JP2008127791A - Seismic-control repair method for existing truss steel-frame building - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a construction cost and a construction period, which are required for seismic-control repair work. <P>SOLUTION: In this seismic-control repair method for an existing truss steel-frame building 10 which comprises a column 11a, a beam 11b, a horizontal brace and a vertical brace 12, a seismic-control brace 14, which is plastically deformed before the start of the buckling deformation of the vertical brace 12, is mounted in a plane 13 of structure, which is enclosed by the column 11a and the beam 11b and where the vertical brace 12 is not arranged. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a seismic retrofit method for an existing truss steel building such as a boiler support structure.

As a seismic retrofitting method for an existing truss steel building, a method is adopted in which an existing brace is removed from the construction surface and, for example, a history damper disclosed in Patent Document 1 is installed instead of the removed brace.
JP 2006-176996 A

However, in this conventional method, it is necessary to remove the existing braces and separately install a frame for installing the hysteresis damper, which increases the construction cost and construction period required for the seismic retrofitting work. .
In addition, after installing a separate frame for installing the hysteresis damper, removing the existing brace, installing the hysteresis damper, and removing the separately installed frame will add a dead load to the hysteresis damper. Cannot be easily performed, and there is a problem that the construction cost required for the seismic retrofitting work increases.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a seismic retrofitting method for an existing truss steel building that can reduce the construction cost and construction period required for the seismic retrofitting work.

The present invention employs the following means in order to solve the above problems.
A seismic retrofit method for an existing truss steel building according to the present invention is a seismic retrofit method for an existing truss steel building provided with a column, a beam, a horizontal brace, and a vertical brace. A seismic brace that is plastically deformed before the vertical brace starts buckling deformation is attached to a frame that is enclosed and not disposed with the vertical brace.

  A seismic retrofit method for an existing truss steel building according to the present invention is a seismic retrofit method for an existing truss steel building provided with a column, a beam, a horizontal brace, and a vertical brace. A seismic control brace that is plastically deformed before the vertical brace starts buckling deformation is attached to a frame that is enclosed and in which the vertical brace is disposed.

According to the seismic retrofitting method for the existing truss steel building according to the present invention, the existing vertical braces are left as they are, and the existing vertical braces are installed in the structure where the existing vertical braces are not installed. It is only necessary to install a new seismic control brace in the plane (that is, there is no need to remove the existing vertical brace from the construction surface as in the conventional method, and there is no need to separately provide a frame for removing the existing vertical brace). Therefore, the construction cost and construction period required for the seismic retrofitting work can be reduced.
In addition, since a dead load is not applied to a seismic brace that is newly installed in a construction surface where an existing vertical brace is not installed or in a construction surface where an existing vertical brace is installed, the seismic bracing is designed easily. It is possible to reduce the construction cost required for seismic retrofitting work.

  On the other hand, in the existing truss steel building that has been subjected to the seismic retrofitting method for the existing truss steel building according to the present invention, for example, when an earthquake load is applied, the existing vertical brace is subjected to vibration control before buckling deformation. The brace is plastically deformed, and the energy is absorbed by the seismic control brace, and the seismic resistance is improved (see FIG. 13).

In the seismic retrofit method for the existing truss steel building, it is more preferable to improve the vertical brace to a second seismic brace that absorbs energy without buckling against compressive force.
According to the seismic retrofitting method for an existing truss steel building, there is no need to remove the existing vertical braces from the construction surface, and there is no need to provide a separate frame for removing the existing vertical braces. Construction cost and construction period required for construction can be reduced.
In addition, since a dead load is not applied to a seismic brace that is newly installed in a construction surface where an existing vertical brace is not installed or in a construction surface where an existing vertical brace is installed, the seismic bracing is designed easily. It is possible to reduce the construction cost required for seismic retrofitting work.

  On the other hand, in an existing truss steel building that has been subjected to the seismic retrofitting method for such an existing truss steel building, for example, when an earthquake load is applied, the damping brace and the second seismic bracing are plastically deformed, The energy is absorbed by these seismic control braces and the second seismic control brace, and the seismic resistance is further improved (see FIG. 20).

  According to the present invention, there is an effect that it is possible to reduce the construction cost and the construction period required for the damping control work.

Hereinafter, a first embodiment of a seismic retrofit method for an existing truss steel building according to the present invention will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of a truss steel building to which the seismic retrofitting method for an existing truss steel building according to the present embodiment is applied.
A truss steel building (for example, a boiler support structure) 10 is configured with a support steel frame 11 and a brace (oblique material) 12 as main elements.
In addition, the code | symbol B in FIG. 1 has shown the boiler main body, and this boiler main body B is supported via several suspension members (not shown) in order not to restrain the thermal expansion during a driving | operation. It is suspended from the top of the steel frame 11. Moreover, the code | symbol G in FIG. 1 has shown the ground.

The support steel frame 11 includes a column 11a extending in the vertical direction, a beam 11b extending in the horizontal direction, and a horizontal brace (not shown) that joins nodes of the columns 11a and 11b.
The brace 12 serves as a vertical brace that connects the column 11a and the beam 11b.

Next, the seismic retrofitting method for the existing truss steel building constructed as described above will be described.
First, the existing brace 12 is not installed, and the optimum (necessary) construction surface (opening surrounded by the columns 11a, 11a and the beams 11b, 11b) 13 is provided to improve the damping performance. Inside, preparation for newly installing the vibration control brace 14 (for example, attachment of the joining member 15 (refer FIG. 2) etc.) is performed.

Subsequently, a vibration control brace 14 prepared in advance is attached to a predetermined construction surface 13.
The damping brace 14 has a plastic deformation performance equivalent to a tensile force with respect to a compressive force, and for example, a damping brace 20 as shown in FIG. 2 can be adopted.
FIG. 2 is a diagram illustrating the overall configuration of the vibration control brace 20.

  As shown in FIG. 2, the damping brace 20 includes an intermediate member 21 disposed at an intermediate portion thereof, one end connected to the intermediate member 21 (a circular steel pipe in the drawing), and the other end connected to an end joint plate. The end joint plate 22 is attached to the joining member 15 by a bolt joint 24. The hysteretic damper member 23 is fixed to the pair.

  Below, the effect | action which concerns on the damping brace 20 is demonstrated. For example, when a seismic load is applied, the seismic brace 20 receives an alternating axial force of tension and compression, and this axial force is a core material 23a of the hysteretic damper 23 from the joining member 15 at both ends of the diagonal member via the end joint plate 22. It is transmitted to the intermediate material 21 through. When the tensile axial force reaches the yield axial force (+ Ny) of the core material 23a, plastic axial deformation (+ δ) occurs, and when the compression axial force reaches the yield axial force (−Ny) of the core material 23a, plastic deformation (− δ) occurs. At this time, the core member 23a that has received the compression axial force tends to buckle and deform, but the deformation is constrained by the circumscribed stiffening steel pipe 23b to prevent buckling. Thus, the entire seismic control brace 20 responds by drawing a hysteresis curve. As a result, the seismic energy is absorbed and the vibration is attenuated.

Further, as the vibration control brace 14, for example, a vibration control brace 30 as shown in FIGS. 3 and 4 can be adopted.
3A and 3B are diagrams showing the overall configuration of the vibration control brace 30, wherein FIG. 3A is a diagram showing a state before plastic deformation, FIG. 3B is a diagram showing a state after plastic deformation, and FIG. It is a partial longitudinal cross-sectional view, wherein (a) is a cross-sectional view taken along the line aa in FIG. 3 (a), and (b) is a cross-sectional view taken along the line bb in FIG. 3 (b).

As shown in FIGS. 3 and 4, the vibration control brace 30 is mainly composed of a single core member 31 and a pair of stiffening members 32 and 32 disposed on the front surface 31 a and the back surface 31 b of the core member 31. It is configured as.
The core material 31 is, for example, a plate-like member having a rectangular shape in plan view formed of ultra-soft steel, and the yield stress level is small compared to the columns 11a and the beams 11b formed of ordinary steel frames. ing. The core 31 has one end 31c provided at the approximate center of the upper edge of the opening 13 and fixed to the lower surface of the upper beam 11b with respect to the other gusset plate (not shown). The end portion 31d is connected to a gusset plate (not shown) disposed at the lower corner of the opening 13 and fixed to the column 11a and the lower beam 11b by a high-strength bolt or the like.
Also, plastic portions (yield portions) 31f and 31g are provided in the vicinity of the end portions 31c and 31d of the core material 31 (that is, between the center portion 31e of the core material 31 and the end portions 31c and 31d), respectively. . Both long sides of the plastic parts 31f and 31g are smaller in width dimension (length in the vertical direction in the figure) than the end parts 31c and 31d of the core material 31 and the central part 31e of the core material 31. It is cut out.

The stiffening member 32 includes a thick portion 31a provided corresponding to the central portion 31e of the core member 31, and a thin portion provided corresponding to the plastic portions 31f and 31g and the end portions 31c and 31d of the core member 31. And a pair of plate-like members having a rectangular shape in plan view.
Each of the thick part 32a and the thin part 32b has a predetermined thickness in the width direction (vertical direction in the drawing) and the longitudinal direction, and between the opposing thin part 32b and thin part 32b, Spaces S for accommodating the plastic portions 31f and 31g (which are overexpressed in the figure but are actually about 1 to 2 mm) are formed.

  As shown in FIG. 4A, which is a sectional view taken along the line aa in FIG. 3A, and FIG. 4B, which is a sectional view taken along the line bb in FIG. Is sandwiched between the stiffening member 32 and the stiffening member 32 so that the front surface 31a and the back surface 31b of the central portion 31e are in contact with the inner surface of the thick portion 32a (so as to be in surface contact). In addition, the core member 31 and the stiffening members 32, 32 are fixed to each other (integrated).

For example, when a compressive force (axial force) as shown by a white arrow in FIG. 3A is applied to the seismic control brace 30 configured in this manner due to the occurrence of an earthquake or the like, the plastic portion 31f of the core 31 is formed. , 31g are displaced according to the compression force (axial force) at that time. That is, the plastic parts 31f and 31g of the core material 31 having a lower yield stress than the columns 11a and beams 11b constituting the truss steel building 10 yield before the truss steel building 10 and cause plastic deformation. The vibration energy of the truss steel building 10 is absorbed, and the vibration response of the truss steel building 10 is attenuated. In this case, the central portion 31e of the core member 31 is integrated so as to be evenly pressed by the stiffening member 32 from both the front surface 31a and the back surface 31b, the cross-sectional area is increased, and the plastic portion 31f is increased. The thickness in the width direction is made larger than 31 g, so that stable hysteresis characteristics of the damper can be exhibited without causing buckling in the central portion.
Further, as shown in FIG. 4B, the plastic portions 31f and 31g that have undergone plastic deformation as shown in FIG. 3B are bent and projecting toward the stiffening member 32 side. The tip of the portion is in contact with the inner surface of the thin portion 32b, so that the buckling deformation of the plastic portions 31f and 31g is suppressed.

Furthermore, as the vibration control brace 14, for example, a vibration control brace 40 as shown in FIG. 5 to FIG. 8 can be adopted.
5 is a front view showing the entire mounting state, FIG. 6 is an enlarged front view of the main part of FIG. 5, FIG. 7 is a sectional view taken along the line XI-XI in FIG. 6, and FIG. It is. In FIG. 7, the rotating device for the flanged nut in FIG.

The damping brace 40 is composed mainly of a V-type brace 41 and a braking force variable friction damper 42. The braking force variable friction damper 42 includes a lower end of the V-type brace 41, a beam 11b.
Further, the braking force variable friction damper 42 includes a friction damper main body 43, a driving device 44 for adjusting the braking force, a detector 45 for detecting a relative moving speed of the upper and lower mounting portion structure of the friction damper main body 43, and a detection. A controller 46 that drives the drive device 44 in accordance with the relative movement speed detected by the device 45 to adjust the friction damper main body 43 to an optimum friction braking force, and an uninterruptible power supply 47 are provided.

As shown in FIG. 6 and FIG. 7, the friction damper main body 43 is fixed in parallel to the beam 11b, one end thereof is integrally fixed to the substrate 47 at the lower end of the V-type brace 41, and multiple arrangements are made with a gap between the plate surfaces, In addition, a metal multiple slide plate 49 provided with an oblong through hole 48 in the displacement direction in the center, and a leg portion on the beam 11b with both ends passing through the gap and the outside of the multiple slide plate 49 and extending forward and backward. Friction with a metal multiple brake plate 50 fixedly supported by 50a and provided with a through hole 50a in the center, and a through hole 51 fixed to the multiple brake plate 50 surface so as to be able to contact both surfaces of the multiple slide plate 49 The plate 52, a pair of presser plates 54 with through holes 53 that are fixed to the outer center of the multiple brake plate 50, and the through holes 48, 50a, 51 of the press plate 54, the multiple brake plate 50, and the multiple slide plate 49. , 53 is fastened through a ball screw 55 The flanged nut 56 screwed onto the ball screw 55 from one of the presser plates 54 and held in the through hole, the flange presser washer 57, the flange 56a and the presser plate 54, and between the flange 56a and the flange presser washer 57. The thrust bearing 58 is interposed, and an elastic body such as a disc spring 58a and a washer 59, 60 are sandwiched between the flange presser washer 57 and a tightening nut 61 screwed to both ends of the ball screw 55. Therefore, the pressing plate 54, the ball screw 55, the flanged nut 56, the flange presser washer 57, the elastic body such as the thrust bearing 58, the disc spring 58a, the washers 59, 60, the tightening nut 61, etc. constitute braking force applying means. .
In FIG. 7, the number of the multiple slide plates 49 is omitted, and only two are shown. However, in the actual machine, the multiple slide plates 49 have a multiple structure of about ten.

  The driving device 44 for adjusting the braking force includes a T-arm 62 fixed to the outer peripheral surface of the flange 56 a of the flanged nut 56 and extending outward, and external teeth provided on the arc-shaped head surface of the T-arm 62. The gear 63 and a servo motor 66 having a drive pinion 65 disposed on the horizontal coupling member 64 near the lower end of the V-shaped brace 41 and meshing with the external gear 63 are configured.

As shown in FIG. 8, the control device 46 includes an input unit 67, a control unit 68, and an output unit 69. The control device 46 receives the signal of the relative movement speed detector 45 into the input unit 67 and detects it by the control unit 68. A control amount of the servo motor corresponding to the relative movement speed is obtained, the servo motor 66 is controlled through the output unit 69, the flanged nut 56 is moved in the axial direction of the ball screw 55, and multiplexed with the multiple brake plates 50 of the friction damper main body 43. The tightening strength (ie, braking force) of the slide plate 49 is automatically controlled to an optimum value.
The servo motor 66, the relative movement speed detector 45, and the control device 46 are operated using the uninterruptible power supply 47 as a power source.

In the vibration control brace 40 configured in this way, an elastic body such as a disc spring 58a is sandwiched between the multiple slide plate 49, the multiple brake plate 50, and the presser plate 54, and the ball screw 55 is tightened by the tightening nut 61. Thus, a fixed initial friction braking force is held and fixed to the multiple brake plate 50 and the multiple slide plate 49 of the friction damper main body 43.
This initial friction braking force is set to a level that can absorb the maximum to intermediate vibration energy expected to be generated in the structure.

  The nut 56 with the flange is pushed by the flange presser washer 57 together with the tightening by the tightening nut 61, and rotates on the ball screw 55 to move to the back. At the position where the tightening nut 61 is completely tightened, the T-arm 62 of the flanged nut 56 is rotated and aligned with the ball screw 55 at a predetermined position where it engages with the drive pinion 65 of the servo motor 66 and fixed.

  When vibration occurs in the truss steel building 10 due to an earthquake or the like, the relative movement speed between the layers of the truss steel building 10 is continuously detected by the detector 45 and taken into the control device 46, and the control device 46 is detected. The servomotor 66 is controlled and driven in accordance with the relative movement speed, and the nut 56 with flange is rotated via the drive pinion 65, the external gear 63, and the T-arm 62, so that the friction damper body 43 is initially set to the friction control. Increase or decrease the power to the optimum value.

  When the detected relative movement speed is equal to or less than the initial friction braking force, the initial friction braking force is weakened by slightly turning the flanged nut 56 in the direction to push the disc spring 58a forward, and the detected relative movement speed is reduced. However, if it is greater than the initial friction braking force, the initial friction braking force set by slightly turning the flanged nut 56 in the opposite direction is increased, and the friction braking force of the friction damper main body 43 is controlled to an optimum value.

  At this time, the relative movement speed between the layers generated by the vibration of the truss steel building 10 and the optimum friction braking force are in a proportional relationship, and the rotation adjustment amount of the flanged nut 56 corresponding to the optimum friction braking force and The adjustment drive amount of the servo motor 66 can also be calculated in advance and set in the control unit 68. For this reason, from the detection of the relative movement speed by the detector 45 to the optimum friction braking force adjustment of the friction damper main body 43 by the control device 46, it is possible to quickly and automatically follow in a very short time.

Thereby, the vibration energy of the whole fluctuation range of the vibration which generate | occur | produces in the truss steel frame building 10 is always effectively absorbed with the optimal braking force, and the effect which suppresses a vibration is acquired.
In addition, such a braking force variable friction damper 42 has a mechanical friction braking force that is initially set, even when the uninterruptible power supply 47 is damaged and the control device 46 system does not operate. There is an advantage that the damping function can be maintained within the range of the friction braking force.
Needless to say, there is no problem even if the friction damper is designed as a vibration control damper adjusted as a constant braking force (friction force) without special control.

According to the seismic retrofit method for the existing truss steel building according to the present embodiment, the existing brace 12 is left as it is, and the seismic brace 14 is newly installed in the construction surface 13 where the existing brace 12 is not installed. (That is, it is not necessary to remove the existing brace 12 from the construction surface 13 as in the conventional construction method, and it is not necessary to provide a separate frame for removing the existing brace 12). Construction cost and construction period can be reduced.
Further, since no dead load is applied to the seismic control brace 14 newly installed in the construction surface 13 where the existing brace 12 is not installed, the seismic control brace 14 can be easily designed and required for the seismic retrofitting work. Construction cost can be reduced.

On the other hand, in the existing truss steel building 10 to which the seismic retrofitting method for the existing truss steel building according to this embodiment is applied, for example, when an earthquake load is applied, the existing brace 12 is controlled before buckling. The seismic brace 14 is plastically deformed, and its energy is absorbed by the seismic control brace 14, and the seismic resistance is improved (see FIG. 9).
In FIG. 9, the broken line indicates a history curve before the seismic retrofit method for the existing truss steel building according to the present embodiment is applied, and the solid line indicates the seismic retrofit of the existing truss steel building according to the present embodiment. The hysteresis curve after a construction method is given is shown.

A second embodiment of the seismic retrofit method for an existing truss steel building according to the present invention will be described with reference to FIG. FIG. 10 is a schematic configuration diagram of a truss steel building to which the seismic retrofitting method for an existing truss steel building according to the present embodiment is applied.
In the seismic retrofit method for an existing truss steel building according to the present embodiment, the existing brace 12 is installed before or after the seismic brace 14 is newly installed in the construction surface 13 where the existing brace 12 is not installed. The second embodiment is different from that of the first embodiment in that the second seismic brace 70 is capable of absorbing energy without buckling against compressive force. Since other components are the same as those of the first embodiment described above, description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment mentioned above.

Next, a repair method for improving the existing brace 12 to the second seismic brace 70 will be described with reference to FIGS.
11 (a) and 11 (b) are diagrams showing the overall configuration when the existing brace 12 is attached to the in-plane weak shaft, and FIGS. 12 (a) and 12 (b) show the existing brace 12 as a surface. FIG. 13 is an overall configuration diagram when attached to the inner strong shaft, and FIG. 13 shows the local buckling prevention stiffener omitted in FIGS. 11 (a), 11 (b) and 12 (a), 12 (b). FIG. 14 (a) is a cross-sectional view taken along the line cc of FIG. 13, FIG. 14 (b) is a cross-sectional view taken along the line dd of FIG. 13, and FIG. FIG. 15B is a detailed view of the reduced cross-sectional area of the seismic brace, and FIG. 15B is a cross-sectional view taken along the line ee in FIG.

  First, as shown in FIGS. 11 (a) and 12 (a), both ends of the existing brace 12 (or the central part of the existing brace 12 as shown in FIGS. 11 (b) and 12 (b), or Part of the upper and lower flange portions (end portions of the upper and lower arm portions of the H-shaped steel) at one end portion of the existing brace 12 is cut to form a cross-sectional area reducing portion 71 as shown in FIGS. 13 and 15. The reduced cross-sectional area is designed so that the yield axial force Nd = σy (A−ΔA) of the reduced section is smaller than the overall buckling axial force Ncr of the existing brace 12. Here, A is the cross-sectional area of the existing brace 12, and ΔA is the cross-sectional area for cutting.

Next, for example, as shown in FIG. 15 (b), a local buckling prevention stiffener 72 including a plurality of I-shaped and L-shaped stiffener plates 72 a and 72 b is connected to the flange portion of the cross-sectional area reducing portion 71. It is installed along both sides and both sides of the web, and each end thereof is joined to a general part (a part where the cross-sectional area reduction part is not provided or the remaining part) 73 via a bolt 74, or FIG. The local buckling prevention stiffener 75 including a plurality of I-shaped and U-shaped stiffening plates 72a and 72c as shown in FIG. It installs and each end part is couple | bonded with the general part through the volt | bolt 74. As shown in FIG.
In addition, as for the bolt coupling | bond part of the local buckling prevention stiffeners 72 and 75 and the general part 73, the one edge part side (left side in FIG. 15) of the local buckling prevention stiffeners 72 and 75 is existing. The brace 12 is coupled to the brace 12 through a long bolt hole 74a so that the existing brace 12 is allowed to be displaced and the axial force is not transmitted to the local buckling prevention stiffeners 72 and 75. More preferably,

Further, as shown in FIG. 16, it is more preferable that a flange 76 is provided in the general portion 73 located at each end portion of the second vibration control brace 70. That is, the second seismic brace 70 (part to be made damper (plasticized)) is separately manufactured in a factory, a necessary portion of the existing brace 12 is cut out, a flange 77 is attached to the part, and then the factory It is also possible to attach the second seismic bracing 70 separately manufactured by the above method to the flange 77 of the existing brace 12 via a fastening member (bolt, nut, etc.) 78.
Note that the method for joining the second seismic brace 70 and the existing brace 12 is not limited to joining using a flange as shown in FIG. 16, but joining using a normal splice plate, or The joining using welding may be sufficient.

Next, when the existing brace 12 is a round steel pipe (or a square steel pipe), a repair method for improving the existing brace 12 to the second vibration control brace 90 will be described with reference to FIGS. 17 and 18. .
FIG. 17 is an overall configuration diagram in the case where the existing brace 12 is mounted in the structural surface 13, FIG. 18A is a detailed view of a cross-sectional area reduction part of the second seismic control brace, and FIG. 18A is a cross-sectional view taken along the line ff in FIG. 18A, and FIG. 18C is a cross-sectional view taken along the line gg in FIG.

  First, as shown in FIG. 17, the central part of the existing brace 12 (or both end parts of the existing brace 12 or one end part of the existing brace 12) is partially cut so as to penetrate in the plate thickness direction. A cross-sectional area reduction portion 91 as shown in FIG. 17 is formed. The reduced cross-sectional area is designed so that the yield axial force Nd = σy (A−ΔA) of the reduced section is smaller than the overall buckling axial force Ncr of the existing brace 12. Here, A is the cross-sectional area of the existing brace 12, and ΔA is the cross-sectional area for cutting.

  Next, for example, a stiffening steel pipe (local buckling prevention stiffener) 92 composed of two half-cracked steel pipes 92a and 92b as shown in FIGS. 18 (a) to 18 (c), After installing the steel pipes 92a and 92b by welding (or bolt / nut joining) so as to surround (cover) the periphery of the cross-sectional area reducing part 91, one end of the steel pipe 92a, 92b is provided as a general part (the cross-sectional area reducing part is provided). It is connected to a stiffening steel pipe fixing bolt 94 to a portion (the remaining portion or the remaining portion) 93.

Further, as shown in FIG. 19A, it is more preferable that flanges 76 are provided in the general portions 93 located at the respective end portions of the second vibration control brace 90. That is, the second seismic brace 90 (part to be made damper (plasticized)) is manufactured separately at a factory, a necessary portion of the existing brace 12 is cut out, a flange 77 is attached to the part, The second seismic brace 90 separately manufactured by the above method may be attached between the flanges 77 of the existing brace 12 via fastening members (bolts, nuts, etc.) 78.
In addition, about the joining method of the 2nd damping brace 90 and the existing brace 12, it is not limited to joining using a flange as shown to Fig.19 (a), The normal splice plate was used. Joining or joining using welding may be used.
Further, as shown in FIGS. 19 (a) to 19 (d), if an inner stiffening steel pipe (local buckling prevention stiffener) 95 is provided inside the cross-sectional area reduction portion 91, it is further possible. Is preferred.

According to the seismic retrofitting method of the existing truss steel building according to the present embodiment, it is not necessary to remove the existing brace 12 from the construction surface 13, and it is not necessary to separately provide a frame for removing the existing brace 12. Construction cost and construction period required for seismic retrofitting work can be reduced.
Further, since no dead load is applied to the seismic control brace 14 newly installed in the construction surface 13 where the existing brace 12 is not installed, the seismic control brace 14 can be easily designed and required for the seismic retrofitting work. Construction cost can be reduced.

On the other hand, in the existing truss steel building 10 to which the seismic retrofitting method for the existing truss steel building according to the present embodiment is applied, for example, when an earthquake load is applied, the seismic bracing 14 and the second seismic bracing 70, 90 is plastically deformed, and the energy is absorbed by the vibration control brace 14 and the second vibration control braces 70 and 90, and the vibration resistance is further improved (see FIG. 20).
In FIG. 20, the alternate long and short dash line indicates a history curve after the seismic retrofit method for the existing truss steel building according to the first embodiment described above, and the solid line indicates the existing truss steel frame according to the present embodiment. The history curve after the building seismic retrofitting method is shown.

A third embodiment of the seismic retrofit method for an existing truss steel building according to the present invention will be described with reference to FIG. FIG. 21 is a schematic configuration diagram of a truss steel building to which the seismic retrofit method for the existing truss steel building according to the present embodiment is applied.
The seismic retrofitting method for an existing truss steel building according to the present embodiment is different from that of the above-described embodiment in that a frame 80 for newly installing the seismic brace 14 is added. Since other components are the same as those in the above-described embodiment, description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as embodiment mentioned above.

In this embodiment, a column 81a that extends vertically along the column 11a, a beam 81b that extends horizontally along the beam 11b, a column 11a and the column 81a, and a frame 82 that connects the beam 11b and the beam 81b. And the vibration control brace 14 is installed in the opening surrounded by the columns 81a and 81a and the beams 81b and 81b, that is, in the composition plane 83.
The seismic retrofit method for the existing truss steel building according to the present embodiment is particularly effective because the boiler pipes and the like are arranged in the construction surface 13 where the existing braces 12 are not installed. This is suitable when the brace 14 cannot be installed.

  According to the seismic retrofit method for the existing truss steel building according to the present embodiment, no dead load is applied to the seismic brace 14 newly installed in the structural surface 83, so that the seismic brace 14 can be easily designed. This can reduce the construction cost required for seismic retrofitting work.

  On the other hand, in the existing truss steel building 10 to which the seismic retrofitting method for the existing truss steel building according to this embodiment is applied, for example, when an earthquake load is applied, the existing brace 12 is controlled before buckling. The seismic brace 14 is plastically deformed and its energy is absorbed by the seismic control brace 14, or the seismic brace 14 and the second seismic brace 70, 90 are plastically deformed, and the seismic brace 14 and The energy is absorbed by the second seismic braces 70 and 90, and the seismic resistance is further improved.

A fourth embodiment of the seismic retrofit method for an existing truss steel building according to the present invention will be described with reference to FIG. FIG. 22 is a schematic configuration diagram of a truss steel building to which the seismic retrofitting method for an existing truss steel building according to the present embodiment is applied.
In the seismic retrofit method for an existing truss steel building according to the present embodiment, the seismic brace 14 is newly installed in the structural surface 13 where the existing brace 12 is installed, and the embodiment described above. Different. Since other components are the same as those in the above-described embodiment, description of these components is omitted here.
In addition, the same code | symbol is attached | subjected to the member same as embodiment mentioned above.

In the present embodiment, the damping brace 14 is shifted from the axial center of the existing brace 12 within the surface 13 where the existing brace 12 is installed and above the existing brace 12. Install it so that it will come off.
The seismic retrofit method for the existing truss steel building according to the present embodiment is particularly effective because the boiler pipes and the like are arranged in the construction surface 13 where the existing braces 12 are not installed. This is suitable when the brace 14 cannot be installed.

According to the seismic retrofit method for the existing truss steel building according to the present embodiment, the seismic brace 14 is newly installed in the structural surface 13 where the existing brace 12 is installed, with the existing brace 12 remaining as it is. (That is, it is not necessary to remove the existing brace 12 from the construction surface 13 as in the conventional construction method, and it is not necessary to provide a separate frame for removing the existing brace 12). Construction cost and construction period can be reduced.
In addition, since no dead load is applied to the seismic control brace 14 newly installed in the construction surface 13 where the existing brace 12 is installed, the seismic control brace 14 can be easily designed and required for seismic retrofitting work. Construction cost can be reduced.
Further, the length of the vibration control brace 14 is shortened, and the axial rigidity of the vibration control brace 14 is easily increased. If the shaft rigidity is high, minute yield deformation can be easily realized with the same yield load.

  On the other hand, in the existing truss steel building 10 to which the seismic retrofitting method for the existing truss steel building according to this embodiment is applied, for example, when an earthquake load is applied, the existing brace 12 is controlled before buckling. The seismic brace 14 is plastically deformed and its energy is absorbed by the seismic control brace 14, or the seismic brace 14 and the second seismic brace 70, 90 are plastically deformed, and the seismic brace 14 and The energy is absorbed by the second vibration control brace 70, and the earthquake resistance is further improved.

It is a figure for demonstrating 1st Embodiment of the damping control method of the existing truss steel building which concerns on this invention, Comprising: The truss steel building of which the damping control method of the existing truss steel building which concerns on this embodiment was applied It is a schematic block diagram. It is a figure which shows the whole structure of one seismic brace. It is a figure which shows the whole structure of another seismic control brace, Comprising: (a) is a figure which shows the state before plastic deformation, (b) is a figure which shows the state after plastic deformation. 3A and 3B are longitudinal cross-sectional views of the main part of FIG. 3, where FIG. 3A is a cross-sectional view taken along the line aa in FIG. 3A, and FIG. 3B is a cross-sectional view taken along the line bb in FIG. It is a front view which shows the attachment state of another seismic control brace. It is an enlarged front view of the principal part of FIG. It is XI-XI arrow sectional drawing of FIG. It is a block diagram of a schematic structure of a control device. It is a figure which shows the energy absorption characteristic of a damping brace. It is a figure for demonstrating 2nd Embodiment of the seismic retrofitting method of the existing truss steel building which concerns on this invention, Comprising: The truss steel building of which the seismic retrofitting method of the existing truss steel building which concerns on this embodiment was applied It is a schematic block diagram. (A) And (b) is a whole block diagram in case the existing brace is attached to the in-plane weak shaft. (A) And (b) is a whole block diagram in case the existing brace is attached to the in-plane strong shaft. FIG. 13 is a detailed view of a portion B in FIGS. 11 and 12 in which a local buckling prevention stiffener is omitted. (A) is cc arrow sectional drawing of FIG. 13, (b) is dd arrow sectional drawing of FIG. (A) is detail drawing of the cross-sectional area reduction | decrease part of a 2nd damping brace, (b) is ee arrow sectional drawing in (a). It is detail drawing of the cross-sectional-area reduction | decrease part of the 2nd damping brace which concerns on other embodiment. It is a whole block diagram in case the existing brace is attached in the composition surface. (A) is a detailed view of the cross-sectional area reduction part of the second seismic control brace according to another embodiment, (b) is a cross-sectional view taken along line ff in (a), and (c) is g in (a). It is -g arrow sectional drawing. (A) is a detailed view of the cross-sectional area reduction part of the second seismic brace according to another embodiment, (b) is a cross-sectional view taken along the line hh in (a), and (c) is in (a). ii arrow sectional drawing, (d) is the j arrow sectional drawing in (a). It is a figure which shows the energy absorption characteristic of a damping brace. It is a figure for demonstrating 3rd Embodiment of the seismic retrofitting method of the existing truss steel building which concerns on this invention, Comprising: The truss steel building of which the seismic retrofitting method of the existing truss steel building which concerns on this embodiment was applied It is a schematic block diagram. It is a figure for demonstrating 4th Embodiment of the seismic retrofitting construction method of the existing truss steel building which concerns on this invention, Comprising: The truss steel building of which the seismic retrofitting construction method of the existing truss steel building which concerns on this embodiment was applied It is a schematic block diagram.

Explanation of symbols

10 Truss Steel Building 11a Column 11b Beam 12 Vertical Brace 13 Surface 14 Damping Brace 70 Second Damping Brace 90 Second Damping Brace

Claims (3)

A seismic retrofitting method for an existing truss steel building with columns, beams, horizontal braces, and vertical braces,
A seismic brace that is plastically deformed before the vertical brace starts buckling deformation is attached to a surface that is surrounded by the column and the beam and in which the vertical brace is not disposed. Seismic retrofit method for existing truss steel building. A seismic retrofitting method for an existing truss steel building with columns, beams, horizontal braces, and vertical braces,
A seismic brace that is plastically deformed before the vertical brace starts buckling deformation is attached to a surface that is surrounded by the column and the beam and in which the vertical brace is disposed. Seismic retrofit method for existing truss steel building.   3. The seismic retrofit method for an existing truss steel building according to claim 1 or 2, wherein the vertical brace is improved to a second seismic brace that absorbs energy without buckling against compressive force.

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