JP4024449B2 - Seismic isolation method for existing buildings - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a seismic isolation method for an existing building, and more particularly to a seismic isolation method for an existing building in which a seismic isolation device is safely and reliably installed between existing pillars that have been cut.
[0002]
[Prior art]
In recent years, seismic reinforcement measures for existing buildings have been actively applied, and many seismic isolation structuring techniques have been proposed for existing buildings.
The existing seismic isolation structuring technologies already proposed can be broadly divided into jacking up existing buildings using jacks, inserting and installing seismic isolation devices in the upper structure and the cut foundations, and jacking down. The seismic isolation system is constructed by inserting the seismic isolation device into the foundation while supporting the upper structure by interposing a reinforcing support around the existing pillar without using a jack, After that, the reinforcing support can be cut and removed to classify the system into a base-isolated structure.
[0003]
As described in Japanese Patent Application Laid-Open No. 2-20767, the above jack method is such that first, a support pile of an existing building is dug, a temporary support is built around it, and a jack is placed above the temporary support. The jack on the temporary support is jacked up to replace the axial force of the support pile with the temporary support.
[0004]
The work after reshaping the axial force is to disassemble the support pile that has been released from the axial force, and to install a seismic isolation device between the steel column and the existing building by building a steel column that changes to a support pile, A typical process is to make the existing building seismically isolated by jacking down to change the axial force of the temporary support to a steel column.
However, in this method, in order to install seismic isolation devices on the piles that support the building, it is essential to excavate the ground until the piles are exposed, as in the construction of mountain retaining walls and wastewater treatment measures. It requires large and difficult work, especially when the axial force that the column bears is excessive, it requires the reinforcement of the foundation beam, etc. ing.
[0005]
In addition, a method has been proposed in which pillars of existing buildings are cut to achieve seismic isolation structure. However, since either method needs to temporarily support the load of the superstructure, a jack is set on the slab and the support column is placed on this, and the support column is buckled. The load of the upper structure must be received as an axial force while avoiding the above. For this reason, a bulky structure having an appropriate strength is unavoidable. Furthermore, this support column is not required after the building is made to be seismically isolated. On the other hand, it becomes a hindrance, so that it is necessary to remove it, which requires a removal cost.
[0006]
On the other hand, as an example in which a jack is not used, there is a system disclosed in Japanese Patent Laid-Open No. 9-1000063.
In this method, the surface finish of the existing pillar 51 is removed, and the embedded anchor gibels 52 and 53 corresponding to the proof stress are attached to the upper and lower portions excluding the portion to be cut off, and the stud gibel 54 and the grout partition are arranged on the outer periphery thereof. A column-reinforced steel plate 56 provided with a plate 55 is wrapped by welding (see FIG. 11). Next, grout mortar is injected and hardened in the portions where the upper and lower stat gibels 54 are disposed, and the intermediate portion 57 of the existing pillar 51 is cut with a diamond chain cutter to remove the seismic isolation device installation portion (see FIG. 12). After installing the seismic device 58 and inserting it into the existing column 51, the upper and lower parts of the seismic isolation device 58 are closed with a holding plate 59 for the injection of grout mortar (see FIG. 13). After that, grout mortar is poured into the upper and lower parts of the seismic isolation device, and after waiting for hardening, the columnar steel plate 56 is cut along the CUT line to complete the existing column 60 with the seismic isolation device (see FIG. 14). ).
[0007]
However, in this method, the function of the column and the formwork is required at the time of construction on the column-wound steel sheet, and after the seismic isolation structure, the role of the main reinforcement of the concrete structure and the shear reinforcement is borne. I have the following problems.
(1) The steel plate becomes thick to support the superstructure, and its weight increases, making it difficult to transport and assemble by hand alone.
{Circle around (2)} Since it is necessary to preliminarily cut the column cutting position of the steel plate and the opening of the additional concrete, it becomes a special steel plate and causes an increase in cost.
(3) In order to receive the beating concrete in the narrow part between the steel plate and the existing column, a siding plate must be provided.
{Circle around (4)} In the case of an independent column, a columnar steel plate can be easily set, but in the case of a column connected to a wall such as a rectangular column or an outer wall, it is difficult to attach the columnar steel plate.
(5) The seam of columnar steel plates must be welded.
(6) After the seismic isolation device is installed, the extra steel sheet will be expensive to cut out.
(7) The exposed columnar steel sheet needs to have a fireproof coating on the fireproof upper surface.
[0008]
[Problems to be solved by the invention]
The present invention is intended to improve in view of the above situation, and the column disposed between the slab and the beam attached to the existing column in order to support the upper load has a small shaft diameter. In addition, it is possible to carry out construction without buckling, and to provide a seismic isolation method for existing buildings that requires less fire protection and requires less excision after the seismic isolation structure.
[0009]
[Means for Solving the Problems]
The seismic isolation method for an existing building according to the present invention includes a step of placing an upper load supporting column between a slab and a beam attached to an existing column while maintaining a predetermined distance from the outer peripheral surface of the existing column, and a seismic isolation of the existing column. The step of placing additional concrete around at least the top of the upper load support column excluding the cutting position for mounting the device, the step of cutting the existing column corresponding to the mounting position of the seismic isolation device, and the cutting position of the existing column Inserting the seismic isolation device into the base, fixing the seismic isolation device to the existing pillars that have been cut, and cutting the exposed portion of the upper load support post from the beating concrete to transfer the upper load to the seismic isolation device Consists of.
As a result, the upper load support strut can be prevented from buckling even when the shaft diameter is kept small, since it can receive the upper load after it is reinforced integrally with the shear reinforcement of the increased concrete. Handling becomes easy. In addition, even after the seismic isolation structure is completed, the cutting portion of the upper load support column can be reduced and fireproofing is not required.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The seismic isolation method for an existing building according to the present invention is to maintain a predetermined distance from the outer peripheral surface of an existing column, arrange an upper load support column between the slab and the beam attached to the existing column, and After the upper load support column excluding the cutting position for attaching the upper load support struts, or surrounding the upper and lower concrete, the additional concrete is placed, and then the existing pillars corresponding to the mounting positions of the seismic isolation devices are cut. Next, the seismic isolation device is inserted into the existing pillar at the cutting point, and the seismic isolation device is fixed to the cut existing column. It consists of the process of cutting and transferring the upper load to the seismic isolation device.
Embodiments of the present invention will be described below with reference to the drawings.
[0011]
1 to 7 show the construction procedure of the seismic isolation method for an existing building according to the present invention.
In FIG. 1, preparation for construction is performed, and the finish is removed along with the mortar over the entire length of the existing pillar 1 to roughen the surface. In addition, about the existing pillar located in the outer peripheral part of a building, the wall of the range of 1 m is taken off from the pillar outer surface.
Next, the core 2 of the existing pillar 1 is removed for the purpose of securing the rotation space of the diamond wire saw when the pillar is cut, but in the work described later, when the cutting portion of the existing pillar is removed and taken out, the cut piece is removed. When the weight is reduced by dividing, the workability is improved. Therefore, not only the pillar is cut at two places in the horizontal direction, but also at two places in the vertical direction between the horizontal cut surfaces.
[0012]
Core removal is performed in advance at a total of 4 locations, 2 locations x 2 stages, but in order to install the seismic isolation device in the middle part of the existing pillar 1, it is already installed on the slab as shown in Fig. 1 (a). In order to install the seismic isolation device between the slab and the lower end of the existing column 1 as shown in FIG. 1 (b), the existing column 1 ′ is left on the slab. In some cases, the position of core removal is changed according to each case as shown in the figure.
In this case, if the core 3 for the hoop bars is also provided at the column / beam joint, the workability of the increased concrete is improved.
[0013]
In FIG. 2, the process of arrange | positioning an upper load support support | pillar between a slab and the beam attached to an existing pillar is shown.
The following steps are described as installing the seismic isolation device in the middle part of the existing pillar. As shown in the figure, a predetermined distance is secured from the outer peripheral surface of the existing pillar, and the slab 4 and the existing pillar are separated. A flat jack 5 for adjustment is arranged on the slab 4 in order to arrange an upper load supporting column 6 made of a square steel pipe filled with concrete inside between the beam 8 to be attached.
Care is taken that the flat jack 5 is positioned above the underground beam, and the upper load supporting column 6 is pushed up and fixed by using a hand hydraulic pump or the like in order to support the upper load. The number of the upper load support columns 6 is the same as the number of beams attached to the column, and the plate 7 is attached to the top end of the upper load support columns 6 so as to be in close contact with the lower end of the beam on the upper floor. The non-shrinkable mortar is injected and the camber is installed as necessary so that the lower end of the beam 8 and the upper load support column 6 are brought into close contact with each other.
And when installing a seismic isolation apparatus between a slab and the lower end part of the existing pillar 1, the lower end part of the said upper load support support column 6 is exposed with the flat jack 5 until it cuts and removes. Since the flat jack is lowered after the seismic isolation device is installed to open the upper load support column 6, it is necessary to keep the jack down.
[0014]
Further, in the above embodiment, a flat jack or the like is interposed under the upper load support column 6, but these jack-ups are not essential, and the upper load support column 6 is disposed directly on the slab 4. By injecting the non-shrink mortar into the lower end, a desired function can be exhibited even if the lower end of the slab 4 and the upper load supporting column 6 are brought into close contact with each other.
That is, when the upper load supporting column 6 is fixed between the slab and the lower beam end of the upper floor by a non-shrinking mortar or the like, the core of the existing column that has been constructed in order to secure the rotation space of the diamond wire saw described above, The rearrangement of the axial force from the existing column to the upper load support column can be carried out without any trouble within a small range of movement between the upper and lower slabs according to the cutting of the existing column.
[0015]
FIG. 3 shows the steps of reinforcing reinforcement (a), forming the formwork, and placing the increased concrete (b).
The vertical bars of the additional hitting portion are fixed by the resin anchors 11 in the slab 4 on the floor where the seismic isolation device is installed, the existing slab 9 on the upper side, and the beam 10 as bending reinforcement bars. The hoop muscle 12 of the additional hitting portion is a high-strength spiral hoop muscle so that the four upper load supporting struts 6 are positioned at the four corners except for a portion to be removed in order to install the seismic isolation device in a later process. Winding the bar arrangement. The column / beam joint is penetrated through the beam and the split hoop 13 is arranged and then welded together.
[0016]
Next, with respect to the increased hitting portions above and below the existing pillar 1, the formwork 14, 15 is installed, and the anchor 16 for the seismic isolation device upper frame reinforcement is set at a predetermined position, and then the increased hit concrete 18, 18 ′ I am setting up.
As a result, the upper load support column 6 is set in a state in which it is embedded in the increased concrete 18, 18 ′ including the flat jack, except for the portion to be removed to install the seismic isolation device. , 18 ′ is cured until it develops a predetermined strength, it retains a strong state reinforced with the hoop bars 12 in the same manner as the longitudinal main bars of the reinforced concrete.
The anchor 16 has a mechanical joint system so that the existing columns can be easily cut, and the concrete for the additional striking part above the existing columns is cast by the press-fitting method to ensure filling up to the lower floor of the slab. I am letting.
[0017]
Moreover, in this Embodiment, the lower part of the existing pillar 1 is cut | disconnected and the existing pillar 1 'is left on a slab so that a seismic isolation apparatus may be installed in the intermediate part of the existing pillar 1, but as above-mentioned In the case where the seismic isolation device is directly installed on the slab, the arrangement of the hoop reinforcement 12 of the additional hitting portion with respect to the lower portion of the upper load supporting column 6, the erection of the formwork 15, and the increase of the concrete 18 ′ are omitted. The lower portion of the upper load support column 6 with a flat jack or the like interposed is left exposed.
[0018]
In FIG. 4, in order to install a seismic isolation apparatus, the process of removing one part of the existing pillar in a cutting position is shown.
As described above, when the intermediate portion below the existing column 1 is cut and the existing column 1 ′ is left on the slab, the arrangement of the hoop reinforcement 12 of the additional hitting portion with respect to the lower portion of the upper load support column 6 Since the frame 15 is built and the concrete 18 'is increased, the upper load supporting column 6 is pushed up by a flat jack or is held on the increased concrete while being in close contact with the slab 4 and the beam 8. Yes. Therefore, a part of the long-term axial force that has been borne by the existing column 1 is partially shared by the upper load support column 6.
Therefore, a diamond wire saw is set at the cutting position of the existing pillar 1, the pillar is cut in the vertical and horizontal order, and the cut pieces that have been divided and reduced in weight are removed. In the cutting of the existing column, the long-term axial force borne by the existing column 1 is replaced by the upper load support column 6 so that the upper load support column 6 supports all of the upper load.
[0019]
On the other hand, when the seismic isolation device is arranged directly on the slab 4, the concrete 18 ′ is not subjected to repeated hitting, and the lower portion of the upper load support column 6 with a flat jack or the like is left exposed. is there. Therefore, in the case of the present embodiment, it is possible to jack up the flat jack again and push up the upper load supporting column 6 upward, so that the upper load borne by the existing pillar 1 is borne as necessary. Can also be reduced. Therefore, since the existing pillar 1 can be cut out by the diamond wire saw in a state where the pressing force is removed, the existing pillar can be cut and divided and removed very smoothly.
[0020]
As described above, the existing column is cut and removed by any of the above-described methods. In any case, in the present invention, most of the upper load supporting column 6 is made of the increased concrete 18 or 18. Since the part that is held in a reinforced state and is exposed alone is only a narrow part left in the gap of the cut surface for installing the seismic isolation device, the shaft diameter is small. Even if the upper load is rearranged with respect to the upper load support column 6, almost no buckling of the upper load support column 6 occurs.
[0021]
FIG. 5 shows a step of placing the base (a) of the base of the seismic isolation device, and placing the formwork and placing the additional concrete (b).
The base 20 of the seismic isolation device is constructed on the cut surface of the existing column 1 ′ reinforced with reinforced concrete and the reinforced concrete 18 ′, or on the slab 4. After fixing with a resin anchor in the strengthened existing pillar 1 'or slab 4 or underground beam, bar arrangement 21 is performed in a cage shape as shown in FIG. 5 (a). Next, the lower base plate 17 for installing the seismic isolation device is set to a predetermined level and temporarily fixed by welding, and then the frame 20 of the frame is built to form the frame 20 as shown in FIG. Concrete 23 is placed for this purpose.
At this time, the lower base plate 17 is surely filled by a press-fitting method so that no gap is formed, and is cured until the concrete exhibits a predetermined strength.
[0022]
FIG. 6 shows a process of setting the seismic isolation device on the lower base plate and coupling the seismic isolation device to the existing column above which is reinforced with the increased concrete.
In this step, the seismic isolation device 25 to which the upper base plate 24 is attached is set on the lower base plate 17 constructed on the existing pillar 1 ′ below. Then, the reinforcing bars of the seismic isolation device upper mount 26 are mechanically fixed to the concrete striking portion 18 and are arranged 27 in a cage shape. Next, the upper base plate 24 of the seismic isolation device 25 is coupled to the concrete striking portion 18 and the existing pillar 1 reinforced. In this connection, the non-shrink mortar 28 is filled between the upper base plate 24 and the cut surface of the existing pillar 1 to strengthen the integration, and is cured until the non-shrink mortar exhibits a predetermined strength.
[0023]
7 and 8 show a state in which the seismic isolation device is coupled to upper and lower existing columns reinforced with increased concrete, and all of the upper load is replaced with the seismic isolation device.
FIG. 7 shows an embodiment in which a seismic isolation device is installed in the middle part of the existing pillar 1.
In the present embodiment, as shown in FIG. 7A, when the installation of the seismic isolation device 25 is completed, the four upper load support columns 6 are cut and removed, and all the upper loads are isolated. It is made to transfer to the apparatus 25. The upper load support column 6 is cut by a normal method, and the axial load from the upper load support column 6 to the existing column is changed without any trouble by cutting and removing the upper load support column 6.
[0024]
FIG. 7 (b) is a plan sectional view taken along arrows (A)-(A) in FIG. 7 (a), and only the increased concrete 18 ′ having the seismic isolation device 25 disposed on the slab. .
Therefore, since there are no exposed portions of steel pipes or reinforcing bars outside of the reinforced concrete 18, 18 ', the fireproofing process is sufficient only by attaching a fireproof coating only to the seismic isolation device, which reduces costs. The construction efficiency has been improved.
[0025]
Further, in the present embodiment, in order to facilitate the above-described cutting operation, a jack or the like is temporarily fitted between the increased concrete 18 of the existing column and the increased concrete 18 'of the lower part, Of course, means for relaxing the pressing force applied to the cutting tool at the time of cutting by jacking up this is considered as necessary.
[0026]
FIG. 8 shows an embodiment in which a seismic isolation device is installed between the lower end of the existing pillar 1 and the slab.
In this embodiment, as shown in FIG. 8A, when the installation of the seismic isolation device 25 is completed as in the embodiment of FIG. 7A, the four upper load support columns 6 are cut. All of the upper load is transferred to the seismic isolation device 25 by changing the axial force.
[0027]
However, in the case of the present embodiment, all of the upper load can be reliably and easily replaced from the upper load support column 6 to the seismic isolation device installed on the existing column.
In other words, the lower portion of the upper load supporting column 6 is exposed to the outside together with the flat jack interposed between the slab from below the increased concrete 18. Therefore, since the operation of the flat jack is free, the upper load can be easily removed from the upper load support column 6 by jacking it down.
[0028]
FIG. 8B is a cross-sectional plan view taken along arrows (A)-(A) in FIG.
As shown in the figure, after the work for installing the seismic isolation device on the existing pillar is completed, the concrete 23 of the gantry 20 having the seismic isolation device 25 disposed on the slab is only disposed. Since there are no exposed steel pipes or reinforcing bars on the outside of 18, the fireproof treatment is sufficient only by attaching a fireproof coating only to the seismic isolation device, achieving cost reduction and improvement of construction efficiency. .
[0029]
FIGS. 9 and 10 show an application example of the present invention as an embodiment with respect to a column in a protruding corner and a column connected to a wall, which are difficult to construct by a conventional jackless method.
FIG. 9 shows an embodiment applied to a pillar at an exit corner, and a seismic isolation device 31 is installed on the pillar 30 at an existing exit corner to make the existing building seismic isolation. The upper load supporting column 32 is installed between the beam 33 attached to the column 30 at the protruding corner and the corresponding underground beam, and the increased concrete 34 is connected to the column 30 at the existing protruding corner. The bar is placed in a state of surrounding the upper load support column 32, and concrete is placed.
Therefore, the application of the seismic isolation method of the existing building according to the present invention to the pillars at the corners is that the construction is almost equivalent to normal field work, and does not involve any special members or special work. Therefore, it is excellent in terms of cost and construction period.
[0030]
FIG. 10 shows an embodiment applied to a pillar connected to an outer wall, and an seismic isolation device 41 is installed on an existing pillar 40 for seismic isolation of an existing building. The upper load support column 42 is installed between the beam 43 and the like attached to the existing column 40 and the corresponding underground beam, and the increased concrete 44 is connected to the existing column 40 and the upper load support column 42. The bars are placed in an enclosed state, and concrete is cast.
Therefore, the application of the seismic isolation method according to the present invention to the walls of an existing building, particularly to the columns connected to the outer wall, is excellent in terms of cost and construction period as in the above embodiment.
[0031]
As described above, the seismic isolation method for an existing building according to the present invention receives the upper load after reinforcing the upper load support strut that temporarily receives the upper load temporarily with the shear reinforcement of the increased concrete. In addition, since only the part where the seismic isolation device is installed is exposed and most of the other parts are buried in the beating concrete, buckling can be prevented even if the shaft diameter is kept small. It is light and easy to handle during construction. Further, even after the seismic isolation structure is completed, the cutting portion of the upper load support column can be reduced, and the cost is reduced by using only the seismic isolation device as the fireproofing treatment.
[0032]
As described above, the present invention has been described in detail on the basis of the embodiment. However, the seismic isolation method for an existing building according to the present invention is not limited to the above embodiment, and its application range, upper load support. It goes without saying that various changes can be made to the specific structure and type of the column and the means for changing the upper load without departing from the spirit of the present invention.
[0033]
【The invention's effect】
In the seismic isolation method for an existing building according to the present invention, when installing the seismic isolation device by cutting an existing column, the upper load supporting column that temporarily receives the upper load is used as the shear reinforcement of the existing column's additional concrete. The concrete is reinforced with reinforcing bars and the upper load supporting struts are embedded in the increased-strength concrete except for the part where the seismic isolation device is installed. The upper load support strut eliminates the need for buckling and has the following effects.
(1) The upper load support strut is small and thin with a shaft diameter or a steel plate thickness, making it possible to reduce the weight, and can be easily handled by hand and assembly.
(2) The upper load supporting column has a simple structure and can reduce the manufacturing cost.
(3) It can be easily constructed even in the case of a column connected to a wall such as a rectangular column or an outer wall.
(4) It is possible to improve the construction efficiency by eliminating the joint welding of the steel plate.
(5) The amount of excised part after attaching the seismic isolation device is small, which reduces the cost.
(6) Fireproof coating is a seismic isolation device only, which reduces construction costs.
[Brief description of the drawings]
[Fig. 1] Preparatory process diagram for seismic isolation method for existing building according to the present invention [Fig. 2] Arrangement of upper load support column for seismic isolation method for existing building according to the present invention [Fig. Fig. 4 Process diagram for removing part of existing pillars to install seismic isolation equipment. Fig. 5 Base construction diagram for seismic isolation equipment. Fig. 7 Fig. 8 (A)-(A) Fig. 7 (A)-(A) FIG. 9 is a diagram illustrating an embodiment in which the present invention is applied to a prism. FIG. 10 is a diagram illustrating an embodiment in which the present invention is applied to a column connected to a wall. Installation diagram of column-wrapped reinforcing steel plate in seismic structuring method [Fig. 12] Steel plate cut-out drawing for installing seismic isolation equipment [Figure 13] Mortar injection diagram in conventional seismic isolation construction method [Figure 14] Installation completion drawing of seismic isolation equipment in conventional seismic isolation construction method ]
1 existing pillars, 2, 3 cores removed, 4 slabs, 5 flat jacks,
6 Upper load support struts, 8 beams, 12 hoops,
13% hoop, 22 formwork, 16 anchor for the upper frame,
17 Lower base plate, 18, 18 'Reinforced concrete,
20 mounts, 21 bar arrangements, 22 formwork, 23 concrete mounts,
24 upper base plate, 25 seismic isolation device, 26 upper frame,
27 Reinforcement, 28 Non-shrink mortar,
30 Columns at the corners, 31, 41 Seismic isolation devices,
32, 42 Upper load support column, 33, 43 Beam,
34, 44 Reinforced concrete, 40 Columns connected to the wall,
51 Existing pillars, 52, 53 Anchor dowels, 54 Stud dowels,
56 Column-wound reinforcing steel plate, 58 Seismic isolation device, 60 Existing pillar with seismic isolation device,

Claims (1)

The upper load support column excluding the stage where the upper load support column is disposed between the slab and the beam attached to the existing column while maintaining a predetermined distance from the outer peripheral surface of the existing column, and the cutting position where the seismic isolation device is installed on the existing column A step of placing the beating concrete around at least the upper part, a step of cutting the existing column corresponding to the mounting position of the seismic isolation device, and inserting the seismic isolation device at the cutting point of the existing column, Seismic isolation of existing buildings consisting of the stage of fixing the equipment to the existing pillars that have been cut and the stage of cutting the exposed parts of the upper load supporting struts from the reinforced concrete and transferring the upper load to the seismic isolation equipment Chemical method.

Images