JP2021011690A - Brace and brace installation method - Google Patents

Abstract

To provide a brace and a brace installation method capable of simplifying a joint structure of the brace and a frame and effectively absorbing vibration energy of a building due to an earthquake.SOLUTION: A brace 20 is provided with a brace body 22 placed in a structure plane H of a frame 10, and a ring spring 30 arranged in a compressed state between the frame 10 and the brace body 22 and pressing the brace body 22 to the frame 10.SELECTED DRAWING: Figure 1

Description

The present invention relates to a brace and a brace installation method.

The following Patent Document 1 discloses a seismic retrofitting structure in which a compression brace is fixed to the skeleton of an existing building by using anchor bolts.

Japanese Unexamined Patent Publication No. 2015-183460

In the seismic retrofitting structure shown in Patent Document 1, it is necessary to perforate the skeleton and insert anchor bolts in order to construct the compression brace. Therefore, it takes time and effort for construction. Further, in this compression brace, energy cannot be stably absorbed on both the compression side and the tension side. Further, residual deformation occurs after the compression yield of the compression brace, which may reduce the energy absorption capacity for the second and subsequent compression forces.

In view of the above facts, an object of the present invention is to provide a brace and a brace installation method capable of simplifying the joint structure between the brace and the frame and effectively absorbing the vibration energy of the building due to an earthquake.

The brace according to claim 1 is a ring spring that is arranged in a compressed state between the brace body arranged in the frame surface and the frame and the brace body, and crimps the brace body to the frame. , Is equipped.

In the brace according to claim 1, a ring spring is arranged between the brace body and the frame in a compressed state. Therefore, the brace body is crimped to the frame by the restoring force of the ring spring. As a result, the brace body can be fixed to the frame without using anchor bolts or the like. That is, the joint structure between the brace and the frame can be simplified.

Further, when a compressive force acts on the brace, the ring spring receives a compressive load. At this time, the outer ring of the ring spring is pressed from the inner ring, and the inner ring is pressed from the outer ring. The frictional force between the outer ring and the inner ring can absorb the vibration energy of the building due to the earthquake.

Further, when a tensile force acts on the brace, the vibration energy of the building due to an earthquake can be absorbed by the energy absorption effect due to the frictional force between the outer ring and the inner ring.

The brace according to claim 2 includes a steel pipe covering the ring spring in the brace according to claim 1, and the brace body is in contact with the steel pipe in normal times.

In the brace according to claim 2, the ring spring is covered with a steel pipe, and the brace body is in contact with the steel pipe. Therefore, when a compressive force acts on the brace, the brace and the steel pipe can resist the compressive force. As a result, seismic performance is demonstrated.

Further, when a tensile force acts on the brace, the vibration energy of the building due to an earthquake can be absorbed by the energy absorption effect due to the frictional force between the outer ring and the inner ring of the ring spring. As a result, vibration damping performance is exhibited.

The brace installation method according to claim 3 includes a compression step of applying pressure to compress the ring spring, an arrangement step of arranging the compressed ring spring and the brace body on the structure surface of the frame, and releasing the pressurization. The brace body is provided with an opening step of crimping the brace body to the frame, and the amount of compression of the ring spring after the opening step is based on the amount of deformation of the ring spring when a predetermined design tensile force acts on the brace. large.

In the brace installation method according to claim 3, a ring spring compressed by pressurization is arranged between the brace body and the frame. By releasing this pressurization, the brace body is crimped to the frame. Further, the amount of compression of the ring spring is larger than the amount of deformation of the ring spring when a predetermined design tensile force acts on the brace. As a result, even if a predetermined design tensile force acts on the brace during an earthquake, it is easy to maintain the state in which the brace body is installed on the frame. Therefore, the brace can be fixed to the frame without using anchor bolts or the like. That is, the joint structure between the brace and the frame can be simplified.

When a compressive force acts on the brace, the ring spring receives a compressive load, the outer ring is pressed from the inner ring, and the inner ring is pressed from the outer ring. The frictional force between the outer ring and the inner ring can absorb the vibration energy of the building due to the earthquake.

Further, even when a tensile force acts on the brace, the vibration energy of the building due to an earthquake can be absorbed by the energy absorption effect due to the frictional force between the outer ring and the inner ring. As a result, vibration damping performance is exhibited.

According to the present invention, the joint structure between the brace and the frame can be simplified, and the vibration energy of the building due to an earthquake can be effectively absorbed.

It is sectional drawing which shows the frame in which the brace which concerns on 1st Embodiment of this invention is arranged. (A) is an elevational view showing a state in which the braces according to the first embodiment of the present invention are arranged in opposite directions on two structural surfaces, and (B) is an elevational view showing two braces arranged in opposite directions on one structural surface. It is an elevation view which shows the arranged state. (A) is a cross-sectional view showing a ring spring used for the brace according to the embodiment of the present invention, and (B) is a graph showing the relationship between the compressive force acting on the ring spring and the shaft contraction. It is a graph which showed the relationship between the compressive force acting on a ring spring and shaft contraction in the example which set the design stroke of the ring spring which concerns on 1st Embodiment of this invention larger than the stroke assumed at the time of an earthquake. It is a graph which showed the relationship between the compression force acting on a ring spring, a brace body and a steel pipe, and shaft shrinkage when the brace according to 1st Embodiment of this invention is compressed until a steel pipe and a brace body come into contact with each other. .. (A) is an elevation view showing the brace before being attached to the frame, (B) is an elevation view showing a state in which the pressurizing member is fixed to the brace, and (C) is a brace using the pressurizing member. It is an elevation view which shows the state which compressed the ring spring of. It is sectional drawing which shows the frame in which the brace which concerns on 2nd Embodiment of this invention is arranged. It is a graph which showed the relationship between the compression force acting on a ring spring, a brace body and a steel pipe which concerns on 2nd Embodiment of this invention, and shaft shrinkage.

Hereinafter, the brace and the brace installation method according to the embodiment of the present invention will be described with reference to the drawings. The components shown by using the same reference numerals in each drawing mean that they are the same components. In addition, description of overlapping configurations and symbols in the drawings may be omitted. The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications such as omitting the configuration or replacing it with a different configuration within the scope of the object of the present invention.

<First Embodiment>
(Frame)
FIG. 1 shows a brace 20 according to a first embodiment of the present invention. The brace 20 is a seismic structure applied to the structure surface H formed by the columns 12 and 14 in the frame 10 of the building including the columns 12 and the beams 14.

In the present embodiment, the columns 12 and the beams 14 are made of reinforced concrete, but these can be made of steel-framed reinforced concrete, steel-framed, or the like. Note that FIG. 1 shows a state in normal times, and it is assumed that no horizontal force is generated in the frame 10 due to an earthquake or the like.

(Arrangement of braces)
The brace 20 is obliquely hung between the joints (joints) between the columns 12 and the beams 14 on the structure surface H. As shown in FIG. 2A, it is preferable that a plurality of braces 20 are bridged along different directions on different structural surfaces H (construction surfaces H1 and H2) on the same floor.

Further, as shown in FIG. 2B, a plurality of braces 20 may be bridged along different directions on one structure surface H. In this case, one end of the brace 20 is joined to the central portion of the beam 14. The other end is joined to the joint between the column 12 and the beam 14.

(Brace structure)
As shown in FIG. 1, the brace 20 includes a brace body 22, plates 24, 26 and a core material 28. Further, the brace 20 includes a ring spring 30 and a steel pipe 40.

The brace body 22 is made of precast concrete, and one end thereof is joined (fixed) to the joint portion between the column 12 and the beam 14 via a grout material G. The brace body may be formed of a steel material such as an H-shaped steel or a square steel pipe.

A steel plate 24 is joined to the other end of the brace body 22. That is, the plate 24 is integrated with the brace body 22 and is a part of the brace body 22. One end of the core material 28, which will be described later, is joined to the plate 24, and a steel plate 26 is joined to the other end of the core material 28. That is, the core material 28 is sandwiched between the plates 24 and 26.

The core material 28 is formed to be stretchable by a rubber material. The core material 28 and the plates 24 and 26 are joined by, for example, vulcanization. As a result, the plate 24 and the plate 26 can move in a direction in which they are relatively in contact with each other.

The core material 28 is not limited to a rubber material as long as it is a stretchable material, and can be formed by using an elastic body such as a coil spring. Further, the method of joining the core material 28 and the plates 24 and 26 is not limited to vulcanization, and an appropriate method such as bonding with screws, bolts or an adhesive can be used.

The plate 26 is joined to the joint portion between the column 12 and the beam 14 via the grout material G. The plate 26 is fixed to the grout material G by the anchor material 26A welded to the plate 26.

(Steel pipe)
The steel pipe 40 is a cylindrical steel material (round steel pipe), and is arranged so as to cover the outer circumference of the ring spring 30. A gap is formed between the ring spring 30 and the steel pipe 40 so as not to prevent deformation (deformation in the radial direction) of the ring spring 30 described later. It is preferable that the steel pipe 40 is appropriately joined to the plate 26 by a method such as welding, bolting, or bonding.

Further, it is preferable that the steel pipe 40 is provided with a flange protruding in the radial direction at the end so that the compressive force from the brace main body 22 can be transmitted when the steel pipe 40 comes into contact with the plate 24.

(Ring spring)
The ring spring 30 is a cylindrical elastic body, and is arranged so that the axial direction of the cylinder substantially coincides with the axial direction of the brace body 22 and surrounds the core member 28. As shown in FIG. 3A, the ring spring 30 is formed by combining a plurality of inner rings 32 and a plurality of outer rings 34. In the following description, the axial direction of the ring spring 30, the inner ring 32, and the outer ring 34 is referred to as "axial direction".

The inner ring 32 is formed in an annular shape and has two conical surfaces 32A and 32B on the outer peripheral surface. The conical surfaces 32A and 32B are formed so that their diameters gradually decrease from the central portion to the end portion in the axial direction (direction along the axis CL) of the inner ring 32, respectively. Further, the inner rings 32 are arranged in a row along the axial direction, and a gap W1 is formed between the inner rings 32 adjacent to each other.

The outer ring 34 is formed in an annular shape having a diameter larger than that of the inner ring 32, and has two conical surfaces 34A and 34B on the inner peripheral surface. The conical surfaces 32A and 32B are formed so that their diameters gradually increase from the central portion in the axial direction of the outer ring 34 toward the end portions, respectively. Further, the outer rings 34 are arranged in a row along the axial direction, and a gap W2 is formed between the outer rings 34 adjacent to each other.

The conical surface 32A of the inner ring 32 and the conical surface 34A of the outer ring 34 are arranged in contact with each other, and the conical surface 32B of the inner ring 32 and the conical surface 34B of the outer ring 34 are arranged in contact with each other. In other words, the inner ring 32 and the outer ring 34 are arranged so as to be alternately overlapped with each other so that the conical surface 32B and the conical surface 34B, and the conical surface 32A and the conical surface 34A are in contact with each other.

When a compressive force (compressive load) P is applied to the ring spring 30, the inner ring 32 and the outer ring 34 are displaced along the axial direction so as to narrow the gaps W1 and W2, and the ring spring 30 contracts in the axial direction. In FIG. 3B, the relationship between the acting compressive force P and the axial contraction ε is shown by a straight line along the arrow L1.

At this time, the conical surface 32A of the inner ring 32 is pressed from the conical surface 34A of the outer ring 34, and the inner ring 32 is reduced in diameter. Similarly, the conical surface 34A of the outer ring 34 is pressed from the conical surface 32A of the inner ring 32, and the outer ring 34 expands in diameter. A frictional force acts between the conical surface 32A and the conical surface 34A, and a frictional force also acts between the conical surface 32B and the conical surface 34B. The ring spring 30 can absorb energy by this frictional force.

Further, when the compressive force P acting on the ring spring 30 is unloaded, the inner ring 32 and the outer ring 34 are displaced along the axial direction so as to widen the gaps W1 and W2 shown in FIG. 3A, and the ring spring 30 Extends in the axial direction. In FIG. 3B, the relationship between the unloading compressive force P and the shaft contraction ε is shown by a straight line along the arrow L2.

(Arrangement of ring springs)
In FIG. 1, the ring spring 30 is arranged in a compressed state (preloaded). Therefore, the ring spring 30 crimps the brace body 22 to the frame 10 via the plate 24 by the restoring force.

Further, the ring spring 30 is arranged so as to be able to expand and contract in the axial direction. That is, when a compressive force acts on the brace 20, the ring spring 30 is displaceable in the contracting direction, and when a tensile force acts on the brace 20, the ring spring 30 is displaceable in the extending direction.

(Action)
In the state shown in FIG. 1 (normal time), as shown in FIG. 4, the ring spring 30 is arranged in a state (state S0) in which precompression (compressive force P0, axial contraction ε0) is applied. That is, the ring spring 30 is arranged between the brace body 22 and the frame 10 in a compressed state. Therefore, the brace body 22 is crimped to the frame 10 by the restoring force of the ring spring 30. As a result, the brace body 22 can be fixed to the frame without using anchor bolts or the like. That is, the joint structure between the brace 20 and the frame 10 can be simplified.

Further, as shown by arrows in FIG. 1, when a horizontal force N1 (horizontal force in the direction of shrinking the diagonal line on which the brace 20 is arranged on the structure H) acts on the frame 10 during an earthquake, a “compressive force” is applied to the brace 20. Acts (under compressive load).

At this time, the ring spring 30 is compressed and contracted, and is deformed as shown by a solid line along the arrow L3 in FIG. At this time, the outer ring 34 of the ring spring 30 shown in FIG. 3 is pressed from the inner ring 32, and the inner ring 32 is pressed from the outer ring 34. When the inner ring 32 and the outer ring 34 press against each other, a frictional force acts on the ring spring 30.

Next, when a horizontal force N2 (horizontal force in the direction of extending the diagonal line on which the brace 20 is arranged on the structure surface H, see FIG. 1) acts on the frame 10 during an earthquake, a "tensile force" acts on the brace 20. As a result, the relationship between the shaft contraction and the compressive force in FIG. 4 changes as shown by the arrow L4.

As described above, in the present embodiment, the vibration energy is absorbed by the expansion and contraction of the ring spring 30 with respect to the horizontal forces N1 and N2 that repeatedly act on the frame 10 during an earthquake. As a result, vibration damping performance can be exhibited. The values of the horizontal forces N1 and N2 are not constant, but are values that change depending on the scale of the earthquake, and are values that change with the damping of vibration.

In the embodiment shown in FIG. 4, the design stroke Δε1 of the ring spring 30 (the length at which the ring spring 30 is “displaceable” from the state S0) is set to be larger than the assumed stroke Δε2 assumed at the time of an earthquake. ..

In other words, when the ring spring 30 is deformed by the assumed stroke Δε2 during an earthquake, the precompressive force (compressive force P0), the contraction ε0, and the ring spring 30 of the ring spring 30 are reduced so that the amount of deformation is smaller than the design stroke Δε1. Elasticity is set.

As a result, the ring spring 30 can continuously expand and contract within the expected amplitude range. Therefore, it is possible to improve the absorption efficiency of vibration energy in a building having a flexible frame that is easily displaced by an earthquake.

That is, the brace 20 can stably absorb energy on both the compression side and the tension side. Furthermore, the energy absorption capacity is unlikely to decrease due to the repeatedly acting compressive force and tensile force.

In FIG. 4, the compressive force acting on the ring spring 30 in the state where the ring spring 30 is compressed to the stroke end of the design stroke Δε1 (state S2) is shown as the compressive force P2. The "stroke end" is a stroke limit point at which the ring spring 30 can be compressed and deformed while absorbing energy by frictional force.

In FIG. 5, the relationship between the compressive force and the axial strain when the compressive force applied to the ring spring 30 becomes the compressive force P2 or more, that is, when the ring spring 30 is compressed beyond the stroke end, is shown by the arrow L5. It is shown by a solid line along.

At this time, the steel pipe 40 shown in FIG. 1 comes into contact with the plate 24 and receives a compressive force from the brace body 22. The brace 20 resists the compressive force by the steel pipe 40 and the brace body 22, and as shown by the solid line along the arrow L5 in FIG. 5, it resists the seismic force with a rigidity larger than the rigidity of the ring spring and can exhibit seismic performance. .. That is, the solid line along the arrow L5 shows the relationship between the compressive force of the steel pipe 40 and the brace body 22 and the axial strain.

As described above, the brace 20 can be set to be compressed beyond the stroke end (design stroke Δε1) of the ring spring 30. As a result, the brace 20 can exhibit not only vibration damping performance but also seismic performance.

Note that FIGS. 4 and 5 show a compressive force P1 acting on the ring spring 30 in a state where a "tensile force" is acting on the brace 20. When the compressive force acting on the ring spring 30 is less than the compressive force P1, the restoring force of the ring spring 30 is small and the force for crimping the brace body 22 to the frame 10 is small. Therefore, the brace body 22 may fall off from the frame 10 due to its own weight.

Therefore, it is preferable to maintain a state in which a compressive force of P1 or more is always applied to the ring spring 30 so that the brace body 22 does not fall off from the frame 10 due to its own weight. That is, it is preferable that the ring spring 30 is set so that the compressive force P3 acting when the stroke on the extension side reaches the maximum value (extension stroke Δε3) does not fall below the compression force P1. The "extension side" of the ring spring 30 indicates a state in which the ring spring 30 is stretched and deformed with the state S0 as the base point.

(How to install the brace)
FIG. 6A shows the brace 20 in a state before it is installed in the frame 10 (see FIG. 1). Prior to installation on the frame 10, a pressurizing member 50 is fixed to the brace 20 as shown in FIG. 6 (B).

The pressurizing member 50 includes fixing portions 52 and 54 and a jack 56. The fixing portion 52 and the fixing portion 54 are connected by a jack 56 and a PC steel rod 58, respectively. The fixing portion 52 is fixed to the brace body 22 with bolts or the like, and the fixing portion 54 is fixed to the plate 26 with bolts or the like.

In this state, the jack 56 is used to move the fixing portion 52 and the fixing portion 54 in a direction approaching each other. As a result, as shown in FIG. 6C, the ring spring 30 in the brace 20 is compressed and a pressurization is applied (compression step).

With the pressurizing member 50 fixed to the brace 20, the brace 20 (the brace body 22 and the compressed ring spring 30) is arranged on the structure surface H of the frame 10 shown in FIG. 1 (arrangement step).

After the brace 20 is temporarily fixed at a predetermined position on the structure surface H, the grout material G is filled between the brace 20 and the frame 10. When the grout material G is cured, the compressive force (pressurization) by the jack 56 is released, and the brace body 22 is crimped to the frame 10 (opening step).

As described above, in the method of installing the brace 20, it is not necessary to perforate the skeleton (column 12 or beam 14) and insert the anchor bolt in order to construct the brace 20. Therefore, it does not require much labor as compared with a configuration in which the skeleton needs to be drilled and anchor bolts are inserted.

The amount of compression of the ring spring 30 (axial contraction ε0, see FIG. 4) after releasing the compressive force of the jack 56 is assumed when a tensile force (a predetermined design tensile force in the present invention) acts on the brace 20. , Greater than the assumed stroke Δε2.

Therefore, even in a state in which a tensile force acts on the brace 20 and the ring spring 30 is extended to the maximum (a state in which the ring spring 30 is extended by the assumed stroke Δε2), the ring spring 30 is maintained in a compressed state. Therefore, even if a tensile force acts on the brace 20 during an earthquake, it is easy to maintain the state in which the brace body 22 is installed on the frame 10.

Further, as shown in FIG. 5, in the present embodiment, the compressive force P3 received when the ring spring 30 is fully extended (in the state where the stroke Δε3 is extended in FIG. 5) is applied to the brace body 22 by its own weight. It is larger than the compressive force P1 to prevent it from falling off.

Therefore, it is possible to enhance the effect of easily maintaining the state in which the brace main body 22 is installed on the frame 10. For example, even when the joint between the core material 28 and the plate 24 or the plate 26 shown in FIG. 1 is broken, the brace body 22 is unlikely to fall off from the frame 10.

<Second Embodiment>
In the second embodiment, as shown in FIG. 7, the ring spring 30 in the brace 20 is precompressed so that the steel pipe 40 and the plate 24 come into contact with each other in normal times. In the present invention, "the brace body is in contact with the steel pipe" includes a state in which the steel pipe 40 and the plate 24 integrated with the brace body 22 are in contact with each other. Further, the "normal time" in the present invention refers to a state in which the frame 10 is not subjected to an external force due to an earthquake, a strong wind, a tsunami, or the like.

Explaining with reference to FIG. 8, the ring spring 30 is arranged in a state (state S4) in which precompression (compressive force P2, shaft contraction ε4) is applied. The state of the ring spring 30 in the state S4 is substantially equal to the state S2 in the first embodiment. However, while the compressive force acts on the brace 20 in the state S2 in the first embodiment, the compressive force and the tensile force do not act on the brace 20 in the state S4 in the second embodiment.

In the second embodiment, when a horizontal force N1 (see FIG. 7) acts on the frame 10 during an earthquake, a “compressive force” acts on the brace 20. At this time, the brace 20 resists by the steel pipe 40 and the brace body 22, and as shown by the solid line along the arrow L5, it resists seismic force as a member having a rigidity larger than that of the ring spring, and can exhibit seismic performance. ..

Next, when a horizontal force N2 (horizontal force in the direction of extending the diagonal line on which the brace 20 is arranged on the structure surface H, see FIG. 7) acts on the frame 10 at the time of an earthquake, a "tensile force" is applied to the brace 20. It works. As a result, the relationship between the shaft contraction and the compressive force in FIG. 8 changes as shown by the arrow L6.

As described above, in the present embodiment, the steel pipe 40 and the brace body 22 exhibit seismic performance against the horizontal forces N1 and N2 that repeatedly act on the frame 10 during an earthquake. On the other hand, the vibration energy is absorbed by the expansion and contraction of the ring spring 30. As a result, vibration damping performance can be exhibited.

Also in this embodiment, it is preferable that the ring spring 30 is set so that the compressive force P5 acting when the stroke on the extension side reaches the maximum value (elongation stroke Δε5) does not fall below the compression force P1. ..

As described above, in the second embodiment, in the state where the compressive force acts on the brace 20 at the time of an earthquake, the ring spring 30 does not absorb the vibration energy, and the seismic performance can be immediately exhibited. For this reason, seismic performance can be efficiently exhibited in a building having a highly rigid frame that is difficult to be displaced by an earthquake (a building for which rigidity strength is desired to be imparted). On the other hand, in a state where a tensile force is acting on the brace 20, vibration damping performance can be exhibited.

In each of the above embodiments, the brace 20 includes a steel pipe 40, but the embodiment of the present invention is not limited to this. For example, as shown in FIG. 4, when the design stroke of the ring spring is set larger than the stroke assumed at the time of an earthquake, the steel pipe 40 and the plate 24 do not come into contact with each other at the time of an earthquake. Therefore, the steel pipe 40 can be omitted. As described above, the present invention can be implemented in various aspects.

10 Frame 20 Brace 22 Brace body 30 Ring spring 40 Steel pipe H Structure surface

Claims (3)

The brace body placed in the frame and the brace body
A brace provided with a ring spring that is arranged between the frame and the brace body in a compressed state and crimps the brace body to the frame. A steel pipe covering the ring spring is provided.
In normal times, the brace body is in contact with the steel pipe.
The brace according to claim 1. A compression process that applies pressurization to compress the ring spring,
The arrangement process of arranging the compressed ring spring and the brace body on the frame surface of the frame, and
It is provided with an opening step of releasing the pressurization and crimping the brace body to the frame.
A brace installation method in which the amount of compression of the ring spring after the opening step is larger than the amount of deformation of the ring spring when a predetermined design tensile force acts on the brace.