Method for seismic isolation of existing building and column structure

Abstract

To provide a method for seismic isolation of an existing building, which can reduce construction costs by making the structure compact when a new seismic isolation device is attached to an existing column of an existing building to realize seismic isolation, and a column structure.SOLUTION: The method for seismic isolation of an existing building 1 includes: a column reinforcement step in which an outer steel plate 21 is placed around the outer periphery of an existing column 2 and concrete is filled between the existing column 2 and the outer steel plate 21 to construct a concrete body 20 with an outer steel plate; a jack installation step in which a jack receiving member 50 is temporarily fixed to the outside of the outer steel plate 21 and a jack 70 is installed between the jack receiving member 50 and an upper structure 12 located above the jack receiving member 50; a seismic isolation device installation step in which, while operating the jack 70 to support the upper structure 12, a part of the existing column 2 is removed and a seismic isolation device 40 is inserted; and a temporary member removal step in which the jack 70 and the jack receiving member 50 are removed.SELECTED DRAWING: Figure 14

Description

[Technical field]

[0001] The present invention relates to a method for seismic isolation of an existing building, in which a new seismic isolation device is attached to an existing column of an existing building to achieve seismic isolation, and to a column structure. [Background technology]

[0002] In recent years, in preparation for the frequent occurrence of earthquakes, seismic isolation devices have been newly installed on specific floors of existing buildings that have already been constructed and are in operation, thereby isolating the existing buildings from seismic isolation. In this regard, Patent Document 1 discloses a seismic isolation method for existing buildings, in which an existing building supported by pile foundations is excavated below to expose the foundation and pile heads, a pressure plate is constructed at the bottom of the excavation, and the superstructure is temporarily supported by temporary support pillars made of steel and jacks erected on top of the pressure plate, and in this state the pile heads, which are the axial force transmission members between the superstructure and substructure, are cut and removed, and a seismic isolation device is installed in the axial force transmission path that was borne by the removed axial force transmission member, and the building load is transferred from the temporary support pillars to the seismic isolation device, thereby performing seismic isolation retrofitting of the existing building. As described in Patent Document 1, the general procedure for seismically isolating an existing building involves placing jacks around existing structures such as pillars and piles, temporarily supporting the load acting on the existing structure with the jacks, cutting the existing structure, inserting seismic isolation devices, and then removing the jacks.

[0003] Here, when installing a seismic isolation device on an existing column, if there is no body part such as a capital that protrudes laterally from the existing column and can transmit a load between the existing column and the existing column at the upper and lower ends of the existing column on the floor where the seismic isolation device is installed, the load acting on the existing column cannot be temporarily supported by the jack even if a jack is installed around the existing column. For this reason, in such a case, it is necessary to newly install a capital or the like at the upper and lower ends of the existing column so that the jack can be installed between the upper and lower capitals, so that when the existing column is cut, the load is transmitted from the upper capital to the lower capital via the jack. Even if a capital or the like is temporarily installed at the upper and lower ends of the existing column, if the capital is small and the position where the jack is to be installed is outside the capital when viewed in plan, it is necessary to enlarge the capital because the jack cannot be installed between the upper and lower capitals, as in the above case. The construction and expansion of capital as described above requires large construction costs, so it is desirable to either avoid constructing new capital or, if expansion is required, to keep the amount of expansion as small as possible in order to reduce construction costs as much as possible.

[0004] In this regard, Patent Document 2 discloses a seismic isolation method for existing buildings in which additional concrete is poured around the outer periphery of the axial force members of an existing building, leaving at least the area where a seismic isolation device should be inserted, and multiple temporary supports are interposed between the top surface of the lower additional concrete and the bottom surface of the upper additional concrete, and then the axial force members are cut in the area where the seismic isolation device should be inserted, after which the seismic isolation device is inserted into the cut portion of the axial force member, and the temporary supports are removed. Patent Document 3 also discloses a seismic isolation method in which reinforced concrete is poured around an existing column, the existing column is removed from the section where a seismic isolation device is to be inserted, the seismic isolation device is inserted into the space created in the removed existing column section, multiple sections of reinforced concrete surrounding the inserted seismic isolation device are removed, jacks are set between the top surface of the lower reinforced concrete and the underside of the upper reinforced concrete in the multiple spaces created in the removed reinforced concrete sections, the remaining reinforced concrete between the multiple jacks is removed, and the jacks are then removed.

[0005] In order to provide a seismic isolation device to an existing column, it is necessary to thicken the column by pouring concrete around the existing column so that the column can sufficiently support the seismic isolation device after construction, including at least the flange plate of the seismic isolation device. In Patent Documents 2 and 3, as described above, when pouring concrete around the upper and lower sides of the existing column, the poured concrete is formed so that the size of the poured concrete when viewed in plan is sufficiently larger than the flange plate of the seismic isolation device, and a certain area is secured between the outer contour of the flange plate and the outer contour of the poured concrete. Then, temporary supports and jacks are installed within this area, and a structure is created in which the load is transmitted between the upper and lower poured concrete by the temporary supports and jacks. In such a configuration, the temporary supports and jacks are installed not around the existing column but in the poured concrete installed on the existing column, so that the capital is basically sufficient if it is expanded to the range that supports the poured concrete installed on the existing column. Therefore, compared to the configuration of Patent Document 1, the amount of expansion of the capital may be reduced. However, in the configurations of Patent Documents 2 and 3, it is necessary to form additional concrete at least large enough to ensure an area for installing temporary supports and jacks outside the flange plate of the seismic isolation device. If this additional concrete could be made smaller, it may be possible to further reduce construction costs. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2013-53407 A [Patent Document 2] Patent No. 3731682 [Patent Document 3] JP 2013-147910 A Summary of the Invention [Problem to be solved by the invention]

[0007] The problem that the present invention aims to solve is to provide a method for seismic isolation of an existing building, and a column structure which, when attaching new seismic isolation devices to existing columns of an existing building, makes the structure compact and reduces construction costs. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention employs the following means. In other words, the method of seismic isolation for an existing building of the present invention is a method of seismic isolation for an existing building by attaching a new seismic isolation device to an existing column of the existing building to isolate the building from seismic energy, and is characterized by including a column reinforcement process of placing an outer shell steel plate around the outside of the existing column and filling concrete between the existing column and the outer shell steel plate to construct a concrete body with the outer shell steel plate; a jack installation process of temporarily fixing a jack receiving member to the outside of the outer shell steel plate and installing a jack between the jack receiving member and an upper structure located above the jack receiving member; a seismic isolation device installation process of operating the jack to support the upper structure, removing a part of the existing column and inserting the seismic isolation device; and a temporary member removal process of removing the jack and the jack receiving member. According to the above-mentioned configuration, the concrete body with the outer steel plate is placed around the existing column, the jack receiving member is temporarily fixed to the outer steel plate, a jack is placed between the jack receiving member and the upper structure, and the jack is operated. Then, the load can be transmitted from the upper structure to the concrete body with the outer steel plate and the existing column below via the jack and the jack receiving member. In this way, the load of the upper structure can be transmitted to the lower structure without going through the existing column, so that the removal of a part of the existing column and the insertion of the seismic isolation device into the removed part of the existing column can be performed reliably. Here, the jack receiving member on which the jack is installed is provided so as to be located outside the outer steel plate of the concrete body with outer steel plate. Therefore, the jack can be provided at a position that protrudes outward from the concrete body with outer steel plate when viewed in a plan view. In this way, the jack does not need to be supported at least entirely by the concrete body with outer steel plate, so when constructing the concrete body with outer steel plate, it is not necessary to make the concrete body with outer steel plate excessively large in consideration of installing the jack outside the seismic isolation device. Therefore, the concrete body with outer steel plate can be formed with a compact size, for example, to the extent that the lower flange plate of the seismic isolation device can be accommodated. In this way, when new seismic isolation devices are attached to existing columns of an existing building to achieve seismic isolation, it is possible to make the structure compact and reduce construction costs. In addition, since the jack support members are temporarily fixed to the outer steel plate, they can be removed after construction and reused for construction of other existing columns, which further reduces construction costs.

[0009] In one aspect of the present invention, the jack receiving members are provided in multiple numbers around the existing column, and the outer steel plate is provided with a plurality of support steel plate portions on the upper side of the outer steel plate that engage and temporarily fix each of the multiple jack receiving members and support them, and a connecting steel plate portion that is provided to surround the existing column and connects the support steel plate portions that are positioned opposite each other. According to this configuration, a jack can be installed between the jack receiving member temporarily fixed to the outside of the outer steel plate and the upper body located above the jack receiving member. When the jack is operated, the load can be transmitted from the upper body to the concrete body with the outer steel plate and the existing column below through the jack and the jack receiving member. When the axial force due to this load acts on the jack receiving member, the support steel plate part is pressed downward. Since the inside of the outer steel plate is filled with concrete and the support steel plate part is supported by the concrete from the inside, the axial force acts on the support steel plate part as a stress in the outward direction, opposite to the existing column. As a result, the support steel plate part tries to deform and displace by moving away from the concrete located on the inside to the outward direction. On the other hand, since the support steel plate parts located opposite to each other are connected by the connecting steel plate parts, the connecting steel plate parts resist the bulging stress generated in the outward direction acting on the support steel plate parts, and the deformation and displacement of the support steel plate parts can be suppressed. In addition, by providing the connecting steel plate section, it is possible to reduce the bulging stress and ensure the strength and durability of the structure.

[0010] In one aspect of the present invention, the column structure of the present invention is a column structure in which a seismic isolation device is attached to an existing column, the existing column being made of reinforced concrete, and an outer shell steel plate is arranged around the outer periphery of the existing column below the seismic isolation device, and concrete is filled between the existing column and the outer shell steel plate to construct a concrete body with an outer shell steel plate, and the outer shell steel plate comprises a steel plate main body and a supporting steel plate portion provided above the steel plate main body and having a thickness greater than that of the steel plate main body, and a notch is provided on the inner surface side of the supporting steel plate portion. According to the above-mentioned configuration, a column structure with a seismic isolation device attached to an existing column can be constructed by following the steps below. First, a concrete body with an outer steel plate is constructed around the existing column. Next, a jack receiving member for supporting a jack is temporarily fixed to the outer steel plate so as to be located outside the outer steel plate. This temporary fixing can be performed by engaging the jack receiving member with a recess provided on the inner surface side of the support steel plate provided on the upper side of the outer steel plate. Then, a jack is installed between the jack receiving member and the upper body located above the jack receiving member, and the jack is operated. As a result, the load can be transmitted from the upper body to the concrete body with the outer steel plate and the existing column below via the jack and the jack receiving member, so that a part of the existing column can be removed and the seismic isolation device can be inserted and fixed. In this way, the jack receiving member on which the jack is installed can be provided so as to be located outside the outer steel plate of the concrete body with outer steel plates. Therefore, the jack can be provided at a position that protrudes outward from the concrete body with outer steel plates when viewed in a plan view. In this way, the jack does not need to be supported at least entirely by the concrete body with outer steel plates, so when constructing the concrete body with outer steel plates, it is not necessary to make the concrete body with outer steel plates excessively large in consideration of installing the jack outside the seismic isolation device. Therefore, the concrete body with outer steel plates can be formed with a compact size, for example, to the extent that the lower flange plate of the seismic isolation device can be accommodated. In this way, when new seismic isolation devices are attached to existing columns of an existing building to achieve seismic isolation, it is possible to make the structure compact and reduce construction costs. In addition, since the jack support members are temporarily fixed to the outer steel plate, they can be removed after construction and reused for construction of other existing columns, which further reduces construction costs. Effect of the Invention

[0011] According to the present invention, it is possible to provide a method for seismic isolation of an existing building and a column structure which can make the structure compact and reduce construction costs when new seismic isolation devices are attached to existing columns of an existing building to isolate the building from seismic energy. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing the configuration of an existing building to which a seismic isolation method for an existing building according to an embodiment of the present invention is applied. [Diagram 2] 1 is a diagram showing a column structure of an existing building that has been seismically isolated by the method for seismically isolating an existing building according to this embodiment. FIG. [Diagram 3] 2. FIG. 3 is a cross-sectional view of the portion viewed from the arrow II in FIG. [Figure 4] This is an enlarged cross-sectional view of the upper part of a concrete body with outer steel plates. [Diagram 5] FIG. 2 is a diagram showing the flow of the seismic isolation method for an existing building according to the present embodiment. [Figure 6] This is a diagram showing the state in which a lower beam reinforcement part is formed on the existing beam on the lower side of an existing building, and an upper footing is formed on the column-beam joint on the upper side. [Figure 7] This is a diagram showing the state in which outer steel plates are placed around the outer periphery of the lower side of the existing column. [Figure 8] This is a diagram showing the state in which concrete has been filled between the existing column and the outer steel plate. [Figure 9] 13 is a diagram showing a state in which multiple jack support members are temporarily fixed to an outer steel plate. FIG. [Figure 10] FIG. 4 is an enlarged cross-sectional view showing a jack support member temporarily fixed to an outer steel plate. [Figure 11] This is a view of the jack support member as seen from the outside of the outer steel plate. [Figure 12] A figure showing a state in which multiple jacks are installed between multiple jack receiving members and an upper body. [Figure 13] This is a diagram showing the state after part of the existing pillar has been removed. [Figure 14] This is a diagram showing the state in which a seismic isolation device is inserted between an existing column and an upper structure. [Figure 15] FIG. 1 is a diagram showing an example of an analytical model used in a simulation analysis. [Figure 16] FIG. 16 is a diagram showing the results of an FEM analysis of the analysis model of FIG. 15. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The present invention relates to a method for seismic isolation of an existing building, in which a new seismic isolation device is attached to an existing column of the existing building to achieve seismic isolation, and a column structure in which a seismic isolation device is attached to an existing column. The method for seismic isolation of an existing building involves pouring additional concrete bodies with outer steel plates around the periphery of the existing column, installing jack receiving members and jacks as temporary axial force support means on the top of the outer steel plates constituting the permanent concrete body with outer steel plates, removing a part of the existing column while supporting the existing structure, and installing a seismic isolation device in the removed part. Hereinafter, a method for seismic isolation of an existing building and an embodiment of a column structure according to the present invention will be described with reference to the accompanying drawings. (Existing building) FIG. 1 shows a cross-sectional view illustrating the configuration of an existing building to which a seismic isolation method for an existing building according to an embodiment of the present invention is applied. As shown in Fig. 1, an existing building 1 to which a seismic isolation method for an existing building according to an embodiment of the present invention is applied has an existing column 2. The existing column 2 extends in the vertical direction. The existing column 2 is joined to existing beams 3 on each floor spaced apart in the vertical direction. The existing beams 3 on each floor support a slab 4 from below. In this embodiment, the existing column 2 and the existing beams 3 are made of, for example, reinforced concrete.

[0014] (Column structure with seismic isolation) FIG. 2 is a diagram showing a column structure of an existing building that has been seismically isolated by the method for seismically isolating an existing building according to this embodiment. As shown in Figure 2, the column structure 10 of an existing building 1 that has been seismically isolated by the seismic isolation method for an existing building of this embodiment, which will be described in detail later, is located between a lower structure 11 and an upper structure 12. The lower framework 11 is formed below the column structure 10 of each floor, and integrally comprises the lower existing beam 3, the slab 4, and lower beam reinforcement parts 14 formed on both sides in the beam width direction of the lower existing beam 3. The lower beam reinforcement parts 14 are formed by pouring additional concrete so as to expand the existing beam 3 outward. The upper structure 12 is formed above the column structure 10 of each floor, and integrally comprises the upper existing beam 3 and an upper footing 15 formed at the joint between the existing beam 3 and the existing column 2. The upper footing 15 is formed by pouring additional concrete to expand the existing column 2 outward and downward in order to reinforce the joint between the upper existing beam 3 and the existing column 2. The column structure 10 comprises a lower portion 2B of the existing column 2 remaining after the upper portion has been removed, a concrete body 20 with an outer steel plate provided around the outer periphery of the lower portion 2B, a seismic isolation device 40 provided between the lower portion 2B of the existing column 2 and the upper structure 12, and a lower base 41 and an upper base 42 to which the seismic isolation device 40 is joined.

[0015] Fig. 3 is a cross-sectional view of the portion viewed from the arrow II in Fig. 2. Fig. 4 is an enlarged cross-sectional view of the upper part of the concrete body with the outer steel plates. As shown in Fig. 2 and Fig. 3, the concrete body 20 with exterior steel plates includes an exterior steel plate 21 and a concrete portion 22. The exterior steel plate 21 is provided at a predetermined interval on the outside of the lower portion 2B of the existing column 2. In this embodiment, the existing column 2 is rectangular in plan view. The exterior steel plate 21 has a rectangular tubular shape in plan view extending in the up-down direction, and has four steel plate bodies 21a-21d arranged at intervals on the outside of the four side surfaces 2s of the existing column 2.

[0016] The outer steel plate 21 has a plurality of supporting steel plate parts 25 at its upper part for supporting a jack receiving member described later. As shown in FIG. 3, the plurality of supporting steel plate parts 25 are provided at the four corners of the outer steel plate 21 when viewed from the top-bottom direction. The plurality of supporting steel plate parts 25 are provided two at each of the upper parts of the steel plate bodies 21a, 21c facing each other among the four steel plate bodies 21a to 21d. The plurality of supporting steel plate parts 25 are provided on both sides in the width direction of the steel plate bodies 21a, 21c. In this way, the plurality of supporting steel plate parts 25 are provided at approximately equal intervals in the circumferential direction of the cylindrical outer steel plate 21. As shown in FIG. 3, the two supporting steel plate parts 25 depicted on the upper side in FIG. 3 are provided facing each other, that is, at positions opposite each other with respect to the existing column 2 as the center. Similarly, the two supporting steel plate parts 25 depicted on the lower side in FIG. 3 are provided facing each other, that is, at positions opposite each other with respect to the existing column 2. A part of the upper part of the steel plate main body 21a, 21c is cut out according to the contour shape of the supporting steel plate part 25, and the multiple supporting steel plate parts 25 are installed and welded to this cut-out part. In this way, the multiple supporting steel plate parts 25 are provided so as to extend in the vertical direction in the same plane as the steel plate main body 21a, 21c, and are joined to the steel plate main body 21a, 21c. The steel plate main body 21a to 21d and the multiple supporting steel plate parts 25 form a part of the outer shell steel plate 21 that surrounds the concrete part 22 described later from the outside. Each supporting steel plate part 25 has a plate thickness larger than that of the steel plate main body 21a, 21c. As shown in Figure 4, a recess 25s is formed on the inner surface side of the upper end of each support steel plate portion 25 so that the height of the radially inner side, i.e., the side facing the existing column 2, of the cylindrical outer shell steel plate 21 is lower than the height of the radially inner side, i.e., the side facing the existing column 2, centered on the axial direction of the outer shell steel plate 21, than the height of the radially inner side, i.e., the side facing the existing column 2. The multiple supporting steel plate portions 25 are provided at positions such that when a jack receiving member described below is provided, the upper surface of the jack receiving member will be at the same height as the upper surface 2t of the lower portion 2B of the existing column 2.

[0017] 2 to 4, the exterior steel plate 21 has a connecting steel plate portion 27 on its upper portion. The connecting steel plate portion 27 is provided so as to extend in a horizontal plane. The connecting steel plate portion 27 is formed in a rectangular shape in a plan view, and has a hole provided in the center. The connecting steel plate portion 27 is provided so that the existing column 2 is inserted through this hole. More specifically, the connecting steel plate portion 27 is formed in a continuous ring shape in the circumferential direction of the existing column 2 so as to surround the lower portion 2B of the existing column 2 when viewed from the top-bottom direction. The connecting steel plate portion 27 is provided on the upper portion of the steel plate main bodies 21a-21d, on the radially inner side of the steel plate main bodies 21a-21d, i.e., on the existing column 2 side. The connecting steel plate portion 27 is welded to the inner side of the multiple supporting steel plate portions 25. As a result, the multiple supporting steel plate portions 25 are connected to each other via the connecting steel plate portion 27. In particular, the connecting steel plate portion 27 connects the supporting steel plate portions 25 positioned so as to face each other. Also, as shown in FIG. 3, the connecting steel plate portion 27 is welded to the inner side surface 21s of the outer shell steel plate 21 in a portion where the multiple supporting steel plate portions 25 are not provided. The inner edge 27a of the connecting steel plate portion 27 is arranged at a distance from each side surface 2s of the lower portion 2B of the existing column 2. Concrete sections 22 , which will be described later, are provided both above and below the connecting steel plate sections 27 , and the connecting steel plate sections 27 are embedded in the concrete sections 22 .

[0018] 2, a plurality of stud bolts 23 are provided on the outer steel plate 21 below the connecting steel plate portion 27. Each stud bolt 23 is welded to the inner surface 21s of the outer steel plate 21. Each stud bolt 23 is provided so as to protrude and extend from the inner surface 21s toward each side surface 2s of the existing column 2 located radially inward, and is fixed to the concrete portion 22 described next.

[0019] The concrete portion 22 is formed by pouring and filling concrete into the gap between the outer steel plate 21 and the existing column 2. The concrete portion 22 is integrally joined to the outer steel plate 21 via the stud bolt 23. The concrete portion 22 is formed so that its upper surface 22t is located at a position higher than the upper end of the exterior steel plate 21. The upper surface 22t of the concrete portion 22 is at the same height as the upper surface 2t of the lower portion 2B of the existing column 2.

[0020] A plurality of post-installed anchors 28 are driven into each side surface 2s of the existing column 2. One end of each of the post-installed anchors 28 is driven into each side surface 2s at intervals in the vertical and horizontal directions. The other end of each of the post-installed anchors 28 protrudes radially outward from each side surface 2s of the existing column 2 and is embedded in the concrete portion 22. The concrete portion 22 is joined integrally to the existing column 2 via the plurality of post-installed anchors 28. Further, a plurality of anchor steel materials 24 are embedded in the lower body 11 in a portion between the exterior steel plate 21 and the existing column 2. Each anchor steel material 24 extends in the vertical direction, and its lower portion is embedded in the lower body 11. An upper portion of each anchor steel material 24 protrudes upward from the lower body 11. An upper portion of each anchor steel material 24 is welded to a plate 29 provided at the lower portion of the exterior steel plate 21 so as to protrude radially inward from each of the steel plate bodies 21a to 21d. An upper portion of each anchor steel material 24 and the plate 29 are embedded in the concrete portion 22. Furthermore, in the portion between the exterior steel plate 21 and the existing column 2, anchor members 30 are embedded at intervals in the circumferential direction of the outer periphery of the existing column 2 in the upper part of the concrete portion 22 in order to transmit a pulling force to the concrete portion 22 when a pulling force acts on a seismic isolation device 40 (described later). A joint 30a is joined to the upper end of the anchor member 30. The joint 30a is provided so that the upper end is exposed from the concrete portion 22. In this way, the anchor steel materials 24, the plates 29, the post-installed anchors 28, and the anchor members 30 are embedded in the concrete portion 22, so that the anchor members 30 are firmly integrated with the outer steel plate 21, the lower portion 2B of the existing column 2, and the lower structure 11. This provides strong resistance to the pull-out force transmitted from the seismic isolation device 40 via the anchor members 30.

[0021] A lower base 41 to which the lower end of the seismic isolation device 40 is joined is provided above the lower portion 2B of the existing column 2. The lower base 41 is made of reinforced concrete, and is provided on the lower portion 2B of the existing column 2 and the concrete body 20 with outer steel plates. The lower base 41 includes a mounting plate 41a to which the seismic isolation device 40 is joined. The mounting plate 41a is provided along the upper surface of the concrete that forms the lower base 41. An anchor bolt (not shown) is joined to the lower surface of the mounting plate 41a. This anchor bolt is embedded in the concrete that forms the lower base 41. An anchor bar 45 is embedded in the lower base 41. An end of the anchor bar 45 protrudes downward from the lower base 41 and is connected to a joint 30a of the anchor member 30 provided so as to be exposed from the upper surface 22t of the concrete portion 22.

[0022] An upper base 42 to which the upper end of the seismic isolation device 40 is joined is provided below the upper footing 15. The upper base 42 is made of reinforced concrete, and is provided on the lower surface of the upper footing 15. The upper base 42 is equipped with a mounting plate 42a to which the seismic isolation device 40 is joined. The mounting plate 42a is provided along the lower surface of the concrete that forms the upper base 42. An anchor bolt (not shown) is joined to the upper surface of the mounting plate 42a. This anchor bolt is embedded in the concrete that forms the upper base 42.

[0023] The seismic isolation device 40 has a lower flange plate 40a, an upper flange plate 40b, and a laminated rubber portion 40c interposed between the lower flange plate 40a and the upper flange plate 40b. The lower flange plate 40a is joined to a mounting plate 41a of the lower base 41. In this way, the seismic isolation device 40 is connected to the lower base 41. The upper flange plate 40b is joined to the mounting plate 42a of the upper base 42. In this way, the seismic isolation device 40 is connected to the upper base 42. The laminated rubber portion 40c is formed by laminating steel plates and rubber alternately in the vertical direction.

[0024] (Methods for seismic isolation of existing buildings) Next, the seismic isolation method for an existing building according to this embodiment will be described. FIG. 5 is a diagram showing the flow of the seismic isolation method for an existing building according to this embodiment. As shown in FIG. 5, the method for seismic isolation of an existing building includes a column reinforcing step S1, a jack installation step S2, a seismic isolation device installation step S3, and a temporary member removal step S4.

[0025] FIG. 6 is a diagram showing a state in which a lower beam reinforcement portion is formed on the lower existing beam of an existing building, and an upper footing is formed on the upper beam-column joint. In the column reinforcement step S1, first, as shown in Fig. 6, in the existing building 1, lower beam reinforcement parts 14 are formed on both sides in the beam width direction of the existing beam 3 below the existing column 2 to reinforce the existing beam 3. This forms a lower structure 11. In addition, an upper footing 15 is formed at the joint between the existing column 2 and the upper existing beam 3 to form an upper structure 12. At this time, the lower portions of the multiple anchor steel materials 24 are embedded in the lower structure 11. The upper portions of the anchor steel materials 24 are made to protrude upward from the lower structure 11. Furthermore, multiple post-installed anchors 28 are driven into each side surface 2s of the existing column 2.

[0026] FIG. 7 is a diagram showing the state in which an exterior steel plate is placed around the lower periphery of an existing column. First, the steel plate bodies 21a-21d, the multiple supporting steel plate parts 25, the connecting steel plate part 27, and the multiple stud bolts 23 are welded together to construct the outer steel plate 21 around the lower periphery of the existing column 2. At this time, the multiple supporting steel plate parts 25 are provided at positions such that when a jack receiving member (described later) is provided, the upper surface of the jack receiving member will be at the same height as an upper surface 2t (see FIG. 2) of the lower portion 2B of the existing column 2, which is formed by removing a part of the existing column 2 as described later. At this time, the upper portions of the plurality of anchor steel materials 24 are joined via the plate 29 to the inner surfaces 21s of the steel plate bodies 21a to 21d. In addition, a plurality of anchor members 30 are set between the existing column 2 and the exterior steel plate 21 using appropriate support materials.

[0027] FIG. 8 is a diagram showing the state in which concrete has been filled between the existing column and the exterior steel plate. Next, as shown in Fig. 8, concrete is filled between the existing column 2 and the exterior steel plate 21. As the concrete hardens, a concrete portion 22 is formed, and the exterior steel plate 21 and the concrete portion 22 are integrated with a plurality of stud bolts 23 to construct a concrete body 20 with the exterior steel plate. This concrete body 20 with the exterior steel plate is joined to the lower structure 11 and the existing column 2 via the concrete portion 22, a plurality of anchor steel materials 24, and post-installed anchors 28. As will be described later, the upper part of the existing column 2 is removed, leaving the lower part 2B of the existing column 2. The concrete part 22 is formed so that its upper surface 22t is at the same height as the upper surface 2t of the lower part 2B of the existing column 2 formed as described above.

[0028] Fig. 9 is a diagram showing a state in which a plurality of jack receiving members are temporarily fixed to an outer steel plate. Fig. 10 is an enlarged cross-sectional view showing the jack receiving members temporarily fixed to the outer steel plate. Fig. 11 is a diagram showing the jack receiving members as viewed from the outside of the outer steel plate. In the jack installation process S2, first, as shown in Figures 9 and 10, a jack receiving member 50 is temporarily fixed to the outside of the upper part of the outer steel plate 21. As shown in Figures 10 and 11, the jack receiving member 50 integrally includes a base plate 51, a locking portion 52, a receiving plate 53, and a plurality of reinforcing ribs 54. As shown in FIG. 10, the base plate 51 is formed in a plate shape so as to fit along the outer surface 25 f of the supporting steel plate portion 25 . The locking portion 52 is formed on the upper end of the base plate 51. The locking portion 52 extends from the upper end side of the base plate 51 in a direction perpendicular to the base plate 51, and has a locking claw 52t formed at its tip so as to extend downward from the tip. The jack receiving member 50 is locked to the outside of the upper part of the outer shell steel plate 21 by engaging the locking claw 52t of the locking portion 52 with the notch portion 25s formed in the support steel plate portion 25. That is, the jack receiving member 50 is provisionally fixed to the outside of the upper part of the outer shell steel plate 21 so that the locking claw 52t of the locking portion 52 is hooked on the notch portion 25s. The jack receiving member 50 can be easily removed by moving the jack receiving member 50 upward to release the locking claw 52t from the notch portion 25s.

[0029] The receiving plate 53 is provided to rise from the upper end of the base plate 51 on the side opposite to the engaging portion 52. Therefore, when the jack receiving member 50 is temporarily fixed to the exterior steel plate 21 as described above, the receiving plate 53 extends radially outward from the exterior steel plate 21. The receiving plate 53 faces upward and supports a jack 70 (described later) from below on the outside of the exterior steel plate 21, i.e., on the side opposite the existing column 2. The jack receiving member 50 provided as shown in Figures 9 and 10 is formed so that the upper surface 53t of the receiving plate 53 is positioned at the same height as the upper surface 22t of the concrete portion 22. 10 and 11, the multiple reinforcing ribs 54 are formed on the underside of the support plate 53. The multiple reinforcing ribs 54 include multiple vertical ribs 54a extending in the up-down direction along the base plate 51, and multiple horizontal ribs 54b extending in the horizontal direction along the base plate 51. The multiple vertical ribs 54a and the multiple horizontal ribs 54b are arranged so as to intersect at right angles to each other.

[0030] FIG. 12 is a diagram showing a state in which a plurality of jacks are installed between a plurality of jack receiving members and an upper body. As shown in FIG. 12, in the jack installation step S2, a plurality of jacks 70 are installed between the plurality of jack receiving members 50 temporarily fixed to the outside of the upper part of the outer steel plate 21 as described above and the upper body 12. Each jack 70 is, for example, a hydraulic jack. Each jack 70 may be a screw jack, an air jack, or the like. Each jack 70 is installed between the upper surface 53t of the receiving plate 53 of the jack receiving member 50 and the upper body 12 located above the jack receiving member 50, that is, between the lower surface of the upper footing 15 of the upper body 12 in this embodiment. As already described, the upper surface 53t of the receiving plate 53 of the jack receiving member 50 and the upper surface 22t of the concrete part 22 are at the same height. Therefore, the jack 70 may be provided so that it protrudes radially inward from the upper surface 53t of the receiving plate 53 and a part of it is positioned on the upper surface 22t of the concrete portion 22.

[0031] In the seismic isolation device installation process S3, the multiple jacks 70 installed on the jack receiving member 50 are operated to extend in the vertical direction and support the upper structure 12 from below. As a result, the load acting downward from the upper structure 12 is transmitted via the multiple jacks 70 to the concrete body 20 with outer steel plates and the lower part 2B of the existing column 2. Here, when the axial force due to the load acts on the jack receiving member 50, each of the multiple supporting steel plate parts 25 is pressed downward. Since the concrete part 22 is formed inside the outer shell steel plate 21 and each of the multiple supporting steel plate parts 25 is supported by the concrete part 22 from the inside, the axial force acts on each of the multiple supporting steel plate parts 25 as a bending stress in the outward direction, that is, in the outward direction, opposite to the existing column 2, on each of the multiple supporting steel plate parts 25. As a result, the supporting steel plate parts 25 move away from the concrete part 22 located on the inside to the outward direction, and tend to deform and displace. On the other hand, since the multiple supporting steel plate parts 25 are connected to each other by the connecting steel plate parts 27, they resist the bending stress in the outward direction, that acts on the multiple supporting steel plate parts 25, and deformation and displacement of the supporting steel plate parts 25 are suppressed.

[0032] Fig. 13 is a diagram showing a state where a part of the existing column has been removed, and Fig. 14 is a diagram showing a state where a seismic isolation device has been inserted between the existing column and the upper body. With the upper body 12 supported by the multiple jacks 70 as described above, a portion of the existing column 2 above the jack receiving member 50 is removed, as shown in FIG. Thereafter, as shown in FIG. 14, a seismic isolation device 40 is installed on the lower portion 2B of the remaining existing column 2 and on the concrete body 20 with the exterior steel plates. More specifically, the lower base 41 is formed on the lower part 2B of the remaining existing column 2 and the concrete body 20 with outer steel plates. More specifically, the anchor reinforcement 45 is arranged above the lower part 2B of the existing column 2, and its lower end is connected to the anchor member 30 embedded in the concrete part 22. Furthermore, after installing the mounting plate 41a, concrete is poured to form the lower base 41. Similarly to the lower base 41, an upper base 42 is formed below the upper footing 15. The seismic isolation device 40 is then positioned between the lower base 41 and the upper base 42, and the lower flange plate 40a and the upper flange plate 40b are joined to the mounting plates 41a, 42a of the lower base 41 and the upper base 42, respectively, thereby installing the seismic isolation device 40.

[0033] In the temporary member removal process S4, after the seismic isolation device 40 is installed as described above, the jack 70 is retracted and the load from the upper body 12 is transferred to the seismic isolation device 40. After that, the multiple jacks 70 are removed, and further the multiple jack receiving members 50 temporarily fixed to the outside of the upper part of the outer shell steel plate 21 are moved upward to release the engagement between the locking claws 52t of the locking parts 52 and the recessed parts 25s of the support steel plate parts 25, thereby removing the multiple jack receiving members 50. This realizes the column structure 10 as shown in FIG. 2. The above-mentioned steps of the method for seismic isolation of an existing building 1 are sequentially and similarly performed on a plurality of existing columns 2 on which the seismic isolation device 40 is to be installed. At this time, the removed plurality of jack receiving members 50 and jacks 70 can be repeatedly reused for the construction of other existing columns 2.

[0034] The method of seismic isolation for an existing building 1 as described above is a method of seismically isolating an existing building 1 by attaching a new seismic isolation device 40 to an existing column 2 of the existing building 1 to isolate the building from seismic energy, and includes a column reinforcement process S1 of arranging an outer shell steel plate 21 around the outside of the existing column 2 and filling concrete between the existing column 2 and the outer shell steel plate 21 to construct a concrete body 20 with outer shell steel plate; a jack installation process S2 of temporarily fixing a jack receiving member 50 to the outside of the outer shell steel plate 21 and installing a jack 70 between the jack receiving member 50 and the upper structure 12 located above the jack receiving member 50; a seismic isolation device installation process S3 of operating the jack 70 to support the upper structure 12, removing a part of the existing column 2 and inserting the seismic isolation device 40; and a temporary member removal process S4 of removing the jack 70 and the jack receiving member 50. According to the above-mentioned configuration, the concrete body 20 with the outer steel plates is provided around the existing column 2, the jack receiving member 50 is temporarily fixed to the outer steel plate 21, the jack 70 is placed between the jack receiving member 50 and the upper body 12, and the jack 70 is operated. Then, the load can be transmitted from the upper body 12 to the concrete body 20 with the outer steel plates and the existing column 2 below via the jack 70 and the jack receiving member 50. In this way, the load of the upper body 12 can be transmitted to the lower body 11 without passing through the existing column 2, so that each of the operations of removing a part of the existing column 2 and inserting the seismic isolation device 40 into the removed part of the existing column 2 can be performed reliably. Here, the jack receiving member 50 on which the jack 70 is installed is provided so as to be located outside the outer steel plate 21 of the concrete body 20 with outer steel plate. Therefore, the jack 70 can be provided at a position that protrudes outward from the concrete body 20 with outer steel plate when viewed in a plan view. In this way, the jack 70 does not need to be supported at least entirely by the concrete body 20 with outer steel plate, so that when constructing the concrete body 20 with outer steel plate, it is not necessary to make the concrete body 20 with outer steel plate excessively large in consideration of installing the jack 70 outside the seismic isolation device 40. Therefore, the concrete body 20 with outer steel plate can be formed in a compact size, for example, to the extent that the lower flange plate 40a of the seismic isolation device 40 can be accommodated. In this way, when a new seismic isolation device 40 is attached to the existing column 2 of the existing building 1 to achieve seismic isolation, it is possible to make the structure compact and reduce construction costs. In addition, since the jack receiving member 50 is temporarily fixed to the outer steel plate 21, it can be removed after construction and reused for construction of other existing columns 2. This makes it possible to further reduce construction costs.

[0035] In particular, in this embodiment, as described above, the concrete body 20 with the exterior steel plates can be formed in a compact size, so when reinforcing the underside of the existing column 2 to form the lower beam reinforcement portion 14 and the footing so as to be able to support the concrete body 20 with the exterior steel plates, the sizes of the lower beam reinforcement portion 14 and the footing can also be made compact to match the size of the concrete body 20 with the exterior steel plates. This makes it possible to further reduce construction costs.

[0036] In addition, multiple jack receiving members 50 are provided around the existing column 2, and the outer steel plate 21 is provided with multiple supporting steel plate portions 25 on the upper side of the outer steel plate 21 that engage, temporarily fix and support each of the multiple jack receiving members 50, and connecting steel plate portions 27 that are provided to surround the existing column 2 and connect the supporting steel plate portions 25 that are positioned opposite each other. According to this configuration, the jack 70 can be installed between the jack receiving member 50 temporarily fixed to the outside of the outer steel plate 21 and the upper body 12 located above the jack receiving member 50. When the jack 70 is operated, the load can be transmitted from the upper body 12 to the concrete body 20 with the outer steel plate and the existing column 2 below via the jack 70 and the jack receiving member 50. When the axial force of this load acts on the jack receiving member 50, the support steel plate part 25 is pressed downward. Since the inside of the outer steel plate 21 is filled with concrete 22 and the support steel plate part 25 is supported by the concrete 22 from the inside, the axial force acts on the support steel plate part 25 as a stress in the outward direction, opposite to the existing column 2. As a result, the support steel plate part 25 tries to move away from the concrete located on the inside to the outside, and deform and displace. In contrast, because the supporting steel plate parts 25 positioned so as to face each other are connected by the connecting steel plate parts 27, the connecting steel plate parts 27 resist the bulging stress acting on the supporting steel plate parts 25 and generated in the outward direction, suppressing deformation and displacement of the supporting steel plate parts 25. Furthermore, by providing the connecting steel plate parts 27, the bulging stress can be reduced, ensuring the strength and durability of the structure.

[0037] Further, the upper surface 53t of the jack receiving member 50 is positioned at the same height as the upper surface 22t of the concrete portion 22. According to this configuration, when the jack 70 is mounted on the jack receiving member 50, it can be mounted so that it protrudes radially inward from the jack receiving member 50 and a portion of it is positioned on the upper surface 22t of the concrete portion 22.

[0038] In addition, a stud bolt 23 is provided on the inner surface 21s of the exterior steel plate 21 facing the existing column 2, a post-installed anchor 28 is provided on the side surface 2s of the existing column 2 so as to protrude from the side surface 2s, and an anchor steel 24 is installed between the existing column 2 and the exterior steel plate 21 so that its lower side is embedded in the lower structure 11 located below the existing column 2 and its upper side protrudes from the lower structure, and the anchor steel 24 is joined to a plate 29 joined to the inner surface 21s of the exterior steel plate 21, and a concrete portion 22 is formed so as to embed the stud bolt 23, the post-installed anchor 28, the anchor steel 24 and the plate 29. According to this configuration, by firmly integrating the existing column 2, the outer steel plate 21, and the lower structure 11, it becomes possible to resist the pull-out force acting through the seismic isolation device 40.

[0039] Furthermore, the column structure 10 as described above is a column structure 10 in which a seismic isolation device 40 is attached to an existing column 2, the existing column 2 being made of reinforced concrete, and an outer shell steel plate 21 is arranged around the outer periphery of the existing column 2 below the seismic isolation device 40 of the existing column 2, and concrete is filled between the existing column 2 and the outer shell steel plate 21 to construct a concrete body 20 with outer shell steel plate, and the outer shell steel plate 21 comprises steel plate main bodies 21a-21d and a supporting steel plate portion 25 provided on the upper side of the steel plate main bodies 21a-21d and having a thickness greater than that of the steel plate main bodies 21a-21d, and a recess 25s is provided on the inner surface side of the supporting steel plate portion 25. According to the above-mentioned configuration, the column structure 10 with the seismic isolation device 40 attached to the existing column 2 can be constructed by following the procedure below. First, the concrete body 20 with the outer steel plate is constructed around the existing column 2. Next, the jack receiving member 50 supporting the jack 70 is temporarily fixed to the outer steel plate 21 so as to be located outside the outer steel plate 21. This temporary fixing can be performed by engaging the jack receiving member 50 with the recess 25s provided on the inner surface side of the support steel plate portion 25 provided on the upper side of the outer steel plate 21. Then, the jack 70 is installed between the jack receiving member 50 and the upper body 12 located above the jack receiving member 50, and the jack 70 is operated. This allows the load to be transmitted from the upper structure 12 via the jack 70 and the jack support member 50 to the concrete body 20 with outer steel plate, and then to the existing column 2 below, so that part of the existing column 2 can be removed and the seismic isolation device 40 can be inserted and fixed in place. In this way, the jack receiving member 50 on which the jack 70 is installed can be provided so as to be located outside the outer steel plate 21 of the concrete body 20 with outer steel plate. Therefore, the jack 70 can be provided at a position that protrudes outward from the concrete body 20 with outer steel plate when viewed in a plan view. In this way, the jack 70 does not need to be supported at least entirely by the concrete body 20 with outer steel plate, so that when constructing the concrete body 20 with outer steel plate, it is not necessary to make the concrete body 20 with outer steel plate excessively large in consideration of installing the jack 70 outside the seismic isolation device 40. Therefore, the concrete body 20 with outer steel plate can be formed in a compact size, for example, to the extent that the lower flange plate 40a of the seismic isolation device 40 can be accommodated. In this way, when a new seismic isolation device 40 is attached to the existing column 2 of the existing building 1 to achieve seismic isolation, it is possible to make the structure compact and reduce construction costs. In addition, since the jack receiving member 50 is temporarily fixed to the outer steel plate 21, it can be removed after construction and reused for construction of other existing columns 2. This makes it possible to further reduce construction costs.

[0040] (Simulation example) A simulation analysis was carried out on the pillar structure 10 described above, and the results are shown below. FIG. 15 is a diagram showing an example of an analytical model used in the simulation analysis. 15, model M of column structure 10 has a configuration in which a jack receiving member 50 is fixed to the upper end of an L-shaped member in plan view that corresponds to the outer steel plate 21. The lower end of the outer steel plate 21 is pin-supported at multiple points, and both ends of the outer steel plate 21 are supported by multiple axial springs extending in the in-plane direction of the steel plate bodies 21a, 21b. A contact load of 2500 kN was applied to a total of six points on the top surface of the jack support member 50, and the response at that time was analyzed using FEM. FIG. 16 is a diagram showing the results of an FEM analysis of the analysis model of FIG. In this example, the stress is 235N / mm 2 The required stress is smaller than the required stress, and the FEM analysis results show that the von Mises stress is 207N / mm 2 It was found that sufficient strength was obtained. In reality, the concrete part 22 that is strong against compression is provided on the inside of the outer steel plate 21, so that the deformation of the outer steel plate 21 toward the inside is suppressed, and the actual stress is 207 N / mm 2 From 190N / mm 2 It is expected that the level of [Explanation of symbols]

[0041] 1 Existing building 22 Concrete section (concrete) 2 Existing column 25 Support steel plate 10 Pillar structure 25s Recessed part 12 Upper frame 27 Connecting steel plate section 20 Concrete body with steel outer plate 40 Seismic isolation device 21 Outer steel plate 50 Jack support member 21a~21d Steel plate body 70 Jack

Claims

1. A method for seismic isolation of an existing building by attaching a new seismic isolation device to an existing column of the existing building, A column reinforcing process in which an outer steel plate is placed around the outer periphery of the existing column, and concrete is filled between the existing column and the outer steel plate to construct a concrete body with an outer steel plate; A jack installation process includes temporarily fixing a jack receiving member to the outside of the outer steel plate and installing a jack between the jack receiving member and an upper body located above the jack receiving member; a seismic isolation device installation process in which, while the jack is operated to support the upper body, a part of the existing column is removed and the seismic isolation device is inserted; a temporary member removal process of removing the jack and the jack receiving member; A method for seismic isolation of an existing building, comprising:

2. The jack receiving member is provided in a plurality around the existing column, The outer steel plate includes a plurality of support steel plate portions that engage and temporarily fix each of the plurality of jack receiving members on the upper side of the outer steel plate, and a connecting steel plate portion that is provided so as to surround the existing column and connects the support steel plate portions that are positioned so as to face each other. The method for seismic isolation of an existing building according to claim 1.

3. A column structure in which a seismic isolation device is attached to an existing column, The existing pillar is made of reinforced concrete, An outer steel plate is arranged around the outer periphery of the existing column below the seismic isolation device, and concrete is filled between the existing column and the outer steel plate to construct a concrete body with an outer steel plate; A column structure characterized in that the outer steel plate comprises a steel plate main body and a supporting steel plate portion provided on the upper side of the steel plate main body and having a plate thickness greater than that of the steel plate main body, and a recess is provided on the inner surface side of the supporting steel plate portion.

Images