parallel with the work, and the work is congested, the welding work of the steel pipe and the concrete placing work must be replaced and put on standby, and the advantage of rapid construction is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to suppress the shaking caused by an external force in a state where a group of steel pipes has been built up to a planned height in advance, thereby ensuring sufficient work safety. An object of the present invention is to provide a method for constructing a pier that can perform construction in one step while securing the pier.

Another object of the present invention is to provide a vibration damping method adapted to a natural period which changes from a state where a group of steel pipes is erected to a time when the construction is completed, and which can be adjusted to an optimum period. Is what you do.

[0009]

In order to achieve the above object, the present invention provides a plurality of hollow steel pipes which are erected on a foundation and arranged in accordance with the cross-sectional shape of a leg. Construction of a bridge pier that is built up by welding, etc., and concrete is sequentially poured from the ground to the top by slip form method etc. on the outer periphery of the built-in steel pipe group to form a leg body The method is characterized in that after the steel pipe group is built up to the planned height position of the pier, a vibration damping device is arranged at a top scaffolding position or the like arranged by connecting the steel pipe group.

As described above, according to the method of the present invention, even if the steel pipe is erected to the target height at one time, the vibration can be suppressed by the vibration damping device, and the safety of work can be ensured. In addition, after the building is completed, the slip-form method may be carried out, so that it is possible to eliminate problems such as setup changes and waiting for replacement of workers, as compared with the conventional two-stage construction method. It is suitable for construction of high piers exceeding

Further, according to the vibration damping method of the present invention, the vibration damping device comprises:
One or a plurality of tuned liquid dampers composed of a liquid storage tank installed on the scaffold or the like and a liquid stored in the liquid storage tank are used.

In the present invention, the tuning liquid damper (T
LD = TunedLiquidDamper, hereafter TL
D) is a type of passive damper for structural damping utilizing the fluctuation of liquid in a container. By adjusting the size of the container and the depth of the liquid, the sloshing (oscillation) period of the liquid is synchronized with the natural period of the structure, and the vibration of the target structure is suppressed.

The damping principle is based on the tuning mass damper (= T
Similar to MD), mounting a TLD on a structure alters the dynamic properties of the structure while simultaneously absorbing vibrational energy and reducing the response of the structure.

The TLD requires an optimal liquid sloshing damping, and the damping effect is a damper mass ratio (liquid mass /
(Structural mass). Therefore, in the present invention, it is possible to easily follow the periodic change of the structure by adjusting the amount of the liquid sealed therein in accordance with the periodic change of the structure due to the construction.

In the present invention, the liquid is muddy water or weighted muddy water, so that the installation space can be reduced.

The characteristics of the heavy muddy water TLD are as follows. Conventional TLDs mostly use water, and since sloshing attenuation based only on the viscosity of water is smaller than the optimal attenuation required, an additional attenuation increasing device is often required.

On the other hand, muddy water is bentonite, and heavy muddy water is a liquid obtained by adding a weighting material (barite) to bentonite.
It has properties such as high viscosity (several times or more of water), high specific gravity (1.4 times or more of water), material stability, and low cost. When used as a liquid for the TLD, it is expected that the vibration damping effect of the TLD will be improved and the structure will be simplified (the additional attenuation increasing device will not be needed) due to the optimum sloshing attenuation and high mass ratio.

Further, in the present invention, since the liquid storage tank is a liquid sealing portion formed by vertically dividing the upper part of the steel pipe, it is possible to save the trouble of newly installing the storage tank of the apparatus.

[0019]

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIGS. 1A to 1D show a procedure for constructing a tall pier according to the present invention. First, in (a), a steel pipe 2 is placed on a pier foundation 1 constructed in the ground.
Are arranged along the cross-sectional shape of the pier, and concrete is cast to a height at which the steel pipe 2 can maintain its self-supporting wind resistance and safety.

After the concrete is cast, the scaffold 3 is assembled around the obtained lower side frame as shown in FIG.
The steel pipe 2 is suspended by the crawler crane 4, and the welding work of the lower steel pipe 2 and the upper steel pipe 2 is repeated, and the steel pipe 2 is built up to the top of the planned pier.

After the completion of the installation of the steel pipe 2, the scaffold 3 is also assembled to the uppermost part in parallel with this as shown in FIG. At this stage, by installing the TLD 5 serving as a vibration damping device on a scaffold arranged around the top of the steel pipe, a vibration damping effect of the steel pipe group at this height can be obtained.

Further, a slip-form reaction force table 6 is arranged at the top of the group of steel pipes, and a slip-form suspension member 7 is hung below the slip-form reaction table. At this stage, it is also possible to arrange the main bars described later.

Thereafter, as shown in FIG. 2D, a tower crane 8 is arranged on the top, the slip-form form device 9 assembled on the lower side of the frame is connected to the suspension member 7, and the reaction By repeating the work of placing concrete inside while gradually increasing the force, the frame 10 of the pier is sequentially constructed.

FIG. 2 shows the arrangement of the TLD 5 at the top position, and FIG. 3 shows the internal structure of the TLD 5. In the figure, a total of nine steel pipes 2 in three rows and three rows are arranged in a pier cross-sectional shape at predetermined intervals, and a work scaffold 1 is provided between the pipes.
They are linked by 1.

Then, four TLDs 5 are arranged around the steel pipe 2 which is the center of the steel pipe 2 and the X axis of which the longitudinal direction is the horizontal direction.
By arranging two in the axial direction and two in the Y-axis direction so as to be point symmetric, it is possible to uniformly respond to the swing in each axial direction,
In addition, by arranging the steel pipes in two stages in the vertical direction to make a total of eight pieces, a mass ratio when the steel pipes 2 are arranged in a narrow gap is secured.

Each TLD 5 is, as shown in FIG.
Rectangular storage container 12 having a width corresponding to the shape of the gap between the two
Inside, heavy mud is stored.

As described above, heavy muddy water is a liquid obtained by adding a weighting material (barite) to bentonite and has a high viscosity (water number 1).
0 times or more), high specific gravity (1.4 times or more of water), and material stability. When the group of steel pipes 2 vibrates due to external force, sloshing occurs following the vibration and the storage container as shown in the figure. 12 collides with the inner wall.

The vibration is suppressed by setting the mass ratio of the heavy muddy water to the mass ratio tuned to the mass of the primary natural period of the pier, so that the capacity is smaller than in the case where water is used as the conventional liquid. Since the same function can be achieved in the above-described manner, it is possible to sufficiently secure the mass tuned to the natural period of the structure even in a narrow place as described above.

As described above, when a large external force such as an unsteady strong wind or seismic force is input, the vibration is attenuated at an early stage, and an unstable state due to shaking is corrected. In addition, it is possible to suppress the shaking caused by the steady wind force and the like, so that work safety can be secured.

Further, the natural vibration period of the group of steel pipes 2 changes sequentially from the initial state of the building just after the concrete is poured or the load changes, and the weight in the TLD 5 is changed according to the change. Increase or decrease the amount of mud, TLD
5 can be easily dealt with by increasing or decreasing it.

FIG. 4 shows a slip-form form device 9. This device 9 is arranged around the frame 10,
And a yoke 15 supported by the hanging member 7 via an ascending jack 14 in a suspended state, and a mold 16 fixed to the inside of the yoke 15 and formed in an inner shape corresponding to the outer shape of the frame 10. A lower working floor 17 fixedly arranged below the yoke 15 and surrounding the frame 10;
5 is provided on the upper work floor 5, and the main rebar 2 projecting above the frame 10 by a strand winding wheel 19 circling on a rail formed on the work floor 18.
The work of winding the PC strand 21 around the zero is performed prior to or in parallel with the concrete casting.

Therefore, while raising the above-mentioned form device 9 by driving the lifting jack 14, the winding of the PC strand 21 and the binding to the main bar 20 are performed at the upper part,
On the lower side, concrete 10 is poured into the inside of the formwork 16, so that the skeleton 10 is constructed consistently up to the uppermost position.

The liquid stored in the TLD 5 may be muddy water instead of heavy muddy water. Further, in the above embodiment, heavy muddy water was stored in the rectangular storage container 12, but the upper side of the steel pipe 2 at the top may be vertically divided by a partition wall or the like, and the upper part may be used as a storage part.
In this case, even after the completion of the tall pier and the bridge girder bridged over the pier, it can be used as it is as a vibration damping structure.

[0035]

Next, embodiments of the present invention will be described. However, the present invention is not limited only to the embodiments.

FIG. 5 shows a part of an actual pier, and a free vibration test (manual vibration) was performed on a steel pipe 2 having a height of 75 m from the surface of the actual pier before and after the installation of heavy muddy water TLD. , Its displacement waveform, Fourier spectrum, and attenuation state were compared.

In the free vibration experiment method, several persons reciprocated horizontally on the top of the pier in accordance with the natural period of the pier, and vibrated using the inertial force. When the displacement amplitude at the pier top reaches about 1 cm, the excitation is stopped, and the free vibration acceleration of the pier is measured three times with a measuring instrument connected to the accelerometer attached to each position in the cabin. And the average was calculated.

The results are shown in FIGS. First, FIG.
7 (a) and 7 (b) show free vibration waveforms in a direction perpendicular to the pier top (Y direction) before and after the installation of heavy muddy water TLD.
(B) is a Fourier spectrum before and after the same, FIG.
(A), (b) is the amount of attenuation before and after the same (calculated from the free vibration waveform).

As is clear from the results shown in the above graphs, the installation of the heavy muddy water TLD reduces the pier attenuation by about 1.5 to 2.5 times at the minute amplitude and about 2.5 to 3 times at the large amplitude. .0
It was confirmed that it increased twice.

By mounting the heavy muddy water TLD in the case of a large amplitude, the attenuation value is a value that does not cause unstable vibration such as vortex excitation due to wind or galloping (δ = 0.06).
It was confirmed that work safety was larger.

In the above embodiment, the present invention is applied to a method of constructing a pier, but the present invention is not limited to this. For example, vibration control at the time of constructing a control tower, a suspension bridge, a main tower, and the like. Needless to say, it can also be used for high-rise permanent structures in addition to the above.

[0042]

As is apparent from the above description, in the method for constructing a pier according to the present invention, the work safety can be improved by suppressing the swing caused by the external force when the steel pipe group is erected to the planned height. The construction can be performed in one stage while ensuring sufficient performance, compared to the conventional two-stage construction method,
There is no setup change or waiting for replacement of workers, so the construction period can be shortened. Therefore, for example, it is suitable as a method for constructing a tall pier having a height of 60 m or more. Further, the vibration damping method of the present invention includes:
There is an advantage that it can be adapted to the natural period that changes from the state where the steel pipe group is erected to the completion of the construction and can be adjusted to the optimum period.

[Brief description of the drawings]

FIGS. 1A to 1D are explanatory views showing a procedure for building a tall pier according to the present invention.

FIG. 2 is a plan view showing an arrangement state of heavy muddy water TLD in a portion A of FIG.

FIG. 3 is a sectional view taken along line CC of FIG. 2;

FIG. 4 is a detailed view of a slip-form form device in a part B of FIG. 1;

FIG. 5 is an explanatory diagram showing an arrangement relationship of an actual pier, a vibration meter, and the like in the embodiment.

FIGS. 6A and 6B are graphs showing free vibration waveforms before and after the installation of the same heavy muddy water TLD.

FIGS. 7A and 7B are graphs showing Fourier spectra before and after the installation.

FIGS. 8A and 8B are graphs showing attenuation before and after the installation.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Foundation 2 Hollow steel pipe 5 TLD (tuned liquid damper) 9 Slip-form formwork apparatus 10 Frame 11 Top scaffold 12 Storage container

Continued on the front page (72) Inventor Toshiaki Kato 2-3-3 Kandaji-cho, Chiyoda-ku, Tokyo Obayashi Corporation Tokyo head office

Claims (6)

[Claims] 1. A plurality of hollow steel pipes erected on a foundation and arranged in accordance with the cross-sectional shape of a leg are erected and integrated to a required height for each steel pipe, and are formed on the outer periphery of the erected steel pipe group. In the method of constructing a pier in which concrete is cast and a leg skeleton is formed, after the steel pipe group is erected to a planned height position of the pier,
A method for constructing a pier, comprising: disposing a vibration damping device at an uppermost portion connecting the steel pipe group. 2. The method according to claim 1, wherein the concrete is cast by a slip-form method. 3. The pier construction method according to claim 1, wherein the vibration damping device is installed on a work scaffold located at an uppermost position connecting the steel pipe group. 4. The method for constructing a pier according to claim 1, wherein said vibration damping device comprises one or more tuned liquids comprising a liquid storage tank and a liquid stored therein. A method of damping a pier, which is a damper. 5. The method according to claim 4, wherein the liquid is muddy water or weighted muddy water. 6. The method according to claim 4, wherein the liquid storage tank is a liquid enclosure formed by vertically dividing an upper portion of the steel pipe.