JP2021161763A - Seismic retrofitting structure - Google Patents

Abstract

To provide a seismic retrofitting structure that can be more effectively reinforced in the renovation work of an existing building having the brace structure by adding a reinforcing member so as to be overlapped with the existing brace to be left.SOLUTION: The seismic retrofitting structure includes an existing frame having a lower horizontal member, an upper horizontal member, and a pair of columns erected between the lower horizontal member and the upper horizontal member, a pair of existing braces arranged on the existing frame, and an energy absorbing member added to the existing frame. The energy absorbing member is provided in a region where the existing frame and the pair of existing braces do not exist in the front view.SELECTED DRAWING: Figure 1

Description

The present invention relates to a seismic retrofitting structure.

Conventionally, some buildings such as houses have a brace structure in which a pair of braces are arranged in an X shape in a front view between a pair of pillars. It may be necessary to remove the existing brace in the renovation work that involves such a change in the floor plan of the building. In such cases, in order to compensate for the deterioration of seismic performance due to the removal of the existing brace and to further improve the seismic performance of the renovated building from which the existing brace was removed, a reinforcing brace is superimposed on the remaining existing brace. The technique has been proposed by the applicant (see Patent Document 1). According to such technology, the position of the existing brace to be left and the position of the reinforcing brace are the same, so that the reinforcing brace can be installed without reducing the degree of freedom in designing the floor plan by adding the reinforcing brace. The seismic performance of the building can be maintained.

JP-A-2017-172139

However, in the technique described in Patent Document 1, since the existing braces and the reinforcing braces are arranged so as to overlap each other diagonally in a front view within a limited wall thickness, the braces tend to interfere with each other. , It was difficult to take measures such as increasing the diameter of the brace to improve the seismic performance from the state before the renovation work.

In view of these circumstances, the present invention is more effectively reinforced in the renovation work of an existing building having a brace structure by adding a reinforcing member so as to overlap the existing brace to be left and performing seismic reinforcement. The purpose is to provide a seismic retrofitting structure that can be used.

The gist structure of the present invention is as follows.
(1) An existing frame having a lower horizontal member, an upper horizontal member, and a pair of columns erected between the lower horizontal member and the upper horizontal member.
A pair of existing braces placed on the existing frame and
The energy absorbing member added to the existing frame is provided.
The energy absorbing member is a seismic retrofitting structure provided in a region where the existing frame and the pair of existing braces do not exist in a front view.

(2) The energy absorbing member has a displacement direction parallel to a member located at the base in a region of a substantially isosceles triangle in front view, which is divided by the existing frame and the pair of existing braces. The seismic reinforcement structure according to (1) above, which is arranged near the member located at the bottom.

(3) The energy absorbing member is arranged so as to avoid interference with the pair of existing braces when a horizontal force acts on the existing frame and a maximum relative displacement occurs. ) Described in the seismic reinforcement structure.

(4) The seismic retrofitting structure according to any one of (1) to (3) above, wherein the pair of existing braces and the energy absorbing member are made of a steel material.

(5) The energy absorbing member is attached to the existing frame via the attachment member.
The energy absorbing members are substantially U-shaped and are paired, and their curved portions are arranged close to each other so as to face each other.
The length dimension of the contact surface to which the energy absorbing member of the mounting member is abutted matches the length dimension of the energy absorbing member as a whole, according to any one of (1) to (4) above. Described seismic reinforcement structure.

According to the present invention, it is possible to provide a seismic retrofitting structure that easily enhances seismic performance.

It is a front view which shows the seismic retrofitting structure which concerns on one Embodiment of this invention. It is a figure which shows an example of the energy absorption member. It is a front view which shows the seismic retrofitting structure which concerns on other embodiment of this invention. It is a figure which shows the arrangement which becomes the contrast of the energy absorption member. It is a figure which shows typically the deformation of the energy absorption member which becomes a contrast. It is a figure which shows the arrangement of the energy absorption member of a suitable example. It is a figure which shows typically the deformation of the energy absorption member of a preferable example.

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

FIG. 1 is a front view showing a seismic retrofitting structure according to an embodiment of the present invention. As shown in FIG. 1, the seismic retrofitting structure 1 of the present embodiment includes an existing building having a brace structure, and an energy absorbing member 2 and a rigid body 3 added to the existing building. The existing frame that constitutes the existing building is a steel structure composed of steel columns and beams. First, the existing frame and brace will be described.

<Frame>
The frame is composed of a foundation beam having a reinforced concrete structure and an upper frame composed of columns and beams (upper horizontal members) constructed on the foundation beam. In this example, the seismic retrofitting structure installed on the ground floor (first floor) will be described. As shown in FIG. 1, the frame has a foundation beam (lower horizontal member) 4, a beam (upper horizontal member) 5, and a pair of columns 6 and 7. Further, a pair of braces 8 and 9 are arranged on the frame. The top and bottom here are the top and bottom of the building in the vertical direction, and coincide with the top and bottom of the figure. Further, the left and right are one side and the other side in the horizontal direction in the horizontal plane orthogonal to the vertical direction, and are the left and right in the drawing.

<< Horizontal lumber >>
As shown in FIG. 1, the foundation beam 4 extends in the horizontal direction. Further, the beam 5 extends in the horizontal direction so as to overlap the foundation beam 4 in a plan view. Although not shown, the ends of the upper lumber 5 are fixed to columns or other lumbers. The beam 5 can be formed of, for example, H-shaped steel. The upper and lower flanges of the H-section steel are drilled with one or more holes for bolting at a predetermined pitch.

<< Pillar >>
The left column 6 and the right column 7 are connected to a column body made of a square steel pipe, a stigma connected to the upper end of the column body and joined to the beam 5, and a lower end of the column body, respectively. It has a column base portion configured to be joined to the foundation beam 4.

The column body is made of a square steel pipe as described above. The stigma has four standing pieces that are substantially plate-shaped and formed in a cross shape in a plan view, and horizontal pieces that are square plate-shaped and are arranged so as to cover the upper ends of the standing pieces. Each standing piece is provided with a hole for bolting the brace. Further, the horizontal piece is provided with a hole for bolting to the lower flange of the beam 5. The column base has four standing pieces that are substantially plate-shaped and formed in a cross shape in a plan view, and horizontal pieces that are square plate-shaped and are arranged so as to cover the upper ends of the standing pieces. Each standing piece is provided with a hole for bolting the brace. Further, the horizontal piece is provided with a hole for joining the foundation beam 4 via an anchor bolt.

The left column 6 and the right column 7 are joined to the foundation beam 4 via anchor bolts inserted into the holes in the column base, respectively, and the bolts inserted into the holes in the capital of the column 5 are joined to the beam 5. It is joined through.

<Brace>
The pair of braces 8 and 9 has a brace body and a pair of joint pieces provided at both ends of the brace body. The brace body is made of a round bar-shaped steel material, and the joint piece is made of a plate-shaped steel material, and holes for bolting are formed in the stigma and the column base of the column. One brace 8 of the pair of braces is bolted to the stigma of the left column 6 and the column base of the right column 7. The other brace 9 of the pair of braces is bolted to the stigma of the right column 7 and the column base of the left column 6.

<Energy absorption member>
FIG. 2 is a diagram showing an example of an energy absorbing member. The energy absorbing member 2 has a function of absorbing energy and attenuating the shaking of the building by deforming itself in response to the inter-story deformation of the building when a horizontal force such as an earthquake acts on the building. be. The energy absorbing member 2 can be, for example, any of a steel damper, a friction damper, an oil damper, a viscous damper, and a viscoelastic damper. In this embodiment, the case where the energy absorbing member 2 is a steel damper is shown. By forming the energy absorbing member 2 with the same steel material as the pair of braces 8 and 9, it is difficult for the energy absorbing member 2 to affect each other with respect to the structural characteristics, and the structural analysis becomes easy.
As shown in FIGS. 1 and 2, in the present embodiment, the energy absorbing member 2 has a substantially U-shape, and a pair extending continuously from each of the curved portion 2a and both ends of the curved portion 2a. It has an intermediate portion 2b of the above and a pair of fixed portions 2c extending continuously from the ends of the pair of intermediate portions 2b. A part of the pair of intermediate portions 2b and the pair of fixed portions 2c form a pair of facing portions facing each other (in a non-deformed state). The energy absorbing member 2 has the above-mentioned shape (substantially U-shaped) by bending a rectangular plate-shaped steel material. In the energy absorbing member 2 having such a shape, the pair of fixed portions 2c repeat the relative displacement in the extending direction in the positive and negative directions while maintaining the state parallel to each other (the curved portion in one facing portion). The vicinity of the curved part is curved with almost the same curvature as the curved part, and the other facing part is deformed so that the vicinity of the curved part becomes flat) and absorbs the energy corresponding to the displacement (deformation). can do.

The energy absorbing member 2 is provided with a plurality of holes for bolt joining in the fixing portion 2c of the seismic element, and is joined to the contact surface of the mounting member by bolt joining or the like as described later. The region where the deformation to the curved shape is constrained by and the flat shape is maintained is the fixed portion 2c, and the region where the arcuate curved shape is always maintained is the curved portion 2a, which changes between the curved shape and the flat shape. The possible region is the intermediate portion 2b.

Further, the state in which the one intermediate portion 2b is deformed into a curved shape up to the boundary portion with the fixed portion 2c and the other intermediate portion 2b is flattened to the boundary portion with the curved portion 2a is the relative energy absorbing member 2. The maximum amount of displacement is reached, and the maximum amount of relative displacement of the energy absorbing member 2 is determined by the position of the joint (the farther the position of the joint is from the curved portion, the smaller the region of the fixed portion 2c becomes. , The maximum amount of relative displacement of the energy absorbing member 2 becomes large).

In this example, as shown in FIG. 1, a pair of energy absorbing members 2 are arranged so that the curved portions 2a face each other (the curved portions 2a are closest to each other or are in contact with each other). It is preferable to leave a space of 5 to 10 mm between the curved portions 2a in consideration of deformation of the curved portion 2a, but it is also possible not to provide a gap. When the energy absorbing members 2 are provided as a pair, the fixed portions 2c may be arranged so as to face each other (so that the fixed portions 2c are closest to each other or in contact with each other). Further, the length dimension of the energy absorbing member 4 (not a pair but a single body) can be, for example, 250 to 400 mm, and the height dimension (dimension from one contact surface to the other contact surface) and width. The dimensions can be, for example, 50 to 150 mm.

When the energy absorbing members 2 are used in pairs, the fixing portions 2c may be arranged so as to face each other (so that the fixing portions 2c are closest to each other or in contact with each other). As shown, it is preferable to arrange the curved portions 2a so as to face each other (so that the curved portions 2a are closest to each other or in contact with each other). As shown in FIG. 4A as a comparison, when a pair of energy absorbing members 4 are arranged so that the fixing portions 2c face each other, a pair of restraining members having a contact surface having a length equal to that of the energy absorbing member 2 on both sides. As shown schematically in FIG. 4B, even if the energy is sandwiched between the two, when the displacement is relatively large, the vertical binding force is lost, so that the deformation is locally different from the initial curvature and has an inhomogeneous curvature. Is likely to occur, and the original function of the pair of facing portions absorbing energy due to relative displacement may not be fully exhibited. On the other hand, as shown in FIG. 5A, by arranging the pair of energy absorbing members 2 so that the curved portions 2a face each other, FIG. As schematically shown in (opposite direction of), the energy absorbing member 2 is always constrained by the pair of restraining members even when the relative displacement occurs, so that the curvature is the same as the initial curvature. Deformation in curvature is maintained, so that energy can be sufficiently absorbed and the shaking of the building can be dampened even more quickly. Further, according to such a configuration, the space required for installing the energy absorbing member 2 can be minimized.

<Mounting member>
The mounting member has a function of interposing between the frame (column / beam) and the energy absorbing member to cause a relative displacement according to the interlayer displacement when the frame is displaced between layers due to a horizontal force such as an earthquake. Have. The greater the rigidity of the mounting member, the more effectively it gives relative displacement to the energy absorbing member 2. However, the mounting member only needs to have enough rigidity to cause relative displacement of the energy absorbing member 2, and is a completely rigid body. It does not have to be.

<First mounting member>
The first mounting member 10 has a rectangular plate-shaped upper horizontal piece, a rectangular plate-shaped lower horizontal piece, and a rectangular plate-shaped standing piece that stands between the upper horizontal piece and the lower horizontal piece. It is a member with a substantially I-shaped cross section. A hole for bolting to the beam 5 is bored in the upper horizontal piece. Further, the lower surface of the lower horizontal piece is a contact surface to which the upper fixing portion 2c of the energy absorbing member 2 is in contact, and a hole for bolting to the energy absorbing member 2 is bored. When a horizontal force such as an earthquake acts, the first mounting member 10 is displaced following the displacement of the beam 5.

<Second mounting member>
The second mounting member 11 has a pair of rod-shaped members 11a and 11b, and a connecting member 11c to which the energy absorbing member 2 is joined to the pair of rod-shaped members 11a and 11b and having a contact surface. The pair of rod-shaped members 11a and 11b each have a pair of flat hollow members and a joining piece joined to the lower end of the pair of hollow members. The pair of hollow members are arranged so as to face each other so that the flat surfaces are separated from each other so as to avoid interference with the pair of braces 8 and 9. The lower end sides of the pair of rod-shaped members 11a and 11b are joined to the side surfaces of the pair of columns 6 and 7 near the lower ends of the column main body by a drill screw via a joining piece. Further, the connecting member 11c is a member having a substantially U-shaped cross section having a rectangular plate-shaped horizontal piece and a pair of hanging pieces that are rectangular plate-shaped and hang down from both ends of the horizontal piece, and each hanging piece has a substantially U-shaped cross section. A pair of rod-shaped members 11a and a pair of hollow members 11b are brought into contact with each other on the outer surface and joined with a drill screw. The upper surface of the horizontal piece is a contact surface to which the lower fixing portion 2c of the energy absorbing member 2 is in contact, and a hole for bolting the energy absorbing member 2 is formed. When a horizontal force such as an earthquake acts, the second mounting member 11 is displaced following the displacement of the foundation beam 4.
By attaching the pair of rod-shaped members 11a and 11b so that the pair of hollow members sandwich the pair of braces 8 and 9, interference with the pair of braces 8 and 9 is avoided. Further, the pair of rod-shaped members 11a and 11b intersect with the pair of braces 8 and 9 only at one place in the front view. Further, the pair of hollow members have a symmetrical shape when viewed from the extending direction of the structure surface.

In the pair of energy absorbing members 2, the pair of fixing portions 2c are bolted to the contact surface of the first mounting member 10 (upper surface of the upper horizontal piece) and the contact surface of the second mounting member 11 (lower surface of the lower horizontal piece). Has been done. The pair of energy absorbing members 2 are arranged so that the curved portions 2b side face each other and approach each other, and the end portions of the pair of energy absorbing members 2 on the fixed portion 2c side are the portion mounting members 10. It is configured to coincide with the contact surface and the end of the contact surface of the second mounting member 11.
Further, the energy absorbing member 2, the first mounting member 10, and the second mounting member 11 are contained within the thickness range of the pillars 6 and 7, and do not protrude from the surface connecting the surfaces of the pillars 6 and 7.

When the structure is deformed between layers due to the action of horizontal force such as an earthquake (that is, when the beam 5 is repeatedly displaced relative to the foundation beam 4 in the left-right direction), the contact surface of the first mounting member 10 corresponds to this. And the contact surface of the second mounting member 11, repeated relative displacements in the left-right direction occur, which deforms the energy absorbing member 2. At this time, the energy absorbing member 2 is repeatedly deformed while being restrained by the pair of contact surfaces and maintaining the same curvature. Further, the energy absorbing member 2 is a position closer to the beam 5 (a member located at the base of the isosceles triangle) in a region of a substantially isosceles triangle surrounded by the beam 5 and a pair of braces 8 and 9, and absorbs energy. Even when the maximum relative displacement occurs in the member 2, the energy absorbing member 2 and the lower mounting member 10 do not interfere with the pair of braces 8 and 9, and are substantially in the same direction as the extending direction of the beam 5. It is arranged so that relative displacement occurs.

Hereinafter, the action and effect of this embodiment will be described.

According to the seismic retrofitting structure of the present embodiment, the energy absorbing member 2 which is responsible for energy absorption and is the most important element in seismic performance is arranged in the area where the existing braces 8 and 9 do not exist in the front view. The degree of freedom in selecting the mechanism, size, shape, etc. of the energy absorbing member 2 is increased, the seismic performance can be easily improved, and the workability and maintainability are also good.

Further, in a region of a substantially isosceles triangle in front view divided by a frame and a pair of braces 8 and 9, the displacement direction of the energy absorbing member 2 is parallel to the member located at the base and at the bottom. Since it is arranged closer to the located member, interference with the existing frame is unlikely to occur, and damage to each component during an earthquake can be prevented.

Further, since the energy absorbing member 2 is arranged so as to avoid interference with the pair of braces 8 and 9 when a horizontal force acts on the frame and the maximum relative displacement occurs, each configuration at the time of an earthquake It is possible to prevent damage to the members.

Further, since the energy absorbing member 2 is made of the same steel material as the pair of braces 8 and 9, it is unlikely to affect each other with respect to the structural characteristics, and the structural analysis becomes easy (the structural analysis results calculated individually are simplified. By adding up to, structural analysis can be performed when both are combined).

Further, the energy absorbing members 2 are substantially U-shaped and are paired, and the curved portions are arranged close to each other so as to face each other. The length dimension of the contact surface of the first mounting member 10 and the second mounting member 11 matches the length dimension of the energy absorbing member 2 as a whole. Therefore, the energy absorbing member 2 can be made compact, and damage to each component can be prevented.

Further, in the present embodiment, since the side surfaces of the rod-shaped members 11a and 11b and the hanging pieces of the connecting member 11c are overlapped and joined with a drill screw at the overlapping portion, slippage and loosening are less likely to occur, and further. Since the surface is used, joining is easy, dimensional adjustment (absorption of error) is easy, and construction is easy. Further, in the present embodiment, since the rod-shaped members 11a and 11b and the column base are also drill-screw-joined, slippage and loosening are less likely to occur at this location, and construction is easy. It is also possible to bolt-join (co-sew) the lower end of the second mounting member 11 to the column base of the column with a single bolt together with the brace.

Subsequently, another embodiment of the present invention will be described with reference to FIG. The same configuration as that of the embodiment shown in FIG. 1 will be omitted, and different points will be described. FIG. 3 is a front view showing a seismic retrofitting structure according to another embodiment of the present invention. In the embodiment shown in FIG. 3, the first mounting member 10 and the second mounting member 11 are arranged in the left-right direction, and relative displacements of the first mounting member 10 and the second mounting member 11 occur in the vertical direction. The first mounting member 10 has a rectangular plate shape and is joined to the side surface of the pillar body of one pillar 6 with a drill screw (note that the first mounting member is omitted and the side surface of the pillar body of one pillar 6 is omitted. The energy absorbing member 2 may be joined to.) The second mounting member 11 extends from the other pillar 7 toward one pillar 6. The rod-shaped members 11a and 11b of the second mounting member 11 are joined together with the existing brace by one bolt by using the holes for bolting the existing brace of the column head and the column base (the column body). It may be joined to the side surface of the portion with a drill screw, or may be joined to the foundation beam 4 or the beam 5).
According to the seismic reinforcement structure of the embodiment shown in FIG. 3, the energy absorbing member 2 (and the second mounting member) in which the base of the isosceles triangle region in which the energy absorbing member 2 is housed is long and is relatively displaced in the vertical direction is provided. , Can be made less likely to interfere.

The seismic retrofitting structure is such that, for example, the energy absorbing member 2 having seismic performance equal to or higher than that before the renovation is overlapped with the existing brace to be removed in the same direction as the existing brace to be removed. It can be used by a method including a first step of installation and a second step of removing the outer peripheral wall or partition wall of the area where the opening is provided and the existing brace inside the wall. According to this method, it is possible to carry out renovation work such as removing the partition to make a large space or providing an entrance / exit and a window while maintaining structural safety without affecting other spaces. At this time, it is preferable to perform the second step after the first step, whereby the structural stability can be maintained even if an earthquake or the like occurs during the repair work.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. For example, the seismic retrofitting structure of the present invention may be applied to the second floor or higher, or may be applied to the reinforcement of a horizontal structural surface composed of horizontal braces. It can also be applied to buildings with wooden frames and braces. Further, the existing brace can be applied to various shapes such as a plate shape, a square shape, a pipe shape, etc., and may be arranged in a cheek cane shape, and further, energy in a form other than the brace. It can also be applied to absorbent members. Further, the existing brace may be arranged diagonally with respect to the square frame-shaped structure instead of the pillar.

1: Seismic retrofitting structure,
2: Energy absorbing member,
4: Foundation beam (lower horizontal lumber),
5: Beam (upper horizontal lumber),
6: Pillar,
7: Pillar,
8: Brace,
9: Brace,
10: First mounting member,
11: Second mounting member

Claims (5)

An existing frame having a lower horizontal member, an upper horizontal member, and a pair of columns erected between the lower horizontal member and the upper horizontal member,
A pair of existing braces placed on the existing frame and
The energy absorbing member added to the existing frame is provided.
The energy absorbing member is a seismic retrofitting structure provided in a region where the existing frame and the pair of existing braces do not exist in a front view. The energy absorbing member is arranged so that its displacement direction is parallel to the member located at the base in a region of a substantially isosceles triangle in a front view divided by the existing frame and the pair of existing braces. The seismic reinforcement structure according to claim 1, which is arranged near a member located at the bottom. The second aspect of the present invention, wherein the energy absorbing member is arranged so as to avoid interference with the pair of existing braces when a horizontal force acts on the existing frame and a maximum relative displacement occurs. Seismic retrofitting structure. The seismic retrofitting structure according to any one of claims 1 to 3, wherein the pair of existing braces and the energy absorbing member are made of a steel material. The energy absorbing member is attached to the existing frame via the attachment member, and the energy absorbing member is attached to the existing frame.
The energy absorbing members are substantially U-shaped and are paired, and their curved portions are arranged close to each other so as to face each other.
The method according to any one of claims 1 to 4, wherein the length dimension of the contact surface to which the energy absorbing member of the mounting member is abutted matches the length dimension of the energy absorbing member as a whole. Seismic reinforcement structure.

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